Uso de célula combustível microbiana na recuperação de energia elétrica proveniente do tratamento de esgotos por wetlands construídos

Abstract

From the operation of three built wet treatment systems, one control system (WC-A) and two systems with microbial fuel cell (WC-B and WC-C), the voltage and electric current generated were evaluated and the quality of synthetic sewage treatment. The systems had an average useful volume of 18.5 L and operate in continuous mode with TDH 24h and vertical upflow. The filter medium used was a red ceramic, from the civil construction residue, or which gave an average effective porosity of 45%. The substrate used was synthetic domestic sewage in a concentration compatible with a classification for weak sewage. A chosen macrophyte was an Eichhornia Crassipes with a density of 20 units per m². The systems operate in two stages, one without aeration (stage II) and the other with subsurface forced aeration (stage III). Microbial fuel cell systems receive carbon electrodes to be used as a cathode and anode. During the two stages, even with aeration, the characteristic environment systems is anoxic, however voltage measurements up to 661 mV were observed in the WC-B system. During an aerated stage, the quality parameters of the analyzed effluent (COD and nitrogen series) obtain the best removal efficiency, except for the phosphorus that does not change. The average removal of organic carbon materials in terms of COD was 91%. The average removal of phosphorus was 70%, attributed to the adsorption capacity of the filter medium used. It was observed an increase of 45% in the efficiency of removal of NTK and 53% in the efficiency of removal of N-amon in systems with MFC. Regarding the conversion of electrical energy or system, WC-B obtained more expressive results, showed an increase in power of up to 74.2 mW m-2 and Coulombic efficiency of up to 15.32%.