新型填料A/O生物滤池处理低碳氮比农村污水脱氮

针对低碳氮比导致低污染农村污水生物处理时出水总氮(total nitrogen, TN)质量浓度高不能满足排放标准的问题,以普通砾石A/O生物滤池为对照组(1号),采用芦竹和活性炭分别作为缺氧段和好氧段填料的A/O生物滤池(2号)处理人工模拟农村污水并研究其脱氮效果.结果表明,当进水化学需氧量(chemical oxygen demand, COD)、氨氮(ammonia nitrogen, NH~+_4-N)和TN质量浓度分别为(79.47±14.21)、(34.49±2.08)和(34.73±3.87)mg·L~(-1)时,两套装置对COD、NH~+_4-N和TN的去除率分别为(88.00±7.00)%和(89.00±10.00)%、(90.00±2.00)%和(97.00±7.00)%、(37±15)%和(68±7)%,表明添加新型填料芦竹和活性炭能显著增强A/O生物滤池对NH~+_4-N和TN的去除.高通量测序结果显示, 1号装置中参与硝化过程的微生物主要为Proteobacteria(变形菌门), 2号则是变形菌门和Nitrospirae(硝化螺旋菌门)共同作用;1号装置缺氧段中发挥反硝化作用的主要细菌门类包括Chloroflexi(绿弯菌门)、变形菌门、Bacteroidetes(拟杆菌门)和Planctomycetes(浮霉菌门),而2号缺氧段中则主要是拟杆菌门、变形菌门、Firmicutes(厚壁菌门)和Patescibacteria.实时荧光定量聚合酶链式反应(quantitative real time polymerase chain reaction, qPCR)结果表明, 2号装置中生物膜的硝化功能基因(amoA和Nitrospira 16S rDNA)、反硝化功能基因(narG、nosZ、nirS和nirK)和厌氧氨氧化功能基因(ANAMMOX)丰度均高于1号装置,除narG和nosZ基因外,其余几种都有1～2个数量级的差别.

Nitrogen Removal in Low-C/N Rural Sewage Treatment by Anoxic/Oxic Biofilter Packed with New Types of Fillers

When low-concentration rural sewage is treated biologically, the effluent total nitrogen (TN) concentration often does not meet the discharge limit because of its low carbon-to-nitrogen ratio (C/N). To solve this problem, a laboratory-scale anoxic/oxic (A/O) biofilter packed with Arundo donax and activated carbon as the anoxic and aerobic column fillers (No. 2) was operated for treatment of simulated rural sewage and advanced nitrogen removal, while an ordinary gravel-packing A/O biofilter (No. 1) was set up as the control group. The results were as follows. When the influent chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), and TN concentrations were (79.47±14.21), (34.49±2.08), and (34.73±3.87) mg·L^-1, respectively, the No. 1 and No. 2 reactors achieved removal efficiencies of (88.00±7.00)% and (89.00±10.00)%, (90.00±2.00)% and (97.00±7.00)%, and (37±15)% and (68±7)%, respectively. The results revealed that using Arundo donax and activated carbon new fillers could significantly enhance NH₄⁺-N and TN removal. High-throughput sequencing results indicated that the microorganisms involved in the nitrification process in the No. 1 reactor mainly belong to Proteobacteria, whereas those in the No. 2 reactor belong to Proteobacteria and Nitrospirae. In addition, the main denitrification bacterial phyla in the anoxic column of the No. 1 reactor were Chloroflexi, Proteobacteria, Bacteroidetes, and Planctomycetes, whereas those in the anoxic column of the No. 2 reactor were primarily Bacteroidetes, Proteobacteria, Firmicutes, and Patescibacteria. Quantitative real time polymerase chain reaction (qPCR) results showed that the microbial nitrification (amoA and Nitrospira 16S rDNA), denitrification (narG, nosZ, nirS, and nirK), and anaerobic ammonium oxidation functional genes (ANAMMOX) in the No. 2 reactor were significantly higher than those in the No. 1 reactor. All the genes, except for the narG and nosZ genes, had one to two orders of magnitude of improvement in the No. 2 reactor compared to those in the No. 1 reactor.