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Temiz üretim uygulamalarında mevcut en iyi tekniklerin belirlenmesi için yeni çok kriterli karar verme metodu geliştirilmesi
Bu tez çalışmasında, sanayi sektörlerinde temiz üretim uygulamalarının geliştirilmesine katkı sağlamak amacıyla, "mevcut en iyi tekniklerin (MET/BAT)" önceliklendirilmesini sağlayacak çok kriterli karar verme metodu geliştirilmiştir. Geliştirilen modelin uygulamaya aktarılabilmesi için ise "Temiz Karar Yazılımı" isimli web tabanlı bir yazılım tasarlanmıştır. Çalışma, özellikle tekstil sektörü odağında gerçekleştirilmiştir. Gerçek saha verilerine dayalı olarak MET önceliklendirme süreci Temiz Karar Yazılımı ile sistematik biçimde değerlendirilmiştir. Araştırmada ilk olarak temiz üretim yaklaşımına ilişkin temel ilkeler, çevresel politika çerçeveleri ve MET kavramı detaylı biçimde ele alınmıştır. Bu kapsamda, literatür ve uzman görüşleri doğrultusunda MET seçiminde kullanılabilecek 52 adet değerlendirme kriteri belirlenmiştir. Ardından, bu kriter setiyle uyumlu olacak şekilde literatürde yaygın kullanılan 29 çok ölçütlü karar verme (ÇÖKV) yöntemleri incelenmiş ve uygunluk kriterlerine göre 22 yöntem değerlendirme kapsamına alınmıştır. Söz konusu 22 yöntemin 52 değerlendirme kriterleri ile uygulanması sonucunda değerlendirme süresi ve bilgi karmaşası gibi önemli zorluklar gözlemlenmiştir. Kriter sayısının fazla olması; doğru ve tutarlı bir şekilde puanlama yapılmasını zorlaştırmış, ayrıca yöntemin uygulanma performansını da etkilemiştir. Bu sebeple, uygulama sonuçları dikkate alınarak kapsam daraltılmış, önem derecesi yüksek, ölçülebilir ve karşılaştırılabilir 10 adet değerlendirme kriterleri belirlenmiştir. Değerlendirme kriterlerinin tanımları yapılmış, skor seviyeleri belirlenmiş ve nihai hale getirilmiştir. Bu noktadan sonra, elde edilen veriler doğrultusunda temiz üretime özgü çok kriterli bir karar modeli geliştirilmiştir. Geliştirilen model beş adımdan oluşmaktadır: (i) MET'lerin 1–5 ölçekle karar matrisine puanlanması, (ii) kriterlerin "Tam Tutarlılık Yöntemi (FUCOM)" ile ağırlıklandırılması, (iii) 29 yöntem arasından seçilen "İdeal Çözüme Benzerlik Yoluyla Tercih Sıralama Tekniği (TOPSIS)", "Çok Ölçütlü Optimizasyon ve Uzlaşık Çözüm Tekniği (VIKOR)", "Birleştirilebilir Uzaklık Esaslı Değerlendirme Yöntemi (CODAS)" ve "Uzlaşma Çözümüne Göre Alternatiflerin Ölçülmesi ve Sıralaması (MARCOS)" yöntemleri ile alternatiflerin sıralanması, (iv) bu sıralamaların Copeland yöntemi ile bütünleştirilmesi ve (v) modelin güvenilirliğini test etmek amacıyla duyarlılık analizinin yapılmasıdır. Bu yapı sayesinde hem sıralama çeşitliliği hem de karar sağlamlığı güvence altına alınmış, MET önceliklendirmesi nesnel temele dayanmıştır. Modelin doğruluğunu ve yazılımın işlevselliğini test etmek amacıyla bir entegre tekstil işletmesinde saha çalışması gerçekleştirilmiştir. Bu kapsamda, üretim ve yardımcı proseslere ilişkin proses akım şemaları hazırlanmış, üç yıla ait enerji, su, kimyasal madde, yakıt ve hammadde tüketim verileri ile atık su, atık gaz ve katı atık oluşumuna dair veriler toplanmıştır. Bu verilerden yararlanılarak spesifik (birim ürün başına) değerler hesaplanmış, "Entegre Kirlilik Önleme ve Kontrolü (IPPC-EKÖK-96/61/EC) MET referans (BREF)" dokümanları ve literatür verileriyle karşılaştırmalar yapılmış ve potansiyel azaltım oranları işletmede su tüketiminde %26, enerji tüketiminde %18, kimyasal kullanımında %21, katı atık oluşumunda %16, atık gaz emisyonlarında %14 ve gürültü düzeyinde %11 oranında azalma potansiyeli hesaplanmıştır. Temiz üretim etüt analiz çalışması neticesinde, tekstil sektörüne özgü genel önlemlere yönelik, hammadde yönetimi, su-atıksu yönetimi, enerji yönetimi, kimyasal yönetimi, atık gaz yönetimi, katı atık yönetimi ve gürültü yönetimine ilişkin MET kategorileri sekiz başlık altında toplam 321 adet MET belirlenmiştir. Geliştirilen karar modeli, kullanıcı dostu bir arayüze sahip olacak şekilde "Temiz Karar Yazılımı" adlı web tabanlı yazılım haline getirilmiştir. Yazılım, kullanıcıların değerlendirme kriterlerini ve MET alternatiflerini tanımlayabildiği, farklı yöntemlerle analiz yapabildiği, tablosal karşılaştırmalar sunan, dinamik bir karar destek sistemidir. Yazılım, karar vericilerin birden fazla yöntemi karşılaştırmalı biçimde kullanmasına, yöntem sonuçlarını analiz etmesine ve tesis koşullarına en uygun MET'leri nesnel biçimde seçmesine olanak tanımaktadır. Modelin geçerliliğini test etmek amacıyla, entegre bir tekstil işletmesinde detaylı saha çalışması yürütülmüştür. İşletme personeli tarafından ağırlıklandırılan MET'ler, Temiz Karar Yazılımı üzerinden puanlanarak TOPSIS, VIKOR, CODAS ve MARCOS yöntemleriyle önceliklendirilmiş ve Copeland yöntemi ile sıralamalar bütünleştirilerek nihai sıralama elde edilmiştir. Ayrıca, geliştirilen modelin karar sağlamlığını değerlendirmek amacıyla duyarlılık analizi gerçekleştirilmiş ve elde edilen sonuçların alternatif sıralamalar üzerindeki etkisi ortaya konulmuştur. Analizler sonucunda, maliyet etkin, kolay uygulanabilir ve bilgiye dayalı kontrol sağlayan MET'lerin birçok yöntemde öncelikli çıktığı görülmüştür. Özellikle "kütle dengelerine dayalı yıllık atık ve emisyon envanter raporlarının hazırlanması", "makine bazlı su tüketimi ölçümü", "kimyasal dozajlama sistemlerinin kurulması" ve "enerji izleme sistemlerinin entegrasyonu" gibi MET'ler hemen her yöntemde üst sıralarda yer almıştır. Bu tez çalışması, literatürde bir ilk olarak, genellikle tek bir yöntem ve sınırlı sayıda kriterle yapılan MET önceliklendirme yaklaşımlarına karşılık; çok kriterli ve çok yöntemli yapıyı entegre eden, gerçek saha verisiyle test edilmiş ve kullanıcı dostu bir karar destek sistemi geliştirmiştir. Yazılım, karar süreçlerini şeffaflaştırmakta, farklı senaryoların analizine olanak tanımakta ve çevresel performans artışı ile kaynak verimliliği sağlamayı hedefleyen sanayi işletmeleri için etkili bir araç sunmaktadır. Sonuç olarak, Temiz Karar Yazılımı sadece akademik düzeyde değil, sanayide uygulanabilirliği yüksek, esnek ve sektörel ölçeklenebilirliği olan bir araç olarak değerlendirilmiştir. Gelecekte farklı sanayi sektörlerine özgü MET listeleriyle genişletilmesi, bulanık mantık veya yaşam döngüsü analizi gibi karar destek teknikleriyle entegre edilmesi ve uygulama sonrası izleme modülleriyle desteklenmesi önerilmektedir.
