WITHDRAWN: An integrated process of methanol coagulation and side-stream membrane bioreactor for the treatment of rice gruel wastewater

Abstract

The demand for water supply is increasing rapidly across the world due to the exponential growth of population, swift urbanization, and industrialization. Methods for recovery of reusable water from domestic, industrial and agricultural wastewater should be cost-effective, and environmentally safe for the sustainability of water resources. Domestic wastewater is one of the contaminated water sources which need efficient treatment before discharge into water bodies. The novelty of the present study is to treat domestic rice gruel wastewater by coagulation integrated aerobic membrane bioreactor (AMBR) for the generation of reusable water. A hydrophilized ultrafiltration (HF-UF) spiral wound membrane of 5 kDa molecular weight cut off was used for the treatment of rice gruel wastewater at a feed temperature of 30 °C and 80 °C to study separation performance. Further, a comparison study was carried using various coagulants such as methanol, ethanol, and HCl for integration with HF-UF membrane to determine overall process efficiency at 30 °C. Methanol coagulation + HF-UF membrane based integrated process was able to achieve 93.77%, 95.4%, 91%, and 78.6 %, respectively of total dissolved solids (TDS), turbidity, conductivity, and chemical oxygen demand (COD). Further, this process was integrated with a bioreactor operated under aerobic conditions to improve the process efficiency and purified water quality. From the overall experimental results, the integrated coagulation + AMBR process attained a maximum removal of 93.9, 96, 91, and 94.6 percent of TDS, turbidity, conductivity and COD, correspondingly. Finally, an economic estimation of a 1000 Lh-1 capacity pilot plant is described in detail. The study depicts unique advantages of economy, process safety, small footprint, and eco-friendly for rice gruel wastewater by a combination of chemical coagulation with AMBR.