M.S. Theses

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Reuse of textile dyebaths by treatment with advanced oxidation
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 1998., 1998.) Tezcanlı, Gökçe.; İnce, Nilsun.
The urgent need to conserve, recycle, and reuse the limited water resources of the earth has forced mankind to research and develop new methods and technologies for treating and managing used waters from process, cooling and/or rinse facilities of industrial applications. This is especially important in textile dyeing and finishing industries, where huge amounts of water are consumed in dyeing and washing/rinsing ofthe fabrics. The purpose of this study was to investigate the reusability of dyebath effluents in a textile batch dyeing process, by a homogeneous advanced oxidation system, involving H20 2 and ferrous sulfate in the presence and absence of UV-light. Synthetic dye bath effluents were prepared using a reactive azo-dye, Procion Red HE-7B, which was selected as a model compound for its wide use in the industry. Effectiveness of the system was tested by monitoring the degree of color and total organic carbon degradation. Parameters such as chemical oxygen demand and total dissolved solids were also monitored. Reusability of the treated water was tested in a dyehouse with various azo dyes. Under the experimental conditions employed, it was found that complete color removal and 71 % total organic carbon degradation is possible in 20 min of UV irradiation. The treated effluent was found to be reusable in cotton batch dyeing, yielding satisfactory dye quality on the fabric. Estimated cost of reusing dyebath effluents after treatment with the proposed technique was found to be 1.54 per m3 • The corresponding cost of using commercial water supply was estimated to be 2.42 per m3.
Powdered activated carbon addition to activated sludge in the treatment of landfill leachate
(Thesis (M.S.) - Bogazici University. Institute of Environmental Engineering, 1999., 1999.) Aktaş, Özgür.; Çeçen, Ferhan.
Powdered activated carbon (PAC) addition to activated sludge is a convenient method in the treatment of wastewaters that contain high amounts of nonbiodegradable and inhibitory organics. In the biological treatment of leachate in combination with domestic wastewater, leachate constituents may exert adverse effects on the efficiency of the activated sludge process. The purpose of this study was to investigate the effectiveness and applicability of PAC added activated sludge systems in the treatment of leachate in combination with synthetic domestic wastewater. The first step in the experimental path of the study was the determination of adsorption characteristics of the activated carbon used in the study. The succeeding steps involved the biological treatment studies in PAC added activated sludge reactors. The second step was treatment of leachate in batch reactors. The third step was treatment in Semi-Continuously Fed Batch reactors which were used to simulate the Continuous-Flow Stirred Tank: Reactor (CFSTR). The fourth step was PAC addition to a continuous-flow activated sludge reactor. The results of the study demonstrated that PAC addition to activated sludge is a promising method for the treatment of leachate in combination with domestic wastewater. PAC addition resulted in considerable reductions in the effluent concentrations of organic matter due to the adsorption of nonbiodegradable organics. It was found that the removal of organic matter was a simple combination of adsorption and biodegradation in the PAC added activated sludge systems for the conditions encountered in this study. Also, bioregeneration of activated carbon hypothesis was not valid. But, PAC addition increased nitrification rates through the enhancement of nitrifier activities by adsorbing the inhibitory and/or toxic compounds in the leachate.
Deretmination of the remaining stabilization potential of landfilled solid waste by sludge addition
(Thesis (M.S.)- Bogazici University. Institute of Environmental Technology, 1999., 1999.) Güleç, Şükran Başak.; Onay, Turgut T.
