Study Of Influence Factors On Ammonia Nitrogen Removal In Wenzhou Typical Rivers

With the development of society,more and more untreated pollutants are discharged into the city river,causing serious pollution of river.Ammonia nitrogen is one of the main pollutants in the river,it can consume dissolved oxygen,cause eutrophication of water body,threaten the survival of aquatic life and human health.Consequently,it is practical significance to study the influencing factors of ammonia nitrogen removal in Wenzhou.In this paper,we selected the 20 river courses in Wenzhou,including Lucheng District,Ouhai District and Longwan District.We carried out the seasonal test of river pollution index,analyzed the seasonal variation of the index,the comparison of the indicators of the river,the relationship between ammonia nitrogen and other indicators;And then the alkalinity dosing experiment is used to compare the effect of ammonia removal.The significant influencing factors and optimum experimental conditions of ammonia nitrogen removal were obtained by orthogonal experiment.Ammonia nitrogen removal was studied under the optimum conditions.Finally,we selected seven rivers to add the alkalinity experiment to determine the best effect of those rivers.This research method is helpful to reduce the economic cost of river regulation and provides a new idea for the research and development of river channel management technology.The results of quarterly survey of 20 rivers in Wenzhou show that the pollution in the spring is slightly better than that in other quarters,and the pollution degree in summer,autumn and winter is close to each other.Ammonia nitrogen is the average annual value of 11.2mg / L,the year are in the inferior ? class standards;ammonia nitrogen in the river as the main pollutant;ammonia nitrogen value is the highest grain station after the river,the lowest for the Zhangli River;with ammonia increased,DO and pH decreased with the trend,ammonia nitrogen and CODMn,TP,water temperature have no significant change in relations.The experimental results show that the addition of alkalinity will help to remove ammonia nitrogen,the higher the alkalinity is,the higher the removal rate of ammonia nitrogen is,the less pH fluctuation in the addition of alkalinity experimental and the decrease of the pH value of the water sample.The alkalinity of the water samples is lower than the water of adding alkalinity.The higher the alkalinity is,the higher the removal rate of the TN,TP and CODMn are.Orthogonal experimental studies have shown that during the whole experimental stage,alkalinity is the main influencing factor of ammonia nitrogen removal and has a significant effect on the removal of ammonia nitrogen.The best experimental conditions: alkalinity = 160 mg / L,CODMn = 7mg / L,TP = 0.3mg / L,ammonia nitrogen = 6mg / L.Under the best experimental conditions,0 ~ 24 h,the decrease rate of ammonia nitrogen was 16.5%.24 ~ 60 h,the decrease rate of ammonia nitrogen was 92.2%.60 ~ 72 h,the decrease rate of ammonia nitrogen was 98.5%.The experimental study of adding alkalinity in 7 water samples shows that the ammonia nitrogen of two rivers quality have reached the standard of class?,five rivers quality reaches the standard of class ?after 72 h.The method of adding alkalinity(sodium carbonate)is suitable for the removal of ammonia nitrogen in seven rivers,and Optimum effect is Pan Fen straight river.