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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Evaluation of in-situ chemical flushing and oxidation technologies for the remediation of aquifer systems contaminated with DNAPLs
Organic compounds- such as petroleum hydrocarbons and chlorinated solvents- are widely used in numerous industrial applications. Because of their low solubility many of these compounds are often present in the environment in the form of dense non-aqueous phase liquids (DNAPLs) that act as long-term sources of pollutions. This study focuses on two technologies for the remediation of groundwater resources contaminated with DNAPLs: in-situ enhanced solubilization (ISES) and in-situ chemical oxidation (ISCO). The research aimed to investigate the synergetic benefits of combining these two technologies. Additionally, a numerical multiphase flow model was used to simulate the DNAPL fate and transport to improve our understanding of process mechanisms, and to explore alternative remediation methodologies and strategies. The performed laboratory experiments and modeling work show that the non-ionic surfactant Tween 80 is effective for the recovery of PCE entrapped in both silica sand and natural calcareous soil. For multicomponent DNAPL mixtures, the enhancement factor of each component plays an important role in determining the remediation efficiency. Combining surfactant enhanced dissolution with potassium permanganate produced improved overall mass removal. Pulse injection can yield longer contact times, resulting in more effective DNAPL removal. Heat-activated persulfate oxidation, whereby the system temperature is raised to about 50 ℃, can successfully activate the persulfate, resulting in improved DNAPL mass recovery. Furthermore, this study shows that multiphase modeling is an effective tool that can accurately simulate ISES and ISCO technologies, and potential help in the design and opitimization of field scale remediation of groundwater contaminated with DNAPLs.
Assessing microplastic abundance and distribution in rivers: A mechanistic modeling approach
Rivers are major transport pathways for microplastics to reach the oceans. Microplastics have numerous different shapes; however, theoretical models generally assume microplastics as spherical particles. This study aims to investigate (i) spatiotemporal distribution and the potential sources of microplastics in an industrially polluted river, (ii) the relationship of microplastic abundance with river's morphological and hydrodynamic characteristics, and (iii) vertical transport of microplastics and the effect of particle and flow characteristics on settling and resuspension. To achieve these aims, water and sediment samples were collected from six sites of the Ergene River in May 2019 and Sep 2020. A mechanistic model was developed using the data of microplastics, and river hydrodynamics and morphology. According to the results, the Ergene River had excessive levels of microplastics compared to many other rivers. Microplastic concentrations in water correlated positively with depth but negatively with channel width. Fibers were the most abundant shape of microplastics suggesting that effluents from textile industries were the foremost contributor of microplastics in the river. The model results revealed that the residence time of microplastics in water was directly related to the flow characteristics, while initial concentration of particles in water dominates the other parameters in settling and resuspension fluxes of microplastics. According to the scenario analysis, settling and resuspension fluxes increased with increasing sphericity and size of the particles, as well as higher bed shear stress. The model results were sensitive to changes in shape factor developed for this model, therefore this parameter should be improved in future studies.
Portakal kabuğundan hazırlanan aktif karbon ile sulu ortamdan ibuprofen gideriminin incelenmesi
Bu tezde, steroid olmayan anti-inflamatuar bir ilaç olan ibuprofenin portakal kabuğundan hazırlanan aktif karbon ile sulu ortamdan giderimi araştırılmıştır. Bunun için çalışmanın ilk adımında portakal kabuğundan aktif karbon hazırlanmış ve bazı analizler ile karakterize edilmiştir. Çalışmanın ikinci adımında ise, hazırlanan aktif karbonun adsorpsiyon etkinliğini belirlemek için bu aktif karbon kullanılarak sulu ortamdan ibuprofen giderimi kesikli adsorpsiyon deneyleri ile çalışılmıştır. Çözeltinin başlangıç pH'ı, aktif karbon dozu, başlangıç ibuprofen konsantrasyonu ve sıcaklık gibi çeşitli parametrelerin ibuprofen giderim etkinliği üzerindeki etkileri incelenmiştir. Çalışmanın sonuçları, ibuprofen gideriminin asidik şartlarda daha yüksek olduğunu göstermiştir. Bununla birlikte, çalışılan diğer pH'larda da etkili bir giderim sağlanmıştır. Giderim verimi aktif karbon dozunun artışı ile artarken, başlangıç ibuprofen konsantrasyonunun artışı ile azalmıştır. Sıcaklık artışı ise giderim veriminde az bir artış sağlamıştır. Farklı sıcaklıklarda elde edilen deneysel veriler Langmuir ve Freundlich izotermlerine uygulanmıştır. Sonuçlar ibuprofen adsorpsiyonunun Langmuir izoterm modeline daha iyi uyduğunu göstermiştir. Langmuir izoterm modeline göre, 25, 40 ve 55 oC sıcaklıklarda aktif karbonun maksimum adsorpsiyon kapasitesi (qmax) sırasıyla 243.90, 250.00 ve 270.27 mg/g olarak belirlenmiştir. Deneysel veriler birinci ve ikinci derece kinetik modellerine uygulanmış ve sonuçlar aktif karbon ile ibuprofen adsorpsiyonunun yalancı ikinci dereceden kinetik modeli takip ettiğini göstermiştir. Bu çalışmanın sonuçları, portakal kabuğundan elde edilen aktif karbonun su ortamlarından ibuprofen giderimi için yüksek verimli ve geri dönüştürülebilir bir adsorbent olduğunu ortaya koymuştur. Sonuç olarak, bu aktif karbon, su ortamlarından ibuprofen giderimi için umut verici bir adsorbent olarak önerilebilir.