Seramik membran prosesi ile jeotermal sulardan bor giderimi
Son yıllarda temiz ve yenilenebilir enerji kaynaklarına olan ilginin artması, jeotermal kaynakların sürdürülebilir kullanımını önemli hale getirmiştir. Ayrıca, temiz ve sürdürülebilir su kaynaklarına yönelik artan talep, yüksek bor (B) içeriğine sahip jeotermal sular için etkili arıtma teknolojilerine olan ihtiyacı ortaya koymuştur. Jeotermal sular; elektrik üretimi, bölgesel ısıtma ve tarımsal uygulamalar gibi alanlarda alternatif bir kaynak olarak öne çıkmaktadır. Ancak bu suların yüksek B içeriği, uygun şekilde arıtılmadan deşarj edildiğinde çevresel ve tarımsal tehlikeler oluşturmaktadır. Aşırı bor; toprak yapısının bozulmasına, yeraltı suyu kirliliğine ve bitkilerde toksisiteye neden olarak tarımsal verimliliği olumsuz etkilemektedir. Tez çalışmasında, 1 kDa gözenek boyutuna sahip tübüler seramik ultrafiltrasyon (fine-UF) membranı kullanılarak, jeotermal sulardan B giderimi için yenilikçi ve maliyet etkin bir yöntem geliştirilmesi amaçlanmıştır. Çalışmanın temel hedefi, model ve gerçek jeotermal sulardan, poliol destekli (mannitol, sorbitol ve ksilitol) B giderimini değerlendirmek ve optimum işletme koşullarını belirlemektir. Seramik membranlar, yüksek sıcaklıklı jeotermal su uygulamalarında sağladıkları üstün kimyasal, termal ve mekanik dayanıklılık özellikleri sayesinde, polimerik membranlara kıyasla önemli avantajlar sunmaktadır. Ancak mevcut seramik membranların bor tutma kapasitesinin sınırlı olması, bu teknolojilerin yaygın kullanımını kısıtlamaktadır. Bu sınırlamayı aşmak amacıyla, bor ile kararlı kompleksler oluşturabilen poliol bileşiklerinin kullanıldığı hibrit bir yaklaşım önerilmektedir. Poliol bileşikleri, borik asit (H₃BO₃) ile kompleks oluşturarak moleküler boyutlarını artırmakta ve seramik membranlar tarafından daha etkin bir şekilde tutulmalarını sağlamaktadır. Tez çalışması 4 ana fazda gerçekleştirilmiştir. Faz I ve Faz II aşamalarında, model bor ve model jeotermal su örnekleri kullanılarak seramik membranların performansı değerlendirilmiş; Faz III ve Faz IV aşamalarında ise model ve gerçek jeotermal su örnekleriyle poliol destekli bor giderimi araştırılmıştır. Faz I ve Faz II kapsamında yürütülen filtrasyon deneyleri, farklı işletim basınçlarında (1, 2 ve 4 bar) ve pH seviyelerinde (doğal ve pH 9,5) gerçekleştirilmiştir. Elde edilen sonuçlar, seramik membranların tek başına bor giderim veriminin %0-11 (model jeotermal su) arasında kaldığını ve bu seviyelerin sulama suyu standartlarını karşılamadığını göstermiştir. Faz III ve Faz IV deneylerinde, laboratuvar ölçekli çapraz akışlı seramik membran testleri; membran basıncı (2 ve 4 bar), besleme suyu pH'ı (doğal ve 9,5) ve farklı bor konsantrasyonlarında (10 ve 20 ppm B-model jeotermal su) model ve gerçek jeotermal su örnekleri (18 ppm B) kullanılarak gerçekleştirilmiştir. Elde edilen veriler, bor giderim etkinliğinin çözeltinin pH'ına, uygulanan basınca ve kullanılan poliol türüne bağlı olarak önemli ölçüde değiştiğini göstermiştir. Genel olarak, sorbitol doğal pH koşullarında daha yüksek bor giderimi sağlarken, mannitol pH 9,5 koşullarında daha etkili sonuçlar vermiştir; ksilitol ise her iki koşulda orta düzeyde performans göstermiştir. Sorbitol ilaveli model jeotermal suda, en yüksek bor giderimi %41 ile 20 ppm B konsantrasyonunda, pH 9,5 ve 4 bar basınçta elde edilmiştir. Benzer şekilde, mannitol içeren model suda (10 ppm B, pH 9,5) %38 oranında giderim sağlanarak süzüntüdeki B konsantrasyonu ~6 ppm'e düşürülmüştür. Bu değer, toleranslı bitkiler (4.0-6.0 ppm B: yonca, mor çiçekli bitki, maydanoz, kırmızı pancar, şeker pancarı, domates) ve çok toleranslı bitkiler (6.0-10.0 ppm B: sorgum, pamuk, kereviz) için önerilen sulama suyu sınırları ile uyumludur. Gerçek jeotermal su için en yüksek bor giderim verimi %34 olarak sorbitol ile 4 bar ve pH 9,5'te kaydedilmiştir. Ancak, arıtılmış sudaki bor konsantrasyonları gerçek su örneklerinde ~12-14 ppm arasında kalarak tarımsal sulama standartlarını (≤10,5 mg/L) karşılamamıştır. Filtrasyon testlerinde süzüntü akısı, işletme basıncı ve pH'tan etkilenmiştir. En yüksek süzüntü akısı, mannitol içeren model jeotermal suda 4 bar basınç ve pH 7,5 koşullarında 38 LMH; sorbitol içeren gerçek jeotermal suda ise 4 bar basınç ve pH 7,4'te 29 LMH olarak ölçülmüştür. Bu çalışma, belirlenen koşullarda bor giderim kapasitesi çok düşük (%0-11) olan seramik UF membranlarının, poliol ilavesi ile bor tutma veriminin %41'e kadar artırılabileceğini kantitatif olarak ilk kez ortaya koymuştur. Böylece membranların yapısal avantajları korunurken, fonksiyonel seçicilik kazandırılmıştır. Bununla birlikte, arıtılmış gerçek jeotermal sudaki bor konsantrasyonu (~12 ppm), tarımsal sulama için öngörülen sınır değerlerin üzerinde kalmaktadır. Bu durum, önerilen yaklaşımın tek başına yeterli olmadığını; ancak ters osmoz gibi ileri arıtma teknolojilerinden önce, çok aşamalı arıtma sistemlerin de etkili bir ön arıtma seçeneği olabileceğini göstermektedir. Polioller, borat iyonlarıyla kararlı kompleksler oluşturarak bor giderimini artırmış, ancak membran tıkanmasına yol açmamıştır. SEM ve SEM-EDX analizleri, seramik membranların yapısal bütünlüğünü ve gözenek homojenliğini doğrulamıştır. Ekonomik değerlendirmede, özellikle ksilitol kullanımı işletme maliyetlerini artırmıştır. Ancak seramik membranların uzun ömürlü ve tıkanmaya karşı dirençli yapısı, uzun vadede jeotermal uygulamalarda avantaj sağlayabileceğini göstermektedir. Bu bulgular, bor giderimi için seramik membran ve poliol kullanımının potansiyelini ortaya koymakta; ancak sulama standartlarına ulaşmak için ek arıtma adımları gerekliliğini de göstermektedir. Gelecek çalışmalar, proses verimliliğini artırırken çevresel ve ekonomik sürdürülebilirliği hedeflemelidir.
Isparta organize sanayi bölgesinin sürdürülebilirlik açısından incelenmesi ve yeşil organize sanayi bölgesi için model önerisinin geliştirilmesi
Bu tez çalışması, Türkiye'deki organize sanayi bölgelerinin (OSB'lerinin) sürdürülebilirlik perspektifiyle ele alınması gerekliliğinden hareketle, Isparta Süleyman Demirel Organize Sanayi Bölgesi (ISDOSB) özelinde gerçekleştirilmiştir. Çalışmanın temel amacı; ISDOSB'nin mevcut çevresel yönetim uygulamalarını analiz ederek, sürdürülebilir kalkınma ilkeleri çerçevesinde sıfır atık politikalarının uygulanabilirliğini değerlendirmek, endüstriyel simbiyoz olanaklarını ortaya koymak ve nihayetinde bölge için örnek bir yeşil OSB modeli geliştirmektir. Araştırma dört ana iş paketi (İP) kapsamında yapılandırılmıştır. İlk olarak, birinci İP kapsamında, tesislerin sektörel yapısı ve çevresel performans verileri analiz edilerek, birim ürün başına spesifik kaynak tüketim değerleri Mevcut En İyi Teknik Referans (BREF) dokümanlarında yer alan spesifik değerler ile kıyaslanmıştır. Ardından, ikinci İP'de, OSB genelindeki atık ve yan ürün akışları incelenerek endüstriyel simbiyoz potansiyeli tespit edilmiştir. Üçüncü İP'de, yeşil dönüşümün önündeki finansal, kurumsal ve mevzuatsal engeller, tesis yöneticileriyle yapılan görüşmeler ve anketler aracılığıyla değerlendirilmiştir. Son olarak, dördüncü İP'de ise, tüm bu bulgulara dayanarak ISDOSB için uygulanabilir bir Yeşil OSB model önerisi sunulmuştur. Araştırma bulgularına göre, özellikle mermer ve tekstil sektörlerinde yer alan tesislerin enerji ve su tüketim değerlerinin BREF referans değerlerinin üst sınırına yakın olduğu ve önemli bir çevresel iyileştirme potansiyeli taşıdığı tespit edilmiştir. OSB genelinde %9 oranında bir endüstriyel simbiyoz potansiyeli belirlenmiş olmasına rağmen, bu potansiyelin henüz yeterince değerlendirilemediği görülmüştür. Yeşil dönüşümün önündeki en büyük engellerin ise tesis yöneticilerinin belirttiği gibi yüksek yatırım maliyetleri ve mevcut teşviklerin yetersizliği olduğu sonucuna varılmıştır. Yapılan ekonomik analizler, tesis yöneticilerinin %68'inin yatırım maliyetlerini, %74'ünün ise teşvikleri yetersiz bulduğunu ortaya koymaktadır. Ayrıca, ISDOSB'nin mevcut durumunun, kurumsal yönetim, planlama süreçleri ve performans raporlaması gibi temel Yeşil OSB kriterlerine tam uyum sağlamadığı belirlenmiştir. Bu bulgular, OSB'nin yeşil dönüşümünün yalnızca tesis bazlı teknik iyileştirmelerle sınırlı kalmaması, aynı zamanda kurumsal ve finansal engelleri aşacak bütüncül bir strateji gerektirdiğini göstermektedir. Bu sonuçlar ışığında geliştirilen model, ISDOSB'nin sürdürülebilirlik hedeflerine ulaşması için yol gösterici bir çerçeve sunmakta ve bölgenin ekonomik rekabet gücünü artırmayı hedeflemektedir.
Investigation of waste stabilization potential of a medium aged solid waste in a biorector landfill
The production of solid waste is an inevitable consequence of human life. The tremendous increase in the solid waste generation makes the use of landfills, especially bioreactor landfills imminent. Research has shown that municipal solid waste can be rapidly degraded by enhancing and controlling the moisture within the landfill under aerobic and/or anaerobic conditions. Some studies indicate that bioreactors increase the feasibility for cost effective LFG recovery, which in turn would reduce fugitive emissions. This presents an opportunity for beneficial reuse of bioreactors in energy recovery projects. The most common method of creating a land ll bioreactor is the recirculation of leachate, which enhances the degradation of waste.The objective of this study is to evaluate the waste degradation mechanisms of the stabilized waste applying Retrofit Bioreactor Concept. Determination of the further stabilization potential of stabilized solid waste is important for the development of the rehabilitation strategies. Moreover, the study using stabilized refuse provides better understanding of the rehabilitation of traditional landfills and the conversion of existing conventional landfills to operate as a bioreactor concept.
Application of photocatalysis for the treatment of grey water
Defined as the all wastewater coming from urban areas except any input from toilets, grey waters constitute the largest fraction of the total domestic wastewater consumption which may fluctuate in quality and quantity diversely. Since grey water is less contaminated by nutrients, inorganics and hazardous organic substances, it is a potential `?non-conventional?? water resource. As a consequence, several treatment technologies to treat and reuse grey water have been studied widely. As one of these processes, photocatalytic oxidation, which relies upon the generation of highly reactive hydroxyl radicals under UV radiation, has become an innovative and effective technology for the treatment of grey water in terms of degradation of refractory organic matter and potential disinfection mechanism.This study aimed to investigate applicability of photocatalytic oxidation process to treat grey water sources. In this manner, synthetically prepared grey water samples were subjected to photocatalytic oxidation in the presence of TiO2 as the semiconductor photocatalyst. Further assessment of the system performance was observed by making compositional alterations of grey water samples in terms of organic matter loading, anion concentration, and microbiological content particularly. The results of photocatalytic oxidation experiments were deliberated by the determination of selected specified and specific UV-vis and fluorescence parameters. In addition to specified UV-vis parameters, DOC and bacterial content of samples were also evaluated in terms of removal efficiencies and photocatalytic degradation kinetics expressed by pseudo- first order kinetic modeling.As a consequence, photocatalytic oxidation of low load grey water with microorganism and low anion content revealed the most effective results in terms of the removal of selected parameters whereas lowest removal efficiencies for the selected parameters were achieved by photocatalytic oxidation of high load grey water with high anion content indicating the impact of organic matter loading and anion strength on the performance of photocatalytic oxidation process.
Evaluation of biogas production as a source of renewable energy through co-digestion of agricultural residues and poultry manure
The need for alternative energy sources for Turkey is obvious. Biogas production via agricultural residues and manure seems to be an advantageous option for Turkey, since the main income is generally provided from the agro industry. Through anaerobic digestion of agricultural residues and poultry manure, wastes will be properly disposed and biogas, which is a clean and sustainable source of energy, will be continuously recovered. As a renewable energy source, biogas production from agro industrial wastes is a useful management option, energy independent and environmentally friendly. Biogas can be usedfor production of heat, electricity, as fuel in vehicles and as a substitute of natural gas.The objective of this study was to investigate the potential of biogas generation via anaerobic co-digestion of the chosen agricultural residue -sunflower residues- and poultrymanure. Mixtures composed of different amounts of substrates were prepared and digested under anaerobic conditions with the addition of inoculum culture (seed sludge), using batch tests under mesophilic laboratory conditions.If the potential of biogas production from co-digestion of poultry manure and agricultural residue can be determined by batch-tests, then it will be possible to calculate the theoretical amount of energy that can be produced from these substrates, since the production amounts of agricultural residue and manure are known. According to the results obtained, it will be possible to use these substrates for the continuous lab scale studies or larger scale commercial agricultural biogas plants.Within the scope of this study, several compositions of sunflower residue, poultrymanure and inoculum mixtures were elaborated and digested under mesophilic conditions. However reliable methane production could be only achieved in the first two trials. This outcome is mainly attributed to the low biodegradability of the sunflower residues thus further studies, including pretreatment methods are recommended.