Research activities on the innovative landfill management techniques are becoming attractive research areas in the last decades due to increasing amounts of solid waste by increasing industrialization and urbanization. In these landfill management techniques, determination of the stabilization potential of solid waste and the degree of stabilization at the site play important role because the degree and rate of stabilization in a landfill can be valuable parameter for future predictions of leachate and gas generation, determination of the feasibility of a landfill methane recovery program, evaluation of the closure time and the final use of the site. In this study, the remammg stabilization potential of solid waste retrieved from an operating landfill was investigated by the anaerobic digestion of the waste with anaerobically digested sludge with differing sludge:waste ratios. Four reactors were placed in a temperature controlled aquarium and loaded with different sludge:waste ratios in order to determine the remaining stabilization potential, to find the optimum ratio for the highest methane yield and to investigate the use of sludge as an enhancement technique for the waste degradation. The results of the study suggested that the addition of anaerobically digested sludge was an effective technique for the enhancement of solid waste degradation. Among the different sludge:waste ratios, the highest ratio 1:4 was found the optimum one for the enhancement and for the methane production in the study. The remaining stabilization potential of the retrieved solid waste was determined as 7% at the end of the study.
Evaluation of in situ leachate management alternatives on municipal solid waste stabilization in sanitary landfills
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 1999., 1999.) San, İrem.; Onay, Turgut T.
An alternative approach for treating municipal solid waste involves the treatment of the waste after landfilling by addition of moisture to the waste. Increasing attention is being given to municipal solid waste landfill leachate recycle (recirculation) as a means of in situ leachate treatment and landfill stabilization. Using a leachate recycle, a landfill may be operated as a municipal solid waste bioreactor treatment system rather than as a conventional waste dumping site. In order to study the feasibility of an in situ leachate management alternative to provide leachate treatment and waste stabilization two landfill simulating reactors, one with leachate recycle and one without, were constructed and sited in the laboratory's hot room (34°C). Leachate recirculation volume and frequency of recirculation were changed periodically to investigate the effects of different operational moisture regimes on waste stabilization and leachate treatment. Both reactors were filled with municipal solid waste having typical solid waste composition determined in Istanbul. This research showed that the leachate recirculation is a feasible way to treat the leachate in situ, and, therefore, decrease the cost of further external treatment. Leachate recirculation management strategy accelerates the stabilization rate of waste matrix, decreasing time required for stabilization to a matter of months rather than years. Four times per week recirculation strategy was found to provide highest degree of waste stabilization.|Keywords: leachate recirculation, landfill stabilization
An state-of-the-art design technique in landfill engineering :|a case study
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2001., 2001.) Aykan, S. Birkan.; Onay, Turgut T.
Disposal of solid wastes, the final functional element of the solid waste management system. is a major problem throughout the industrialized world. Sanitary landfilling is today widely recognized as the most common and economic method and viable solution for the disposal of municipal and industrial solid wastes. Despite the implementation of waste reduction recycling and transformation technologies disposal in landfills still remains an important component of integrated solid waste management strategy. The purpose of this study was to present the design steps of sanitary landfills through Sinop (Meşedağı) sanitary landfill project. The study indicates that planning and design of modern landfills involves the application of a variety of scientific. economic and engineering principles. The main criteria in design studies were the Turkish Environmental Regulations. The other main feature of the study was the evaluation of the differeat models and approaches employed in the design of modern landfills. In this manner. it is intended to gather appropriate data by comparing the results. The major topics covered in this study include description of the landfill site, estimation of population and solid waste generation. definition of waste properties, slope and berm stability analysis. design of sub-base liners and Dnal (ap, estimation of leachate generation and design of leachate collection system. design of surface water drainage system, estimation of gas generation and design of gas venting system, design of leachate treatment plant and closure of landfill and longterm monitoring.
In situ immobilization of the selected heavy metals by sulfide compounds in landfills under methanogenetic conditons
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2001., 2001.) Erses, Aliye Suna.; Onay, Turgut T.
