Study On Enhanced Removal Of Total Nitrogen From Water By Artificial Infiltration System

Artificial infiltration system is attracting more attention for its low construction cost, simple operation, high nitrogen and phosphorus removal efficiency. In this paper, Taking mariculture wastewater with low organic carbon but high nitrogen and phosphorus concentration as the research object, the operational condition of artificial infiltration system was studied and pollutants removal condition was researched. Artificial infiltration system was structured by layered brown soil and sand. Peanut shell and shell were also added as growth promoter for microorganism growth. The results showed as follows:(1) TN and NH3-N removal rate were the highest of43.89%and86.09%respectively when hydraulic loading was20cm3/(cm2·d) in the hydraulic operation period of6h/18h. Inadequate anaerobic condition was the reason for the poor effect of NO3-N or NO2-N removal. The removal of TP was not influenced by hydraulic load change and COD removal rate decreased with hydraulic load increasing.(2) NO3-N was basically removed in the working condition of6h/6h and hydraulic loading of20cm3/(cm2-d). NO2-N removal rate was about30%and TN removal rate can reach the maximum of54.88%in the working condition of6h/6h. Operation period had little influence on NH3-N and TP removal rates which can reach85%and75%respectively in the all three working conditions. COD removal rate decreased slightly due to organic matter dissolving out from filtering layer. Increasing dry-wet alternation frequency was beneficial for pollutants removal effect.(3) with water outlet pipe prolonged by50cm, NO3-N and NO2-N removal rates significantly increased, TN and COD removal rate increased slightly, NH3-N and TP removal rate were almost unchanged in the working condition of6h/6h and hydraulic loading of20cm3/(cm2-d).(4) NH3-N and TP removal processes happened mainly within the70cm of percolation column. At this height, NH3-N and TP removal rates can reach89.45%and92.84%respectively. To the contrary, TN, NO3-N and NO2-N removal processes mainly occurred in the saturated section and COD concentration increased slightly in the same section for the reason that some soluble matter was not used by the denitrifying bacteria.