Gökhan Ekrem Üstün

Occurrence and removal of metals in urban wastewater treatment plants

In this study, nine metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) found in urban wastewater treatment plants (WTPs) in Bursa (Turkey) were monitored for 23 months in 2002 and 2007. Metal influent and effluent concentrations of wastewater stabilization ponds (WSPs) and the activated sludge process (ASP) measured via 24-h composite samples were used to determine removal efficiencies. Average influent concentrations ranged between 2 microg/L (Cd) and 1975 microg/L (Fe). In the stabilization ponds, the removal efficiency was 58% for Cr, while for Cd, Mn, and Pb, it was less than 20%. The activated sludge process yielded high removal efficiencies, ranging from 47% for Ni to 95% for Cr. The use of treated wastewaters for agricultural purposes was investigated, and it was determined that all metal concentrations met application limits, with the exception of Cr in wastewater stabilization pond effluent. Results showed that wastewater stabilization pond effluent reduced the receiving water quality with respect to Cr, Cu, Ni, and Pb. In addition, it was shown that effluent from the activated sludge process temporarily improved the receiving water quality with regard to the Cd, Cu, Mn, and Zn parameters. However, considering the periodic variations of the metals in both processes, water quality, and agricultural practices, it was determined that they should be monitored continuously.

Advanced oxidation and mineralization of 3-indole butyric acid (IBA) by Fenton and Fenton-like processes.

The degradation and mineralization of 3-indole butyric acid (IBA) in aqueous solution was examined using Fenton and Fenton-like processes. Various operating conditions were evaluated including pH and the concentrations of iron ions (Fe(2+) and Fe(3+)) and hydrogen peroxide (H(2)O(2)). The highest COD removal efficiency was achieved at 0.2 mM/0.6 mM Fe(2+)/H(2)O(2) ratio and 0.2 mM/1.0 mM Fe(3+)/H(2)O(2) ratio at pH 3 for Fenton and Fenton-like processes, respectively. IBA degradation and mineralization exhibited pseudo-first-order kinetics while the depletion of H(2)O(2) and Fe(2+) or Fe(3+) exhibited zero-order kinetics during both processes in all experiments. 97% of IBA degradation proceeded via two distinctive kinetic regimes. The initial phase of the reaction was directly attributable to the Fenton reaction wherein nearly all of the OH radicals were generated. This was followed by a slower degradation phase, which can be thought of as a series of Fenton-like reactions within a Fenton process. In the Fenton-like process, the initial phase lasted longer than in the Fenton process because the generation of OH radicals proceeded at slower rate; however, 98% degradation of IBA was achieved. The mineralization of IBA was 16.2% and 50% for Fenton and Fenton-like processes, respectively. After 24 h, H(2)O(2) was the limiting reagent for further mineralization of IBA intermediates present in the system. The results of the study showed that Fenton Process may be more useful when only removal of IBA is required and mineralization is unnecessary. But if mineralization of IBA is needed, Fenton-like process gains more important than Fenton Process due to its mineralization efficiency.

Treatability studies on wastewater from textile dyeing factories in Bursa, Turkey

The textile industry is one of the most rapidly developing industries in Turkey. It generates a large amount of wastewater, with corresponding concerns about pollution. The main sources of pollution in wastewater are the dyeing and finishing processes. The dyestuffs and polyvinyl alcohol (PVA) are the main refractory organics of concern in terms of meeting more stringent effluent standards of chemical oxygen demand (COD) and colour. In this study, wastewaters from textile dyeing factories in Bursa were characterized, and physical, chemical and biological treatability studies were carried out. In the physical and chemical studies, 60-80% COD, 80% suspended solids (SS) and 10-92% turbidity removal efficiencies were obtained. In the biological studies, 90% COD and 40% SS removal were obtained. The initial soluble inert COD of wastewater was determined by using comparison methods. The initial inert COD of wastewater and the microbial product concentration were determined as 37 mg/l and 13 mg/l, respectively.

