| With the rapid development of economy, environment for urban has been seriously polluted. Eutrophication has become a serious problem with the continuous inflow of external contaminants such as nitrogen and phosphorus. How to solve the problem of water shortage and pollution is already of the ulmost urgency. In this paper, combined process consisted of pre-BAF and Cellulose Column was applied to denitrification with external carbon source according to preliminary investigation. Camphor leaves were chosen as cellulose carbon source and carrier for denitrifying bacteria. Furthermore, demonstration project aiming to removal nitrogen and phosphorus was carried out based on laboratory studies. Conclusions are as follows:Water quality monitoring data of New City District and demonstration project points in campus showed that index of routine analysis such as pH (weak alkaline) and SS (<50 mg/L) were normal on an average. Chlorophyll-a varied with the season, and had higher content during the late spring to early autumn. The mean range of TN, TP and COD were 3.41-9.94 mg/L,0.040-0.314 mg/L and 27.8-86.1mg/L. The main form of inorganic nitrogen were NO3--N and NH4+-N. Results showed that all rivers were seriously polluted especially in nitrogen pollution by evaluation of Nemerow Pollution Index method.In order to select appropriate carbon sources for biological denitrification,4 synthetic starches and 8 natural cellulose carbon sources were considered. Results showed that denitrification reaction followed a zero-order kinetics, and denitrification of potato and wheat synthetic starches were better than that of cassava and corn with the removal rate up to 90% in 7 days. The difference in surface characteristics and structures leading to the change of organic matter release rate (γcassava>γwheat>γcom≈γpotato) could answer for the difference in denitrification efficiency. Cellulose carbon source had definite adsorption of NO3--N and had no toxic effects, which could reach a better denitrification rate of 96% under the pretreatment of alkali according to univariate analysis of rariance. NO2--N accumulation were found in both processes (basic and alkali pretreatment). NH4+-N, contributed by the release and DNRA process of some carbon sources, were also detected. In summary, camphor leaf was considered as the best denitrification carbon source according to the source, pretreatment cost and nitrogen removal rate.Because the organic nitrogen was also existed in the river water, combined process consisted of pre-BAF and Cellulose Column Filter was selected in order to removal the nitrogen completely. BAF could sustain high hydraulic and organic loading by natural biofilm cultivation. Simultaneous nitrification-denitrification was existed in BAF reactor, and NH4+-N was mainly removed at the filter height of 30 cm. For Cellulose Column Filter, the system had the highest removal rate under condition of hydraulic loading 0.189 m3/(m2·h) and pH 6. Filter had good resistance to hydraulic loading capacity with river water as influent raw water, and reaction rate constant K could reach 0.0256 by Eckenfelder formula fitting. For the combined process, TN of final effluent was decreased from 1.09-1.79 mg/L to 0.16-0.55 mg/L, which was lower than the surface waterⅢ-grade standard. A pilot investigation combining of nitrogen and phosphorus removal process was carried out based on the previous research. In this paper, pollutants degradation ability of three bio-reactors such as biological contact oxidization pond, oxygen-consumed tank and anoxic tank were studied systematically.The system had a better removal efficiency of inorganic nitrogen under the stable condition, TN final effluent was 0.41-0.80 mg/L while the mean influent TN was 1.04 mg/L, TP was also removed partially and the removal rate was 33.15%.
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