改性沸石湿地脱氮除磷效能及机制

为明确改性沸石湿地对分散性农村生活污水中氮磷的去除效能,并探索其脱氮除磷机制,将改性沸石作为折流湿地填料层填料,应用于厌氧折流板反应器(ABR)+折流湿地(BFCW)组合工艺,为苏州市农村生活污水处理提供新途径.结果表明,改性沸石湿地对氮磷去除良好且稳定,脱氮量和除磷量较沸石湿地分别增大1.8%和1倍多.湿地主要通过填料的吸附截留作用脱氮除磷,以Ca-P和Al-P为主要沉淀磷素形式,植物的泌氧和吸收作用有助于稳定出水水质.湿地前端和后端分别以填料的吸附截留作用和微生物的硝化反硝化作用为主要脱氮途径.改性过程对沸石磷素吸附沉淀性能的大幅提升是在多重途径的协同作用下实现的,湿地构型和植物根系的影响是造成相同区域填料氮磷截留量差异的主要原因.硝化作用强度的高低是改性沸石湿地脱氮效果及稳定性季节性波动的主因.

Efficiency and Mechanism of Nitrogen and Phosphorus Removal in Modified Zeolite Wetland

To study the efficiency and mechanism of nitrogen and phosphorus removal for decentralized rural sewage in modified zeolite wetland, the modified zeolite was applied as substrate into a combined process composed of anaerobic baffled reactor (ABR) and baffled flow constructed wetland (BFCW), providing a new way for rural sewage treatment in Suzhou City. The study was contrasted with zeolite wetland. The results showed that the modified zeolite wetland had high efficiency and stability of nitrogen and phosphorus removal, and the nitrogen and phosphorus removal quantities of modified zeolite wetland were 1.8% and 1 times higher than those of zeolite wetland during the trial. The modified zeolite wetland mainly removed nitrogen and phosphorus by substrate adsorption, and the main fractions of modified zeolite were Ca-P and Al-P. The oxygen-secretion and absorption of plants stabilized the water quality of the effluent. The substrate adsorption was the main nitrification removal pathway in front of the wetland, and nitrification and denitrification were the main nitrification removal pathways at the end of the wetland. The nitrogen and phosphorus adsorption capacities during the pilot test were much higher than those of the static test. The optimization of phosphorus adsorption capacity for modified zeolite was achieved under the synergy of multiple pathways. The effect of configuration and plant root was the main reason for the difference of nitrogen and phosphorus adsorption quantities. Nitrification intensity led to the seasonal fluctuation of nitrogen removal effect and stability in modified zeolite wetland, and the low nitrification intensity in the front of wetland was related to the strong adsorption of NH₄⁺-N by the modified zeolite.