Tavuk kesimhanesi atıksularının yeni geliştirilen bir ananaerobik reaktörle arıtımı
Bu çalışmada kuvvetli organik içeriğe sahip endüstriyel bir atıksu olan tavuk kesimhanesiatıksuyunun arıtımında yeni geliştirilen bir anaerobik reaktörün (Sabit Granül YataklıAnaerobik Reaktör, SGYAR) performansı araştırılmıştır. Çalışmada, ayrıca SGYAR'ninmodifiye edilmiş bir başka hali olan anaerobik granül yerine anaerobik çamur (Sabit ÇamurYataklı Anaerobik Reaktör, SÇYAR) kullanımının da performansı nasıl etkilediğiaraştırılmıştır.Bu amaçla yatak malzemesi olarak, biri 3070 ml anaerobik granül, diğeri ise altta 675 mlanaerobik granül (reaktörün % 25' lik aktif hacmi) üst kısımda 2.025 ml anaerobik çamur(Reaktörün % 75' lik aktif hacmi) kullanılan iki adet reaktör kurulmuş ve tavukkesimhanesinden gelen atıksu ile beslenmiştir. Hidrolik bekletme süresi sırasıyla 60, 48, 36 ve30 saat olarak ayarlanmıştır. Çalışma sonunda SGYAR' de hidrolik bekletme süresi 60, 48, 36ve 30 saat aralıklarında iken KO giderim verimleri sırasıyla, %94,2, %95,1, %95,0 ve %96,2 olarak gerçekleşmiştir. SÇYAR' de ise KO giderim verimleri 60 ve 48 saatlik hidrolikbekletme sürelerinde sırasıyla, %94,7, %95,2 değerlerini almış 36 saatlik bekletme süresindegeçen 2 haftada ise %96,7 değerinde çıkmıştır. Ancak 36 saatlik bekletme süresinegeçildikten 3 hafta sonra SÇYAR atıksuyu drene edememiştir. Çalışma sonuçlarına göreSGYAR uygulanan hidrolik bekletme süresi ve organik yüklerde oldukça başarılı bir arıtımgerçekleştirirken, SÇYAR 36 saatlik hidrolik bekletme süresine kadar uygulanan organikyüklerde çok iyi bir arıtım gerçekleştirmiş, ancak 36 saatlik hidrolik bekletme süresininardından hacimsel yükü kaldıramadığı ve tıkandığı gözlemlenmiştir.Anahtar Kelimeler : Granül, anaerobik çamur, sabit granül yataklı anaerobik reaktör(SGYAR), sabit çamur yataklı anaerobik reaktör (SÇYAR), mezbaha atıksuları
Antibiyotik toksisitesinin mikrobiyal yakıt hücresi (NHY) tabanlı biyosensör kullanarak tespiti
Antibiyotikler, insan ve hayvanlarda bakteriyel enfeksiyonların tedavisinde yaygın bir şekilde kullanılan antimikrobiyal ilaçlardır. Antibiyotiklerin dünya genelinde kullanımının giderek artması sonucunda bu bileşikler atıksu arıtma tesislerine ulaşmakta ve aktif çamur prosesinin performansını etkilemektedir. Biyolojik arıtma tesislerinde erken uyarı sistemleri toksik bileşiklerin saptanması için kritik öneme sahiptir. Bu tez çalışmasında üç farklı tetrasiklin antibiyotiklerinin (terasikilin, klortetrasiklin ve oksitetrasiklin) mikroorganizmalar üzerindeki toksik etkisinin mikrobiyal yakıt hücresi (MYH) tabanlı biyosensörler kullanılarak tespiti araştırılmıştır. MYH reaktörlerine enjekte edilen antibiyotik konsantrasyonu 0.25-50 ppm aralığında olacak şekilde ayarlanmıştır. Söz konusu antibiyotik konsantrasyonları altında MYH reaktörünün performansı detaylı bir şekilde araştırılmıştır. Çalışma sonuçları MYH sistemine enjekte edilen antibiyotik konsantrasyonu ile MYH'nin güç üretiminde meydana gelen inhibisyon oranı arasında korelasyonun mevcut olduğunu göstermiştir. En yüsek toksik etki klortetrasiklin antibiyotiğinde meydana gelmiştir. Diğer taraftan, antibiyotik konsantrasyonunun artışı ile biyofim direncinin arttığı belirlenmiştir. İşletme süresi sonunda anot yüzeyinden alınan SEM görüntülerinde az sayıda bakterinin varlığına rastlanmıştır. Ayrıca membran yüzeyinde yüksek miktarda bir çökelti tabakasının mevcut olduğu görülmüştür. Elde edilen sonuçlar MYH tabanlı biyosensörlerin antibiyotiklerin tespiti için kullanılabileceğini göstermiştir.
