Research On Water Quality Early-warning And Emergency Management Of Urban Reclaimed Plant

The object of this paper is the reclaimed water plant which the influent iswastewater treatment plant’s secondary effluent. In order to find the main operatingindicators of reclaimed water, the history operating data of the reclaimed plant wereanalyzed. For the purpose of ensure the plant security operation, water qualitywarning model of raw water, sedimentation tank effluent and treated water were made,meanwhile the emergency management plans for a variety of unconventional waterwere developed.First of all, the water quality change law should be found so as to determine thekey index of water quality model. This paper used mathematical statistical methods toanalyze the change rule of pH, turbidity, color, ammonia and chlorine, thewater-quality change rule with time and treatment process of raw water and keyprocess point were found.Secondly, based on the water-quality change rule, the gray system prediction,neural network time series forecasting methods and BP neural network were used toestablish water quality model of raw water, sedimentation tank effluent and treatedwater, this models were used to predict water quality trend. According to thediffidence among the application forecasting scope, accuracy and difficulty degree ofeach modeling, the gray prediction model was used to predict the raw water pH andcolor, Neural network time series model was used to predict influent ammonia, BPneural network was used to predict sedimentation tank effluent turbidity and the planteffluent chlorine.Thirdly, the warning-levels and warning-limits of pH, turbidity, color, ammonia,and chlorine were formulated based on the water quality standard and the processfeatures of reclaimed plant. A set of emergency management plan was established todeal with unexpected situation.Finally, for the water which depletes large amounts of chlorine and the waterwith high turbidity, a lot of studies were made. When confronted with the water whichconsumes large amounts of chlorine, the first task was to find the substances that mayconcept chlorine, then one by one to exclude, at last the material was identified asSCOD. It was found by experiment that ozone and chlorine can solve this problem. For high turbidity water, it is not economical by increasing the dosage of PAC tosolve this problem. By experiments found that turbidity could be reduced to very lowlevels by extending the settling time.In general, in order to guarantee the water quality safety, the water quality modelof raw water and key process were established in this paper, the emergencymanagement plan could be taken as the operation guidance of reclaimed water plant.