Nitrogen and phosphorus removal is often required before discharge of treated wastewater to sensitive water bodies. Kayseri Wastewater Treatment Plant (KWWTP) is a biological wastewater treatment plant that includes nitrogen and phosphorus removal along with carbon removal. The KWWTP receives both municipal wastewater and industrial wastewaters. In this study, KWWTP was modeled by using a software called GPS-X, which is developed for modeling municipal and industrial wastewaters. The Activated Sludge Model No.2d (ASM2d) developed by the International Association on Water Quality (IAWQ) was used for the simulation of the treatment plant. In this model, carbon oxidation, nitrification, denitrification and biological phosphorus removal are simulated at the same time. During the calibration of the model, initially, sensitivities of the model parameters were analyzed. After sensitivity analysis, dynamic parameter estimation (DPE) was carried out for the optimization of the sensitive parameters. Real plant data obtained from KWWTP were used for DPE. The calibrated model was validated by using different sets of data taken from various seasons after necessary temperature adjustments made on the model. Considerably good fits were obtained for removal of chemical oxygen demand (COD), total suspended solids (TSS) and nitrogen related compounds. However, the results for phosphorus removal were not satisfactory, probably due to lack of information on volatile fatty acids concentration and alkalinity of the influent wastewater.

Biological nitrogen removal was simulated for a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR) operated in METU campus. In order to simulate the biological MBR plant, a dynamic model that describes the process is needed. In this thesis, the Activated Sludge Model No.1 (ASM1), which still is the most widely used model developed by the International Association on Water Quality (IAWQ), has been used to simulate the carbon oxidation, nitrification and denitrification processes occurring in the plant using AQUASIM software package. Once the model was established, sensitivities of the model parameters were analyzed. Then, parameter estimation was carried out for the optimization of the sensitive parameters. As we have several distinct data sets available two parallel modeling study was carried out for the calibration of the model. Finally, the calibrated model by different data sets was validated by using the remaining data sets. The model results were consistent with the measured data especially in terms of MLSS concentration in the system. However model results for the nitrogen removal were not extremely successful / the reason for this might be the inadequate available data on nitrification-denitrification process occurring in the system.

Hydrodynamic behavior in reactors used for water treatment, particularly in ozone contactors with serpentine flow, is known to strongly affect the process efficiency. However, exact flow characteristics inside these reactors are not well understood, as traditional approach either considers these reactors as black box or relies on less accurate Reynolds-Averaged Navier-Stokes (RANS) simulation. In order to provide a deep understanding of the hydrodynamics and solute transport phenomena in these reactors, high resolution numerical studies using the Large Eddy Simulation (LES) method are performed. The reactor geometries investigated in this research are Constant Baffle Spacing Multi-Chamber (CBSMC) ozone contactors and a Variable Baffle Spacing ozone contactor Model (VBSM). The LES results in two multi-chamber ozone contactors (CBSMC -Normal-Width and -Half-Width) suggest that the flow through these reactors is characterized by the presence of extensive short-circuiting and large internal recirculation. The results also suggest that the flow is highly three dimensional with a pair of symmetric counter-rotating secondary vortices. LES studies based on VBSM, the baffle spacing of which varies between 0.5 times to 5 times the size of the base chamber; suggest that the width of the recirculation zone grows at about the same rate as the baffle spacing. Instantaneous turbulent eddies are prevalent in the chamber and increase turbulent mixing. The elevated levels of turbulence are found in the short-circuiting flow path. The tracer is dispersed along the short-circuiting path and strongly into the recirculation zone due to turbulent diffusion. Baffle spacing greater than the entrance gate height, but also smaller baffle spacing, worsens the disinfection efficiency. Finally, the turbulent Schmidt number of RANS simulation was investigated by employing the previously validated LES simulation. Due to the presence of very strong turbulent diffusion in the reactors, the turbulent Schmidt number is found out to be much less than the values commonly used, and is also specific to the baffle spacing.