An approach to wastewater treatment in organised industrial districts: a pilot-scale example from Turkey

In this study, a detailed wastewater profile and treatability studies of Demirtas Organized Industrial District (OID) were undertaken on a pilot-scale. The industrial categorisation of Demirtas OID was determined, and the wastewater characterisations of each industrial sector were analysed and the flow-rates were measured. The results were used to design a wastewater treatment plant for Demirtas OID. Pilot-scale chemical and biological treatability studies were carried out. The steady-state performance of the pilot-scale treatment system in removing chemical oxygen demand (COD) and suspended solids (SS) was studied for a period of three months. The removal efficiencies obtained in this study were 42% of COD and 67% of SS in the chemical treatment, and 84% of COD and 25% of SS in the biological treatment. The overall removal efficiency of the pilot-scale system was 91% COD and 75% SS. The pilot-scale study showed that the wastewater from Demirtas OID could be treated with biological and chemical methods, and the treated wastewater met the Regulation of Discharge Standards of Turkey. The significance of this study is that it is the first such system in Turkey to be tested on a pilot scale.

Removal of Pb(II) Ions in Fixed-Bed Column from Electroplating Wastewater of Bursa, an Industrial City in Turkey

Removal of Pb(II) ions from electroplating wastewater of Bursa, an industrial city in Turkey, was investigated in fixed-bed column. The experiments were conducted to study the effect of important design parameters such as column bed height and flow rate. The breakthrough profiles were obtained in these studies. At a bed height of 14 cm and flow rate of 6 mL/min, the metal-uptake capacity of poly(ethylene glycol dimethacrylate-1-vinylimidazole) [poly(EGDMA-VIM)] beads for Pb(II) ions was found to be 90 mg/g. Bed Depth Service Time (BDST) model was used to analyse the experimental data and evaluate the performance of adsorption column. For various flow rates, adsorption capacity per unit bed volume () and adsorption rate constant () are in the range of 2370–3560 mg/mL and 0.0225–0.0616 L/mg h, respectively. The saturated column was easily regenerated by 0.1 M HNO3 and the poly(EGDMA-VIM) beads in fixed-bed column could be reused for Pb(II) ions removal.

Treatment of 3-indole butyric acid with solar photo-catalytic reactor

Abstract Solar photo-catalytic process is an emerging and promising technology both as an alternative treatment to conventional wastewater treatment methods and enhancement of biodegradability of highly toxic and recalcitrant pollutants. In this study, results for the treatment of 3-indole butyric acid solutions using pilot scale solar photo-catalytic treatment process are presented. The effecting parameters, such as adsorption of 3-indole butyric acid on TiO2, pH, the initial concentration of 3-indole butyric acid and catalyst concentration, on the treatment of 3-indole butyric acid using solar photo-catalytic system were investigated. Solar photo-catalytic processes demonstrated high COD (>80%), TOC (>80%) and 3-indole butyric acid (>90%) removal efficiencies for the samples in this study. The increase of the 3-indole butyric acid concentration from 10 to 150 mg/L decreases the removal rate constant from 0.0757 to 0.0088 1/min in 240 min of oxidation using 100–1500 mg/L TiO2 at 3–9 pH.

The reclamation of municipal effluent for irrigation by a pilot-scale advanced treatment plant

This study concerns about the reclamation of municipal effluent for agricultural irrigation by the application of a pilot-scale advanced treatment plant capable of rapid sand filter and disinfection. The rapid sand filter significantly reduced suspended solids and turbidity. Average reductions in these parameters 76 and 62%, respectively, were achieved. The percentage removals of chemical oxygen demand and biological oxygen demand by the rapid sand filter were 32 and 55%, respectively. The amounts of heavy metals in the rapid sand filter effluent were below the national and international standards. The pilot-scale advanced treatment plant eliminated almost the 100% of fecal coliforms. Hence, the treatment costs of the pilotscale advanced treatment plant were calculated approximately US

Colour and COD removal from textile effluent by coagulation and advanced oxidation processes

0.063/m 3 . These results showed that the pilot-scale advanced treatment plant provided a low-cost water source which can be used for agricultural irrigation.