Celal F. Gokcay

Land-based sources of pollution along the black sea coast of Turkey: Concentrations and annual loads to the black sea

Abstract Concentrations of inorganic pollutants, pesticides and PCBs were measured in 42 sources including rivers, streams, and industrial and domestic discharge points along the Turkish Black Sea coast in three seasons of the year 1993. The measured concentrations were compared with water quality standards currently effective in Turkey in order to determine the levels of pollution in the rivers and streams. Concentrations were also combined with the water discharge data to determine annual loads of pollutants discharged from each source into the Black Sea. Concentrations of measured parameters were much higher in domestic and industrial discharges, as expected. Most of the rivers and streams were polluted with organic material, nitrogen and phosphorous species due to discharges of untreated domestic wastes into these streams. Metal concentrations measured in the rivers and streams were fairly low due to the lack of extensive industrialization in the drainage areas of the streams. Some of the small streams, including the Neyren, Kilimli, Zafir and Tabakhane streams, are heavily polluted and were identified as sources having the potential to generate hot spots along the coast. Annually, a total of 39.700 tons of nitrogen, 3.700 tons of phosphorous, 15 tons of Cd, 340 tons of Cu, 60 tons of Pb, 1.200 tons of Zn, 12 tons of heptachlor, 11 tons of aldrin, 31 tons of dieldrin, 180 tons of endrin and 500 tons of DDT are discharged from Turkish sources into the Black Sea. Except for trace metals, rivers and streams dominate the flux of pollutants. Large industries along the coast that discharge their wastes directly to the Black Sea account for a significant fraction of the annual metal discharges. Pesticides and PCBs were detected in most of the sources included in the study indicating their illegal use in agriculture. The Sakarya river was the most important source of pesticides.

Mechanistics of nickel sorption by activated sludge

Biomass from activated sludge reactors operating at different dilution rates (0.09, 0.16, and 0.24/h) was used to examine the effect of sludge age on Ni2+ removal characteristics, running batch adsorption tests. The kinetic studies have revealed that sludge grown at all dilution rates, exhibits both active and passive uptake of Ni2+. Although percentages of active and passive uptake changed with the age of activated sludge biomass, passive uptake was the dominant mechanism in Ni2+ sorption. The data obtained were interpreted in the form of adsorption isotherms. At all dilution rates, linear adsorption isotherms were obtained, indicating the presence of equilibrium between biomass and the free nickel species.

Combined effects of Ni(II) and Cr(VI) on activated sludge

Abstract The combined effects of Ni(II) and Cr(VI) on activated sludge kinetics were studied in this paper. The metals were added to a synthetic medium with a chemical oxygen demand (COD) of 1300 mg 1 −1 to give various combinations of Ni(II) and Cr(VI). Activated sludge performance, in terms of COD removal, was not adversely affected in an acclimatized culture by the metal combinations, compared with the single metals. The combination effects of Ni(II) and Cr(VI) on biokinetic constants, i.e. the maximum specific growth rate, μ m , was found to be stimulatory in general. The same effect was observed on the half-saturation substrate concentration, K s . Effects were therefore classified as synergistic with respect to these constants.

Effect of nickel(ii) on activated sludge

Abstract There is little information in the literature to describe the effects of heavy metals on activated sludge kinetics. The purpose of this study is to evaluate the toxic effect of nickel on activated sludge. Different concentrations of Ni(II) (5.0, 10.0 and 25.0 mg l −1 ) were maintained in a laboratory-scale completely mixed activated-sludge unit, without recycle, treating, simulated wastewater. The feed solution contained 650 mg l −1 protein (corresponding to 1300 mg l −1 COD) as a source of carbon. Experimental results indicated that the treatment efficiency was not adversely affected by the presence of nickel up to a concentration of 10.0 mg l −1 . However, a concentration of 25.0 mg l −1 Ni(II) caused serious upsets in the system, while 5.0 mg l −1 Ni(II) in feed solution had some stimulatory effects. The maximum specific growth rate, μ m , of the culture also doubled when the nickel concentration was 5.0 mg l −1 and better floc formation was noticed at this nickel concentration.