Water pollution is a major concern in vast countries such as India and other developing nations. Several methods of water purification have been practiced since many decades, Semiconductor photocatalysis is a promising technique, for photodegradation of various hazardous chemicals that are encountered in waste waters. The great significance of this technique is that, it can degrade (detoxify) various complex organic chemicals, which has not been addressed by several other methods of purification. This unique advantage made this field of research to attract many investigators particularly in latter eighties and after. This thesis incorporates the studies on the various semiconductor photocatalysts that have been employed for the detoxification purposes. The fundamental principles involved in the photoelectrochemistry, reactions at the interface (solid - liquid or solid - gas) and photocatalytic reactions on fine particles are briefed. General nature and size quantization in semiconductor particles, photocatalytically active semiconductors, TiCh and ABO3 systems, chemical systems and modifications for solar energy conversions are brought out in the introduction chapter besides giving brief description about photocatalytic mineralization of water pollutants with mechanism involved, formation of reactive species and the factors influencing photomineralization reactions. Scope of the present work is given at the end of the first chapter. Second chapter deals with the materials used for the preparation of photocatalyst, preparative techniques, methods of analysis, instruments employed for the photodegradation experiments and a brief description of material characterization methods such as X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential thermal analysis, optical absorption spectro photometry, Electron paramagnetic resonance (EPR), and gas chromatograph - mass spectroscopy (GC - MS). Various preparative routes such as wet chemical and hydrothermal methods for obtaining TiO2 (both rutile and anatase forms), BaTiOs and SrTiO3 fine particles and the chemical analysis of their constituents have been described in brief. Third chapter presents the results of materials characterization. T1O2 (rutile and anatase), BaTiO3 and SrTiO3 have been characterized separately using various techniques. Different routes of obtaining the photocatalyst fine particles, heat treatment at various temperature ranges, experimental procedures and the results of characterization are brought out in this chapter. Fourth and fifth chapters present the details of degradation studies carried out on the photomineralization of chlorophenol, trichloroethylene and formaldehyde. Studies include photodegradation of the pollutants with different catalysts varying experimental conditions to check the effects of change in concentration of pollutants, oxidizer, pH, surface hydroxylation, etc. The most favorable conditions for the complete mineralization of the pollutants have been studied. In case of TiO2, anatase form has shown greater photoactivity when compared to rutile and complete mineralization of chlorophenols has been achieved at low pollutant concentrations, neutral pH, with H2O2 and UV illumination. Retarding effects of surface hydroxylation and the formation of peroxotitanium species during photodegradation have been presented. TCE and HCHO degradation with BaTiO3/SrTiO3 has been studied. Photocatalyst heat-treated at 1100°G-1300°C is found to be highly active in combination with H2O2 as electron scavenger. HCHO is not getting degraded to its completeness in aqueous conditions owing to the strong competition in surface adsorption posed by H2O molecules. Vapour-solid phase reaction however gave good results in the detoxification of HCHO via disproportionation. Summary and conclusions are given at the end of the thesis.

<p>The access to water in the regions around Lake Victoria varies with the rainy seasons. Today the daily labor of fetching water is a heavy burden for people in the rural areas. In the process of this study farmers in the Western and Nyanza provinces in Kenya are interviewed, water samples are analysed and present rainwater harvesting techniques and purification methods are observed. As a result, suitable solutions to the problems found are discussed. An optimal system is chosen for the region with a concept selection matrix. An elaborated dimensioning tool for roof and purpose-built harvesting systems is developed. Finally a summarized manual is attached in order to raise interest for rainwater harvesting among the farmers that the non-governmental organisation SCC-Vi Agroforestry cooperates with.</p> / <p>Tillgången till vatten i områdena kring Victoriasjön varierar med regnperioderna. Det dagliga arbetet med att hämta vatten är idag en stor börda för människor på landsbygden. Under processen av denna studie intervjuas bönder i Western och Nyanza provinserna i Kenya, vattenprover analyseras och nuvarande regnvatteninsamlingstekniker och reningsmetoder observeras. Som ett resultat diskuteras passande lösningar på de problem som hittats. Ett optimalt val av komplett system för regionerna tas fram med hjälp av en konceptvalsmatris. Ett genomarbetat verktyg för dimensionering av tak- och ändamålsbyggda insamlingssystem utvecklas. Slutligen inkluderas en sammanfattande manual för att väcka intresse för regnvatteninsamling bland de bönder som den ideella organisationen SCC-Vi Agroforestry samarbetar med.</p>

M.Tech. Engineering: Chemical. / Aims at demonstrating the application of semi-continuous and continuous magnetic adsorption separation (MAS) techniques to extract Cr (VI) ions from wastewater streams using PPy-Fe3O4 nanocomposite. Specifically, the research aims to achieve the following objectives: to design, synthesize and characterize new generation PPy-Fe3O4 nanocomposite with varied magnetite composition for hexavalent chromium removal ; to generate batch adsorption kinetic data in a continuously stirred tank reactor (CSTR) and apply existing kinetic models to aid in water treatment system design.; to design and construct magnetic adsorption separation (MAS) device that can operate in a semi-continuous and continuous mode and explore their performances and to optimize the systems' performance.

Ceramic membrane processes are a rapidly emerging technology for water treatment, yet virtually no information on the performance and fouling mechanisms is available to the industry. Ceramic microfiltration of model feed solutions and a synthetic river water was examined, and a systematic comparison with polymeric counterpart was performed. The results suggested that the models which have been applied to polymeric membranes agreed well with the ceramic membrane filtration data. The fouling was characterized by the initial pore blocking mechanism and transition to the cake filtration mechanism at a later phase. Cake resistance was dominant and readily removable by physical cleaning. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Experimental evaluations further included resistance-in-series model analysis, organic matter fouling visualization using quantum dots, batch adsorption test, and contact angle measurement, and provided a quantitative a quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on the fouling behavior with ceramic membranes were mostly similar with polymeric membranes in terms of trends, while the extents varied depending on water quality parameters. Less fouling tendency and better cleaning efficiency were observed with the ceramic membranes, which was a promising finding for ceramic membrane application to surface water treatment. The study further examined a coagulation-ceramic membrane process as a robust option for surface water treatment. The performance of the hybrid system was evaluated using selected surface waters by varying coagulation conditions and types of coagulants. Results suggested that ceramic membranes experienced relatively less fouling and had better cleaning efficiency than polymeric counterpart. The results of this study provide critical information to guide the industry practitioners, consultants, and regulatory agents considering early adoption of this new technology as well as fundamental knowledge upon which further in-depth studies can be built.

