Molasses Waste Treatment And Energy Generation By Bioelectrochemical System At Low Temperature

Molasses wastewater treatment using conventional anareobic microbialtreatment needs to maintain the reactor above30℃, which increase the cost greatlybecause of energy input. In additional, Complexity and high COD concentrationlimits the treatment and energy recovery from biomass a lot. In order to reduce thecost of molasses wastewater treatment and produce energy at the same time,electricity and hydrogen production using biology microbial system（BES） fed bymolasses wastewater at low temperature are discribed here.Single chamber brush anode MFC was set up using pre-enriched bacteriumsolution at25℃、15℃and9℃, and compared the electricity production of reactorran at COD2000mg/L、3000mg/L、5000mg/L respectively. A maximum powerdensity of278.2mW/m²and coulombic effiency of29%was obtained at9℃.Butyric acid increased in the effluent due to the relatively long running period, andbacterium belongs to Clostridia were detected by analysis of the result of high-thought16S rRNA gene454pyrosequencing. Bacterium from room temperaturerunning MFC （RMFC） mainly belongs to Firmicutes and the most bacterium fromlow temperature running MFC （LMFC） belongs to Proteobacteria demonstratedthat although the anode biacterium of RMFC and LMFC shared the same inoculum,the bacterial community structures are different greatly. There is41%Comamonasin LMFC but just2.66%in RMFC, Comamonas has the ability of degradation ofrecalcitrant compounds and removal of nitrogen and niaromatic hydrocarbons, it isa good choice for using in bioremediation. Flavobacteria which was detected atLMFC belongs to Psychroserpens. Discovery of this genus contribute a lot forrearch of psychrotolerant exoelectrogens.The method of hydrogen generation by MEC is promising, however, the costfor catlyst limits the way to application of the technology. In this study, MEC withcatalyst-coated cathode（CMEC） and MEC with biocathode（BMEC） were operatedat9℃using2000mg/L COD inffluent respectively. The hydrogen yield (Y_H2)of115mgH₂/gCOD at energy recovery efficiency based on electricity input of195%(E_ap=0.6V)was achieved by catalyst CMEC, When to BMEC the hydrogen yieldof56.7mgH₂/gCOD at energy recovery efficiency of134.1%(E_ap=0.6V)wasobtained at low temperature of9℃, respectively. Biofilm bacterial communitystructure change a lot from the reactor start-up to running stable,which analysed bythe map of DGGE. Hydrogen and electricity generation using molasses wastewater will reduce thecost of wastewater treatment, and recover the biomass which can not recyclethoroughly by conventional method. The low temperature MEC technology canreduce generation of methane, so the purity of hydrogen production increase greatly.BMEC becomes a promising hydrogen generation technology due to its cost-saving.Study of bacterial community structure by molecular biology methods will preparefor the improvement of biomass recovery.