Çoklu tetrasiklin grubu karışımının hidrojen ve oksijene dayalı membran biyofilm reaktörlerinde giderimi
Tetrasiklin antibiyotikler (TCs) yaygın olarak insan tedavisi, hayvan tedavisi ve tarımda kullanılan geniş spektrumlu antimikrobiyal bileşiklerdir. Bu çalışmada hem H2'ye hem de O2'ye dayalı MBfR'larda eş zamanlı tetrasiklin, oksitetrasiklin, klortetrasiklin ve azotlu bileşiklerin giderimi çalışılmıştır. Hidrojene dayalı MBfR'da eş zamanlı olarak TC, OTC, CTC ve NO-3 giderimi çalışılırken, oksijene dayalı MBfR' de eş zamanlı olarak TC, OTC, CTC ve NH4 giderimi çalışılmıştır. Reaktörler 4 psi gaz basıncında ve 1-10 saat arasında değişen HRT' lerde işletilmiştir. Ayrıca çalışma sonuçlarına göre antibiyotik giderim verimleri, akı değerleri, hidrojen ve oksijen eşdeğer akıları hesaplanmıştır. Çalışma sonuçlarına göre H2-MBfR' de 10 saatlik HRT' de antibiyotik giderim oranları TC, OTC ve CTC için sırasıyla %93, % 91 ve % 99 olarak bulunmuştur. HRT 5 saate düşürüldüğünde giderim oranları sırasıyla % 66, % 69 ve % 91 'e düşmüştür ve HRT 1 saate alındığında antibiyotik giderim oranları belirgin düşüşler göstererek TC, OTC ve CTC için sırasıyla % 14, % 24, % 42 olarak hesaplanmıştır. Akı değerleri 10 saatlik hidrolik bekleme süresinde ortalama TC akısı 2,23 mg/m2.gün, ortalama OTC akısı 2,52 mg/m2.gün ve ortalama CTC akısı 2,87 mg/m2.gün olarak bulunmuştur. 1 saatlik HRT değerinde akı ve hidrojen eşdeğer akıları artış göstererek TC, OTC ve CTC ortalama akıları sırası ile 4,08 mg/m2.gün, 6,72 mg/m2.gün, 12,12 mg/m2.gün olarak bulunmuştur. O2-MBfR' de yapılan çalışma sonuçlarına göre ortalama TC giderim verimi %53, ortalama OTC giderim verimi %55, ortalama CTC giderim verimi % 71 olarak bulunmuştur. 5 saatlik hidrolik bekleme süresinde TC, OTC ve CTC ortalama giderim verimleri sırası ile % 21, % 37 ve % 45 olarak bulunmuştur. HRT 1 saate düşürüldüğünde giderim verimleri daha da kötüleşerek % 7, % 24 ve % 32 olarak bulunmuştur.10 saatlik hidrolik bekleme süresinde çoklu antibiyotik karışımındaki ortalama TC akısı 1,57 mg/m2.gün, ortalama OTC akısı 1,61 mg/m2.gün ve ortalama CTC akısı 2,08 mg/m2.gün bulunmuştur. 1 saatlik HRT değerinde ise TC, OTC ve CTC ortalama akıları sırası ile 1,92 mg/m2.gün, 7,08 mg/m2.gün, 9,36 mg/m2.gün olarak bulunmuştur. Anahtar kelimeler: Membrane Biofilm Reactor, Tetrasiklin, Oksitetrasikline, Klortetrasikline, Giderim Akısı, Eşdeğer Akı
Pseudomonas fluorescens (NRRL B-2641) bakterisi kullanılarak lipaz üretimi
Bu çalışmada, bir gram (-) bakteri olan Pseudomonas fluorescens kullanılarak kesikli fermantasyon ile hücre dışı lipaz enzim üretimi gerçekleştirilmiş ve enzim üretimi üzerine ortam parametrelerinin etkisi incelenmiştir.Araştırmanın ilk bölümünde; sentetik fermantasyon ortamında kullanılan karbon ve azot kaynakları ile iz elementler değiştirilmiş ve optimum enzim üretim ortamı belirlenmiştir. Fermantasyon ortamına eklenen farklı karbon kaynakları içerisinde en yüksek aktivite %1 mısır yağı konsantrasyonunda elde edilmiştir. Farklı azot kaynağı konsantrasyonlarında P.fluorescens, organik azot kaynaklarında hem daha iyi büyüme hem de daha yüksek aktivite göstermiştir. Azot kaynakları içerisinde en yüksek aktivite % 0.4 pepton içeren fermantasyon ortamında bulunmuştur. Daha sonra fermentasyon ortamında bulunan fosfat konsantrasyonu değiştirilmiş ve en yüksek aktivite % 0.1 KH2PO4 ve K2HPO4 içeren ortamda elde edilmiştir. İyonlarının etkisini incelemek