The inherent thermal resistance of ceramic membranes allows for treatment of industrial waters at elevated temperatures. Traditionally, the high temperature of wastewater has been an issue compromising the integrity of polymeric membrane systems or requiring the temperature to be lowered for further treatments. In ceramic membrane systems, a decrease in viscosity with increasing temperature, however, can be utilized, which increases the permeate flux. In this study, the fouling of ceramic ultrafiltration by feed solutions containing colloidal silica was evaluated at temperatures between 25 – 90 °C seen in various industries. Ceramic membranes were able to perform well at elevated temperatures up to 90 ºC with sustained mechanical and chemical integrity. Results showed net benefit of filtration at elevated temperatures on permeate flux in spite of increasing total fouling resistance with temperature. When the temperature increased from 25 to 90 °C, there was a 90% increase in steady-state permeate flux. The dominant resistance was physically removable fouling, and the increase in fouling with feed temperature was supported by force balance analyses. This study provides a foundation from which further studies can be developed including pilot-scale testing, use of real wastewater, and the effects of operating conditions.

Wastewaters from textile industry contain organic dyes, which cannot be easily treated by biological methods. Therefore, pretreatment by an advanced oxidation process (AOP) is needed in order to produce more readily biodegradable compounds and to remove color and chemical oxygen demand (COD) simultaneously. In this research, ozone (O3) is combined with hydrogen peroxide (H2O2) for the advanced oxidation of an azo dye solution, namely aqueous solution of Acid Red 151, which is called as &ldquo / Peroxone process&rdquo / . The aim of the study is to enhance the ozonation efficiency in treating the waste dye solution. The effects of pH, initial dye and initial ozone concentrations and the concentration ratio of initial H2O2 to initial O3 on color and COD removals were investigated. Also, the kinetics of O3-dye reaction in the presence of H2O2 was approximately determined. As a result of the experimental study, it was seen that an increase in the initial dye concentration at a constant pH and initial ozone concentration did not change the COD % removal significantly, from a statistical analysis of the data. The results obtained at pH values of 2.5 and 7 gave higher oxidation efficiencies in terms of color and COD removals compared to those at pH of 10. The best initial molar ratio of H2O2 to O3 was found to be 0.5, which yielded highest treatment efficiency for each pH value studied. The results of the excess dye experiments suggest that the ozonation of Acid Red 151 follows an average first order reaction with respect to ozone at pH=2.5 and pH=7 whereas it is around 0.56 at pH=10. By Initial Rate Method, the orders with respect to individual reactants of O3 and dye were determined as one, the total order of the reaction being two for all the studied pH. As a conclusion, a further study of the peroxone process at a pH of 10 can be recommended to determine the reaction kinetics and mechanism at this pH, where radicals play an important role.

Coagulation and flocculation processes are important parts of water and wastewater treatment. Coagulation or destabilization of colloidal suspensions results in aggregation of colloidal particles by physical and chemical processes. Flocculation results in the formation of larger and settleable structures by bridging. Alginate, a polysaccharide obtained from marine brown algae, produces a gel structure when mixed with calcium ions, which is expected to be a potential coagulant in water treatment. This study aims to determine the use of calcium alginate as a potential coagulant during water treatment and determine its capabilities and deficiencies in coagulation processes. The study was conducted on turbid water samples prepared in the laboratory and those taken from the inlet of Ankara ivedik Water Treatment Plant (IWTP) by running typical jar tests. The main experimental variables were initial alginate and calcium doses, initial turbidity of water samples and the order with which the two chemicals are dosed. The main criteria investigated to check the success of the system was the final turbidity values and the turbidity removal capacity of calcium- alginate. Experiments were conducted on three different laboratory &ndash / prepared turbid water samples and on the raw water taken from the inlet point of Ankara ivedik Drinking Water Treatment Plant (IWTP). These were prepared as high (150 NTU) medium (80 NTU) and low (10 NTU) turbidity samples. The calcium concentrations tested varied between 30 and 200 mg/L and alginate concentrations tested varied between 0.04 to 40 mg/L. Depending on the initial turbidity and initial calcium concentration of water sample the results depict that calcium alginate could be used as an effective coagulant for high (150 NTU) and medium (80 NTU) turbidity water sample especially at the calcium doses of 120 and 160 mg/L for low alginate concentration doses like 0.4 mg/L. The final turbidity met both the requirements of Drinking Water Standards applied in Turkey and Europe. Generally, the higher the initial turbidity was, the higher the turbidity removal efficiency achieved, even with very low alginic acid concentration. As the initial turbidity decreased, initial concentration of calcium required for the effective coagulation processes decreased. However, for low (10 NTU) turbidity water samples the system did not work properlyHowever, for low turbidity water samples, the turbidity removal efficiency decreased, and it was difficult to meet the limits.