Production of biogas through anaerobic co-digestion of ice cream plant wastewater and ice cream production residue
The primary objective of this study is to determine whether it is possible to dispose of ice-cream production residue (off-spec) and ice-cream wastewater together and to recover energy by anaerobic co-digestion process. Mesophilic batch anaerobic digestion tests were performed under laboratory conditions to evaluate production of methane (CH4) from these substrates. It was found out that it was possible to obtain a high methane yield of 0.338 L CH4 g-1 CODremoved from anaerobic digestion of wastewater alone, with almost 70 % of methane in biogas, while anaerobic digestion of off-spec alone did not seem feasible, due to particular characteristics of the off-spec. When wastewater and off-spec were mixed at a ratio of 9:1 (WW:O) by weight, a methane yield of 0.131 L CH4 g-1 CODremoved could be observed. Lower methane yields for anaerobic co-digestion of wastewater and off-spec could be attributed to high concentrations of sulfate and oil & grease coming from off-spec. Since both ice-cream wastewater and off-spec had variable pH ranges and a poor buffering capacity, adequate amount of buffer must always be present in the anaerobic system to sustain anaerobic degradation.
Impacts of sewage sludge codisposal on waste degredation in aerobic and anaerobic bioreactors
Due to economical, endustrial and technological developments, waste and wastewater sludge productions are increasing gradually all over the world. This situation constitutes to the problem of sustainable solid waste and sludge disposal. Especially diffuculties in finding new landfill spaces, high cost of wastewater sludge management and environmental concerns are forced to find a new method for disposal. Although there are many methods such as incineration, surface disposal and composting, codisposing of wastewater sludge with MSW in the aerobic and anaerobic bioreactors are most used and economical way. Therefore, the objective of this study was to obtain information about sludge codisposal with MSW in the aerobic and anaerobic bioreactors in order to evaluate and determine an efficient and cost-effective landfill management system by utilizing two stage laboratory experiments. These stages include, the lab-scale reactor set-up in order to determine optimum solid waste to sludge ratios by using anaerobic bioreactors and then pilot scale reactor set-up in order to understand the effect of sludge addition on waste stabilization process by using aerobic and anaerobic bioreactors. The results of this study showed that in the lab-scale reactors, codisposal of wastewater sludges with MSW is a very promising method. This method accelerates waste stabilization rates in the anaerobic bioreactors while the energy potential of the sludge is used beneficial. In the pilot scale reactors this study showed that, aeration is a feasible way to treat leachate, fastens stabilization rate and provides rapid removal of organics and nitrogen. On the other hand, CH4 production in the anaerobic was more promising.
Orta ölçekli suni deri üretim tesisi için çevresel strateji
Environmental friendly production through industries has become one of the most favorable necessities in recent years due to gradually increasing environmental concerns. It is a fact that the old manufacturing facilities, which are the initial step of environmental pollution, are lack of environmental technologies. By taking this into consideration, in this study, the effects of a medium scale synthetic leather facility on the environment were evaluated before and after the application of the proposed strategy to show the improvements in water consumption, waste generation, energy consumption, and the emissions. The results of the study showed that the implementations of the proposed strategy minimized the effects of the focused synthetic leather facility on the environment. In the facility, the dye preparation unit was separated from the process line to prevent of extra water consumption and indoor pollution. In line with energy audits the water leakage points were determined and the facility?s conventional taps were replaced with the photocell basin taps to reduce the water consumption for the domestic usage. All of these improvements in the water consumption systems led to a 38,5 % reduction of in the water consumption rates. In order to minimize energy consumption, energy audits were started by the facility. The audits determined energy consumption and energy loss points and captured a picture of the operations which caused waste in energy. The major energy consuming equipment and their energy efficiencies were identified. Lightning systems were supported by multiple glazing windows and mercury containing fluorescent lighting replaced with energy saving LED lighting, or high-pressure sodium or ceramic metal bulb lighting. All of these energy audits and the improvements enabled a reduction from 812.574kwh/year to 569.963kwh/year and led to a 30% reduction in the energy consumption rates. The synthetic leather facility had no waste management plan and all types of wastes were collected together. In order to separate collection of the hazardous wastes and non-hazardous wastes, waste management plan and a separate collection were put into practice at the facility. Through the waste management policy; the waste was collected based on its type. The reuse of waste in production cycles as secondary raw material was started. Waste was disposed of by licensed companies, and waste management training for employees were also given in the synthetic leather facility. Both the generation of the waste itself as well as effects of the disposed waste on the environment were minimised. While the synthetic leather facility?s emission measurement results did not exceed the limit values, the odour level was high throughout the facility. The VOC emissions were creating this pervasive odour. Furthermore, indoor air emissions were at the harmful level according to occupational health and safety. The synthetic leather facility did not have a ventilation system or effective emission collection system. The door and window systems were the only source of ventilation. The facility?s emissions were not under control. For controlling the system emissions and reducing the low ? value VOCs; waste gas collection and combustion systems, and the new ventilation systems were installed. Since these improvements, the synthetic leather facility does not have any reduction in the waste gas, but indeed, it started to prevent high level of indoor air pollution. Another result is that the facility has had huge odour reduction efficiency approximately 78%. When the by-pass stack flue gas and combustion system analysis results are compared, there is an emission reduction efficiency of around 98%. After the all emission systems? improvements, waste gas emissions and their effect on environment have been brought under control.
Effect of enzymatic pre-treatment on aerobic and anaerobic digestion of wastewater sludges
Aerobic and anaerobic digestion processes aim to degrade the organic matter content of the sludge, remove pathogenic microorganisms from sludge, and produce a stabilized sludge. In the last years, pre-treatment of sludge prior to the digestion process gained more importance due to the potential of increasing sludge solubilization and minimization. This study investigates the effect of enzymatic pre-treatment application prior to the aerobic and anaerobic digestion processes of wastewater sludges. For this purpose, sludge samples were obtained from four different urban and domestic wastewater treatment plants. Digestion tests were carried by operating one control reactor and one enzymatically pre-treated reactor for each sludge sample obtained. An enzyme mixture consisted of alpha-amylase, beta glucanase, lipase, protease, and celllulase was added to the sludge samples 0,5% by volume. The results of the study showed that the enzymatic pre-treatment plays an important role on the performances of the digestion processes. In aerobic digesters, minimization of sludge production was enhanced by the application of enzymatic pre-treatment. Enzyme added reactors showed better TS, VS, MLSS, and MLVSS removals by 43%, 51%, 44%, and 46% reduction in average, compared to the removals of control reactors by 24%, 31%, 28%, and 32% respectively, in average. Enzymes had great impact on the solubilization of large molecular compounds into smaller molecules by the destruction of cell structure. Compared to the control reactors, enzymatically pre-treated reactors showed better performances on the solubilization, which is determined by increased sCOD and DOC concentrations. Enzymatic pre-treatment also affected the release of extracellular polymeric substances from sludge flocs and enzyme addition led to an increase in the protein and carbohydrate contents of sludge. During the digestion process, COD, sCOD, and EPS contents of the sludge samples decreased, where pre-treated reactors showed better removal efficiencies. The dewaterability of sludge samples was deteriorated when they were enzymatically pre-treated at the initial stage. Then, by the aerobic digestion and the degradation of EPS, dewaterability was improved. Similar results were obtained for the anaerobic digesters in terms of sludge minimization and solubilization. In addition, enzymatic pre-treatment prior to the anaerobic digestion resulted in improved biogas production and increased methane potential. In both digestion processes, removal of pathogens was successfully achieved. At the end of the aerobic digestion, the reductions in TC, FC, and FS were about 99,78%, 99,84%, and 99,82%, respectively. At the end of the anaerobic digestion, the reductions in TC, FC, FS, and salmonella were found to be about 99,82%, 99,96%, <99,99%, and 99,98%, respectively. During the study, both urban and domestic wastewater sludge samples were tested but no relationship was found between the source of the sludge and the digestion process.
Relationship between silver inhibition and feeding of activated sludge
Silver is one of the heavy metals which is widely used in industrial, electronics and medical applications. Increase in the demand of silver and silver containing products cause accumulation of silver in sewer systems. Since silver ions are highly toxic on microorganisms, they affect biological wastewater treatment systems. The objective of this study is to examine the effect of silver ion on different types of activated sludge. Activated sludge was fed with synthetic wastewaters which had different C/N (COD/Nitrogen) ratios and inhibitory effect of silver ion was examined by using a respirometer. The result of the study shows that the C/N ratio in wastewater has a crucial role because it determines the relative ratio between heterotrophs and autotrophs in activated sludge. The inhibitory effect of silver ion changes with the C/N ratio in a wastewater. An activated sludge enriched in terms of autotrophs (C/N ratio = 0) is more sensitive to silver ion than other sludge types. On the other hand, with the increase in C/N ratio heterotrophs dominate in activated sludge and they can tolerate higher concentrations of silver ion.
The estimation of the spatial variability of the flow parameters using hydraulic tomography
Pumping tests are often used for the estimation of flow parameters. However, the interpretation of these tests is routinely performed using conventional methods that assume the parameters are uniform which is in contradiction with most real systems. The main objective of this thesis is to combine a recently developed pumping test interpretation technique, referred to as the Continuous Derivation method, with data obtained from hydraulic tomography. Hydraulic tomography is a novel field data acquisition technique that involves the sequential pumping from a number of wells and observing the groundwater drawdown in adjacent wells as a function of time. Particularly, the goal was to extend the method to the estimation of the statistical spatial structure of the transmissivity using hydraulic tomography data. In geostatistics, the statistical spatial structure of a parameter refers to the pattern of how this parameter varies in space. The emphasis was on estimating how the transmissivity varies with distance from the pumping well and then use that information to estimate the statistical parameters, namely the integral scale and variance.