için Ca2+ ve Na+ iyonları kullanılmış ve % 0.03 CaCl2.2H2O içeren fermantasyon ortamında enzim aktivitesi yükselmiştir. Optimize edilen fermantasyon ortamında (% 1 mısır yağı, % 0.4 pepton, % 0.1 KH2PO4, % 0.1 K2HPO4, % 0.0005 MgSO4.7H2O, % 0.03 CaCl2.2H2O) en yüksek aktivite 3.425 U/mL olarak bulunmuştur.Optimize edilen fermantasyon ortamında (CaCl2.2H2O kullanılmadan); karbon kaynağı olarak atık kızartma yağların kullanıldığı ortamda, en yüksek enzim aktiviteleri patates ve tatlı kızartılmış atık yağlar için sırasıyla, 3.850 ve 3.975 U/mL olarak elde edilmiştir. Bu sonuç, atık kızartma yağlarının enzim üretimi için daha etkin bir substrat olarak kullanılabileceğini göstermektedir. Ayrıca fermantasyon ortamında bulunan yağ asitleri analiz edilmiş ve yağ asitlerinin P.fluorescens'in kullanımı sonucu zamanla azaldığı gözlenmiştir.Çalışmanın ikinci bölümünde; karbon kaynağı olarak bir katı substrat olan ayçekirdeği küspesi kullanılmış ve P.fluorescens'in lipaz enzimi üretilebilirliği araştırılmıştır. Mikroorganizmanın fermantasyon ortamı; musluk suyu, % 10 ayçekirdeği küspesi ve % 1 pepton içerdiği zaman maksimum 6.100 U/mL lipaz enzimi ürettiği belirlenmiştir. Doğal bir substrat olan ayçekirdeği küspesi kullanıldığında enzim aktivitesinin arttığı görülmüştür.Çalışmanın son aşamasında, laboratuar ölçekli 6 L hacmindeki biyoreaktör kullanılarak, farklı karıştırma ve hava akış hızlarında; enzim aktivitesi, sıvı faz hacimsel kütle transfer katsayıları (kLa) ve oksijen tüketim hızları (ro) hesaplanmış, en yüksek aktivite 0.32 vvm hava akış hızı ve 350 rpm karıştırma hızında, 2.350 U/mL olarak bulunmuştur. Bu ortamda en yüksek kLa ve ro değerleri ise sırasıyla 0.0423 s-, 0.0273 mg/L/s olarak elde edilmiştir. Biyoreaktörde gerçekleştirilen üretimlerde hava ve karıştırma hızları ile enzim miktarının arttığı, dolayısıyla da lipaz üretim prosesinde oksijen transferlerinin önemli olduğu görülmüştür.
Ultrasonik ve fenton yöntemleri kullanılarak sulardan renk giderimi
Nüfus artışı ve teknolojik gelişmelerden dolayı çevre kirliliği gün geçtikçe artmaktadır. Günümüzde çevre kirliliğine sebep olan spesifik kirleticilerinden biri de boyarmaddelerdir. Boyarmadde içeren atık sular, alıcı ortama deşarj edildiğinde su ortamında ışığın geçirgenliğini azaltarak fotosentetik aktiviteyi olumsuz yönde etkilemektedir. Ayrıca bazı sucul organizmalarda birikmesi sonucu toksik ve kanserojenik ürünler meydana gelmektedir. Bu çalışmada boyarmaddelerden biri olan Reaktif Siyah 5 (RS5) 40 mg/L derişim değerinde ultrases (US), Fenton (Fe+H2O2) ve US/Fenton reaksiyonlarına tabi tutulmuştur. Renk giderim verimleri araştırılmış ve en iyi renk giderim veriminin yakalandığı şartlarda reaksiyonların Toplam Organik Karbon (TOK) değerleri incelenmiştir. Ayrıca suda bulunan SO4-2, HCO3- ve NO3- iyonlarının ve N2 gazının renk giderime etkisi araştırılmıştır. Son olarak da yüksek derişimin sisteme olan etkisini görmek amacıyla 100 mg/L derişim değerine sahip RS5 boyarmaddesiyle 40 mg/L RS5 için belirlenmiş optimum şartlarda ultrases (US), Fenton (Fe+H2O2) ve US/Fenton reaksiyonlarında renk giderim verimleri ve TOK değerleri incelenmiştir. Yapılan çalışmalar sonucunda 40 mg/L derişime sahip RS5 boyarmaddesi için Fenton reaksiyonunda %91,55; US/Fenton reaksiyonunda %93,59 renk giderim verimi elde edilmiştir. 100 mg/L RS5 için ise Fenton reaksiyonunda % 91,50; US/Fenton reaksiyonunda %92,56 giderim verimi elde edilmiştir.
