Development And Applicating Of EASM1Model For Bio-augmention To Enhance Nitrogen Removal In Municipal Wastewater Treament

Simulation is an effective method for studying and coltrolling complicatedbiological process. A modified model named EASM1(Extented Activated SludgeModel No.1) was developed based on ASM1(Activated Sludge Model No.1) by addedphosphorus removal function and verified by using BSM1model (BenchmarkSimulation Model No1) and ASM2(Activated Sludge Model No.2) model. Finally, themodel was applied in bio-augmention process to enhance nitrogen removal in municipalwastewater treatment.Although ASM1was used widely in the world, it just can be applied to simulatecarbon and nitrogen removal. Based on ASM1model EASM1have been develpoed byadded phosphorous removal, and applied to simulate sequencing batch reactor (SBR)and continuous flow system (A~2/O). According to the characteristics of bio-augmention,this article put forward the specific dosing value (the ratio of dosing flow and influentflow, notes for “a” in percentage), and used specific dosing value to bio-augmentprocess. The simulation results show that under short sludge age conditions (SRT=6d),the more specific dosing flow added, the higher nitrification rate increased. When nobiological dosing flow added (a=0), the system of nitration ration is low, for simulationof50days, ammonia nitrogen removal rate is only17%, ammonia nitrogenconcentration of effluent is35mg/L, When a=0.01, for simulation of50days, removalrate of ammonia nitrogen can achieve80%above, and the ammonia nitrogen of effluentcan plunge to5mg/L; When a=0.2, only for15days of simulation later, the ammonia nitrogen of effluent almost drop down to zero. Compared the simulation results withexperiment results of SBR and A~2/O peocesses, it was concluded that the EASM1model and simulation method is suitable for apply to bio-augmention process toenhance nitrogen removal.Some existing methods of parameter identification which was applicated inactivated sludge model, such as artificial testing method, genetic algorithm, and so on.These methods have some disadvantages, such as algorithm complex, low speedconvergence and low accuracy. It was proposed the support vector machine (SVM)method of pattern recognition applied to activated sludge process. The simulationresults show that, the selection of five sensitivity parameters（Y_H，μ_H，b_H， a， k_h）,was choosed to support vector machine (SVM), the average relative error is1.335%, therelative error of five parameters are0.015%,2.76%,1.43%,0.58%,1.89%, and selectedwith the genetic algorithm method, the average relative error is1.622%, which relativeerror of parameters are0.03%,4.47%,1.47%,0.46%,1.68%, these compared resultshow that the accuracy of support vector machines method is more than geneticalgorithm.For the control based on activated sludge model, which was used the state spacemethod and step acceleration algorithm to describe relationship between the control andwater quality, this article was put forward a kind of control algorithm based on activesludge model. Through analysed the simulation result which have been done theexperiment of A~2/O system, the ammonia nitrogen and nitrate nitrogen were selected astarget variables of effluent flow, dissolved oxygen and inside return sludge ratio wereslected as the control variables. Under the traditional strategy of control, it was couldnot select and confirm the controlled parameter by experience.When sludge age (SRT)is for15days, dissolved oxygen is0.65mg/L, the inside return sludge ratio is50%,ammonia nitrogen of effluent is13.53mg/L, nitrate nitrogen of effluent is24.12mg/L.Ammonia nitrogen and nitrate nitrogen are more than the B level of urban sewagedischarge standard. Through simulation of calculation, dissolved oxygen increment is1.84, the inside return sludge ratio of increment is0.75. After simulating of control,ammonia nitrogen was below4.1mg/L, and nitrate nitrogen of effluent was below9.4mg/L by contorl. The results show that this method can operate the control parameter quantitatively as influent is constant in the wastewater treatment system. Thoughmonitored the quality of influent, this method also achieved forward control inwastewater treatment system.