Photocatalytic oxidation of humic acid in heterogeneous aqueous systems: A comparative investigation between montmorillonite and kaolinite
Humic acids representing the major fraction of the naturally occurring humic substances are composed of highly functionalized carbon rich polydisperse organic fractions. Clay minerals which are responsible for the transport of inorganic and organic contaminants constitute the main component of the suspended inorganic material in natural waters. The understanding of interactions between humic substances and clay minerals is an important task for the achievement of an effective water treatment performance. The aim of this research was to investigate the influence of montmorillonite and kaolinite as representative clay minerals on the TiO2 photocatalytic degradation of humic acid as the model compound of natural organic matter. The interactions prevailing between humic acid, montmorillonite, kaolinite and TiO2 surface were assessed prior to the application of photocatalysis in order to evaluate the adsorptive and photolytic behavior of humic acids. Adsorption of humic acid onto sole TiO2 and TiO2 in the presence of clay minerals either montmorillonite or kaolinite were assessed by batch adsorption experiments. The changes attained in humic acid were described by UV-vis spectroscopic parameters i.e. color forming moieties (Color436) and UV absorbing centers (UV365, UV280 and UV254), and dissolved organic carbon (DOC) contents. Photocatalytic oxidation of humic acid in the presence of clay particles i.e. montmorillonite or kaolinite was also followed by using specific UV-vis parameters (SUVA365, SUVA280, SUVA254 and SCoA) calculated by respective absorbance measurements (E) through conversion to mass of carbon. Fractional UV-vis parameters (E254/E365; E254/E436; E280/E365; E280/E436, and E365/E436) that signify the removal of color forming groups in relation to the removal of UV absorbing centers revealing further information on the different oxidation pathways through photocatalysis. No noteworthy variation could be detected for fractional UV-vis parameters under photocatalytic conditions for sole humic acid as well as for humic acid in the presence of either montmorillonite or kaolinite. However, a significant correlative interaction was attained between the specific UV-vis and fractional UV-vis parameter (E254/E436) (r2 > 0.80). Therefore, it could be concluded that E365/E436 parameter could be effectively used as a discriminative indicator parameter for the type of clay minerals. Application of the pseudo first order kinetic model revealed both enhancement and retardation effect with respect to the applied montmorillonite and kaolinite doses. Upon non-selective oxidation, a slight rate enhancement could be indicated for Color436, UV365, UV280 and UV254 of HA in the presence of either montmorillonite or kaolinite. However, the presence of clay particles did not significantly change the DOC degradation rate of HA. The effect of ionic strength (Ca2+ loading from 5x10-4 M to 5x10-3 M) was also assessed for the photocatalytic degradation of sole HA and HA in the presence of either montmorillonite or kaolinite. The overall effect of montmorillonite and kaolinite on the photocatalytic degradation of humic acid was also evaluated in terms of molecular size distribution profiles (0.45 ?m filtered fraction, 100 kDa fraction, 30 kDa fraction and 3 kDa fraction) described by the specified and DOC normalized specific UV-vis parameters. Besides the effective removal of higher molecular size fractions (100 kDa and 30 kDa fractions), transformation to lower molecular size fractions (< 3kDa) was more pronounced for sole humic acid rather than humic acid in the presence of clay minerals. Scanning electron microscopic (SEM) images accompanying with energy dispersive X-ray analysis were also examined for the elucidation of the surface morphologies of the binary and ternary systems composed of humic acid, TiO2 and montmorillonite or kaolinite both prior to and following photocatalysis. Excitation emission matrix (EEM) fluorescence spectral features were also evaluated for the elucidation of the photocatalytic degradation of sole humic acid and humic acid in the presence of clay minerals either as montmorillonite or kaolinite. The role of Ca2+ ions was also visualized through EEM under the specified conditions. EEM features reflected the irradiation time dependent transformation of the humic like fluorophores to fulvic like fluorophores in accordance with the photocatalytic removal of humic acid. Adsorption of humic acid onto sole TiO2 and TiO2 in the presence of either montmorillonite or kaolinite with Ca2+ were evaluated by the application of batch adsorption experiments. Adsorption properties of humic acid onto sole TiO2 and TiO2 in the presence of clay minerals either as montmorillonite or kaolinite were evaluated in terms of the specified UV-vis parameters as well as DOC. Adsorption isotherms were evaluated in terms of the adsortion isotherm types (Types S, L, and C). Adsorption data of the indicated humic parameters were further modeled by Freundlich and Langmuir adsorption isotherm model. It could be concluded that, the presence of clay particles i.e. montmorillonite and kaolinite would not significantly alter the photocatalytic degradation efficiency of humic acid. This result signifies that photocatalysis could be an alternative treatment option for the successful removal of natural organic matter in water treatement systems. As shown by the results attained through the application of the UV-vis and fluorescence spectroscopic techniques, the chemical composition of the resultant organic matter would be the indicative parameter for the assessment of the drinking water quality. Since chlorination and/or ozonation is widely applied as the final disinfection step, from public health point of view, it is highly recommended that further research should be directed to the evaluation of the possible side effects related to the formation of the disinfection by-products.
Modeling antibiotic transport and mapping the environmental risk in the Marmara region by using geographical information systems (GIS)
As human population increases, livestock farming has become more intensive for several decades. Veterinary antibiotics (VAs) are one of the most widely preferred drugs for animal health and management. Since a considerable fraction of antibiotics is excreted in animal waste; antibiotics can affect both soil quality by leaching from manure to soil and water quality by transporting to surface waters via runoff following to application of animal waste as manure on agricultural lands. Due to the fact that released antibiotics can lead to toxic effects and development of antibiotic resistant bacteria in the environment, there has been an increased concern about the adverse impacts of these micro pollutants causing chemical pollution. The antibiotic concentrations were previously measured in the soil and manure samples collected from various agricultural lands of the Marmara Region of Turkey in the scope of a scientific project. The aim of this study is to create environmental risk maps belonging to the Marmara Region in terms of antibiotic transport by determining risky pasture lands where risk mitigation actions would be essential. First of all, Storm Water Management Model (SWMM) was applied to simulate runoff water quantity stemming from rainfall events and hydraulics in the study area, which is divided into manageable modeling units such as catchments and subcatchments having different hydrological and hydraulic characteristics via Geographical Information Systems (GIS). Secondly, the transport of previously analyzed antibiotics in the Marmara Region was investigated by using the exposure model supplied by National Institute of Public Health and the Environment in The Netherlands (RIVM). Finally, the environmental risk of antibiotic transport in the Marmara Region was mapped with the help of GIS techniques by developing a Multi-Criteria Decision Analysis (MCDA) approach for all pasture lands.
Yüksek biyokütle azot giderim sistemlerinde kek filtrasyon
Pilot scale cake filtration biological reactor (CFBR) and membrane bioreactor (MBR) were operated (capacity: 100 m3/d) for 26 months. The system was evaluated according to conventional cake filtration theory using its plots of V vs. t and t/V vs. V. Standard blocking model plots of CFBR were compatible (R2> 0.95) for the initial period; the latter was best fitted to the cake filtration model (R2> 0.99). The linearity between t/V and V was observed individually, showing a change of filtration characteristics at the transition point. Results of a particular period (six months) with complete sludge retention were presented to state the sludge production pattern and, the activity and diversity of nitrogen converters. The average sludge yield reached equilibrium after day 105 (0.25 kgMLSS/kgCOD, MLSS~15,000 mg/L). Volatile portion of mixed liquor suspended solids (MLVSS/MLSS) increased–decreased–increased and stabilized around 0.57. Inert material stabilization showed that inerts could be degraded at sufficiently long SRTs. The nitrifier population was adversely affected by gradually increased biomass with insignificant effluent quality change. However, coexistence of aerobic and anaerobic ammonia oxidizers in a partially aerated system was confirmed. The total operation cost of such high biomass filtration system could be 9–15 percent less than that of a biological nutrient removal (BNR) plant because of the decreased expenses for sludge disposal.
Surface interactions of humic acid - anion doped titania binary system
Humic acids are natural weak polyelectrolytes which play active role in binding mechanism of organic molecules that results in the transportation of contaminants in soils and aquifers. Humic acids constitute the major fraction of natural organic matter that should be removed during water treatment. Besides conventional treatment methods, application of advanced oxidation processes more specifically photocatalysis has gained much attention in recent decades. Titanium dioxide (TiO2) is universally recognized as a standard photocatalyst. Since photocatalysis occurs through a surface oriented mechanism, the adsorptive properties of TiO2 specimens deserve special attention. Moreover, nowadays visible light activated TiO2 has been the subject of numerous investigations. The understanding of the surface interactions prevailing between the anion doped oxide surface and humic subfractions is important for the determination of the role of humic substances during photocatalysis. The aim of this study was to investigate surface interactions between different molecular size fractionations of humic acid and TiO2 specimens, namely bare TiO2 and anion doped TiO2. In this study, two different commercial TiO2 specimens (Degussa P-25 and Hombikat UV-100) were used. Adsorption experiments were conducted with humic acid solutions having diverse molecular size fractions (0.45 µm filtered fraction, 100 kDa fraction and 30 kDa fraction). Moreover, bare TiO2 and anion doped TiO2 (N-doped TiO2, S-doped TiO2, C-doped TiO2 and N-S co-doped TiO2) specimens in the range of 0.1-1.0 mg mL-1 were used as adsorbents. Adsorption properties of humic acid and its molecular size fractions onto bare TiO2 and anion doped TiO2 specimens were evaluated and compared in terms of UV-vis spectroscopic parameters i.e. color forming moieties (Color436) and UV absorbing centers (UV365, UV280 and UV254) and fluorescence spectroscopy in emission and synchronous scan modes as well as dissolved organic carbon. Adsorption isotherms were evaluated in terms of the adsorption isotherm types (Types C, L and S). Adsorption isotherms were modeled to Freundlich and Langmuir adsorption isotherm models by evaluating the results of specified UV-vis parameters. The effect of doping on two different TiO2 specimens (Degussa P-25 and Hombikat UV-100) could be evaluated through the role of decreasing molecular size of humic acid. The most significant effect could be attributed to the surface properties of TiO2 specimens present in aqueous solutions of humic acid. The results based on varying molecular size fractions of humic acid displayed remarkable differences with respect to the morphological character of TiO2 specimens.
Comparison of three common life cycle environmental impact assessment methodologies for polyolefin crates
In this thesis, a comparative analysis of three different life cycle impact assessment methodologies has been carried out for polyolefin plastic crates. Additionally, improvement possibilities for the waste management of plastic crates have been investigated. In the study, GaBi 4 software tool was utilized for methodology comparison. The three different life cycle impact analysis methodologies assessed in this study include: CML 2001, EDIP 2003 and Eco-Indicator (EI) 99 – "Hierarchist Approach". The differences and similarities of the methods were examined. While EI is an endpoint methodology, EDIP and CML are midpoint methods. In the first part of the study, polyethylene (PE) and polypropylene (PP) plastic crates were analyzed with these methods. In the second part, the CML methodology was selected and applied to observe the effect of recycling and incineration on the products' life cycles. In the comparative analysis, differences of less than 1% were observed in the characterization stage for all methodologies. According to EDIP, the acidification and photo-oxidant formation results slightly favor the use of PP, however, the eutrophication results weakly support PE use. Based on the CML, acidification, photo-oxidant formation and toxicity results approve PP scenarios, whereas eutrophication and global warming results shows PE use as more advantageous. For EI, toxicity results indicate that PP may be favored, however resource depletion and global warming results highlight that PE may be preferred. Thus, it has been concluded that both plastic materials show similar performance. In addition, in global warming and ozone depletion the results do not vary with methodology selection. For other categories, similarities can again be observed. Results also indicate that incorporating recycling into waste management leads to a reduction in emissions. For the comparison of "40% recycling" and "only virgin raw material use" scenarios, it has been deducted that the "40% recycling" scenario achieves a reduction of approximately 39% is achieved in all CML categories. When considering the "60% recycling" scenario, a reduction of about 59% was observed relative to the "only virgin material use" scenario. The reuse of plastics was researched using CML. It has been assessed that a decrease in reuse from 350 times to 300 times led to a reduction of 25.19% in the weighting scores.
Development of greenhouse gases (GHG) reduction scenarios with well to wheel concept for passenger cars
Road transportation is substantially contributing to climate change. Considering greenhouse gas (GHG) emission, which directly affect climate change, is largely driven by passenger car operations in road transportation and passenger cars constitute more than 50% of registered vehicles in Turkey, Turkey should focus to reduce GHG emission from passenger car operations. In this context, the proposed thesis covers the impacts of exchanging new vehicle technologies and introducing alternative fuel/energy types, through implementing different End of Life Vehicles (ELVs) regulations, on decreasing GHG emissions for passenger cars. Four scenarios are determined based on potential ELVs regulations. Scenario A is created according to not implementing any ELVs regulation. Scenario B is selected based on implementing Turkey's 2003 ELVs regulation again for two years. In scenario C, the ELVs regulation is broadened to be perpetual. Finally, scenario D is designed to have more electrical car contribution till the end of 2023, as planned in EU. A Well-to-Wheel (WTW) analysis, the common Life Cycle Assessment (LCA) methodology for transportation, is adapted in this study to evaluate the full life cycle of fuel/energy consumed in each scenario. The life cycle inventory part of LCA is conducted by a statistical model which forecasts the fuel/energy consumption till the end of 2023 based on last five year averages and increasing trends. GaBi 6.0 software program is used as the LCA tool for Life cycle impact assessment and CML 2001 is used as LCA methodology. GHG emissions change is assessed according to global warming potential as the impact category indicator. The results of WTW analysis reveal that 1.0% reduction in global warming potential will be achieved by applying a ELVs regulation for a limited time period in Turkey. The reduction will be 2.8% if the regulation is perpetual. Furthermore, the global warming potential can be decreased by 3.4% if the electrical car contribution will be increased to 4.2% by the end of 2023 in Turkey, as oppose to be 0.8%, if no action is taken.
