高效藻类塘对农村生活污水的处理及氮的迁移转化

研究了高效藻类塘系统处理高氮农村污水氮的去除及其迁移转化规律.高效藻类塘和水生高等植物塘水力停留时间分别为8 d和4 d,进水总氮和氩氮分别为17.13-133.2 mg/L和1.85～108.3 mg/L,两级高效藻类塘对总氮和氨氮的全年平均去除效率分别为29.4%和91.6%,季节处理效率排序为夏季>秋季>春季>冬季.高效藻类塘中氨氮的降解和转化途径依次为硝化作用、藻类同化吸收及其他途径、氨氮挥发;硝化作用占氨氮总转化量的50%以上;高效藻类塘内可以发生氨氮沉淀,但可忽略不计.总氮的去除以藻类同化形成颗粒有机氮经分离后得以去除为主,氨氮挥发较少.可采用藻类塘出水回流至化粪池或改进水生高等植物塘构造强化反硝化.提高系统的整体脱氮效果.

Migration and Transformation of Nitrogen in a HRAP Treating Domestic Wastewater in Rural Area

Abstract:The migration and transformation of nitrogen was studied in a high-rate algal pond (HRAP) treating domestic wastewater. Total nitrogen varied from 17.23 to 133.2 mg/L while ammonia ranged from 1.85 to 108.3 mg/L in domestic wastewater. At HRT of 8 days, the annual average removal efficiency for TN and ammonia were 29.4% and 91.6%, respectively in the two-stage HRAP. The treatment performance ranked in a descending order as follows: summer, autumn, spring, winter. The major mechanism for the migration and transformation of nitrogen in HRAP were nitrification, assimilation by algae and others such as ammonia evaporation. Nitrification contributed to more than 50% of ammonia removal. Despite the possibility, the contribution of ammonia precipitation was negligible in HRAP. The total nitrogen was mainly removed through assimilation into particular organics and subsequent separation. The contribution of ammonia evaporation to total nitrogen removal was marginal. The overall removal of TN can be improved by recycling some treated effluent to the upstream septic tank or by upgrading a polishing hydrophyte pond.