Minimization of excess sludge production
Large amounts of waste sludge are produced with the removal of biodegradable compounds and organic or inorganic matter in municipal and industrial wastewater treatment plants for disposal. It is expected that, in near future, sludge production and the regulation limits for disposal alternatives cause an increase in costs for sludge disposal. The current approach to sludge minimization is the reduction of volume of wet sludge and the reduction of dry mass of sludge. The volume of wet sludge for disposal is reduced significantly with the increase of the sludge solid content by dewatering. The reduction of dry mass of sludge leads to the reduction of solid content and volume and this strategy should be fovoured, beause it allows the immediate reduction of sludge dry mass during its production in the biological treatment stage.The fundamental aim of this thesis is the reduction of sludge production during the biological treatment. All of the techniques for sludge reduction described in this thesis suitable for implementation during the wastewater treatment plants, not after the sludge production, often by retrofitting the specific additional equipment. Two of these techniques were carried out experimentally and evaluated within the scope of this thesis. The effectiveness of ozonation integrated in activated sludge process and oxic-settling anaerobic (OSA) process were investigated on sludge reduction, especially.In the first stage of the study, Box-Behnken Statistical Design Program was used in order to determine the optimum operational conditions. Optimum hydraulic retention time (HRT), solid retention time (SRT) and initial COD (CODi) values for maximum COD removal were determined as 25 h, 25 d and 400 mg/L, respectively. After the determination of optimum operational conditions of activated sludge process, two systems were operated in parallel under these optimum conditions during 45 days until the steady state conditions and the effluent quality and sludge properties of the systems were monitored. When the steady-state conditions were reached, specific batch tests were carried out in order to investigate the biodegradability of disintegrated sludge and determine optimum ozone dose prior to the modification with the addition of ozonation unit to one of the activated sludge process. Optimum ozone dose for return activated sludge disintegration was determined as 0.05 gO3/gTS in terms of disintegration degree with 56.2 %. The higher doses improved disintegration degree, slightly.After the ozone dose optimization study, the effectiveness of partial ozonation of return activated sludge was investigated for the minimization of excess sludge production using ozonation coupled with activated sludge process in two stages. In the first stage of the ozonation, in ozonated system, 10 % of return activated sludge (0.1 QR) was ozonated every day during a month with optimum ozone dose and recirculated to the aeration tank. No excess sludge was withdrawn from the ozonation coupled with activated sludge process. The other activated sludge system was remained unmodified and operated as a control run with optimum operational conditions. Excess sludge was withdrawn every day due to SRT. 43 % observed sludge yield (Yobs) reduction could be achieved in ozone run during the operation period. At he the end of the operation, the 56 % of Yobs reduction was observed in ozone system compared to control system. In ozone run, the effluent quality was weakened slightly in term of COD and NH4-N removal. Sludge settling properties represented by SVI was improved in ozone run. Ozone run had lower dewaterability characteristics with higher CST values. The filterability of sludge was lower in ozone run than control run in terms of SRF.In the second stage of the ozonation 800 mL of the return sludge corresponded to 20 % of of the return activated sludge (0.2 QR) was ozonated with optimum ozone dose. 73 % Yobs reduction could be achieved in ozone run during the operation period. At the end of the operation, the 62 % of Yobs reduction was observed in ozone run compared to control run. The effluent quality was weakned slightly in term of COD and NH4-N removal in ozone run. Sludge settling properties was improved in ozone run in terms of SVI. Lower dewaterability characteristics in ozone run were proved with CST values. The filterability of ozonated sludge was lower than control run in terms of SRF.After the application of ozonation to activated sludge system, one of the system was modified by inserting anoxic tank to comprise OSA system. The other system was remained unmodified as a control system. A specific volume of return activated sludge of OSA system was subjected anaerobic conditions (-250 mV of low ORP level every day. OSA and control system were operated during 45 days. The sludge reduction efficiency and effluent quality were evaluated. After the completion of continuous operation, some batch experiments were conducted in order to investigate sludge reduction mechanisms in OSA process.In OSA system, 62 % reduction efficiency was obtained in yield production in OSA system during the operation. OSA system was also achieved 58 % reduction efficiency of Yobs compared to control run at the end of the operation. It was found that COD concentrations in the effluent in the OSA system were lower than that in the effluent of the control run due to the additional substrates from the anaerobic tank. The NH4-N