Effect of quaternary ammonium ionic liquids on fermentation of cellulose by bacteria
Biofuel and chemical production from lignocellulosic biomass gained significant attention due to high demand of fuels and chemicals. The polysaccharides in lignocellulosic biomass are converted to monosaccharides through enzymatic hydrolysis. The monosaccharides are converted to bioethanol and bio-based chemicals via fermentation. However, the recalcitrance of lignocellulosic biomass to hydrolysis demands a pretreatment process. Current pretreatment methods either have high energy demand or produce wastestreams that are harmful to the environment. Recently, ionic liquids (ILs), which are salts in liquid state, are introduced and utilized as green solvents for cellulose dissolution. However, recent studies showed that ILs are not as "green" as they thought to be in the past. ILs are not only inhibitory to biological processes following the pretreatment, but also they cause ecotoxicity and proliferate antimicrobial resistance among bacteria when released into the environment. The main objective of this research is to couple pretreatment, hydrolysis and fermentation for production of value-added alcohols and organic acids from cellulose in a single phase; utilizing benzalkonium chlorides (BACs), an extensively used quaternary ammonium IL as the reaction medium, cellulose degrading microbial community developed from soil and BACs resistant/degrading Pseudomonas sp. BIOMIG1 as biocatalysts. A microbial community capable of cellulose degradation was developed and the cellulose degradation was tested both in absence and presence of BACs. The soil microbial community utilized 1000 mg/L cellulose aerobically within 6 days. Cellulose utilization by the microbial community was inhibited at and above 50 mg BAC/L. On the other hand, when Pseudomonas sp. BIOMIG1 was supplemented to the community, BACs was utilized at up to 500 mg BAC/L. In addition, the co-culture of BACs resistant Pseudomonas sp. BIOMIG1 and Serratia marcescens BIOMIG4 converted glucose mainly to 2,3 butanediol, ethanol and various acids. In conclusion, a biological system that can convert cellulose to value added organic chemicals in the presence of a quaternary ammonium IL and alleviate the environmental consequences of IL was developed in this study.
Plant and microbe interactions in the phytoremediation of heavy metal contaminated soils
In this study, phytoremediation; the amount of heavy metal (Cu) uptake by plant species, host plants' symbiosis potential with two different species of arbuscular mycorrhizal fungi (AMF), interaction between AMF and host plants for sequestration of Cu available in the soil, as well as generation of glomalin-related soil protein (GRSP). Heavy metal concentrations were 100, 500 and 1000 ppm. For phytoremediation, two commercial crops (sorghum and sunflowers) which are widely cultivated in majority of agricultural fields in Turkey were used as host plants. The results showed a strong variability in sunflower and sorghum plants colonized with both AMF species in terms of GRSP (0.6–11.2 mg g−1 and 0.2-10.75 mg g−1), respectively. Cu content (29.34–249.86 mg kg−1 for the total Cu in sunflower and 12.06– 73.97 mg kg−1 for sorghum rhizosphere colonized by G. mosseae (up to 60%) were observed. This study provides evidence on the role of the plant microbe interactions in Cu sequestration as well as Glomalin generation related to heavy metal stimulation. Findings suggest highly efficient mechanism for AMF to mitigate stress leading to stabilization of polluted soils. Results also provide a new suggestion on the contribution of Glomalin in copper sequestration in polluted soils.
Activated carbon production from pretreated and fermented agricultural residues
All forms of lignocellulosic biomass consist of three major chemical components: cellulose, hemicellulose and lignin. The remaining lignin from bioethanol production can be utilized as a feedstock for green chemicals. The purpose of this study was to produce activated carbon from pretreated and fermented agricultural residues and to investigate the influence of different process conditions such as feedstock type, impregnation ratio, and carbonization temperature on the pore structure of the products. This is the first study that investigated the production of activated carbon as a high value-added product from lignin-rich residues generated from bioethanol processes. The first step in the experimental path of the study was the recovery of lignin-rich biomass samples. Four samples were prepared from ethanol production wastes; the first one was from the pretreatment of corn stover, the second one was from pretreatment of wheat straw, the third one was from fermentation of corn stover, and the fourth one was from fermentation of wheat straw. The second step was the chemical characterization of feedstocks. In the third step, feedstocks were impregnated with 30%, 40% and 50% (w/w) H3PO4 and then carbonized with a rate of 20ºC/min to carbonization temperatures of 400ºC, 500ºC, 600ºC and 700ºC. The N2 adsorption/desorption capacities of products were compared according to their specific surface area and pore volume by applying the Brunauer-Emmett-Teller (BET) equation. The results demonstrated that the best way to produce activated carbon from lignin-rich residue was using pretreated wheat-based lignin, which was impregnated with 40% H3PO4 concentration and carbonized at 700ºC. In addition, both pretreated corn and fermented wheat-based products, which were impregnated with 50% H3PO4 and carbonized at 500ºC, had quite well developed specific surface area. Interestingly, mesoporous structures dominate in H3PO4-impregnated lignocellulosic material-based activated carbon. Therefore, these carbons are ideal for the adsorption of large molecules and decolorization.
Effect of disintegration methods on the characteristics of biological sludges and the biogas production in anaerobic digestion
Pretreatment has become popular to enhance digestibility and minimization of the sludge by increasing its solubility. This study investigated the effects of ultrasonic, microwave and alkaline pretreatments on the efficiencies of aerobic and anaerobic sludge digestion processes. The digestion efficiency was measured in terms of sludge minimization, pathogen reduction and biogas production. In the first part of the study, application conditions of pretreatment techniques were determined. In the second part, unpretreated (control) and pretreated sludge samples were digested aerobically at room temperature and anaerobically at 37oC for 30 d. Sludge pretreatments improved the efficiencies of both aerobic and anaerobic digestion processes by increasing the solubility of sludge solids. In aerobic digestion, VS removal efficiencies improved by 23-68%, 24-33%, 28-78% for sludge pretreatment ratios (SPR) of 10%, 20%, and 25%, respectively. In anaerobic digestion, pretreatments led to 18-53% increase in VS removal efficiency and 41-77% increase in methane production efficiency. The highest biogas yield of 0.52 Lbiogas/gVSadded and methane yield of 0.37 LCH4/gVSadded were obtained from microwave pretreated sludge samples. Sludge dewaterability was deteriorated with the application of pretreatments to 10% of the samples (SPR:10%), dewaterability of alkaline and microwave pretreated sludge samples improved when SPR increased to 20% and 25%.
Evaluation of recovery potential for precious and rare earth metals from e-waste
Considering the enormous production of electrical and electronic wastes in recent years, it is obvious that the research of their material composition is essential in order to manage them properly and prevent health and environmental problems resulting from their inappropriate disposal. On the other hand, it is known that the e-wastes contain valuable metals in them and these valuable metals are lost during the current disposal and recycling processes. Therefore, the detection and quantification of these metals in e-waste samples is important for increasing recycling rate of them. The main objective of this study was to evaluate the recovery potentials of certain precious and rare earth metals from e-waste. The metal characterization of twenty five different e-waste samples collected from various sources was completed as a first step. Selected base, precious and rare earth metals in these e-waste samples were detected and quantified by using ICP-OES. Since the number of printed circuit boards of mobile phone samples and motherboards of computer samples is relatively higher than the number of other samples, their recovery potentials in terms of base, precious and rare earth metals were finally determined. Results of this study show that, while the recovery of precious metals should be the main goal of the recycling process of printed circuit boards from mobile phones, the recovery of both precious metals and rare earth elements should also be the focus of the recycling process of motherboards of computers.
Decision making tools in the production systems of personal care products
Life Cycle Assessment is a method of analyzing the environmental impact of products and services that considers their full life cycle. The goal of this study is to evaluate the ecological footprints and integrate results with ecolabelling approach for selected products. The product and the consumer use data were collected from industry. Environmental impacts of different formulations were conducted by using GaBi 6.0 Software, EcoInvent Database and CML Assessment Methodology. In this study the stages were selected as raw material acquisition, manufacturing, distribution, consumer use and disposal. Additional scenarios were applied to both products to assess the environmental performance improvements. Global warming, acidification, eutrophication, ozone layer depletion and photochemical ozone creation potentials were considered for both hair conditioner and oil spray products. Overall normalized environmental impacts were also assessed. The results of the study demonstrated that, for hair conditioner life cycle, the highest potential impacts for almost all of the impact categories resulted from consumption stage. In addition, for oil spray, the raw materials acquisition stage has the highest impact in overall life cycle. In the comparison of these two products, environmental impact potential of oil spray is lowered drastically in each category compared to regular hair conditioner.
Effects of microwave, H2O2, S2O82-, MD/H2O2 and MD/S2O82- pre-treatments on biochemical methane production potential of the sewage sludges
The considerable increase in the sewage sludge production in wastewater treatment plants becomes a serious problem for a modern society. The treatment of excess sewage sludge is a significant issue. Many different methods and pre-treatment techniques can be applied for the stabilization of the sludge and enhancement of energy production from the sludge. This study investigated the effects of sludge pre-treatments (microwave (MW), H2O2, S2O82-, MW/H2O2 and MW/S2O82-) and also the presence of antibiotics on anaerobic stabilization and biochemical methane production potential of sewage sludges. The pre-treatments applied to sludge samples prior to anaerobic digestion speeded up the hydrolysis step and improved the biodegradability of the organics by increasing their solubility. Application of MW, H2O2 and combined MW/H2O2 (1 g H2O2/g TS (total solids)) pre-treatments increased the methane yields by 65.5%, 20% and 40%, providing 626 mL CH4/g VS, 453 mL CH4/g VS and 529 mL CH4/g VS methane yields, respectively. However, persulfate pre-treatment (1 g S2O82-/g TS) decreased the biogas production and eliminated the methane production due to inhibiting effect of the S2O82- dose on the survival of the methanogenic bacteria. The presence of antibiotics (1 mg CIP/g TS) in sewage sludge samples decreased methane yields in the anaerobic digestion process. The methane yield, obtained in antibiotic contaminated sludge containing reactor, decreased 22% to 275 mL CH4/g VS, while uncontaminated sludge containing control reactor had a methane yield of 352 mL CH4/g VS. The presence of antibiotic in sewage sludge did not show negative effect on the sludge stabilization.
