Simulation And Study On The Operation And Management Of Sewage Treatment Plant Based On SD Model

With the acceleration of urbanization, urban population as well as discharge standard are gradually growing as well, and therefore the urban sewage treatment business is developing rapidly. The requirements for sewage treatment are becoming more rigorous and the emission standards are getting more stringent in our country. In order to manage sewage treatment more efficiently, the administration department has issued a series of operation and management regulations and standards. But a number of problems still exists in the actual implementation process such as insufficient capital investment, infrastructure construction lagging, low operation efficiency, and network facilities construction lagging etc. In this dissertation, to build an operation management system for sewage treatment plant, a certain plant in Shenzhen is taken as an example, and the system dynamics(SD) method is used by the construction of a SD model for the prediction and assessment of the indicators of the sewage treatment plant.The Vensim software is used to establish the SD simulation model, and by means of dimensional consistency inspection, operation inspection as well as historical inspection, the effectiveness of the model is tested. The ratio between the simulated effluent value and the actual effluent value is mostly controlled within the range of 0.8 to 1.2. The sensitivity analysis is carried out on various indicators from the perspective of the pollutant reduction rate, the amount of sludge and the profit of the plant and the primary and secondary order of the principal indicators in terms of their effect on the plant operation quality is determined. The results show that indicators such as the amount of sewage water, influent BOD, and reflux pumps breakdown rate etc. have a greater effect on pollutant reduction rate; indicators such as the amount of sewage water, influent SS, and lift pump failure rate etc. have a greater effect on the amount of sludge; and indicators such as the amount of sewage water, lift pump failure rate and water price ect. have a greater effect on plant profit. These results can provide reference for the operation of the plant.Simulations of the effluent water are carried out with the existing standards, as well as under the condition of improved standards and abnormal inflow water. The results show that the profit is 65.15 million Yuan when primary standard B was executed as normal. After improving the standard from primary standard B to primary standard A without changing the operating conditions, the profit is 64.68 million Yuan, and the profit is 64.58 million Yuan when the standard is improved from primary standard B to primary standard A and the operating conditions are optimized. When the concentration of inflow water is increased by 50 percent and the operation conditions remain the same, the profit is 63.12 million Yuan. However, when the concentration of inflow water is largely increased and the operation conditions are also adjusted, and profit is 62.83 million Yuan. In this case, the plant may choose sewage emission regardless of standards. By revising the policy, for example, by increasing the subsidies to the selected sewage treatment plant in this dissertation from 50 thousand Yuan to 100 thousand Yuan per month, or increasing fines from 150 thousand Yuan to 200 thousand Yuan, or increasing the inspection times from 4 times a month to 6 times a month, the plant will make more profit when choose emission that meets the standards.