Co-disposal is a technique for the controlled disposal of hazardous wastes together with municipal solid waste. Co-disposal of industrial wastes including heavy metals and disposal of household hazardous substances such as batteries, paints, dyes and inks -in paper result in release of heavy metals into a landfill environment. Zinc, iron, nickel, copper and cadmium are the most common heavy metals disposed to landfills. These metals are controlled by several attenuation mechanisms including adsorption, acid-base, oxidation-reduction and precipitation-complexation reactions. This research aimed to better understand the extent of heavy metal attenuation in landfills by means of precipitation by sulfide compounds. The effect of selected heavy metals (Zn, Cu, Cd, Fe, Ni) on solid waste stabilization together with the effect of leachate recirculation on the attenuation mechanisms was also investigated. For this purpose, two landfill simulating reactors were used in the laboratory. These reactors were constructed and filled with shredded and compacted municipal solid waste having typical solid waste composition determined for istanbul region. Two reactors, one with leachate recirculation, the other without were operated in the constant temperature room of 32°C to enhance the growth of anaerobic microorganisms. Moreover, moisture addition was done into the reactors in order to simulate the annual rainfall. After the onset of the methanogenetic conditions in both reactors, the selected heavy metals including iron, copper, nickel, cadmium and zinc were added into the simulated landfill reactors. The metals (Fe, Cu, Ni, Cd, Zn ) were prepared by dissolving the metal salts in one liter deionized water and introduced into the bioreactors according to the amounts suggested for co-disposal under the directives of the Turkish Hazardous Waste Control Regulations to prevent inhibition of the microbially mediated processes during waste stabilization This research indicated that when sulfide concentration was very low or insufficient, the removal of the metals was controlled by other anions such as C03 = and P04- 3 until the reduction of sulfate coming from loaded metal salts into the reactors Moreover, leachate recirculation offers opportunities for more rapid waste stabilization including attenuation of co-disposed heavy metals.
Surfactant sorption & desorption on soil surfaces of varying clay content
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2001., 2001.) Küçükaşık, M. Faruk.; Yenigün, Orhan.; Atay, Zeynep.
In this research, sorption and desorption behavior of selected surfactants were investigated on a soil sample that was mixed with different clays at different ratios. The surfactants investigated were a cationic surfactant Benzethonium chloride (Hyamine 1622) and an anionic surfactant Sodium Dodecyl Sulphate (SDS). The clays were Kaolin, Attapulgite, and Calcium-Montmorillonite. The sorption and desorption isotherms of soils were fitted to the Langmuir and Freundlich isotherm equations, and related sorption and desorption constants were calculated from these isotherms. It was found that the sorption capacities for all of the three different types of clay at different mixing ratio for Hyamine were higher compared to those of SDS. On the other hand, desorption capacities for SDS is better than those of Hyamine.
Microbial population dynamics in an anaerobic completely stirred tank reactor treating a pharmaceutical wastewater
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2001., 2001.) Öz, Nilgün Ayman.; İnce, Bahar Kasapgil.
In this study, effects of a chemical synthesis based pharmaceutical wastewater on performance of an anaerobic completely stirred tank reactor (CSTR) and activity of acetoclastic methanogens, number and composition of methanogens and non-methanogens were evaluated. The CSTR was initially fed with glucose. After that, it was fed with preaerated pharmaceutical wastewater diluted by glucose at different dilution ratios and then with raw pharmaceutical wastewater diluted with pre-aerated wastewater to enable acclimization of acetoclastic methanogens to the wastewater which contains nonbiodegradable/ toxic compounds for the anaerobic treatment. At initial study with glucose, 92% soluble COD removal efficiency was achieved with the CSTR at an organic loading rate (OLR) of 6 kgCOD/m3.d corresponding to an FIM ratio of 0.43 with a HRT of 2.5 days. Methane yield was 0.32 m3CfLJkgCOD and specific methanogenic activity (SMA) was found to be 336 mICHJgTVS.d. After initial study with glucose, the CSTR was fed with several dilutions of pre-aerated pharmaceutical wastewater with glucose (10%, 30% and 70%) and then 100% pre-aerated pharmaceutical wastewater. Due to the deteriation in the performance and decrease in the activity of acetoclastic methanogens after feeding with 100% pre-aerated pharmaceutical wastewater, HRT was increased from 2.5 days to 3.5 days. 71% soluble COD removal efficiency was obtained with a HRT of 3.5 days where methane yield was 0.28 m3CH4/kgCOD. However, SMA value was found to be 166 mICHJgTVS.d indicating approximately 47% activity loss ofthe acetoclastic methanogens compared with the results of feeding with glucose. Finally, raw pharmaceutical wastewater diluted with pre-aerated wastewater was fed into the CSTR in increasing ratios of 10%, 30% and 60%. Although a slight decrease in the performance was seen at a dilution ratio of 10% raw wastewater, there was a decrease in all parameters including soluble COD removal efficiency, methane yield, activity test results and an increase in total VF A concentration at a dilution ratio of 60% raw phannaceutical wastewater. According to the results of the SMA test indicating poor activity of acetoclastic methanogens, the study was discontinued at this ratio. According to the microbiological studies, there were variations in the dominant species and the ratio of acetoclastic methanogens to total bacteria during the operation. Methanococcus like species and short rods were dominant species after the operation with glucose. Short rods and medium rods were dominant at the end of the operation with 100% pre-aerated wastewater while short rods remained most dominant species until the end of the study. The ratio of acetoclastic methanogens to the total bacteria decreased at the end of the operation with glucose from 38% to 30% when 60% raw phannaceutical wastewater was introduced to the CSTR.