Determining the biomethane potential of petrochemical sludge after pre-treatment
Utilizing renewable energy sources has grown in importance in the modern era, particularly in light of the circular economy and sustainability ideas. Biogas is one type of renewable energy source. In addition to being a renewable energy source, biogas generation helps reduce the negative environmental and health effects of the wastes that are disposed of during anaerobic digestion operations. Especially in recent years, the increasing energy need and the use of petroleum-derived materials in energy needs constitute the thesis subject of this study. The main objective of this study was to determine the biogas production potential of pre-treated petrochemical industry wastewater sludge using batch reactors. Biogas tests were examined in two separate parts by evaluating ozone, ultrasound pre-treatment techniques and co-digestion options. In the first part, 27-day and 29-day anaerobic digestion processes were applied in the second part. Heavy metal analyses, TS, TVS, COD, pH parameters were constantly checked throughout the processes. In the first part, the highest biogas production was observed in the in parallel 1 of the second reactor with 6 mL methane /g TSadded. In the second part, the highest biogas production was achieved in the second parallel of the eighth reactor, with 35 mL methane /g TSadded. The reactor with the highest gas production was the hybrid (HYB) reactor and 65 mL biogas /g TSadded production was observed.
Effect of surfactants on heterotrophic activity in a petroleum contaminated soil under aerobic conditions
With the ongoing advancements in industrialization, the importance of petroleum resources has become increasingly evident. However, these developments have also resulted in significant environmental pollution due to petroleum hydrocarbons (PHCs). In this study, the microbial communities in both contaminated and uncontaminated soils were initially analyzed to identify key taxonomic families involved in degrading PHCs. Thereafter, impact of surfactants on PHCs solubility and bioavailability to microorganisms were investigated in the petroleum-contaminated soil. This study evaluated the dissolution efficiency of seven surfactants, including cationic, anionic, and nonionic types at various critical micelle concentrations (CMCs). Native PHC-degrading microorganisms were selectively enriched under aerobic conditions using the most efficacious surfactants identified. Microbial community analyses revealed that the taxonomic families Sphingomonadaceae, Nocardioidaceae, and Moraxellaceae played a major role in PHC degradation. The results showed that surfactants significantly enhance the bioavailability of PHCs to microorganisms, improving solubility and speeding up biodegradation. Among the surfactants tested, CTAB at three different CMC levels showed the highest soluble COD consumption under aerobic conditions, achieving up to 90% removal efficiency. TRIX, on the other hand, offered a good balance between COD removal efficiency and environmental safety, demonstrating significant effectiveness in aerobic conditions. Additionally, TRIX at 1 CMC in aerobic enrichment was effective in removing TPH, achieving nearly 2000 mg/kg removal from the originally contaminated soil. These findings suggest that surfactants can encourage the growth of strong, surfactant-resistant hydrocarbon-degrading microbial communities, making them promising options for the bioremediation of petroleum-contaminated soils.
İstanbul Büyükşehir Belediyesi'nin emisyon ticareti potansiyeli
Cities play a significant role in the climate crisis, causing approximately 80% of the world's total GHG emissions. But besides all their destructive effects, cities can take major steps to combat climate change, especially Istanbul as a metropolis. In this study, the renewable energy production potential was examined of Istanbul Metropolitan Municipality, which serves a population exceeding 16 million, has more than 85 thousand employees, and currently has 2 subsidiaries and 30 affiliates. And according to this examination, its emission trading potential was calculated. The study highlights that from 2019 to 2023, IMM's highest carbon trading capacity is also within the EU ETS, valued at USD 163,246,142. If we look at the total saving potential between 2019 and 2023, IMM's most substantial financial savings are found within the Sweden Carbon Tax System, totaling USD 301,642,712. Crucially, to conduct this analysis with precision, a comprehensive understanding of the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol, and Türkiye's engagement in these international frameworks is indispensable.
Industrial stormwater treatment and reuse: A case study
Stormwater drained from industries has adverse effects on receiving water bodies and sewer systems. Industrial facilities are usually built on large areas of land and receive a high volume of stormwater. Draining industrial stormwater to sewers is a waste of water that can otherwise be re-used in various processes within industries. Many different treatment technologies are studied and applied to minimize the negative effects of stormwater run-off on sewer systems, surface water bodies, and the water cycle in general. This study aims to review the pollutants found in stormwater collected from point sources in industries and evaluate their potential utilization for various on-site applications after proper treatment. Samples were collected from the warehouse of a logistics company during various rain events and parameters including COD, pH, TDS, and TSS were measured. Multiple treatment methods including sedimentation, coagulation, flocculation, sand filtration, and activated carbon filtration were used in a lab-scale experiments to evaluate the treatment efficiencies. It was tested whether stormwater can be brought to a quality that will be suitable for re-use in warehouses of logistics industries for technical purposes. The study showed that after proper treatment, stormwater collected from the warehouse of a logistic company can be brought to a quality suitable for reuse in technical applications.
Ozonation, sonication, and their combination for petrochemical wastewater sludge pretreatment to enhance sludge disintegration
Large volumes of petrochemical waste-activated sludge (PWAS) generated from the oil refinery industry pose an immense risk for the environment and human health due to toxic compounds, high chemical oxygen demand (COD) and poor biodegradability. Anaerobic digestion to treat such sludge is limited due to the presence of recalcitrant compounds decelerating hydrolysis, and enlarging digester volume. Hence, the optimization of single ultrasound (US), single ozone (O3), and hybrid (combined US and O3) pretreatment methods based on sludge disintegration degree (DD) and the characterization of untreated and pretreated PWAS at the optimized process conditions were executed in this study. The highest DD of single US-pretreated PWAS was 72% at 20 kHz, 1.25 W/mL power density, and 61813 kJ/kg TS specific energy for 15 min sonication. The greatest DD of single O3-pretreated PWAS was recorded as 29% at 72.4 mg O3/min flow rate, and 0.157 g O3/g TS ozone dose for 15 min ozonation. When PWAS was pretreated with single US (1.25 W/mL for 15 min), single O3 (0.040 g O3/g TS for 5 min), and hybrid (US followed by O3, 1.25 W US/mL for 15 min, 0.040 g O3/g TS for 5 min) methods, and the most significant DD of 87% was achieved after hybrid pretreatment. Hybrid pretreatment displayed a synergistic effect on sludge disintegration which could be attributed to the contribution of ultrasonic cavitation on the disruption of sludge cell structure by ozonation owing to the amplified rate of mass transfer and ozone decomposition improving oxidation capacity of ozone.
Plastik atıkların geri dönüşümüne yönelik toplum tutum ve davranışlarının anlaşılması: İstanbul'da bir örnek vaka çalışması
Natural resources are rapidly depleting in response to infinite needs of humans. Damage to natural habitats has reached a level that cannot be ignored. In this sense, the most communicated topic is, undoubtedly, the "climate change". Climate change is based on many different factors and activities, one of these being the "waste" problem. Surely, "plastics" are at the forefront of the ongoing discussion on waste. This study discusses recycling of plastic packaging waste. It is aimed to reveal the effects of environmental concerns, consequence awareness, level of plastics knowledge, moral norms, and situational/structural factors on plastic recycling intention, as well as the potential connection between plastic recycling intention, structural factors, and plastic recycling behavior. The study investigates consumer attitudes towards plastic waste and the factors affecting recycling intention and behaviors. In this regard, the Theory of Planned Behavior (TPB) was emphasized and similar studies in this field were examined. To analyze the conceptual model created for the research, an online survey was presented to plastic packaging consumers in Istanbul. The collected 275 survey data were used in the analysis. The data was analyzed by using Logistic Regression analysis with the SPSS (Statistical Package for the Social Sciences) program. According to the results, there is a partial positive relationship between environmental concerns, level of plastics knowledge, moral norms, and situational/structural factors and plastic recycling intention. Results found no significant link between consequence awareness and plastic recycling intention. There was a positive relationship between situational/structural factors and recycling attitude and recycling behavior.
Identification of microplastic and microbial compositions in a wastewater treatment plant employing RBC unit
This study investigates the abundance, characteristics, removal efficiency, and microbial colonization of microplastics (MPs) in a full-scale wastewater treatment plant (WWTP) employing Rotating Biological Contactor (RBC), an attached-growth technology for biological treatment. Wastewater and sludge samples were collected in three seasons (winter, spring, and summer), and a total of 6,160 suspected particles were isolated. Fibers were consistently the dominant morphology across all sampling points and seasons, accounting for 92% of all extracted particles. Seasonal variations were observed in influent concentrations, with the highest MP loads measured during winter and summer, likely corresponding to fluctuations in campus-related human activity patterns. Despite these variations, effluent concentrations remained low (12–14 particles/L), and overall removal efficiencies ranged between 92% and 96%. Sludge was identified as the major sink for MPs, containing 102–132 particles/g. Size-based evaluations revealed that medium-sized particles (250–1000 µm) were the predominant class and were removed more effectively than other fractions. Raman spectroscopy identified polyethylene terephthalate, polyvinyl chloride, nylon, and polypropylene as the most common polymer types. To assess microbial community structure, 16S rRNA gene sequencing was applied to both bulk samples and microplastic-associated fractions collected in November 2024 and February 2025. The dominant bacterial phyla across all samples were Proteobacteria, Firmicutes, Bacteroidetes, and Chloroflexi, although their relative abundances varied by sampling point and date. MP-associated microbial assemblages differed from the surrounding bulk communities, reflecting selective colonization processes on microplastic surfaces.
Effect of trace elements on biogas production: Maize silage
In the last decade, the energy requirement in the world has been increasing drastically. Turkey has been the second country in respect of natural gas and electricity requirement growth after China. The growing energy demand has resulted in dependency on energy imports in Turkey. In order to decrease the energy import, alternative energy sources should be developed. Biogas is a type of renewable energy that is generated by using organic matter like food waste, animal waste and energy crops. Biomass capacity is very high in Turkey, and biogas, as an alternative energy source, has a very grand potential to contribute to meet the energy demand in Turkey. The purpose of this experimental work was to analyze the effect of trace elements on biogas generation from maize silage as substrate. Co, Ni and Mo were selected as trace elements, and these elements were added to the reactors separately or in combination at varied doses. The biogas volume, biogas composition, biogas yield and methane yield were monitored in order to investigate the impact of trace element supplementation. Ni and Co were put to the reactors at a rate of 0.1 mg/L and 0.5 mg/L, respectively. The concentration to be added to the reactors for Mo were selected as 0.05 mg/L and 0.25 mg/L. As a result of the experiments, the trace element addition by Ni, Co and Mo increased the biogas volume, biogas composition, biogas yields and methane yields for anaerobic digestion of maize silage.
Boğaziçi Üniversitesi Sarıtepe Kampüs'teki partikül madde konsantrasyonunun araştırılması
Particulate matter (PM) are released into the atmosphere from both anthropogenic sources such as transport and biomass burning and from natural sources such sea-salt, soil dust and vegetation. The purpose of this study is to evaluate chemical composition and possible sources of airborne particulate matter (PM) at the Sarıtepe campus of Boğaziçi University which is located along the Black Sea coast. The campus is also close to the forests of northwestern Istanbul and the newly opened highway connecting to the Yavuz Sultan Selim Bridge. Particulate matter samples were collected from various locations. The study extended over a period of 10 months (21 March 2017 to 20 January 2018). Sensitive laboratory techniques (ICP-OES, IC, AAS) were used for the analysis of the collected solid and aqueous phases. In total 360 samples were analyzed for 26 parameters: F-, Cl-, NO2-, NO3-, SO42, PO43-, Br-, Mg+, Ca2+, K+, Na+, Cr, Mn, Fe, Ni, Cu, Zn, Al, Cd, Pb, Si, Co, Mo, pH, TDS and electrical conductivity. Potential sources of the collected PM were investigated using a multivariate factor analysis technique (PMF). Results of the study show that the metal compositions are highly correlated to each other. Concentrations of some metals are higher than some reported data in the literature. The composition of the collected PM indicates that both anthropogenic and natural sources have contributed to the PM in the study area. Specifically, PMF analysis suggests that the PM most likely originates from 4 sources: agricultural activity, burning processes, marine aerosol, and roadway transportation.
