Issue 2

This report was aimed at an investigation of efficiency for Photochemical Advanced Oxidation Processes (UV photolysis, UV/H2O2, UV/TiO2, UV/H2O2/TiO2 and UV/H2O2/Fe2+ processes) to decolorize Malachite Green Oxalate (MGO) dye. Experimental runs were performed using laboratory scale photochemical reactor. About 98% decolorization was obtained with initial 100 ppm MGO dye in Photo-Fenton process under optimal conditions (60 ppm Fe2+ concentration, 12 mM of oxidant concentration, at pH 3.0 for 60 min). 97% decolorization was obtained using UV/H2O2/TiO2 process having [TiO2]o of 0.6 gm/L for similar reaction conditions. The percentage decolorization of MGO was in range of 94-95% for both UV/TiO2 and UV/H2O2 processes. Concentration of ferrous salt (60 ppm) was considered as an optimal value to carry out the UV/H2O2/Fe2+ process for MGO decolorization. Influence of oxidant (H2O2) and Fe2+ ions for oxidation of MGO was studied in Photo-Fenton process. Sulphate radical based AOPs was proved to be more effective in treating MGO dye with irradiation. Results indicate that decolorization efficiency by Photochemical AOPs for MGO dye in photochemical reactor were more efficient. Pseudo-first-order model of kinetics was noticed to be the best model fit to explain the decolorization of MGO dye solution.

Microbial community was determined in a pilot-scale two-stage step-feed biological nutrient removal system treating municipal wastewater with 10 m3 d-1 capacity. Grit chamber effluent at Istanbul Ataköy Biological Wastewater Treatment Plant was used as influent wastewater. In the pilot plant, the influent wastewater was split into two fractions to anaerobic and anoxic2 tank. Nitrosomonas, Nitrosospira, Accumulibacter, and Dechloromonas along with some other uncultured microorganisms were determined in the aerobic, anoxic and anaerobic stages. COD, TN, NH4+-N, TP, PO43--P, SS, and VSS removal efficiencies were found to be 86.7%, 80.3%, 92.5%, 89.5%, 87.5%, 94.8%, and 95.0% in average, respectively, at 5000 mg MLSS L-1 and 15 days of SRT and 16 hours of HRT. The results indicated that microbial community in the process was quite similar with those in the nutrient removal processes with no step feeding. This process can be used cost-effectively to remove carbon and nutrients from medium-strength municipal wastewaters.

The main objective of this study was to determine the effect of land use change on runoff in Chenar Rahdar watershed. Land use map of the studied basin was determined using Landsat satellite imagery for 2004 and 2015 using ENVI software. After applying the necessary corrections to the images and field surveys to take the educational points, supervised classification technique and maximum probability algorithm were applied to mapping land use change in the study area. According to results, 6 classes of land use were investigated (bare land, rain fed land, forest land, water agriculture land, rangelands and urban lands). In this study, 21 model parameters were calibrated with monthly runoff using 2004-2012 data and validated using 2012-2015 data. The efficiency coefficient for calibration and validation were between 0.88 and 0.94, respectively. The land use changes trend within the time interval showed that the highest percentage of incremental changes is related to urban lands with 108.45%, whereas, the highest decline was observed for agricultural land with 12.46%. In order to investigate the effect of land use change on surface runoff, different land use maps were applied to SWAT model, supposing constant condition for other parameters of the model. The results show that surface runoff increased by 11%, in 2015 compared to 2004. Comprehensive water management can reduce surface runoff in the watershed. The results showed that if all uncertainties were minimized, the calibrated SWAT model can give acceptable runoff simulation results regarding the land use change. These results can be useful for water and environmental resource managers.