Analysis Of Time-series Variation Characteristics Of Online Effluent Water Quality Data Of Sewage Treatment Plants

In recent years,in order to effectively solve the problem of serious pollution of water resources,urban sewage treatment plants have played an important role.With the increasing number of sewage treatment plants in China,the treatment intensity of sewage is increased,and the pollution degree of sewage to the environment is weakened.However,there are still many problems in the operation of the sewage treatment plant.In some areas,the influent water quality and quantity of the sewage treatment plant fluctuate greatly,and there is a lack of relevant technical personnel.In order to ensure that the effluent water quality can meet the discharge standard,the sewage treatment plant processes the pollutants in the sewage water at a high operating cost（high energy consumption,drug consumption）,and lacks the technical support of energy conservation and consumption reduction optimization system.Therefore,it is very important for the optimal control and efficient and stable operation of the sewage treatment plant to reveal the operation status of the sewage treatment plant by analyzing the time sequence characteristics of the effluent quality data of the sewage treatment plant.However,the historical data of sewage treatment plant is affected by the monitoring equipment,the data quality is different,and the operation optimization cost of a single sewage plant is higher.Therefore,from the perspective of the plant group,this study analyzed the time series characteristics of the effluent water quality data of sewage treatment plants in the three areas of Northern Shaanxi,central Shaanxi and southern Shaanxi,and draws the following conclusions:（1）NH₃-N was mostly operated under the super safe state of high energy consumption and drug consumption.The removal cost of NH₃-N was higher than COD,especially in Guanzhong area where the type of industrial enterprises is complex,the economic level is high and the population is dense.The optimization of NH₃-N treatment process can greatly reduce the operation cost of sewage plant;（2）In areas with imperfect economic systems in northern Shaanxi and southern Shaanxi,and relatively backward operation and management models of sewage treatment plants,the removal of COD and NH₃-N by sewage treatment plants mainly depends on climate changes,and the control technology for pollutant treatment is poor,and the effluent The data was more likely to fluctuate with climate change,of which southern Shaanxi was more significant;here,the effluent NH₃-N data fluctuates more than COD,further indicating that the operation and processing of NH₃-N was more susceptible to external climate changes than COD,including winter the fluctuation range was greater,that is,when the sewage plant was running in winter,the operation management should be strengthened,always paying attention to the operation status of the sewage plant,and thus ensuring that the effluent meets the standard.（3）The strength of the weekend effect of the effluent water quality data of the sewage treatment plant was related to the level of economic development and the number of population.The Guanzhong area has a better economic development,a large population and a dense population.The impact of human activities on the weekend increases,and the weekend effect was more obvious.The impact time of future water quality operation will also be relatively long;（4）Both effluent COD and NH₃-N data had multifractal characteristics,and the Hurst exponent was much greater than 0.5,indicating that the effluent COD and NH₃-N data showed a positive long-range correlation,reflecting the predictable comparison of water quality data good,provided a theoretical basis for the prediction of effluent water quality data;at the same time,the positive long-range correlation of NH₃-N was stronger than COD,and it was more prone to sudden increase or decrease of data,strong mutation,and greater risk of excessive discharge;（5）The multifractal intensity of effluent NH₃-N data was large,and the factors affecting its change are more complicated,indicating that the removal process of NH₃-N was more prone to fluctuations;at the same time,the downward trend of effluent NH₃-N data was less than COD,and almost reaches the limit and the downward trend were not obvious,indicating that further improvement of the effluent NH₃-N emission standard requires the support of advanced technology.（6）Multifractal parameters can better reveal the changing law of effluent data of sewage treatment plants,indicating that multifractal parameters can be used as an important indicator to perceive the operation status of sewage treatment plants.