Global NEST Journal

Photo-Fenton for decreasing concentration of Pb(II) ions in the aqueous solution is systematically studied. The photo-Fenton process was carried out by batch technique, under UV light. The influences of process operating parameters were evaluated. The results of the research demonstrated that by photo-Fenton process, the concentration of Pb(II) ions in the aqueous solution can be decreased, that may be through oxidation mechanism by OH radicals. The decrease is found to be controlled by Fe2+ and H2O2 concentrations, as well as by the pH and the irradiation time. For 20 mg/L of Pb(II) in the 100 mL solution, the optimum condition of the oxidation is obtained to be 10 mmole/L of Fe2+, 200 mmole/L of H2O2, pH 3, and 90 min of the reaction time. It is also confirmed that the oxidation of Pb (II) by OH radical has formed the undissolved PbO2, that is less toxic and easier to be handled.

The textile industry has an important place in the environmental pollution due to its heavy water consumption and to the toxic content of dye. Every succeeding day, the water quality is deteriorated because the wastewater containing the dye is supplied to the receiving medium. In this study, The electrocoagulation and electrofenton processes, which produce less waste than the conventional methods and which are less costly, have been investigated for decolourization of acrylic yarn dyeing wastewater. The electrocoagulation process was involved four electrodes parallel connected. To optimize the treatment, response surface methodology (RSM) was applied. The operating independent conditions were selected as the current density (20 -100 A/m2), reaction time (5-25 minutes) and initial pH (pH 4.3-pH 8.3). As a result of optimization by RSM method, the highest Colour, COD and TOC removal were obtained as 96.2%, 43.8% and 40.4 % , respectively. In order to obtain these results, it was necessary to apply a current density of 100 A/m2 to the wastewater which has been set to an initial pH of 7.2 and 20.7 minutes. With the experimental setup installed, high colour removal can be achieved in as little as 15 minutes. Although the colour removal is high, COD removal does not meet discharge standards. Therefore, electrofenton process was applied for enhancing COD and TOC removal and removal rate increased to 70.0% and 61.5%, respectively. In order to study the removal mechanism for acrylic yarn dye wastewater by electrocoagulation process, kinetic modelling was applied. Energy consumption was also assessed.

Population growth, urbanization and anthropogenic activities are becoming a serious problem for water resources in Turkey, which necessitates their monitoring and maintenance of water quality. In this study, water quality was implemented in the Porsuk Stream in Inner Anatolia, Turkey. Water samples were collected at monthly intervals between the period of 2008-2010 at four selected stations. Twenty one water quality parameters were measured which are water temperature (T), pH, dissolved oxygen (DO), electrical conductivity (EC), salinity, turbidity, chloride, suspended solids, dissolved solids, organic nitrogen (Org-N), ammonium nitrogen (NH3-N), nitrite nitrogen (NO2-N), nitrate nitrogen (NO3-N), total organic carbon, biological oxygen demand (BOD), chemical oxygen demand (COD), total coliform, alkalinity, orthophosphate phosphorus (PO43--P), total phosphorus and chlorophyll-a. The monitoring was conducted to see how the water quality changed along the stream in response to various anthropogenic activities. Besides, a paired t-test was utilized to determine the concentration differences at stations above and below the single most important point source of pollutants (Eskişehir city). Moreover, a regression model was used to establish relations between water quality parameters and flow and to estimate nonpoint source loadings.

This paper presents the results of an experimental study carried out in field-scale test cells in order to determine the effect of aeration and leachate recirculation on waste decomposition rate, solid waste characteristics, landfill gas composition and settlement in the landfill body. Four landfill test cells with the dimensions of 20 m x 40 m x 5 m were constructed in Komurcuoda Sanitary Landfill, Istanbul. Solid wastes representing Istanbul Asian side waste characteristics were landfilled in the test cells and they were operated simulating anaerobic (AN1), leachate recirculated anaerobic (AN2), semi-aerobic (A1) and aerobic landfilling (A2) methods. Alternative landfilling methods for accelerating solid waste stabilization in landfills were investigated by means of solid waste characteristics (elemental analysis, pH, moisture content, TOC, TKN, C/N ratio, volatile solid content (VS), biochemical methane potential (BMP), and stability index (SI) analysis), landfill gas components (CH4, CO2, O2, and H2S), temperature variations in landfill body, and landfill settlement. The study indicated that aeration and leachate recirculation accelerate biodegradation rate. Higher rates of MSW biodegradation eventually provide reduction in the contaminant life span of the landfill by achieving a high waste volume reduction in a relatively short duration than anaerobic test cells, decrease the cost of long term monitoring incurred with post-closure of landfill sites. In case of impossibility of aerobic landfilling based on the results of the cost benefit analysis, it was stated out that semi-aerobic landfilling technology is also a viable method in shortening the stabilization time and accelerating the landfill gas production.