removal efficiency in OSA system was lower compared to control run during the operation period due to denitrification. The setteability characteristics of sludge was also found better than that of the control system in terms of SVI. Higher CST values were obtained in control system compared to OSA system during the long term operation. It was revealed that the OSA system enhanced the filterability of sludge.In order to investigate the sludge decay theory in OSA sistem, two batch experiments with sludge taken from aeration tank of control and OSA systems were carried out. The aim of the first batch experiment was to investigate the relationship among sludge anaerobic reaction time, sludge lysis and sludge yield. The sludge reduction in terms of Yobs caused by sludge decay in OSA batch reactor was 40 % compared to control batch reactor for the first batch experiment. In the second batch test, the investigation of the energy uncoupling theory was aimed. The sludge reduction in terms of Yobs caused by energy uncoupling in OSA batch reactor was 5 % compared to control batch reactor.When the sludge reduction techniques used in this thesis were compared as modified activated sludge processes; the activated sludge process ozonated of 0.2 QR showed better Yobs reduction efficiency than that the fist stage of ozonation process (ozonation with 0.1QR) and OSA system during the operation period. The effluent quality of control systems were better than that modificated systems in terms of COD and nitrogen removal capacity however, the effluent quality of the modificated systems were at satisfactory level. The sludge characteristics of activated sludge were changed even slightly for some paramaters after the application of sludge minimization techniques.Consequently, the ozonation based on cell lysis-cryptic growth mechanism is an applicable and effective technique integrated to the activated sludge process for the minimization of excess sludge production. Besides, it was revealed that the OSA process especially based on sludge decay and energy uncoupling metabolism can be used as another simple effective method for sludge reduction.Keywords: excess sludge minimization, modification of activated sludge process, ozonation, OSA process.
Aliağa endüstri bölgesinde Poliklorlu Bifeniller (PCB) ve Polisiklik Aromatik Hidrokarbonların (PAH) dış hava konsantrasyonlarının yerel ve mevsimsel değişimi
Ambient air samples were collected during the four seasonal (winter, spring, summer, and fall) periods at forty different sampling sites in Aliağa industrial region in İzmir, Turkey. Spatial and seasonal variations of semi-volatile (PAHs and PCBs) toxic organic air pollutants were determined by passive sampling method in 2009 to 2010. Ambient air studies were carried out suburban and urban sites consisted power plant, petroleum refinery, petrochemical industry, several steel plants with arc furnaces, scrap metal and slag storage areas, stack filter dust piles, paved and uppaved roads, coal screening plants, ship dismantling plants and several gas statins and tank fields. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. The major PAH sources in the region were observed as steel plants, petroleum refinery, and ship dismantling plants. Atmospheric PAH concentrations were higher in winter than in summer, indicating that wintertime concentrations were affected by residential heating emissions. On the contrary, highest atmospheric PCBs concentrations were observed in summer, probably due to increased volatilization at higher temperatures. Study results were indicated that steel plants and ship dismantling plants were the major PCB sources in the region. Low molecular weight PAHs (phenanthrene, fluorene, fluoranthene) and PCBs (tri-, tetra-, penta-CBs) were the most abundant compounds in air for both seasons.
Electrokinetic remediation of contaminated soils
Recently, soil pollution has gained importance among the main environmental problems in the world. In developed countries, as well as water and air pollution, soil pollution has become a big issue. This commonly encountered contaminants heavy metals, chlorinated organic compounds, total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH).In the presented study, remediation studies were conducted to determine the effectiveness of electrokinetic method on the treatment of natural soil contaminated with petroleum hydrocarbons, in laboratory scale reactors. Electokinetic remediation of agricultural soil with an initial TPHs concentration of 10000 ppm was investigated under 20 V or 40 V direct current by using NaOH, pure water, Acetic Acid and Ethanol as electrolyte solution, treatment efficiencies were observed according to the distance from the anode chamber and the applied electrical potential. The effect level of electrokinetic remediation on PAHs, which were announced by EPA as in high toxicity group and present in engine oil that was used as contaminant, was also included in the framework of the study. It was observed that high treatment efficiencies for PAHs and TPHs were achieved according to the distance from the anode and the electrical potential applied to the system. Additionally, the operational costs of the systems were also evaluated and it was seen that the applied conditions resulted with lower costs compared with the previous electrokinetic studies reported in the literature and with the other treatment technologies, despite the data exhibit higher treatment efficiencies.