Effect of powered activated carbon addition on substrate removal and sludge characteristics in leachate treatment
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2001., 2001.) Kılıç, Emel.; Çeçen, Ferhan.; Erdinçler, Ayşen.
The performance of activated sludge process depends on substrate removal efficiency and a good separation of biomass from the supernatant. Powdered Activated Carbon (PAC) addition to activated sludge is a promising method in the treatment of wastewater containing non-biodegradable and inhibitory substances. Substrate removal efficiency can be enhanced via addition of PAC to activated sludge systems in the treatment of leachate combined with domestic wastewater. The increase in substrate removal is due to adsorption of non-biodegradable and inhibitory and/or toxic compounds in the leachate. Moreover, addition of PAC has an effect on settling and dewatering characteristics of activated sludge. The purpose of this study was to investigate the effect of powdered activated carbon (PAC) addition on substrate removal and sludge characteristics in the cotreatment of leachate and domestic wastewater. In the first pali of the experimental path of the study, leachate and domestic wastewater were mixed at different ratios and PAC was added at various concentrations to batch reactors. Also, a control reactor was used which was fed under the same conditions as the PAC added reactor. Results showed that leachate could be treated successfully even if the leachate ratios was high (20-25 %) in the activated sludge system. The inert COD in PAC added activated sludge systems was lower than in activated sludge reactors. Results of the study also showed that the Specific Resistance to Filtration (SRF) increased during removal of readily biodegradable COD alld then tended to decline. Moreover, the SRFs of the sludges were higher if the leachate ratio increased. This showed that the dewaterability of the sludge decreased when the leachate ratio in the feed increased. As a general trend, in most of the runs, PAC addition suppressed these SRF increases. In the next step, leachate (diluted) and domestic wastewater were treated alone. The aim was to have an idea about the effect of leachate and domestic wastewater in the case of combined treatment. In the case of diluted leachate, although COD removal was considerable, sludge characteristics were negatively affected. PAC addition to leachate bad a positive effect. The effect of PAC was most obvious in the case of diluted leachate showing that leachate constituents were highly adsorbable onto activated carbon. The presence of domestic wastewater always resulted in a decrease in SRF or an increase in dewaterability. In the treatment of domestic wastewater alone, very high COD removal was observed and PAC addition did not result in additional COD removal. The SRF values of this sludge were much lower compared to leachate and co-treatment.
Effect of radical scavengers on the performance of advanced oxidation processes
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2002., 2002.) Gültekin, Işıl.; İnce, Nilsun.
