Treatment of wastewater and generation of electric current

Abstract

The wastewater treatment processes include activated sludge, trickling filters, oxidation ponds, extended aeration, suspended growth bioreactors, attached-growth bioreactors, rotating biological disc contactor are inefficient as these require the use of electricity and produce heavy sludge during CODremoval. The Bio electrochemical systems (BESs) have recently emerged as an exciting technology for BOD and COD reduction in wastewater. The microbial fuel cell (MFC) technology is a type of BES that converts chemical energy in the chemical bonds of organic compounds to electrical energy through anaerobic bio-catalysis through wide range organic substrates. In current study, wastewater is used instead of high energy substrates.The effect of two different ion exchange (GorTex and ultrafiltration) membraneson current, voltage, current densities, power densities, columbic efficiencies, COD removal and pH were studied using dairy milk wastewater. In batch mode MFC, microbial anode, chromium cathode and potassium per magnate (KMnO4) was used as terminal electron acceptor and each experiment was performed in triplicate for 10 to 12 dayscycle at constant temperature of 35±10C and at initial pH of 7.23. The study was conducted in an anaerobic chamber under 1 atm pressure of a mixture of H2;CO2:N2 gases at the ratios of 5:5:90. Different parameters including current intensity, open circuit voltage (OCV), current density, power density and columbic efficiency was determined after regular intervals of 24 hours using potentiostat. The optimum values of electric current, open circuit voltage, current density, power density and columbic efficiency were recorded to be 0.81 mA, 2.13 mV, 0.031 mA/cm2, 49.4 mW/cm2 and 34.77% respectively. The current and power density was found to be much improved as compared to previous studies. The Monad Model was used to find the kinetics of reaction which apparently found to follow first order reaction. The kinetics of reaction is unaffected by the kind of membranes. The removal efficiency of chemical oxygen demand (COD) was found to be 65.5%. The study was very promising future application for the reduction of COD and generation of electric current from wastewater.