Effect of chromium(VI) on activated sludge

Abstract Hexavalent chromium, which is frequently encountered in the tannery effluents and in the electroplating wastes, is normally considered toxic to the activated sludge culture. Often a physico-chemical pretreatment prior to biological treatment is considered necessary. However, in this study it has been shown that an acclimatized activated sludge culture is fully capable of coping with the Cr(VI)-containing wastes and moreover the culture was significantly stimulated by up to 25 mg l−1 Cr(VI). None of the tested concentrations of this metal were inhibitory to the mixed culture under investigation. In fact, all of the concentrations tested, 1, 5, 10 and 25 mg l−1 Cr(VI), significantly stimulated the maximum growth rate, μm, of the culture. Furthermore, the biomass yield of the activated sludge culture markedly increased in the presence of Cr(VI) while the effect on the biomass decay or maintenance constants was variable.

Microbial solubilization of lignites

Abstract Biological solubilization and subsequent gasification of lignite samples from three of the largest reserves in this country, which are also characterized by high sulphur contents and low calorific values, were investigated in this project. Several white-rot fungi were screened for their ability to solubilize lignites and Phanerochaete chrysosporium was found to depolymerize Elbistan lignites with 60% efficiency. Acetate served perfectly as the primary carbon source. Whereas, Can lignites could be depolymerized only after lengthy pre-treatment with 8N HNO 3 while Beypazari lignites were completely inert to biological attack. Gasification tests with the solubilize material revealed 21% energy recovery through gaseous methane product.

Microbial desulphurization of lignites by a thermophilic bacterium

Abstract As a possible means of abatement of air pollution the use of thermophilic thiobacilli in lignite desulphurization has been investigated in lab-scale batch experiments and 50% organic sulphur 58% total sulphur removal has been achieved in 10% lignite slurries at 50 °C.

Sequential (anaerobic/aerobic) biological treatment of malt whisky wastewater

The anaerobic treatability of malt whisky distillery wastewater was investigated. Biochemical methane potential (BMP) experiments were conducted both with and without basal medium (BM) to observe the effect of nutrient supplementation. For batch reactors containing no nutrients but only NaHCO3, net total gas production at the end of 29 days were observed as 0.019 m3 gas/kg COD removed. With nutrient supplemented reactors the net total gas production was 0.020 m3 gas/kg COD. Continuous reactor experiments were carried out in two stage upflow anaerobic sludge blanket (UASB) reactors. These experiments indicated that the two stage UASB reactor configuration is an efficient system for malt whisky wastewater treatment until up to 33 866 mg/l influent COD concentration. Following the UASB experiments aerobic experiments in batch reactors were also conducted and further COD and BOD removal of up to 55 and 70%, respectively, were achieved.

Effect of chromium(VI) on the biomass yield of activated sludge

Effect of 1‐25 mg/l of influent Cr(VI) concentrations on true biomass yield ( Yt) and decay coefficient (kd) of activated sludge units was investigated in this study. To this purpose, completely mixed, once-through laboratory scale activated sludge units with acclimated cultures were operated. After obtaining dilute-out curves for each Cr(VI) concentration, the values of Yt and kd were determined. The results revealed that presence of Cr(VI) caused stimulatory effects on biomass yield and maintenance up to the Cr(VI) concentration of 25 mg/l. Lower Cr(VI) concentrations exerted higher stimulation of the system. Extended oxidation due to the presence of Cr(VI) and/or increased synthesis of cellular material due to the stimulatory effects of Cr(VI) were thought to be the mechanisms of the observed stimulation.

Effects of CU (II) on a chemostat containing activated sludge

Abstract The purpose of this study was to evaluate the toxic effects of Cu(II) on a chemostat containing activated sludge. Different concentrations of Cu(II) (0.5, 1.0, 5.0, and 10.0mgL‐1) were maintained in a laboratory‐scale completely mixed activated sludge unit, without recycle, treating simulated wastewater. The feed solution contained 650 mgL‐1 protein (corresponding to 1300 mgL‐1 COD) as a source of carbon. Experimental results indicated that the treatment efficiency was not adversely effected by the presence of Cu(II) up to the concentration of 10.0 mgL‐1. Moreover, some stimulatory effects of Cu(II) on the biokinetic parameters were observed.