Effects of arbuscular mycorrhizal fungi interactions and sewage sludge application on heavy metal phytoremediation in mine tailings
Phytoremediation can be enhanced by the substantial symbiotic relationship between Arbuscular Mycorrhizal Fungi (AMF) and the hyperaccumulator plants (sunflower). AMF set up intimate hyphal network of fungi with the host plant root and enables nutrient, water and heavy metal uptakes. Additionally, application of sewage (wastewater) sludge as a soil amending material improves the phytoremediation efficiency by supplying nutrients and promoting the growth of plants. This study aims to investigate the effects of AMF interactions and sewage sludge application on heavy metal phytoremediation in mine tailings. The samples of chrome tailings having very high heavy metal (Cr, Al, and Fe) contents were ameliorated by phytoremediation enhanced by inoculation of Glomus mosseae or Glomus intraradices and application of three different doses of sewage sludge and buffer soil. The results showed that AMF inoculation improved the efficiency of phytoremediation by increasing the metal uptake of plants. The sludge application improved the growth of plants. The combined Glomus mosseae and sludge (20 g/kg) amendments resulted with the highest plant heavy metal uptake and phytoremediation efficiency. This study offers confirmation on the role of the plant biomass and phytoextraction efficiency interactions in Cr mine tailings as well as mycorrhizal associations and the contribution of the sewage sludge to the plants growth. The outcome of the study confirms that Glomalin related protein rose with the mycorrhizal associations. Meanwhile, the sewage sludge also helped the plant to propagate glomalin protein.
Recovery of silver and neodymium from aqueous solutions by using microalgae
Electronic waste is one of the fastest growing streams of waste due to the increase in electronics production. Electronic waste consists of valuable elements that many governments and companies wish to extract from the waste. Although the increase in the usage of electronic devices is inevitable, eco-friendly and easily operated recovery methods for the valuable elements can be developed. In this study, characterization of electronic waste were carried out by using three different digestion methods; USEPA 3051, USEPA 3050B and Modified Microwave Digestion Method to define focus elements. The recovery of selected elements was carried out by using green microalgae, Chlorella vulgaris. Results showed that silver and neodymium were found as major precious metal and rare earth element, respectively. Biosorption capacities were found as 151.7 mg/g for silver, and 296.8 mg/g for neodymium. Bioaccumulation capacities refer to 161.6 mg/g for silver and 239.7 mg/g for neodymium. When there were multi-elements in the solution, the uptake capacities decreased and uptake of selected element can be limited via changing the process parameters. Variations in functional groups were observed that suggests binding of elements to the microalgae. Silver and neodymium were seen on algal surfaces as particles and scattered, respectively. Pseudo-second order kinetics fitted better both to biosorption and bioaccumulation for silver and neodymium. Freundlich isotherm model and linear model was found suitable for biosorption and bioaccumulation, respectively. In the context of sustainability, this study supports the achievement of United Nations Sustainable Development Goals by following Goals: 3, 9, 11, and 12.
Occupational safety dynamics in onshore LNG receiving terminals: A systems modeling approach
In onshore LNG receiving terminals (LNGRTs), any unsafe condition and/or act that may cause fire and explosion during LNG processes may lead to major occupational accidents that may endanger people, equipment and the environment. Hence, to prevent accidents, determining factors that result in unsafe condition and/or act is crucial. LNGRTs are complex systems of interacting elements of managerial and employee decisions pertaining to occupational safety. Accordingly, in this study, based on system dynamics approach, a dynamic simulation model is developed to unravel the dynamic feedback structures that operate over time and can reveal unsafe conditions and/or acts, which signal probabilities of major occupational accidents. To gain insight into the system, besides literature review, fieldwork is done in a major onshore LNGRT. The model structure comprises the activities of LNG processing, equipment maintenance and repairing, employee training, where the management's time allocation decision under specific resource constraints is the fundamental driver. The model simulates for 5 years and is validated first structurally then behaviorally. Subsequently, system behaviors are analyzed by applying several scenarios and policies on the model. Though these analyses, the model behaviors reveal that possibility of major occupational accidents increases by decrease in allocated labor time for maintenance that increases unsafe conditions and by decrease in allocated labor time for training that increases unsafe acts. The model can also be used as an experimental platform to test the influence of several factors on safety, such as; schedule pressure, incident learning, equipment reliability, turnover rate, overwork, and occupational experience of employee.
A life cycle perspective for hydrometallurgical and biohydrometallurgical metal recovery from WEEE
Rare earth elements (REEs) are being employed in an increasing number of critical or widely popular consumer/ industrial products leading to increase in their demand particularly in the last few decades. Since almost all of REEs are produced in China, the European Commission and US energy department have identified REEs as critical elements and have directed special efforts to obtain sustainable resources of REE. End of life consumer electrical products contain significant amounts of metals and plastics. Thus the aim of this study is focused on recycling metals from waste electric and electronic equipment (WEEE). WEEE contains high amounts of base metals, precious metals and REEs. The concentration of metals in waste streams is higher than that of natural ores. Current recycling methods consume high amounts of energy and chemicals. Economically feasible industrial facilities (waste incineration) perform poorly for environment. In this study life cycle assessment (LCA) of two metal recovery systems were examined: biohydrometallurgical recovery of copper and hydrometallurgical recovery of neodymium from WEEE. Biohydrometallurgical methods are identified as environmentally friendly and low cost operation methods. An ex-ante scaled-up life cycle assessment (LCA) model was created for copper metal recovery. Results show that recovering only copper metal from WEEE is neither economically feasible nor environmentally friendly. The feasibility and environmental performance of neodymium metal recycling experiment model was investigated with a LCA scenario of neodymium iron boron magnet production model. It was found that neodymium metal recycling economically and environmentally performed better than virgin magnet production.
Identification of micropollutants in Ergene river and their biotransformation potential under anaerobic conditions
Ergene River spans Thrace from northeast to southwest and joins to Maritsa River, then falls to Aegean Sea at Turkey-Greece border. The river suffers pollution from different sources such as industrial and urban discharges, runoff from agricultural and animal farms. In this study, 222 micropollutants which are listed as contaminants of emerging concern or priority substances, 18 heavy metals and 13 conventional water pollution parameters were measured in 300 samples taken from 75 points on Ergene River at four seasons in the years of 2017-2018. Moreover, major source of micropollutants as well as pollutant fingerprint of major pollution source zones in the watershed were identified. Among the most important conventional parameters, COD, varied between 17 to 1660 mg/L during the year. The highest COD values were observed next to the Evrensekiz OIZ as well as Büyükkarıştıran OIZ consist of different industries such as textiles, dyes, food and chemical industries. Arsenic, aluminum, zinc, copper, lead and chromium concentrations reached to 1.0, 83.9, 33.6, 14.6 and 7.1 mg/L next to the OIZs, respectively. 131, 135, 96 and 103 organic micropollutants were detected in at least one point during summer, fall, winter and spring sampling, respectively. Concentration of micropollutants ranged from 10 ng/L to 330 mg/L. The micropollutants embraced a wide spectrum of chemicals originated from various industrial, agricultural and domestic activities. Benzotriazoles, hexa(methoxymethyl) melamine (HMMM), tris (2-butoxyethyl) phosphate (TBEP) and benzalkonium chlorides (BACs) were the most frequently detected chemicals as well as the ones with the highest concentration. OIZs located next to the Çorlu and Ergene Creeks as well as Büyükkarıştıran OIZ were the main sources of those pollutants. For instance, HMMM was mainly originated from the textile industries located in Büyükkarıştıran OIZ. In addition, biotransformation potential of the aforementioned micropollutants which are mainly discharged from textile and metal industries into the river, at the simulated water-sediment system was tested under anaerobic and sulfate reducing conditions. Benzotriazoles and TBEP were degraded partially whereas no biodegradation was determined for HMMM and BACs. The outcomes of this study can be used to understand the fate of dominant contaminants in the river sediment and develop future pollution mitigation strategies for Ergene River.
İstanbul'da transit gemi trafiğinin sebep olduğu hava kirliliğinin sağlık ve maliyet açısından değerlendirilmesi
Air pollution has become a leading environmental concern as a result of rapid urbanization in recent decades. The pollutants of most concern relating to the burning of fossil fuels include sulphur dioxide (SO2), nitrogen oxides (NO2) carbon monoxide (CO) and particulate matter (PM). The purpose of this study is to evaluate the contribution of transit marine traffic through the Bosphorus (Istanbul Strait) on the air quality of Istanbul. Atmospheric emissions originating from ships passing through the Bosphorus were computed and the EPA-approved CALPUFF atmospheric dispersion modelling computer program was used to estimate the air pollutant concentration distributions resulting from maritime traffic. The corresponding health impacts and related health costs due to emissions from maritime traffic are estimated using the EVA (Economic Valuation of Air pollution) methodology. The results show that, ship emissions have major effect on the overall air quality. Along the Bosphorus strait, the yearly average impact due to ship emissions is upto 60 % of the SO2 Turkish air quality standard, nearly 35 % of the NO2 Turkish air quality standard and approximately 2.5 % of the PM10 Turkish air quality standard. The corresponding health impacts expressed in morbidity and premature mortality estimates as significant. It is estimated the transit maritime traffic through the Bosphorus is causing about 2,540,000 adverse health incidents, the vast majority are asthma. More severe morbidity impacts include 47 cases of lung cancer and 116 cases of congestive heart failure. The model also estimates 69 cases of acute death and 2255 of YOLL (years of life lost). The total associated health-related costs are estimated to be 83.3 million euros. Given the proximity of large populations to the Bosphorus strait and the large volume of maritime traffic that passes thorugh it, there is a need to impose stricter standards on ship stack emissions.
Environmental sustainability for selected packaging wastes
Rapid production and consumption have led to increase in the waste generation in the past several decades. According to the Eurostat (2018) 19% of total municipal solid waste is comprised of packaging waste. To alleviate the environmental impacts associated with packaging waste in both production and disposal phases, recycling is a key solution. The aim of this study is to evaluate selected plastic and glass beverage packaging wastes in Turkey according to the national recycling targets using a Life Cycle Assessment (LCA) methodology and provide science-based recommendations for development of roadmap for achieving sustainable consumption and production goals. For this purpose, the current years (2017 and 2018) and the future (2025) national and EU recycling targets were assessed by LCA on an annual basis. The data for both production and recycling processes were obtained from packaging factories and recycling facilities. The energy processes used in the study were calculated according to the primary energy sources of the relevant year. With this study, the contribution of recycling to the environmental impacts of glass and PET packaging during the life cycle was analyzed.
