Surface Flow Constructed Wetland Wastewater Treatment Plant Of Small Towns Water Ammonia Nitrogen, COD Degradation Research

Under four water hydraulic loading conditions.(0.03m3/m2·d、0.04m3/m2-d、0.05m3/m2-d、0.06m3/m2-d), and before and after the influent distribution system is reformed, this paper studies surface flow constructed wetland degradation the conventional sewage treatment plants out water ammonia nitrogen and COD in small towns. The experiment improves the influent distribution system. It uses water-dropping to increase atmospheric reoxygenation to raise the concentration of dissolved oxygen in water, which enhanced the efficiency of nitrogen and COD taken off.When the water hydraulic loading is0.03m3/m2-d, the average concentration of ammonia nitrogen is23.2mg/L, and that of COD is87.6mg/L for influent water. In unit A, the average concentration of ammonia nitrogen is3.9mg/L, and that of COD is22.6mg/L, the total removal rate of ammonia nitrogen is83%, and that of COD is74.2%; in wastewater, the average removal rate of ammonia nitrogen is28.8kg/d, and that of COD is97.5kg/d. In unit B, the average concentration of ammonia nitrogen is3.1mg/L, and that of COD is22.2mg/L, the total removal rate of ammonia nitrogen is86.6%, and that of COD is74.6%; in wastewater, the average removal rate of ammonia nitrogen is30.1kg/d, and that of COD is98.1kg/d.When the water hydraulic loading is0.04m3/m2·d, the average concentration of ammonia nitrogen is22.6mg/L, and that of COD is85.9mg/L for influent water. In unit A, the average concentration of ammonia nitrogen is4.3mg/L, and that of COD is25.5mg/L, the total removal rate of ammonia nitrogen is81%, and that of COD is70.3%; in wastewater, the average removal rate of ammonia nitrogen is36.6kg/d, and that of COD is121kg/d. In unit B, the average concentration of ammonia nitrogen is3.4mg/L, and that of COD is25.3mg/L, the total removal rate of ammonia nitrogen is85.1%, and that of COD is70.5%; in wastewater, the average removal rate of ammonia nitrogen is38.5kg/d, and that of COD is121kg/d.When the water hydraulic loading is0.05m3/m2-d, the average concentration of ammonia nitrogen is20.3mg/L, and that of COD is80.2mg/L for influent water. In unit A, the average concentration of ammonia nitrogen is5.8mg/L, and that of COD is30.2mg/L, the total removal rate of ammonia nitrogen is71.5%, and that of COD is 62.4%; in wastewater, the average removal rate of ammonia nitrogen is36.3kg/d, and that of COD is125kg/d. In unit B, the average concentration of ammonia nitrogen is4.6mg/L, and that of COD is29.7mg/L, the total removal rate of ammonia nitrogen is77.4%, and that of COD is63.0%; in wastewater, the average removal rate of ammonia nitrogen is39.3kg/d, and that of COD is125kg/d.When the water hydraulic loading is0.06m3/m2·d, the average concentration of ammonia nitrogen is20.5mg/L, and that of COD is81.2mg/L for influent water. In unit A, the average concentration of ammonia nitrogen is8.5mg/L, and that of COD is42.4mg/L, the total removal rate of ammonia nitrogen is58.4%, and that of COD is47.8%; in wastewater, the average removal rate of ammonia nitrogen is35.9kg/d, and that of COD is116kg/d. In unit B, the average concentration of ammonia nitrogen is7.2mg/L, and that of COD is41.7mg/L, the total removal rate of ammonia nitrogen is64.9%, and that of COD is48.6%; in wastewater, the average removal rate of ammonia nitrogen is39.9kg/d, and that of COD is116kg/d.The four water hydraulic loading can improving the efficiency of denitrtflcation of the surface flow constructed wetland wastewater treatment system by3.6%5-6.5%after the influent distribution system is reformed. It cannot clearly change the removal amount and rate. If to reach the primary A standard in table1in ’discharge standard of pollutants for municipal wastewater treatmentplant’(GB18918-2002), we can choose the water hydraulic loading of0.04m3/m2·d or0.05m3/m2·d. Only to reduce the concentration of COD, ammonia nitrogen, we can choose the water hydraulic loading of0.06m3/m2·d or more, so to treat more wastewater using surface flow constructed wetland wastewater treatment system. can decrease the content of ammonia nitrogen in water of small towns.This research shows, the surface flow constructed wetland sewage treatment system is a practical method for wastewater treatment plant of small towns to depredate water ammonia nitrogen, COD in our country at present stage, with its less investment, lower operating cost, simpler management, better denitrification effect and stable operation.