电流对MEC-3DBER-S脱氮除磷效果的影响及机理分析

针对低C/N污水处理厂二级处理出水中氮、磷去除问题，基于三维电极生物膜工艺（3DBER）反硝化脱氮碳源消耗量少的特点，构建了微电凝聚-三维电极生物膜耦合硫自养强化脱氮除磷工艺（MEC-3DBER-S）.对比研究了3DBER与MEC-3DBER-S在不同电流强度条件下的运行特性，并结合基于nirS基因的克隆文库技术分析了MEC-3DBER-S中反硝化微生物的构成.运行结果表明，MEC-3DBER-S有效强化了氮、磷的去除效果，特别是提高了低电流条件下的脱氮效率；同时电流作用能够促进海绵铁腐蚀，提高除磷效果.当C/N=1.5、HRT=8h、I=300mA条件下，其TN和TP去除率分别达到75%和78%，分别比3DBER高10%和28%左右.基于nirS基因的克隆文库结果表明，MEC-3DBER-S中同时存在与具有异养、氢自养、硫自养和铁自养反硝化功能的菌属相似的细菌.该体系中有机碳源、H2、单质硫和Fe²⁺等电子供体可相互补充，强化了脱氮；同时，体系中还存在物化联合生物除磷的作用，强化了除磷.因而，MEC-3DBER-S复合反硝化体系保证了较高的脱氮除磷效果.

Influence of electric current for enhancing nitrogen and phosphorus removal efficiency and mechanism analysis on micro electrocoagulation combined 3-dimensional-biofilm-electrode with sulfur autotrophic denitrification technology

A 3-dimensional biofilm electrode reactor (3DBER) coupled with sulfur autotrophic denitrification system was developed by integrating with micro-electrocoagulation process. The novel process, namely MEC-3DBER-S, was set up to enhance the removal efficiency of nitrogen and phosphorus for the effluent of low C/N ratio from municipal wastewater treatment plant (WWTP). The characters of MEC-3DBER-S were compared with that of 3DBER under different current conditions. Moreover, the biofilm denitrifying bacteria community was also analyzed in MEC-3DBER-S system based on the library of nirS gene cloning technology. The results indicated that the removal efficiency of nitrogen and phosphorus are intensified in MEC-3DBER-S process as compared to 3DBER, especially the denitrification under the lower current conditions. Phosphorus removal efficiency could be improved by the sponge iron corrosion process that was induced by the function of current. The nitrogen and phosphorus removal efficiencies were reached about 75% and 78% respectively, which were 10% and 28% higher than that of 3DBER under the condition of C/N=1.5, HRT=8h, I=300mA. In addition, it was found that heterotrophic denitrifying bacteria, hydrogen autotrophic denitrifying bacteria, sulfur autotrophic denitrifying bacteria and iron autotrophic denitrification denitrifying bacteria simultaneously existed in MEC-3DBER-S system, which could respectively utilize organic carbon, H2, sulfur and Fe²⁺ as electron donors for denitrification. The denitrification efficiency could be improved and stabilized by the mutual complementation of the different electron donors. In the meantime, there would be the physical, chemical and biological effects that were resulted in more efficient for phosphorus removal in the system. Thus, a higher nitrogen and phosphorus removal efficiency could be guaranteed in MEC-3DBER-S process.