Process Control And Operation Optimization Of An Enzyme Preparations Wastewater Treatment Plant

Taking an enzyme preparations wastewater treatment plant as the study object,the study brought up that the main problems in the operation were bad settleability ofactivated sludge, low DO level at high inlet COD load, high effluent nitrate, laggingautonomous system and inadequate treatment capacity faced with about15%capacityexpansion of the enzyme preparations factory with the analysis of the plant’soperation. Afterwards, the methods were brought to optimize the wastewatertreatment system and the sludge treatment system aimed at the problems.Aimed at the problem of activated sludge’s bad settleability, the way was broughtup to decrease MLSS of activated sludge in the condition of high organic matters’removal rate in the wastewater treatment system. The pilot production showed thatsludge blanket height of the secondary clarifier could be controlled effectively, andCOD of the bioreactor increased6.63%but under control when MLSS of activatedsludge was decreased from the level7000mg/l to5000mg/l.Aimed at the problems of activated sludge’s bad settleability, low DO level athigh inlet COD load, high effluent nitrate and lagging autonomous system, the newcontrol method was brought up. In the method, online ammonia value was putforward to indicate the organic matter degradation degree of the bioreactor, and DOconcentration setpoint of the bioreactor was set according to ammonia concentration–DO concentration setpoint curve, and air valve was adjusted to ensure the consistencyof DO concentration and DO concentration setpoint. The control was divided into3phases. The process of simultaneous nitrification and denitrification was adoptedwhen organic matters were degraded very well, and DO setpoint increased with onlineammonia value’s increase when the degree of organic matter degradation became bad,and the aerobic process was adopted when organic matters were degraded badly. Thepilot production showed that the capacity of the bioreactor to resist impulse loadincreased, and the removal rates of COD and ammonia maintained the original level,and the removal rates of nitrate and total nitrogen increased significantly and SV ofactivated sludge decreased slightly with the new control system. Besides, the airconsumption was decreased14.45%and the cost was saved. Aimed the need of improving the capacity of the industrial wastewater treatmentplant, the optimization object of the sludge treatment system was located to decreaseCOD concentration of the centrate from the sludge treatment system and to decreasethe load of the wastewater treatment system. In this way, the overall ability of theplant could be improved. Firstly, the impact factors on COD concentration of thecentrate were chosen by the analysis on the sludge treatment process. Secondly, theJMP software was adopted to design the first-group experiments and analyze theresults of the experiments. The significant impact factors determined were heatingtemperature and heating time considering the results of the experiments and thesludge treatment process’ condition. Lastly, the second-group experiments weredesigned to obtain a set of optimum parameters combination of heating temperatureand heating time in the condition of no GMO in dewatering sludge. The result showedthat70℃heating temperature and60min heating time were the optimum parameterscombination.