No abstract

The effect of configuration of activated sludge systems on heavy metal toxicity was investigated. Two bench-scale completely mixed activated sludge systems were operated identically in order to determine the toxic effects of Cr(VI), Zn(II) and industrial wastewater on the activated sludge biomass. One system was operated with an aerobic selector and the other without. Batch experiments based on OECD 209 (Organisation for Economic Cooperation and Development) were performed using a respirometer to find out potential toxicity reduction effect of an aerobic selector. The IC 50 (concentration of a chemical that exhibits 50% respiration inhibition) values of Cr(VI), Zn(II) and industrial wastewater in the activated sludge were determined. Results indicated that the heavy metals and industrial wastewater caused less inhibitory effect on the selector activated sludge system in comparison to the conventional activated sludge system. Cr(VI) was found to exert higher inhibition on both systems.

Within the context of this study, two lab-scale aquatic plant reactors consisting of duckweed (Lemna minor) ponds, were investigated for the removal of nitrogen forms during the secondary treatment of domestic wastewater. TKN, NH3-N and NO3-N parameters have been measured in both reactors for hydraulic retention times ranging from 3.3 days to 23 days and at various distances from the inlet of reactors. The results were evaluated for hydraulic retention times, hydraulic loading rates and mass loading rates. It was concluded that hydraulic and mass loading parameters were more meaningful than hydraulic retention time. Optimum nitrogen removal values of hydraulic loading rate and mass loading rate were found to be 1.2 cm/day and 90-160 mg TKN/m2-day, respectively. At the higher and lower loading rates, nitrogen removal efficiency was lower than those at optimum conditions. Effluent TKN concentration was around 2.5 to 3.0 mg/l while NH3-N concentration was almost zero at these loading conditions. On the other hand, effluent NO3-N concentrations changed between 7 mg/l to 11 mg/l. When investigating the longitudinal profile, values were reduced rapidly along the reactors. It was concluded that most of the nitrogen conversion occurred at the beginning of the reactor.

Öz: Petrol içeren atık sular, kaynağına bağlı olarak, askıda ve çözünmüş katı madde, organik tuzlar, yağ ve gres, alifatik ve aromatik hidrokarbonlar, sülfitler ve metaller gibi oldukça karmaşık bir bileşime sahiptir. Bu içeriği nedeni ile toprak, su, hava ve insan hayatına karşı bir tehlike oluşturmaktadır. Bu nedenle, petrol atık suyu arıtımı acil çözüm gerektiren bir problem haline gelmiş olup, arıtım teknikleri konusundaki çalışmalar son zamanlarda hız kazanmıştır.Petrol içeren atık suyun arıtılması için elektrokimyasal arıtım, membran filtrasyonu, biyolojik arıtım, hibrit teknolojiler gibi pek çok yöntem uygulanmaktadır. Elektrokimyasal arıtım, membran filtrasyonu, biyolojik arıtım, hibrid teknolojiler bu yöntemlerden bazılarıdır. Bu çalışmanın amacı, bir akaryakıt depolama tesisinden kaynaklanan atık suların kimyasal arıtılabilirliğini belirleyerek, deşarj limitlerini sağlayacak bir kimyasal ve biyolojik arıtma sistemini tasarlamaktır. Araştırma sonuçlarına göre asit kraking, çözünmüş hava flotasyonu ve aktif çamur sisteminden oluşan arıtma sisteminin ardından KOİ giderim verimi %94, askıda katı madde giderim verimi %96 ve yağ gres giderim verimi %98 olarak tespit edilmiştir. Abstract:The oily wastewater depending on the source, has a very complex composition, such as suspended and dissolved solids, organic salts, oil and grease, aliphatic and aromatic hydrocarbons, sulfides and metals. Because of this content, it poses a danger to land, water, air and human life. Therefore, oil wastewater treatment has become a problem requiring urgent solution, and studies on treatment techniques have recently gained momentum. Many methods such as electrochemical treatment, membrane filtration, biological treatment and hybrid technologies are used for the treatment of oilcontaining wastewater. Electrochemical treatment, membrane filtration, biological treatment, hybrid technologies are some of these methods. The aim of this study is to design a chemical and biological treatment system that will provide the discharge limits by determining the chemical treatability of the wastewater from a fuel storage facility. According to the results of the research, COD removal efficiency was determined as 94%, suspended solids removal efficiency was 96% and oil grease removal efficiency was 98% after treatment with acid cracking, dissolved air flotation and activated sludge system.

Toxic effects of five commonly used pesticides on the biomass of a municipal activated sludge system were determined on the basis of the reduction in the oxygen uptake rate (OUR) and specific oxygen uptake rate (SOUR). Toxicity levels of the selected pesticides were determined by employing a modified OECD 209 (Organisation for Economic Cooperation and Development) method which was performed as batch experiments using a respirometer. S and 2,4-D were 860 and 3664 mg/L, respectively. Results indicated that toxicity effects of copper-based pesticides were higher than that of synthetic organic pesticides. CuSO 4 Á 5 H 2 O was found to exert the highest toxicity among the copper-based pesticides, whereas, C 12 H 12 ClN 5 O 4 S was determined to be the most toxic among the organic pesticides on activated sludge biomass.