Research On New Technique Of Microbial Electrochemical Coupling With Anaerobic/Aerobic Degrading The Wastewater From Cotton Dyeing Pretreatment

The wastewater from cotton dyeing pretreatment is hard to degrade due to its high pollutant concentration strong alkaline and low biodegradability.Severe environmental issues and tightening emissions standards make it more arduous to treat wastewater from cotton dyeing pretreatment.New technique of microbial electrochemical coupling with aerobic/anaerobic was built to treat this wastewater from cotton dyeing pretreatment by combining the electric field to anaerobic and aerobic biological treatment technology to come up with this problemWater treatment efficiency of different operation modes(electrochemical system(ES),biological system(BS)and microbial electrochemical systems(MESs))of the new designed technique using wastewater from cotton dyeing pretreatment were discussed in this research.Then operation parameters(applied voltage,HRT,temperature and electrode size)were explored.The effect of applied voltage on the sludge concentration,particle size distribution of sludge and microbial community structure was studied to offer some related technical support for the practical engineering application of new technique of MESs coupling with A/O and provided new ideas for degration of wastewater from cotton dyeing pretreatment.We came to some conclusions when self-manufactured carbon brush electrode was used at more than 180 days stable operation after reactors start up for 35 days:1.The water treatment efficiency of MESs was better than the efficiency of ES and BS.Only 3.2%of COD was removed because of the adsorption of carbon fiber in the operation mode of ES.when the influent COD changing from 5200 mg/L to 5800 mg/L the COD,PVA and NH4+-N removal efficiency of MESs was 69.13%,20%and 68.72%respectively ascending 20.23%,9.93%and 68.72%compared to the BS when the applied voltage was 0.6V.But TP removal efficiency ranged from41.8%to 48.1%both in the BS and MESs.The GC-MS results indicated that some refractory materials(Long-chain fatty acids,Ketones,indoles,benzene and phenolics)were degraded by the MESs and the effect was better than the BS.2.At the optimal operation condition(U=0.6V,T=32?,HRT of anode chamber was 28h and the HRT of cathode chamber was 14h)when the influent COD changing from 4800 mg/L to 6780 mg/L and B/C was changing from 0.41 to 0.45 while the influent pH was 7,COD and PVA removal efficiency respectively were 69.98%and 24.06%.Under the same condition,the biogas production rate of anode chamber was 0.6694 m3/m3 d.When the temperature rise from 22?to 32?and 42?,COD removal efficiency of anode chamber came to 34.98%,50.57%and 49.84%.Meanwhile the biogas production rate of anode chamber came to 0.2944 m3/m3 d,0.6694 m3/m3·d and 0.6529 m3/m3 d.COD removal efficiency of cathode chamber at 32?was 37.5%and better than that at 22?(28.26%)and 42?(20.11%).When the size decreased from 11cm×3cm to 8cm×3cm and 5cm×3cm,the COD removal efficiency of MESs decreased from 69.13%to 56.52%and 51.32%,and biogas production rate of anode chamber decreased from 0.6694 m3/m3d to 0.4062 m3/m3·d and 0.3883 m3/m3 d.3.Applied voltage promoted the growth of microorganisms and increased the sludge floc size.The increase range of anode chamber was from 10?m to 30?m and cathode chamber was from 18?mto 52?m.Only a few of energy used for synthetic cells when microbial decomposing organic matter and MLVSS/MLSS was lower than other applied voltage under the applied voltage of 0.6V so sludge production became less.Applied voltage promoted the diversity of microbial community and selectively effected on different species.In anode microbial community the percentage of Thermovirga and MesotogaAt increased under the applied voltage of 0.6Vwhile the percentage of Syntrophomonas and Desulfovibrio decreased and anode newly increased Smithella.In cathode microbial community the percentage of Azoarcus and WCHB1-69 norank increased while the percentage of Thauera decreased and Fluviicola disappeared under the applied voltage of 0.6V.Dominant of archaea in anode is Euryarchaeota.Under the applied voltage of 0.6V the percentage of Methanocorpusculum decreased while the percentage of Methanosarcina and Me tha nosp irillu m were increased,which rich anaerobic methangenesis way so that promoted pollutants removal rate and improved biogas production rate.