Air quality in workplace of an aluminum wheel production plant
The aim of this study was investigating workplace air quality in an aluminum wheel industry plant. Aluminum smelting and shaping process plant (wheel factory) was chosen for this study. We performed particulate matter (PM10 and occupational dust), gases (VOC) and trace elements sampling at 7 sampling points in the plant. Ventilation system of a part of the plant was renewed during the study. Therefore, the sampling could be conducted before/after the modification. PM mass concentration and metal concentrations were measured. Metal to be studied were chosen according to literature and raw materials and ingredients in the production, included Si, Fe, Cu, Mn, Zn, Mg, Pb, Sb, Sr, Sn, As, Cr, Cd, Se, Al in PM phase. Results are compared to WHO, NIOSH, OSHA limit values and the literature.Si, Fe and Al concentrations in PM were shown to come into prominence from other elements. Also PM10 concentrations were measured to bounded of limit concentration but all of the results were shown lower than limit values.
Arsenic pollution and health risk assessment in the groundwater of Simav Plain, Kütahya
The aim of this study was to conducted a multidisciplinary study to understand the origin of high arsenic levels within the water resources of Simav Plain, to identify relations between drinking water quality and observed diseases in the villages, and to make risk assessment for the public health.To achieve this objective, representative samples from geothermal fluids, surface waters, and groundwater were collected as part of a field survey and were analyzed using standard techniques. Besides, individual household surveys and oral autopsies were made by interviewing villagers. In water quality monitoring, a total of 45 points (33 which of are from groundwater, nine which of are from surface waters and three which of are from geothermal waters) were sampled to determine physical parameters, major anions and cations and heavy metals and trace elements. Mean arsenic levels were found to be 162.64 ppb for groundwater and 76.56 ppb for surface waters. Cardiovascular diseases (37.7%), gastrointestinal system diseases (16.7%), diabetes mellitus (12.7%) and cancers (%2.6) were detected during health surveys. Among cancer group, uterus malign neoplasm (41.2%), colon malign neoplasm (17.8%), breast malign neoplasm (11.8%) and amiloidosis (11.8%) were mostly observed. According to results, high arsenic levels were mostly related to iron oxyhydroxides/hydroxides sorption in the groundwater samples. In surface waters, high arsenic levels were mostly related to metal oxyhydroxides/hydroxides sorption and uncontrolled discharge of geothermal fluid into surface drainage network. The health risk assessment showed that there is a high possibility for internal organ cancers and adverse health problems in the study area.
Inventory of industrial packaging wastes in Izmir city
Significant legislative acts have been passed involving environmental issues in particular within the process of Turkey?s candidation for EU, one of which is packaging waste control and management. For the purpose concerned, studies have been accelerated involving methods and bases established within the context of Regulation of Packaging Waste Control issued by The Ministry Environment and Forestry. The biggest problem is that there is not any sufficient inventory concerning packaging waste control.The study has examined Waste Management Action Plan in 2008-2012 prepared by The Ministry of Environment and Forestry as well as regulations on packaging waste control in Europe and Turkey. Waste Management Action Plan is of great importance in determining the present status covering the waste management in Turkey, considering which a prediction has been made on inventory of packaging waste likely to appear in province of Izmir. In doing so, annual amounts and types of packaging waste produced and sales on output of industries in different sectors have been taken into account.The study has managed to achieve annual packaging waste amounts likely to be caused by 81 industries in nine different sectors in Izmir Metropolitan Area and their percentile break downs based on data obtained.
Public opinion on water reuse applications in Turkey
Nowadays, water resources are rapidly polluted and run out importance. Depending on the population growth, water demand and wastewater generation will increase in the future. Many communities throughout the world are approaching, or have already reached, the limits of their available water supplies. Hence, water reclamation and reuse have almost become necessary for conserving and extending available water supplies. The recycling and reusing of water have a great importance. However, negative response of the public on water reuse creates some problems in application. Therefore, public should be informed and common fallacies needs to be changed. This study was planned and a survey sheet (questionnaire) was prepared. There are some questions related with participant?s age, gender, education, income range and fifteen questions about water reuse in the survey. This questionnaire was sent to different regions of Turkey and 375 questionnaires were returned. Questionnaires after collection, these data was evaluated with SPSS statistical analysis and excel programs. The results of survey studies will be given opinion of Turkish people on water reuse applications. According to study results; participants have suspicion about reuse of treated wastewater.
