T. Ölmez

The optimization of Cr(VI) reduction and removal by electrocoagulation using response surface methodology.

In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the removal of hexavalent chromium (Cr(VI)) by the electrocoagulation with stainless steel electrodes. Central Composite Design (CCD) was used for the optimization of the electrocoagulation process and to evaluate the effects and interactions of process variables: applied electric current, electrolyte concentration and application time on the removal of Cr(VI). A sample of metal finishing industry wastewater having a high Cr(VI) concentration of 1470 mg/L was used in the experimental study. The optimum conditions for complete (100%) Cr(VI) removal were established as 7.4A applied electric current, 33.6 mM electrolyte (NaCl) concentration and 70 min application time. The amount of sludge produced under the conditions optimized based on the results from the model was lower than the amount generated by chemical treatment with FeSO(4).7H(2)O and non-hazardous in nature.

Pollution of Coastal Region Impacted by Acid Mine Drainage in Morphou Bay, Northern Cyprus

Abstract Abandoned copper mines, located in Lefka–Xeros area by the Morphou bay were primarily producing copper. Secondary products, such as silver and gold were also produced for a century by cyanide leaching method. The residues of mining processes were deposited in large tailing ponds that were constructed with primitive technology. In this research, water samples from several different points of tailing ponds, Lefka river and coast of Morphou bay are collected. The laboratory analysis of the samples is then carried out, considering basic pollutant parameters such as copper. The cross-shore and Longshore numerical modelling technique is applied associating the wave climate and the morphologic characteristics of the Morphou bay with the laboratory results to measure long-term effects of the pollution, diffused into the Mediterranean sea.

ADVANCED TREATMENT BY CHEMICAL OXIDATION OF PULP AND PAPER EFFLUENT FROM A PLANT MANUFACTURING HARDBOARD FROM WASTE PAPER

Abstract This study attempts to evaluate the applicability of chemical oxidation processes to polish biologically treated effluent of a plant manufacturing hardboard from waste paper to comply with the discharge limit of 120 mg l−1 chemical oxygen demand (COD). In the first step, a chemically assisted settling was applied. The optimum results were obtained with alum plus lime with the alum dose of 200 mg l−1. In the second step, chemically assisted settling effluent was fed into an activated sludge system and over 80% COD removal was achieved. In the last step of the experimental study, a series of ozone oxidation and Fenton oxidation methods were tested to remove residual COD. Ozone oxidation provided 80% COD removal. An ozone dose of 40 mg min−1 with a reaction time of two hours was found to be optimum. Catalytic ozonation by using ferric iron, as well as high pH ozonation, Fenton process and H2O2/O3 oxidation did not prove to be more efficient than plain ozonation under these study conditions.

Reaction Kinetics of Spent Reactive Dye Bath Ozonation Process

Oxidation of a spent reactive dye bath containing a mixture of Remazol brand dyes as well as two main inorganic additives was carried out using ozone and decolorization was obtained in a relatively short time (10–30 min) and ozone utilizations were between 329 and 1609 mg. The spent dye bath oxidation could not be represented by any simple kinetics. Ozonation kinetics and decolorization character was evaluated using synthetic samples with dyes and assisting chemicals. Synthetic Dye Sample decolorization was achieved in 90 s with ozone utilization of 32 mg. NaCl addition decelerated the decolorization rate and increase the ozone utilizations. Na2CO3 addition resulted in high pH and alkalinity and changed the mechanism of ozonation process as well as decolorization reactions yielding a better oxidation than that of the sample containing only NaCl.

Treatment of Antibiotic Formulation Wastewaters by Fenton Process

Abstract Pharmaceuticals formulation plants have a variety of wastewater sources. A significant part of these wastewaters can be directly conducted to central biological treatment. Among the wastewater groups that need a pretreatment, antibiotic wastewaters require a special attention due to their toxicity to biological treatment and low biodegradability. In this study, pretreatment of antibiotic formulation wastewaters by Fenton oxidation process was experimentally investigated. Three different antibiotic formulations, all having common use, were selected. The basic formulation of the antibiotics used were; cefuroxime axetil, ceftriaxone and sulfisoxazole. Strength of all three samples was similar and around 1000 mg/L COD. Fenton oxidation proved very effective on all samples. Optimum conditions of oxidation were found as; pH 2, Fe2+/H2O2 of 0.49 g/g and H2O2/TOC ratio varying from 2 to 6 g/g. High degree of conversion was completed within 2 hours. The process provided flocculation of particulate organics, oxidation and mineralization. 80-93% COD removals in all three samples were achieved. A marked increase in biodegradability could only be obtained after a high degree of COD removal. The ceftriaxone sample was very resistant to biodegradation. A satisfactory level of biodegradation could be achieved after 80% COD removal indicating that for such cases Fenton process can be conceived as a final treatment rather than a pretreatment.