Bio fuel cells sustainable technology for the treatment of coconut industry wastewater

Abstract

Coconut cultivation and related sectors employ a large rural population worldwide. Discharge of a large amount of high strength coconut wastewater cause soil and water pollution. Microbial fuel cells (MFC) and Microbial Desalination Cells (MDC) are two types of bio-fuel cells that have emerged as promising technologies for simultaneous wastewater treatment via anaerobic degradation and energy recovery via direct electricity generation. newlineThe laboratory scale MFC and MDC batch reactors were developed in this study, to treat the high strength coconut wastewater from coconut processing industries and compared the treatment efficiency and generation of bio-energy from cells. The first stage of the study was carried out to optimize various process parameters of a two chambered MFC, such as concentration of KMnO4 solution as Catholyte, Catholyte pH, reactor temperature, azo dye mediators with Anolyte, electrode materials and spatial configurations of the anode. Within a 102-hour detention period, the MFC achieved a maximum COD removal efficiency of 62.72 % using 2000 mg/L of KMnO4 solution buffered at pH 5 as Catholyte at ambient temperature using carbon cloth anode spatially distributed in coconut wastewater seeded with yeast as Anolyte. The cell generated a maximum electrical potential of 1.16 V and a maximum power density of 6.52 W/m3, with a cell average power density of 4.14 W/m3 throughout the detention period of the reactor. newlineiv newlineIn the second stage of investigation, three-chambered MDC reactor was fabricated. It measured the COD removal efficiency of coconut wastewater with bio-electricity production, based on same process parameters as in MFC except the study of the effect of salt water concentration in the central chamber. MDC achieved a maximum COD removal efficiency of 60.18 % using 2500 mg/L of KMnO4 solution buffered at pH 5 as Catholyte using carbon cloth anode spatially distributed in Anolyte, within 102-hour detention period at ambient temperature.