Abstract:

The performance of nitrogen removal and electricity generation of a novel bio-electrochemical-granular sludge reactor at different influent nitrogen concentration was investigated. The impact mechanism of granular sludge, key enzyme activity, extracellular polymer composition and microbial community distribution were systematically studied. The results showed that COD, NO₃^--N, NO₂^--N and dissolved methane were efficiently removed in stages Ⅰ, Ⅱ, Ⅲ and Ⅳ (Influent NO₃^--N and NO₂^--N concentrations were 60 and 20 mg·L^-1, 100 and 40 mg·L^-1, 140 and 60 mg·L^-1, 180 and 80 mg·L^-1, respectively). The removal efficiency of COD was the highest in stage Ⅳ, and it was above 96%. The effluent concentration of NO₃^--N was the most stable at stage Ⅱ, and the removal efficiency was over 99%. The NO₂^--N removal efficiency was above 99% in each stage. In stage Ⅳ, the maximum power density and output voltage was 471.2 mV·m^-3 and 608.1 mV at the fourth compartment, respectively. The polysaccharide and protein content of LB-EPS was the highest in stage Ⅱ of the fifth compartment, 13.7 mg·g^-1 and 14.7 mg·g^-1, respectively. Coenzyme F₄₂₀ activity was the lowest in the first compartment. The protease activity of the sludge was increased due to the increase of influent nitrogen concentration. From stage Ⅰ to stage Ⅳ, the relative abundance of Protebaoteria was decreased, while the relative abundance of Chloroflexi, Firmicutes and Planctomycetes were increased. Although Thauera with denitrification effect was decreased by 8.64% in the first compartment, the nitrogen removal was still well in the reactor. The relative abundance of Methanothrix was increased to 12.3% in the fourth compartment, indicating that Methanothrix could co-exist with other bacteria in the reactor.

Key words: electrochemistry, anaerobic, nitrogen concentration, wastewater, microbial community

摘要：

探讨了新型生物电化学-颗粒污泥反应器在不同进水氮浓度下的脱氮效能与产电性能，并从颗粒污泥的关键酶活性、胞外聚合物组分以及微生物群落分布等角度系统研究了其影响机制。结果表明，COD、NO₃^--N、NO₂^--N和溶解性甲烷在第Ⅰ、Ⅱ、Ⅲ、Ⅳ阶段（进水NO₃^--N和NO₂^--N浓度分别为60 mg·L^-1和20 mg·L^-1、100 mg·L^-1和40 mg·L^-1、140 mg·L^-1和60 mg·L^-1、180 mg·L^-1和80 mg·L^-1）均得以有效去除，其中COD去除率在第Ⅳ阶段效果最佳，去除率达96%以上，NO₃^--N出水浓度在第Ⅱ阶段更为稳定，其去除率达99%以上，NO₂^--N去除率在各阶段均达99%以上；该反应器最大的功率密度与输出电压值为第Ⅳ阶段的4号格室，分别为471.2 mV·m^-3和608.1 mV。污泥疏松型胞外聚合物（LB-EPS）中多糖与蛋白含量最高为第Ⅱ阶段的5号格室，分别为13.7 mg·g^-1和14.7 mg·g^-1；1号格室污泥中辅酶F₄₂₀活性最低，进水氮浓度的增大提高了污泥中蛋白酶活性。由第Ⅰ阶段至第Ⅳ阶段，该反应器中变形菌门（Protebaoteria）相对丰度减少，而绿弯菌门（Chloroflexi）、厚壁菌门（Firmicutes）和浮霉菌门（Planctomycetes）相对丰度增加；具有脱氮作用的陶厄氏菌属（Thauera）在1号格室减少了8.64%，但该反应器脱氮效果未受到影响；甲烷丝状菌属（Methanothrix）在4号格室相对丰度增至12.3%，表明产甲烷菌可在该反应器中与其他菌群联营共存。

关键词: 电化学, 厌氧, 氮浓度, 废水, 微生物群落