间歇曝气-反冲洗人工湿地净化性能及微生物作用

Performance and Microbial Action of Intermittent Aeration-Backwashing Constructed Wetland

构建了新型间歇曝气耦合气水联合反冲洗人工湿地系统(CW_(1)),考察了该系统与传统人工湿地(CW_(1))的净化性能及微生物作用。结果表明,间歇曝气维持CW_(1)床体内溶解氧浓度在0.5~3.5 mg/L,营造出厌氧/缺氧-好氧交替的微环境,在稳定运行期间CW_(1)对COD、NH^(+)_(4)-N、TN和TP的平均去除率较CW_(0)分别提高了7.2%、13.1%、8.4%和6.5%;采用水冲强度为8 L/(m^(2)·s)、气冲强度为6 L/(m^(2)·s)、频率为5 min/6 d的气水联合反冲洗,能够促进活性位点和基质孔隙结构的恢复,增强生物膜内外底物和代谢物的传输能力;间歇曝气-气水联合反冲洗提高了CW_(1)床体中微生物群落的丰富度和多样性,使norank_f__NS9_marine_group(3.9%)、norank_f__Saprospiraceae(3.4%)和norank_f__norank_o__Saccharimonadales(4.1%)等厌氧/缺氧和好氧功能菌同时富集,且发现参与糖类和氨基酸代谢过程的功能基因占比均超过5%,加速其介导的有机物降解及氮素去除代谢。

A novel intermittent aeration coupled air-water backwashing constructed wetland system(CW_(1)) was constructed, and the performance and microbial action of CW_(1)and traditional constructed wetlands(CW_(1)) were investigated. The results showed that intermittent aeration maintained the dissolved oxygen in CW_(1)bed between 0.5 mg/L and 3.5 mg/L, creating an anaerobic/anoxic-aerobic alternating microenvironment, and the average removal efficiencies of COD, NH^(+)_(4)-N, TN and TP by CW_(0)increased by 7.2%, 13.1%, 8.4% and 6.5% respectively, compared with CW_(1)during the stable operation period. The combined backwashing with water intensity of 8 L/(m^(2)·s), gas intensity of 6 L/(m^(2)·s) and frequency of 5 min/6 d promoted the recovery of active sites and substrate pore structure, and enhanced the transport capacity of nutrients/metabolites inside and outside the biofilm. Intermittent aeration coupled with water-air backwashing increased the richness and diversity of microbial communities in CW_(1), and simultaneously enriched anaerobic/anoxic and aerobic functional bacteria such as norank_f__NS9_marine_group(3.9%), norank_f__Saprospiraceae(3.4%) and norank_f__norank_o__Saccharimonadales(4.1%) at genus level, and the functional genes involved in the processes of carbohydrate metabolism and amino acid metabolism accounted for more than 5% in CW_(1), accelerating organic matter degradation and nitrogen removal metabolism mediated by these genes.