Removal and discharge of microplastics from the wastewater treatment plants in Istanbul
Wastewater treatment plants (WWTPs) act as both receivers and sources of microplastics as they both receive microplastics from household and commercial activities and release the particles that could not be retained. This study investigated several units of a tertiary WWTP with a nutrient removal unit. Samples after physical treatment and from the effluent were also taken as 3h composite samples in order to observe fluctuation effect of influent wastewaters. Dried sludge from the WWTP was also investigated for potential hazards with application of the sludge to the soils. Particles isolated from samples were divided into fibers, fragments, nylons, pellets and glitters based on their morphological characters. Fibers were the most dominant shape, followed by fragments. 500-1000 μm and 1000-2000 μm was the most common size ranges for wastewater samples and sludge, respectively. Size distributions were different for shape classes. Particles in different size ranges demonstrated distinct behaviors for some size classes in various units of the WWTP. Fragments <500 μm were removed more efficiently where fibers with sizes 250-500 μm and 1000-2000 μm were removed better within the WWTP. 84.6 and 93.0% removal were observed with grab and composite samples. Despite the high removal rates 5,151x106 particles/d were released to Marmara Sea where, 36 days of discharge was equal to abundance value reported for Marmara Sea and 5,069x106 particles/d were present in the dried sludge. Polymer structures were not confirmed therefore, the rates calculated represent the microlitter release and microplastic release rate should be lower with a characterization step utilized.
Investigation of temporal variations in particle number concentrations of ambient air in Ankara and the relationship between particle number and mass concentrations
In this study, temporal variations in the number and mass distribution of atmospheric particles are investigated. Particle number distribution of particles was measured using a laser spectrometer at every minute for 12 months. In addition to particle number measurements, PM2.5 and PM10 samples were collected at the same time and at the same location. Particle mass concentrations were measured in the collected samples. Statistical tests are used to determine factors affecting variations in particle number concentrations. The effect of meteorological variations and the effect of anthropogenic and natural events on particle count and mass concentration data are analyzed. In the study, a mathematical model is developed, based on the collected data, to convert the particle number concentration data to particle mass concentration data and evaluate the direct effect of meteorological data on the particle count concentration data. The model is verified by a detailed comparison of the results obtained from the model with the GRIMM mass concentration results.
The impact of flow connectivity on the interpretation of pumping test data
The spatial variability of subsurface flow parameters, such as the transmissivity or storativity, is a common feature of all geologic systems. Traditional geostatistical techniques expressed this heterogeneity in terms of two-point correlations. Recent research suggests that such characterization technique may not be adequate to fully represent the complex patterns of flow and transport in heterogeneous subsurface systems. The concept of flow connectivity has been introduced to describe how different regions of the aquifer relate to each other. In this study, the impact of point-to-point flow connectivity on radially convergent flow towards a well is investigated numerically. A Monte Carlo approach is adopted whereby a large number of heterogeneous aquifer systems with different levels of connectivity are synthetically generated and then used to simulate pumping tests. Two pumping test methods, the Cooper-Jacob Method and the Continuous Derivation Method, are used to estimate the flow parameters from the time-drawdown curves, and examine how the estimated parameters relate to the underlying heterogeneous aquifer systems. Results indicate that the estimated transmissivity value approaches to the geometric mean of the full transmissivity field as the time-drawdown derivative dataset is included in the interpretation. On the other hand, the estimated storativity is strongly influenced by the spatial distribution of the transmissivity, the aquifer point-to-point flow connectivity and the relative locations of the observation and pumping wells. The relations between the estimated storage coefficient and a static measure of connectivity are also examined.
Groundwater appropriation game: A dynamic simulation approach
This research explores the common pool resource (CPR) characteristics of groundwater resources by dynamic simulation modeling and computer gaming. As the largest source of freshwater in the world, groundwater is deemed one of the most valuable resources. Due to the difficulty of excluding potential users and high subtractability of the benefits consumed by one user from those available to others, groundwater resource is conceptualized as a CPR. As a CPR, groundwater is prone to both provision and appropriation problems including but not limited to drying up of wells, increased pumping costs and deterioration of water quality due to the intrusion of salt water. In this research, allocation of flow (the extracted groundwater) from the resource stock (extractable water at the aquifer bed) during a single irrigation season is investigated. When groundwater users act independently to increase their water extraction, the resulting drawdown of the water table may lead to an increase in energy costs and reduce overall, as well as individual benefits. This represents a CPR dilemma among the irrigators, where the actors have to cooperate for the quantity and coordinate for the timing of their irrigation activity to increase overall benefits. To facilitate learning in and about the dynamic complexity of this dilemma, a network based dynamic simulation game is developed. The game is grounded on a dynamic simulation model. The model represents the groundwater dynamics (i.e. groundwater flows within the aquifer and recharge mechanism) and dynamic relationship between water extraction and crop yield. The model also calculates biweekly and end- of-the-season statistics for the individual farms on finances and water use efficiencies. Namely the Groundwater Irrigation Game is a multiplayer, dynamic game in which participants seek to maximize their farm profits while they are faced with the renewable resource limits. This game allows participants to explore consequences of different strategies and gain insights about the complex dynamics of the commons. Accordingly, the initial observations obtained from the pilot gaming indicate that the game instructions are sufficient for participants to develop a strategy and achieve their goals.
Removal of organics in reverse osmosis concentrate by advanced treatment
Due to its effective and reliable purification performance, reverse osmosis technology is one of the practical and affordable ways to produce high quality recycled water. However, a major drawback of reverse osmosis is the production of concentrate usually accounting for 15-20% of the input stream containing high levels of organic pollutants some of which could be toxic and bio-accumulative. Possessing a threat to the environment, reverse osmosis concentrate (ROC) must be treated to reduce or even eliminate the negative impact associated with the presence of organic pollutants. The main objective of this research was to investigate the applicability of homogeneous and heterogeneous advanced oxidation processes on municipal wastewater derived reverse osmosis concentrate treatment. For this purpose, reverse osmosis concentrate samples in the absence and presence of emerging contaminants were synthetically prepared with respect to physicochemical characteristics reported in the literature. Sulfamethoxazole and Carbamazepine were selected as target emerging contaminants owing to their common presence in wastewater sources. UVC/H2O2 and Fenton processes were selected as homogeneous advanced oxidation processes whereas solar photocatalysis by using commercially available photocatalysts as well as synthesized ones was considered as heterogeneous advanced oxidation process. Assessment of selected processes for their effectiveness on the removal of complex organic matter was presented in comparison to the sole photolytic oxidation conditions. Since molecular size distribution profiles of organic compounds in ROC plays an important role in order to assess the removal of different pollutants with respect to different molecular size fractions ROC samples were exposed to molecular size fractionation prior to and following photolytic and photocatalytic degradation processes. Expected potential risk was investigated through toxicity assessment prior to and following photodegradation and photocatalytic degradation processes. Organic fraction of reverse osmosis concentrate samples were monitored mainly by UV-vis and advanced fluorescence spectroscopic techniques in combination with PARAFAC modeling as well as organic carbon content.
Aggregation of natural colloidal particles under solar irradiation
Aggregation/agglomeration of nanoparticles affects their fate and transport in natural waters. Although nanoparticles behave as colloidal matter expressing aggregation/agglomeration properties under natural water conditions, the role of aggregation/agglomeration during photocatalysis has not been demonstrated clearly so far. The main objective of this study could be described as assessment of the colloidal behavior of the binary system i.e., NOM representative organics and nanoparticles representative of photocatalyst specimens described by following basic experimental procedures prior to, during and under post photo-treatment conditions. To fulfill this aim, dynamic light scattering, sedimentation and turbidity experiments were performed. Aggregation and/or agglomeration of TiO2 nanoparticles were assessed by using the above indicated physico-chemical parameters in relation to water matrix effects as well as photocatalytic removal efficiencies. Aggregation and/or agglomeration behavior of both matrix components provided information on expected reactivity under irradiation during photocatalysis. Overall evaluation of the systems provided information both during photocatalysis as well as light induced reactions under environmental conditions. Therefore, a broader insight was deduced on the fate of nanoparticles through photocatalysis.
Enhanced anaerobic mono-digestion and co-digestion of crop residues by NaOH alkali pre-treatment
The main objective of the study was to determine the effect of different dosages of NaOH alkali pre-treatment on the lignocellulosic structures and the methane production of crops' residues. In this regard, NaOH pre-treatment was implemented with different dosages on three different crops' residues: wheat, rye, and rice straws. Substrates were soaked into NaOH solutions at different dosages with solid to liquid ratios of 100 and 200 gTS/L to investigate both conditions. Anaerobic digestion process was conducted using AMPTS II under mesophilic conditions. By 8 % NaOH pre-treatment dosage, the reduction of hemicellulose and lignin was 81 % and 62 % for rice straw, 86 % and 69 % for wheat straw, 80 % and 74 % for rye straw, respectively. The concentrations of CODs in the liquid fraction after pre-treatment were regarded as 3 times higher than untreated samples. Pre-treatment with 8 % NaOH dosage increased the methane yield of rice, wheat, and rye straws by 55 %, 40 %, and 46 % respectively. During the co-digestion test, an increase in VFA production was regarded by (rice/wheat) and (rice/wheat/rye) sets by values of 1930 and 1710 mg/L total acetic acid on the 5th day. Samples from digesters that produced the highest methane yield were chosen for further molecular analysis. Proteobacteria was found the most abundant bacterial phylum in the inoculum used, while Methanothermobacter and Methanoculleus were the major archaeal communities found. Compared to untreated digesters, 16S rRNA gene amplicon sequencing revealed more diverse microbial communities in NaOH digesters.
Numerical modeling of the coupled mechanisms underlying salt accumulation in agricultural soils
Sodicity is a widespread significant threat to agricultural soils with adverse impact on soil properties and crop yields. The main processes underlying this environmental hazard is the excessive accumulation of sodium ions within the soil due to the use of saline groundwater for irrigation along with high rates of evaporation. This situation naturally puts agricultural soils in arid and semi-arid regions into that risk and therefore understanding the mechanisms behind it gains importance. Although, there have been numerous studies to understand and model the problem, a detailed modeling of the coupled processes can provide further insight into the different mechanisms and their interactions. The main processes included in the model include liquid and vapor water flow, solute transport and sorption, heat transport, and evapotranspiration assess, and according to that, a numerical 1D model code is developed using an explicit finite difference method. The model is applied to a series of different cases with crop and meteorological data adopted from the Konya Closed Basin a significant agricultural region of Turkey and under the risk of sodicity with increasing drought in recent years. The factors tested in assessing soil sodicity are irrigation water quality, crop type and climate change. The importance of including heat and vapor transport during such calculations are presented and discussed.
Türkiye'de elektrik üretimi kaynaklı CO2 emisyonlarının Boğaziçi Üniversitesi enerji modellemesi sistemi (BUEMS) kullanılarak analizi
Due to factors such as industrialization, increase in population and economic growth electricity demand has shown a significant increase at global scale. This increase has put forward discussions concerning electricity supply security, source diversification and clean electricity generation. Fossil based electricity generation featured the transition to clean generation in this sector. Particularly, towards the goal of the Paris Agreement, policy developments have gained momentum to reach carbon neutral electricity sector by 2050. These developments have been closely monitored by Turkey. The purpose of this thesis is to evaluate long-term results of the CO2 emissions resulting from electricity sector in Turkey by using BUEMS model in line with latest available data and updated policy papers. Total electricity installed capacity, generation portfolio and increase in electricity demand were investigated. In the context of the thesis, a Base scenario was established. The response of the electricity sector under carbon tax and emission restrictions and their effect to CO2 emissions were analyzed. The results of the study showed that tax and emission targets played an important role for CO2 emission reduction. In Base Scenario, Total CO2 emissions exceeded 1,000 Million tons and electricity sector's contribution was almost 680 Million tons in the year 2057. Among all scenarios the highest decrease was obtained under Peak Emission Scenario. Total emissions reduced to 705 Million tons and emissions from electricity sector decreased by 61% compared to Base Scenario and fell to 244 Million tons in 2057 by means of renewables and nuclear penetration.