Study On Electricity Generation From Waste Biomass By Using MFC

As a kind of solid waste,waste biomass has threat to regional water environment,atmosphere and soil.Waste biomass was usually treated together with other kinds of solid waste.The traditional treatment methods include landfill,incineration,composting.However,these methods could cause the secondary pollution of leachate,serious corruption odor and other environmental pollution problems.Microbial fuel cell(MFC)is a good way to convert chemical energy into electrical energy.It could also avoid the combustion steps required by the conventional biomass power generation,result in improving the energy conversion efficiency.MFC could treat and utilize the waste biomass properly.Meanwhile,it has a broad application prospect.In this work,waste biomass was hydrolyzed by enzyme.The enzyme transforms the macromolecular organics into micromolecular organics,solving the problem that MFC can not use the waste biomass to produce electricity.Two-chamber MFC was used as a reactor.Heavy metal ions were utilized as cathode liquid.Waste biomass hydrolysate was utilized as anode liquid,exploring the electricity production performance of MFC from different kinds of waste biomass hydrolysates.First of all,this work explored the feasibility of electricity generation from waste biomass of starch(waste bread)and cellulose(waste rice husk).The reducing sugar yields of bread and rice were 170 g/kg and 50 g/kg at 20 min,respectively.After adding the bread hydrolysate and rice hydrolysate to MFC,the maximum voltage of the external resistance(1000 ?)could reached 0.386 and 0.369 V,respectively.The maximum power density was 29.96 m W/m2 and 25.08 m W/m2.The results confirmed that enzymatic hydrolysis and MFC could be utilized to transform biomass energy into electric energy potentially.Secondly,in order to reduce the cost of industrial production,the effect of enzyme concentration on the hydrolysis process of waste biomass was also investigated.(1)Different enzyme concentration gradients(S1: 0.02 m L/L,S2: 0.1 m L/L and S3: 0.2 m L/L)on the performance of leftover rice hydrolysis was evaluated.The highest reducing sugar concentrations of S1,S2 and S3 were 18.7 g/L,23.2 g/L and34.6 g/L.The highest COD concentrations were 60.6 g/L,67 g/L and 77.5 g/L.Theenzyme concentrations of S3 and S2 were 10 and 5 times as high as S1 respectively.However,the COD production of S2 and S3 was only 10.6% and 28% higher than S1.This experiment proved that the enzyme volume of 0.01 m L/L(S1)could be used as an economic choice for the hydrolysis of leftover rice.The maximum voltage of MFC was 0.260 V by using leftover rice hydrolysate to produce electricity.When the current density was 20 m A/m2,the maximum power density was 8 m W/m2(2)Different enzyme concentration gradients(W1: 0.5 g/L,W2: 1 g/L,W3: 2g/L and W4: 3 g/L)on the performance of office waste paper hydrolysis was also evaluated.The concentrations of reducing sugar were 0.55 g/L,1.2 g/L,2.43 g/L and2.88 g/L.The concentrations of COD were 1851 mg/L,3084 mg/L,6115 mg/L and6377 mg/L.COD concentration of W4 was 262 mg/L higher than that of W3.However,the enzyme concentration of W4 was 1.5 times as high as that of W3.The results showed that the enzyme volume of 2 g/L(W3)could be used as an economic choice for the hydrolysis of office waste paper.The maximum voltage external resistance(1000 ?)could reached 0.287 V when the hydrolysate of office waste paper was inoculated in the MFC anode.When the current density was 42.1 m A/m2,the maximum power density reached 11.28 m W/m2In this work,four kinds of representative waste biomass were treated by enzymatic hydrolysis and electrochemical anaerobic,providing a new way for the safe and environmental protection disposal of waste biomass.