Optimization of electrocoagulation and integration of microbial fuel cells for brewery wastewater treatment

Abstract

Brewery industries hold a significant position in the economy of any country, but it also poses serious challenges including high water consumption and release of high strength wastewater into the environment. This study reports the sequential treatment of the brewery effluent by two electrochemical methods–Electrocoagulation (EC) and Microbial Fuel Cells (MFC). Initially, the brewery wastewater was pre-treated by EC process using aluminium electrodes. The primary factors involved in the process were optimized for maximizing COD removal and minimizing energy consumption using the Central Composite Design (CCD) of Response Surface Methodology. A mean COD removal of 44.2% and an energy consumption of 11.14 kWh/m3 was achieved by the EC process at optimized conditions of pH 6.6; current density 13.2 mA/cm2; electrolysis time 39.3 min. The limited COD removal by EC process is attributed to the presence of most of the COD in the soluble form. EC process at the optimized conditions achieved a TSS removal of 88%, nitrate removal of 71.6%, phosphate removal of 93.17% and soluble COD removal of 11.5%. When the EC-treated wastewater, diluted to one-third strength, was used as substrate in a dual-chambered MFC with abiotic cathode, it attained a COD removal of 91.9% and highest power density of 11.81 mW/m2, thus releasing a treated effluent with discharge standards. The results show that the EC and MFC are thus complementary processes that can efficiently remove the suspended organic matter and soluble organic matter respectively when sequentially employed. This study is the first to statistically optimize the EC pre-treatment of brewery wastewater using CCD-RSM in a sequential EC–MFC configuration.