Study On The Characteristics Of Dispersed Swine Washing Wastewater Treatment With Enhanced Nitrogen Removal Constructed Wetland

Based on the characteristics of dispersed swine washing wastewater in the southern hilly rural area which is riching in nitrogen and phosphorus and discharging disorderly,considering the principles of economically feasible and convenient operation,using the dynamic equilibrium of adsorption-regeneration of the biological zeolite and organic carbon source of cellulose as basis,treating the wastewater after ABR-functional zoning type artificial wetland of enhanced nitrogen removal(the ammonia was about 150 mg/L).This paper focused onresearching the removal capability of decentralized swine washing wastewaterof the functional zoning type constructsd wetland to enhance nitrification and denitrification.Meanwhile, the mechanisms of denitrification and phosphorus removal were studied.Further more,we studied the performance of the integration technology of ABR-functional zoning type artificial wetland(inclouding the zone of enhanced nitrogen removal、nitrification and denitrification) treated the dispersed hoggery flushing water with the low temperature condition.Microbial community structure in different units of constructed wetland were analynised with 16 s ribosomal DNA sequence.The main conclusions are as follows:(1)The starting time of the functional zoning type constructed wetland of nitrification was about two months and the effect of reoxygenation in the zoolite layer was acceptable after starting successfully.The production rate of nitrate nitrogen was stable.Zeolite could achieve the rapid adsorption-biological regeneration dynamic balance when it absorpted ammonia nitrogen. The maximum nitrification rate was 0.0259kg/(m3·d).(2)The main way of nitrogen removal was nitrification/denitrification, followed by the zeolite adsorption in the functional zoning type constructed wetland of nitrification, accounting for 58.43% and 33.29%,respectively.The effect of microbial assimilation and plant absorption were little.Stromal adsorption was the main mode of phosphorus removel in the artificial wetland, brick and zeolite adsorption accounted for 84.33% and 12.86% in the phosphorus removal,plants absorption and microbe assimilation occupied only 2.81%.(3)The removal efficiency of nitrate nitrogen was stable in the functional division type constructed wetland of denitrification(with rice straw as solid carbon source), the removal rate could reach up to 95%, the maximum denitrification rate was 0.0579 kg/(m3·d) and it did not cause the accumulation of nitrite nitrogen in the effluent.The filled rice straw at the first time could provide stable and sustainable carbon source to denitrification for three months,then the supplement should be 2 kg once a month.(4)When the integration technology of ABR-functional zoning type constructed wetland treating the dispersed hoggery flushing water under the low temperature condition, COD, NH4+-N, SS, TN, TP and Fecal coliform were decreased from 2390mg/L, 137mg/L,4991mg/L, 224mg/L, 49mg/L and 509 × 104/L to 108mg/L, 45mg/L, 102mg/L, 58mg/L, 6mg/L and less than 1×104 piece/L that were all less than the emission limits of Discharge standard of pollutants for livestock and poultry breeding(GB18596-2001).The average removal rate were 95.45%、67.22%、89.71%、74.12%、87.76% and 99.80%, respectively.(5)The dominant bacteria(at the phylum level,the same below)on the surface of zeolite in the strengthen nitrification of functional zoning type constructed wetland were Proteobacteria and Nitrospirae, the predominant bacteriaon of the brick surface were Firmicutes and Proteobacteria; The superiority bacteria on the surface of rice straw in the strengthen denitrification of functional zoning type constructed wetland were Chloroflexi, Bacteroidetes,Proteobacteria and Fibrobacteres, thedominant bacteriaon of the brick surface were Firmicutes, Proteobacteria and Bacteroidetes.