Management of phosphorus removal in municipal wastewater treatment plants
As a result of uncontrolled discharge of wastewaters containing high levels of phosphorus to the receiving bodies could create adverse effects on water quality. Therefore phosphorus should be eliminated prior to discharging into aquatic environment together with carbon and nitrogen to reduce eutrophication risk. Control of effluent phosphorus level by enhanced biological methods became a standard wastewater treatment application due to its high wastewater purification efficiency and its enhancing effect on overall biological treatment stages. In enhanced biological phosphorus removal (EBPR) processes, carbon, nitrogen and phosphorus could be removed simultaneously with higher efficiencies as compared to the conventional biological treatment methods.Another common method applied in wastewater treatment plants (WWTPs) for removal of phosphorus is chemical precipitation method in which aluminum and ferrous salts, lime were used as coagulants. Although these methods are not able to remove phosphorus completely from the theoretical aspect, significant phosphorus removal efficiencies could also be achieved. However chemical phosphorus removal methods could increase sludge production rate significantly in WWTPs. Investigations indicated that characteristics of this chemical sludge are very different from typical activated sludge. It was also reported that sludge treatment applications including thickening ? dewatering, anaerobic digestion, thermal drying and incineration could be more complex and costly as compared to the non-chemical sludge.In this study, fundamental characteristics of EBPR were investigated in a large wastewater treatment plant by full-scale and laboratory scale methods. The process configuration in which investigations were carried out was very similar to 5-Stage Modified Bardenpho process. To obtain accurate results mass balances were established around biological treatment units performing detailed influent and effluent characterization. In addition to the wastewater characterization, phosphorus content of both activated sludge and phosphorus accumulating organisms (PAOs) were examined under variable nutrient loading ratios and variable operational conditions. Anaerobic phosphorus release rate, soluble substrate utilization rate, anoxic phosphorus uptake rate, simultaneous denitrification rate and aerobic phosphorus uptake rate were also determined by laboratory-scaled batch tests in addition to the full-scale investigations. Importance of particulate substrate forms in EBPR was also studied using both full-scale and batch-scale methods.Results of the investigations proposed that EBPR method could be the main phosphorus management method in WWTPs. However it was also observed that the stability of the EBPR processes could not be maintained continuously since the process influences by several wastewater and operational parameters. Therefore EBPR processes could be supported by chemical phosphorus removal methods to achieve target effluent phosphorus level.It was also demonstrated that COD/TP ratio of the influent is very important for the optimization of the EBPR processes. Obtained results indicated that COD/TP ratio of 65 could be required for the domination of phosphorus accumulating microorganisms (PAOs) that are perquisites EBPR processes in the scale of İzmir WWTP. Serious adverse effects of electron acceptors, present in both influent and return sludge line, on EBPR performance were also determined. In the scope of this thesis, several operational strategies for the optimization of the EBPR plant were also developed.
Material recovery from used cables in Turkey
The aim of this study is to define the material recovery capacity from used cables in Turkey, in details. Also, general instructions about cable recovery are given to support the base of the thesis.For this purpose, at first, cable manufacturing process is explained. One of the key components of a wire is its insulation. Its selection is determined by a number of factors. There are major types of materials used in a cable which are; resins, plasticizers, stabilizers, flame retardants, fillers, lubricants, and colorants.Since there are a lot of different types of cables are in use, variety of used cables presence in recycling circle, too. These cables are classified according to their energy value, telecommunication uses, and their special uses.During the experimental part of the study; each type of cable is divided into its components and weight percent of each different material used is determined gravimetrically for unit length of the cable. Then the calculated theoretical material recovery ratio for each type of used cable is found to determine the market capacity in Turkey by using the data obtained from cable manufacturers that shows annual cable production in the county.
Spatial and temporal asssessment of groundwater quality for the Nif mountain karstic aquifer
This thesis presents a groundwater quality assessment study for the Nif Mountain karstic aquifer, which is located to the southeast of İzmir. The objectives were to present groundwater quality data, provide a spatial assessment of groundwater quality and to implement a statistical evaluation of seasonal alteration of groundwater quality. The study was basically conducted as a four-stage process involving field work and sampling, sample analyses, production of spatial distribution maps of groundwater quality data, and statistical analyses to test significance of temporal changes in groundwater quality and to understand the relationship between different groundwater quality parameters. Groundwater samples were collected from 59 different sampling points in April and September 2006, representing the wet and dry seasons, respectively. Laboratory analyses of major cations and anions were performed. Concentration distribution maps for nitrate, chloride, electrical conductivity (EC) and hardness were generated using a GIS. Moreover, statistical analyses were performed to test the significance of temporal groundwater quality change. The resulting distribution maps showed that groundwater quality in general deteriorates as water travels from the uplands to the plains. Nevertheless, all the investigated groundwater quality parameters were for the most part of the study area in compliance with drinking water standards, with the exception of some occurrences of high concentrations. The temporal assessment using the paired samples t-test and the Wilcoxon Signed Rank tests revealed that the apparent increase in nitrate, chloride and hardness concentrations from the wet to the dry season was statistically not significant. However, the observed increase in EC values was significant. It was concluded that less groundwater recharge in the dry period of the year does not always cause higher concentrations and that other factors such as water circulation times, lithology, quality and extent of recharge and land use also play an important role on the alteration of groundwater quality.