电流强度对高盐废水混合生物阴极MFC脱氮及产电的影响

Effect of current intensity on nitrogen removal and electricity generation in hybrid biocathode MFC for high-salinity wastewater treatment

构建了双室混合生物阴极微生物燃料电池(microbial fuel cell,MFC)处理高盐榨菜废水,探讨了不同电流强度对混合膜MFC脱氮的影响,并分析了产电特性及微生物群落特征。结果表明,高电流通量可缩短双室混合膜MFC的完全脱氮周期,且主要缩短的是稳定期周期。相对于其他3个实验组,电流强度最大的S3实验组硝酸盐平均去除速率((5.72±0.10)mg·(L·d)^(−1))与硝酸盐最高去除速率((8.45±0.15)mg·(L·d)^(−1))均最大,且实现总氮100%去除的时间最短(19 d),稳定期硝酸盐去除速率k(6.1225 mg·(L·d)^(−1))最大,这说明增大电流强度可促进混合膜MFC电营养反硝化。电营养反硝化菌可直接利用电子进行反硝化反应,而较大的电子通量给阴极电活性自养脱氮微生物提供了丰富的生命燃料。在产电方面,曝气阶段开路电压(S1、S2、S3、S4分别为750、729、721、699 mV)随外加电阻的增大而增大,最大功率密度相差却并不显著(1.09、0.94、1.04、1.02 W·m^(−3));停止曝气阶段,阴极室电子受体的减少,导致MFC产电性能普遍下降,外电阻最大的S1实验组开路电压(746 mV)与最大功率密度(0.77 W·m^(−3))为最高。高通量测序结果表明,承担电营养反硝化功能的菌群可能为norank_f_Hydrogenophaga,Azoarcus。以上研究结果可为后续双室混合膜MFC处理高盐废水提供技术参考。

A dual-chamber hybrid biocathode microbial fuel cell(MFC)was constructed to treat high-salinity mustard wastewater,the effect of different currents intensities on nitrogen removal of the hybrid biocathode MFC was discussed,and the electricity generation characteristics and microbial communities were analyzed.The result shows that high current intensity can shorten complete nitrogen removal cycle of the dual-chamber hybrid biocathode MFC,mainly shorten the stable phase cycle.Compared with other three groups,both the average removal rate of nitrate(5.72±0.10)mg·(L·d)^(−1) and the highest nitrate removal rate(8.45±0.15)mg·(L·d)^(−1) of the S3 experimental group with the highest current intensity were the largest,the complete removal cycle of total nitrogen(19 d)was the least,and the nitrate removal rate(6.1225 mg·(L·d)^(−1))in the stable phase of S3 was the largest,indicating that the increase of current intensity was beneficial to the electrotrophic denitrification of the hybrid biocathode MFC.The electrotrophic denitrification bacteria could directly use electrons to conduct the denitrification reaction,and large electron flux provided abundant fuel for the cathodic electrophilic autotrophic denitrifying microorganisms.In terms of electricity production,the open circuit voltage(S1:750 mV,S2:729 mV,S3:721 mV,S4:699 mV)during the aeration phase increased with the increase of the external resistance,but the difference of the maximum power density was slight(1.09,0.94,1.04,1.02 W·m^(−3)).When the aeration phase stopped,the electron acceptors in cathode chamber decreased,which led to the general decrease of the electricity generation of MFC,both the open circuit voltage(746 mV)and the maximum power density(0.77 W·m^(−3))of the S1 group with the largest external resistance were the highest.Finally,high-throughput sequencing showed that the bacteria with electrotrophic denitrification function may be Hydrogenophaga,Azoarcus.This research provides ideas and solutions for the subsequent research on the treatment of high-salinity wastewater with dual-chamber hybrid biocathode MFC.