Zeytin karasuyunun kimyasal şartlandırma destekli entegre membran filtrasyonu sonrasında biyolojik arıtılabilirliğinin araştırılması

Environmental biotechnology has been as area where extensive scientific efforts have been devoted to realize the characteristics and biodegradation of complex pollutants in different wastewaters and illuminate related biochemical reactions. Biological treatment has been traditionally based on the activated sludge process involve primary settling, aeration and secondary settling. However, the obligation to comply with new concepts of environmental sustainability, which require reducing the use of recourses and making the most energy efficient systems, underline the need for recognizing the full potential from the new and emerging technological options in wastewater treatment. Olive oil wastewater is one of the most complex and strong agro-industrial wastewaters which cause significant pollution problems in environments if appropriate treatment is not applied before disposal. The disposal and treatment of this wastewater is an important subject specially for the Mediterranean countries as most of olive oil producers in the world are located in this region. Due to specific characterization of this wastewater, especially high amount of organic, toxic and recalcitrant compounds, and on the other hand it's seasonally generation, it is necessary to find most appropriate method to have the best treatment efficiency. The most abundant organic substance in olive mill wastewater are polyphenols which are generally cause the high strength characteristic of wastewater, responsible for antimicrobial and toxic attribute of it, and are barriers in the wastewater biological treatment. This study, intended to provide the starting move towards the olive mill wastewater treatment by using the function of chemical conditioning and membrane filtration in reduction of the organic compounds of wastewater to the lowest level, that allows domestic biological treatment plant to be operated as final treatment system. For this application, in this work a significant amount of COD has been removed by means of chemical conditioning and membrane filtration using ultrafiltration and nanofiltration processes. In this framework, the olive oil wastewater with an initial COD of 106500 mg/L was subjected first to a coagulation - flocculation process, applying PAC supplemented with anionic polyelectrolyte yielded excellent effluent quality with COD level of 40800mg/L under optimum condition after coarse filtration (62 % overall COD removal). The particle size distribution analysis was conducted before and after chemical conditioning. This method is a beneficial tool for wastewater characterization that supplies valuable data about COD fractions for different size intervals and shows the relation between these COD fractions and particle size distribution of the wastewater. It can also compare different treatment technologies as a function of Particle Size Distribution. The results revealed that the chemical precipitation effectively removed the particulate fraction of COD and the highest COD removal efficiency was achieved on this fraction which appeared as the major fraction of raw wastewater. While after coagulation flocculation, the most COD portion remained on soluble fraction below 2 nm, but also with a similar significant removal from 27.500 mg/L in raw wastewater down to 21.000 mg/L. This level represented 53% of the remaining COD after chemical conditioning, which gives clear indication that major change occurred in the size range below 2 nm particularly important for membrane filtration. Applying ultrafiltration and nanofiltration yielded significant results in reducing COD. First step was started with a raw wastewater with a COD level of 51000 mg/L after coarse filtration. Ultra filtration using UC010 was able to reduce this level down to 33300 mg/L, and the nanofiltration step further reduced the COD concentration to 8300 mg/L. , with a final overall COD removal efficiency of % 92. Second step was started with chemical conditioning prior to membrane filtration, the effluent COD decrease to 29300 mg/L after ultrafiltration and finally to 5870 mg/L after nanofiltration steps. The third step involved the sequence of ultrafiltration, chemical conditioning and nanofiltration; a final COD of 6200 mg/L was obtained after the final nanofiltration step, which is a great efficiency in COD removal for this strong wastewater. The next part was the biological treatability of the integrated chemically- physically treated wastewater. A laboratory-scale sequencing batch reactor with a net volume of 5L was conducted with activated sludge taken from a domestic wastewater treatment plant. The system was fed with synthetic substrate (peptone mixture) with the same characteristics of domestic wastewater, in terms of organic carbon content and COD fractions with various biodegradation characteristics. It was operated for 2 months at steady state condition and a sludge age of 8 days, to get acclimated biomass. Respirometric measurements were used to determine the possible inhibitory effect of olive oil wastewater on the biodegradation of domestic sewage and to choose best mixture ratio of domestic sewage and olive mill wastewater for the biological treatment. Biodegradability of the olive mill wastewater when mixed into a domestic wastewater was essentially tested on the basis of oxygen uptake rate (OUR) profiles generated in respirometric measurements. Respirometric tests were conducted in 2L batch reactor started with biomass taken from SBR system at endogenous respiration stage. The first OUR measurement was conducted with synthetic wastewater or peptone mixture only, as control to evaluate biodegradation characteristics of domestic sewage. In tests 2 and 3 the biodegradability of pretreated olive oil and peptone mixture with mixing ratios of 15% and 50% were evaluated to determine the effect of olive oil wastewater in different concentrations on combined biological treatment. In 4th measurement, pretreated olive oil wastewater with no additional peptone was applied to assess its characteristics and behavior in biodegradation. In last OUR measurement, raw olive oil wastewater with total COD of 200mg/L in respirometric vessel was applied to understand the biodegradation characteristic od olive oil wastewater before any pretreatment. The results of model calibration show two major COD fractions in pretreated OMW: the readily biodegradable fraction, and the slowly biodegradable COD fraction. Three different COD fractions were shown for peptone: readily biodegradable, rapidly hydrolysable and slowly hydrolysable COD. Two hydrolysable fractions undergo hydrolysis to breaking down into readily biodegradable COD, then utilized by microorganisms. The respirometric results displayed the recalcitrant nature of row olive mill wastewater, without proper pretreatment. Significantly tampered and reduced OUR profile obtained with raw olive wastewater dosing in last OUR measurement, shows only limited and partial biodegradation. According to basic mass balance between oxygen consumed and substrate utilized in a biochemical reaction, the magnitude of the COD utilized in the test was 46 mg COD/L, corresponding to only 21% of the 200 mg COD/L dose used in the experiment. Also results indicated that olive oil wastewater becomes fully biodegradable after a pretreatment scheme involving chemical conditioning and membrane filtration with an ultrafiltration/nanofiltration sequence, due to removal of nonbiodegradable COD fraction. Biodegradation was tested in mixture with peptone, which properly simulates and approximates the biodegradation characteristics of sewage after appropriate dilution of OMW. Results indicate complete removal of OMW together with peptone mixture in all conducted OUR measurements. Olive mill wastewater dosing, even at highest dosage did not exert any appreciable impact on the biodegradation of the peptone mixture as growth and hydrolysis kinetics basically remained the same in all respirometric measurements. Also there were no inhibitory/toxic impact of OMW dosing on the biomass, as the amount of active biomass remained the same in all tests. Full biodegradation of OMW was achieved by biomass acclimated only to peptone and without any acclimation to olive oil wastewater.