Advanced Oxidation Processes (AOPs) rely on the generation of short-lived, powerful and non-selective hydroxyl radicals (·OH) that are responsible for the destruction of a wide range of contaminants in wastewaters. The efficiency of AOPs depends on the production of ·OH and utilization of it effectively by the target contaminants. Non-target substances, or radical scavengers that exist in wastewaters reduce the efficiency of AOPs by consuming significant amounts of ·OH.The purpose of this study was to investigate the kinetics of reactive dyestuff degradation by an advanced oxidation system using ultraviolet light (UV) and hydrogen peroxide (H2O2), and the effect of ·OH scavenging species such as bicarbonate, carbonate and chloride on the efficiency of the process.The method involved preparation of synthetic dye solutions using a reactive azo dye, Procion Red HE-7B, which was selected as a model compound for its wide use in the industry. The effectiveness of the employed system was tested by monitoring the degradation of color and organic carbon in the absence and presence of scavengers.It was found that in the absence of scavengers, 15 minutes was sufficient for complete color removal, whereas 1 hour contact time was necessary for 92 per cent organic carbon degradation. In the presence of scavenging species, the rate of color removal was inhibited and the degree of inhibition increased with increasing concentrations of bicarbonate and carbonate species. It was further found that chloride inhibited the degradation of color only at 100-1250 mM chloride, and did not affect the rate at higher concentrations.The rate of color and organic carbon degradation was found to follow first order kinetics with respect to concentration, and second order kinetics with respect to ·OH. The bimolecular color and organic carbon rate constants with ·OH was estimated by using a simplified kinetic model describing the reaction mechanism. The estimated constants were in good agreement with the published data for azo dyes.
Land use change analysis of Erdemli-Kız Kalesi region by using GIS methodology
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2002., 2002.) Oral, Hasan Volkan.; Yenigün, Orhan.; Mater, Barış.
According to scientific authorities in the year of 2025, the majority of the world's population around 5 billion people will be living in urban areas. As human settlements expand, prime agricultural land and habitats such as wetlands, forests, and watersheds are transformed into land for housing, roads and industry. In the developing countries the urban poor, searching an alternative place to live, often establish informal settlements in ecologically fragile areas.Changes in land-use and land cover have important consequences for natural resources through their impacts on soil and water quality, biodiversity, and global climatic systems. Land use and changes are particularly related to increase of population and intensive agriculture. With the awareness of the importance of land-use changes at coast sides, the study of regional or global land use change has become the focus of much scientific authorities and international organizations. From past to future remote sensing technology has been recognised as a useful means of supplying up to date information on activities within the urban environment . At the same time, computer based geographic information systems are being used to improve the management and use of information. The aim of the study is : to determine the land use changes through the years in the coast of Erdemli and Kizkalesi by using the Geographical Information System , ARC- VIEW GIS software and ER MAPPER .
Modeling of SO2 emissions from Yatağan power plant
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2003., 2003.) İm, Ulaş.; Yenigün, Orhan.
The meteorological model, CALMET, and its plume dispersion model, CALPUFF, were used in order to simulate the dispersion of SO2 emitted from Yatağan Power Plant and its effect on Yatağan district in the episodic event on December 2 and 3, 2000. CALMET was used to predict the hourly meteorological fields for 96 hours, starting from December 1, 2000, to December 4, 2000, while CALPUFF was used to predict the hourly ground level SO2 concentrations over a region of 15 km x 15 km grid with 1 km resolution. The meteorological data were obtained from two meteorological stations: surface data from Yatağan Meteorological Station, and upper air data from Isparta Meteorological Station. The emission data was taken from Yatağan Power Plant. It is found that south westerly and light winds and the nighttime surface inversion layers lead to accumulation of pollutants over Yatağan district. The results are compared with the measurements done by Local Environmental Authorities of Muğla. The simulation results indicate that the maximum ground level concentrations were found northeast from the source, which agrees with experimental measurement. On the other hand, the magnitude of results obtained with the model shows some differences compared with experimental measurements. The SO2 concentration levels are calculated to be very high in the morning hours of December 2 and 3, 2000. Overall, the results indicate that Yatağan district suffered seriously on these days. The sensitivity analysis showed that the concentrations are directly proportional to the emission rates, but wind speed is the most significant meteorological parameter on air pollution modeling compared to other meteorological parameters.
Effects of ozonation, photocatalystic oxidation, and sequential oxidation on coagulation of humic acids
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2004., 2004.) Şen, Sibel.; Bekbölet, Miray.
