Nitrate Removal From Groundwater Using Biofilm-Electrode Process

Nitrate pollution in groudwater is increasingly severe, in order to aviod somedisadvantages such as secondary pollution in traditional biological treatmentprocess, biofilm-electrode process was studied in this paper which has manyadvantages such as simplicity of operation、 high efficiency、 without furthertreatment.This paper designed a self-made two dimensional biofilm-elecrtode reactorand a self-made three dimensional biofilm-elecrtode reactor based on the theory ofbiofilm-electrode process and sdudied the following contents: contrast studiesbetween two dimensional biofilm-elecrtode reactor and4contrast reactors such asconventional bacterial film reactor; the main influence factors of the twodimensional biofilm-elecrtode reactor and three dimensional biofilm-elecrtodereactor such as HRT、 electric current、 m(C)/m(N)、 temperature、 influentconcentration of nitrate nitrogen;research results as follows:(1)Nitrate degradation rate is98%in Biofilm-electrode process and it is higherthan4contrast reactors such as conventional bacterial film reactor.(2)Nitrate degradation rate in two dimensional biofilm-elecrtode reactor growsfistly and then reduces when current rises from1mA to15mA, nitrate degradationrate is highest when current is5mA,the rate is100%; Nitrate degradation rate inthree dimensional biofilm-elecrtode reactor grows fistly and then reduces whencurrent rises from10mA to60mA, nitrate degradation rate is highest when currentis40mA,the rate is98.5%.(3) Nitrate degradation rate in two dimensional biofilm-elecrtode reactorgrows fistly and then reduces when temperature rises from15°C to40°C, nitratedegradation rate is highest when temperature is35°C,the rate is100%; Nitratedegradation rate in three dimensional biofilm-elecrtode reactor grows fistly andthen reduces when temperature rises from10°C to40°C, nitrate degradation rateis highest when temperature is30°C,the rate is95.3%.(4) Nitrate degradation rate in two dimensional biofilm-elecrtode reactorgrows when m(C)/m(N) rises from0to2.5, nitrate degradation rate is100%whenm(C)/m(N) is2.5; Nitrate degradation rate in three dimensional biofilm-elecrtode reactor grows very slowly when m(C)/m(N) rises from0to2.5, nitrate degradationrate is92%when m(C)/m(N) is1.(5) Nitrate degradation rate in three dimensional biofilm-elecrtode reactorreduces from100%to45%when concentration of nitrate inflow rises but nitratedegradation quantity increases from50mg to95mg.The best technological parameter for two dimensional biofilm-elecrtodereactor is: HRT is6hours、current is5mA、m(C)/m(N) is2-2.5、temperature is30°C-35°C; The best technological parameter for three dimensional biofilm-elecrtodereactor is:HRT is3hours、current is40mA、m(C)/m(N) is1、temperature is30°C.Some Basic law and the best technological parameter for biofilm-electrodeprocess were got in this paper and will lay a foundation for biofilm-electrodeprocess to be used in practical application.