Feasibility study on EO/EG wastewater treatment using pilot scale SBR

The sequencing batch reactors were developed to treat the actual wastewater from ethylene glycol/ethylene oxide producing industry. Four identical reactors with total and effective liquid volumes of 9 and 7 L were operated respectively in parallel. Laboratory experiments were conducted with different organic loadings of 500, 1000, 1500 and 3000 g-COD/m[3]. day and the performance of the reactors was studied under different sludge ages of 10, 20 and 30 days, the kinetic constants at optimal operational conditions were also determined. According to the results, the efficient removal of COD was 79.5 and 83.5% [SRT = 20 days] and 86% [SRT = 30 days] for SBR 1 and 2 respectively [OLR = 0.5 to 1 kg-COD/m[3]. day] with required reaction time of about 17 h. In order to reach the COD removal efficiencies over 86% at higher OLR values, the researchers required longer reaction periods about 34.5 h for SBR 3 and 4. However, the SRT values have no significant effects on the performance of SBR 1 and 2 at the aeration times greater than 22.5 h while in the case of reactors 3 and 4, with an increase on SRT at all aeration times, the COD removal efficiency increased. It is concluded that the system used in the present study could show an acceptable stability and performance in the treatment of the wastewater containing high concentrations of organic matters especially from EO/EG industries

[Application of reverse osmosis technology for arsenic removal from drinking water]

Arsenic [As] is a highly toxic metalloid found in ground and surface waters. Arsenic contamination in drinking water leads to harmful effects on human health. In this study, the efficacy of Reverse Osmosis [RO] membrane technology was evaluated for arsenic removal from drinking water. This experimental study was carried out on RO membrane spiral- wound module [model: 2521 TE, CSM Co. Korea] in pilot scale. After preparation of sodium arsenate solution in the laboratory, performance of RO membrane system in arsenic [As] removal was investigated. Experiments were conducted with five different pressures [100, 130, 160, 190, 210 Psi], pH [4, 5.5, 7, 8.5, 10], temperature [20, 25, 30, 35, 40°C] and an initial As concentration of 0.2 mg/L. The influence of different feed concentrations [0.2, 0.5, 1, 1.5, 2 mg/L] on As removal efficiency was also examined. In each step, flux was measured and after 30 minutes samples were taken. Arsenic amount in feed and permeate were measured by silver diethyldithiocarbamate [AgDDTC] method. The results of this study demonstrated that greater than 90% of As can be eliminated from drinking water. Also the results showed that the pressure of 190 psi, As concentration of 0.2-0.5mg/L, temperature of 25-30°C and pH = 6-8 were the optimal conditions. Arsenic removal efficiency in optimal conditions of system performance was up to 99%