In this study, coagulation behavior of untreated and treated humic acids with two different types of metal coagulant and two types of polyelectrolyte as coagulant aid were investigated. The aim of this study was to understand the coagulation efficiencies of different type of coagulant and the mechanisms underlying the contribution of pretreatments to coagulation. Pretreatment were done by ozonation, photocatalytic oxidation and sequential oxidation in which ozonation was applied as pretreatment stage for partial oxidation of humic acids prior to photocatalytic oxidation using TiO2.The coagulation properties of humic acid were evaluated according to Color436 and UV254 values. These parameters were calculated for treated and untreated humic acid samples as well as for alum, ferric chloride, and combination of metal coagulant with anionic and nonionic polyelectrolyte. Coagulation efficiencies decreased with pretreatments regardless of the type of the coagulants used. However, anionic and nonionic polyelectrolytes were effective coagulant aids for the coagulation of humic acid. Especially, polyelectrolyte more effective for untreated humic acid than treated humic acid. Removal percentages of UV254 and Color436 values increased with using metal salts combining with anionic and nonionic polyelectrolyte. Nevertheless, applied high dosage of primary coagulant combining with low synthetic polyelectrolyte led to higher removal percentages of humid acid than applied low dosage of primary coagulant combining with high dosage of synthetic polyelectrolyte. Furthermore, using metal salts combining with anionic and nonionic polyelectrolyte lead to decrease in used primary coagulant.
Mathematical modeling of a biogas recovery system at the İZAYDAŞ, Kocaeli sanitary landfill
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2004., 2004.) Cıngır, Alper.; Onay, Turgut T.; Copty, Nadim.
The purpose of this study is to asses the potential of landfill gas generation and recovery from Lot 7 of the İZAYDAŞ solid waste disposal site in Izmit, Turkey. A multi-step model is developed to evaluate the performance and aid in the operation of an active gas collection system for Lot 7. The model consists of three main components: a water balance model, HELP; a gas generation model, LANDGEM; and a gas flow model, MODAIR, based on the MODFLOW computer program. The results of this study indicate that the main factors influencing the efficiency of the gas collection system are: decay rate of the organic component of the solid waste, the mode of operation of the active gas collection system, the air permeability of the soil cover. Specifically, the decay rate controls the duration of the most active gas generation period and the required extraction rates to capture the generated gases. Time-dependent gas extraction rates, as opposed to time-invariant extraction rates, was shown to lead to reduced gas losses into the atmosphere and higher landfill gas concentration in the collected gas. Moreover, the use of low permeability soil cover can also lead to reduced air intrusion into the collection system.
Interactions between azo dyes and selenium in their toxicity to Dunaliella Tertiolecta and Vibrio Fischeri
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2005., 2005.) Özkovalak, Nilüfer.; Saçan, Melek Türker.
In this study, the interactions between assisting chemicals, dye bath, three azo dyesand selenium in their toxicity to Dunaliella tertiolecta and Vibrio fischeri were determined.Three response parameters, including optical density at 750 nm, in vivo chlorophyll fluorescence and cell number were used to monitor the growth of algae exposed to thetested substances in batch culture. The bioluminescence was measured in a luminometer(ToxAlert by Merck).In order to understand whether the toxicity is due to the light absorption of azo dye or the dye itself, the preliminary experiments were carried out at two light intensities (37.4uE m-2s-1 and 76.8 uE m-2s-1). Algal growth was also examined with different forms and concentrations of selenium under two different light regimes. Selenite and selenate haddifferent effects on the growth of alga. When the light intensity was lowered, thestimulatory effects of all forms of selenium decreased. However, when algae were exposedto dye bath, no significant decrease was observed in the algal growth. The results reflectthat selenium is linked to energy-dependent processes and toxicity of dye bath to algae isnot due to the light absorption of colored dye bath itself. D. tertiolecta was found to be more sensitive than V. fischeri to the tested chemicals,since for all the tested chemicals with and without selenium, hormetic response wasobserved on the growth of D. tertiolecta, however, only inhibitory effect was observed on V. fischeri. Considering the average 8-d IC25, SC20 and 30-min EC25 values expressed asper cent dilution (v/v) the order of toxicity was found as Dye Bath= Remazol Black5 Reactive Yellow 37 Reactive Orange 69=Assisting chemicals. For algae, seleniumincreased the stimulatory effect of all the tested chemicals at low concentration range,whereas it decreased the inhibitory effect at high concentration range, except assistingchemicals and Reactive Orange 69. On the other hand, selenium did not change the inhibitory effect of the tested chemicals on V. fischeri. Additionally, the influences ofstimulation and inhibition of algal growth on aquatic ecosystem were discussed.
