Heavy Metal And Energy Recovery In BES From Wastewater Treatment

Based on microbial electrochemical theory knowledge,this study constructed the self-drive MFC for molasses-metal ion wastewater treatment and electricity production and powered-MEC for hydrogen production and treatment of Chinese traditional medicine wastewater.Both MFC and MEC contain anode and cathode chambers.Anode chambers in MFC and MEC were filled with molasses wastewater traditional medicine wastewater,respectively,as the anode substrate and together with electroactive microorganisms while the cathode chamber in MFC was filled with electroplating wastewater containing metal ion(Ag+)as a cathode electron acceptor.This research demonstrated the use of the constructed continuous flow MFC with organic wastewater as anode and wastewater contain different concentrations of Ag+as an electron acceptor at the cathode to produce electricity stably.In terms of COD removal,the MFC with Ag+concentration of 500 mg·L-1,1000 mg·L-1,and 2000 mg·L-1 as the cathode electron acceptor,the COD removal rate of anode molasses wastewater was 68.16%,79.63%,81.2%,respectively.Among them,the highest removal rate of Ag+reached 71.6%.The maximum voltage was 331.7 mV,447.2 mV,514.5 mV,with respect to 500 mg·L-1,1000 mg·L-1 and 2000 mg·L-1 Ag+concentrations.The maximum power density were 62.82 mW·m-2,42.68 mW·m-2,and 23.93 mW·m-2,respectively.The results show that the Coulomb efficiency was not high and the electron recovery effect is not ideal.The two MEC systems,used immobilize activated sludge and non-immobilize activated sludge containing traditional Chinese medicine wastewater as a substrate to demonstrate hydrogen production.Studies have shown that the optimal system of MEC reaches the maximum hydrogen production rate of 8.39(±0.10)and 10.0(±0.17)when the organic load was 24 g COD L-1·d-1.The COD removal rate of the immobilized system MEC is stable at between 43.6%-50.1%,and higher than the COD removal rate of the non-immobilized reactor,which has stable COD removal rate between 25.8%-38.9%.The experimental data indicated that the immobilized sludge system has better stability and higher production capacity.