Effects of dual polymer conditioning on sludge dewatering
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2006., 2006.) Koray, Elif Fulya.; Erdinçler, Ayşen.
The sludge dewatering has been known as one of the most expensive and hard to handle processes in water/wastewater treatment. Alum sludges have been recognized as difficult to dewater due to the containing 40 per cent bound water, are often conditioned with polymers prior to dewatering. Dual conditioning leads to an improvement in the sludge dewaterability. In dual conditioning, the better dewaterability can be achieved by using same or less amount of polymer than that of single conditioning. Dual conditioning increase the solid content of the sludge cake, enhance the solids capture and so reduce the blinding of the filter media. Rheology is known a direct proportionality relationship between shear stress and shear rate. The conditioned sludges show a non-Newtonian behavior. The rheological measurements are very useful in understanding wastewater treatment performance. This study investigates the effect of dual conditioning on sludge dewaterability and the rheological behavior of the conditioned alum sludges. Based on the results of this study, dual conditioning leads to an improvement in the dewaterability of sludges. The best sludge dewaterability was obtained by adding anionic polymer first and cationic second.|Keywords : Dual conditioning, Sludge dewatering, Alum sludge, Polymer, Rheology
Development of water quality index as a sustainability indicator in Küçükçekmece watershed, İstanbul
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2007., 2007.) Taner, Mehmet Ümit.; Erdinçler, Ayşen.; Üstün, Beyza.
Küçükçekmece Watershed, located in the European side of Istanbul is a highly deteriorated and polluted region as a result of unplanned urbanization and industrialization. The purpose of this study is to assess the water quality trends in Küçükçekmece Lagoon and in its tributaries Eskinoz and Sazlıdere Creeks by using an aggregate water quality index (WQI). The index aimed to focus on issues such as organic contamination, euthrophication and stresses on aquatic species with a set of parameters including dissolved oxygen, chemical oxygen demand, chlorophyll-a, total nitrogen to total phosphorus ratio, nitrate, orthophosphate, turbidity, electrical conductivity and pH. These parameters were normalized and subsequently aggregated by a weighted sum function. The final scores were represented on a scale between 0 and 100. The water quality data evaluated by the index covered the total of 14 stations and a period of more than 5 years. The results have showed that the index approach can be effective to indicate problems such as seasons of algal blooms or long-term pollution trends. According to the results, the most polluted stations of the Watershed were found as E2 and E3 at Eskinoz Creek while station D3, located on Sazlıdere Dam, was found as the least polluted. During the algal blooming seasons, sharp declines were observed in the index scores and the water quality dropped below “critical” levels. Consistently, low COD and dissolved oxygen scores were found at many stations, which can be accepted as an evidence of high industrial and domestic discharges into the Basin.
Oxidative treatment of algogenic organic matter
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2007., 2007.) Karakaya, Eylem.; Bekbölet, Miray.
Nowadays, removal of organic substances from natural waters (NOM) is getting greater concern gradually because they form carcinogenic substances (DBP, THM, HAAs, etc.). Consequently, alternative methods have been tried to treat organic substances. Advanced treatment methods like titanium dioxide and photocatalytic oxidation are used as alternative methods through their non by-product formation characteristics. Experimental studies showed that, natural water content of organic materials contains humic acid, fulvic acid, hydrophilic acid, protein, lipid, amino acid and hydrocarbons. The objective of this research was to characterize the spectroscopic properties of algal organic matter (AOM) which comes from the algae degradation as model compounds to represent the natural organic matter (NOM) in aquatic systems. The photocatalytic oxidation of AOM aqueous solution was carried out using TiO2 Degussa P-25 as the photocatalyst. The degradation kinetics was assessed based on pseudo first order kinetic models. The related data for all working solutions were comparatively presented in terms of UV-vis parameters such as Color436, Color400, UV365, UV280 and UV254. Furthermore, the molecular and structural characteristics of the AOM solution were monitored by spectroscopic techniques during photocatalytic oxidation. For all of the working solutions, higher removal rates were achieved in terms of UV254 values compared to that of Color436. According to obtained data, the aqueous solution of AOM was efficiently oxidized by photocatalytic due to TiO2 amount and dilution rates. However degradation time did not significantly affect removal efficiencies. Moreover, considering the complexity of the algal derived organic macromolecules; they were fractionated into well defined subcomponents of known molecular sizes using ultrafiltration through membranes in the range of 1-100 kDa. The effect of photocatalytic oxidation on the molecular size fractions of algal organic matter was also evaluated on a comparative basis by UV-vis and fluorescence spectroscopy. As confirmed by the spectroscopic evaluation of the molecular size distribution data, photocatalytic degradation of algal organic matter aqueous solution results in the formation of higher UV-absorbing compounds.
Biogas production from sugar beet and maize at various total solid contents
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Bayır, Zeynep.; Yenigün, Orhan.
Nowadays, energy required in almost all fields of everyday life is provided mostly by expensive imported energy sources in Turkey. In order to meet the increasing demand of energy, it is indispensable to find alternative sources. Research activities on the biogas production by using energy crops are becoming attractive research area due to abundant availability of the crops in Turkey in addition to the reasons mentioned above. The objective of this study was to evaluate the performance of biogas production system using sugar beet and maize as substrates. Additionally, the optimum total solid content at which the most efficient biogas production took place was investigated for each crop. For this purpose, eleven different lab-scale digesters which were loaded with energy crops were monitored regularly. Anaerobically digested granular sludge was also added to the reactors and the digesters were placed in a temperature controlled water bath. During the experiments which were carried out by using maize as a substrate, the effect of inoculum to substrate ratio on the biogas production efficiency of the system was also investigated. The results confirmed that the digester including maize and seeding sludge at 12 % total solid content with an inoculum to substrate ratio (I/S) of 1.5 performed the most efficient digestion process with regard to its biogas production, methane yield and biogas yield. On the other hand, methane generation could not be observed for the reactor including the same amount of total solid content but using the lower inoculum to substrate ratio of 1. This conclusion was attributed to high levels of VFA generated as a result of biological decomposition. The amount of seeding sludge was found to be insufficient to neutralize the negative effects of organic acids which were formed by degradation of high concentrations of organic matter contained in the reactor.
Effect of ultrasound on the enhancement of biodegradability: a study with olive mill wastewaters
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Çoker, H. Sertan.; İnce, Nilsun.; Üstün, Beyza.
Olive mill wastes are a significant source of potential or existing environmental pollution in the Mediterranean region. The environmental impacts of olive mill wastewaters are considerable with the dangerous effects such as colouring of natural waters, threat to the aquatic life, causing surface and groundwater pollution, changing soil quality and plant growth. In this research, the removal efficiencies of organic matter and the biodegradability enhancement in the treatment of olive mill wastewaters via applying Ultrasound, UV irradiation, Fenton, photo-Fenton and combinations of them were investigated. The aim of the study was to determine the most appropriate process and its operating conditions for the treatment of olive mill wastewaters using advanced oxidation methods. It was found that ultrasonic bath used in this study was ineffective to produce sufficient hydroxyl radicals for degradation of organic matter. However, the effectiveness of the bath increased when the system was combined with AOP processes like Fenton and UV irradiation either sequentially or simultaneously. The sequential processes of US/UV followed Fenton Process was determined the most effective method for treating olive mill wastewater in terms of COD, BOD5 removal and biodegradibility enhancement.

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