Problems in urban sewage treatment plants

In recent years, the Chinese government has paid high attention to environmental pollution issues and proposed sustainable development strategies. Urban sewage treatment has undergone rapid development, but overall, there are still some shortcomings in the management and control of urban sewage treatment.

① Process Control System (PLS) and Management In Information System (MIS) are separated.

Many urban sewage treatment plants often neglect various types of information in the control system when establishing and planning management information systems, resulting in a disconnect between PCs and MIS. This will inevitably lead to the following situations: a lack of accurate and timely raw data and situation analysis; b. Information redundancy, poor accuracy, and lack of smoothness; c. Poor planning ability leads to uneven production, affecting the quality of effluent and the rational utilization of energy.

② The level of process control is not high, especially in terms of optimization control and management. Due to the characteristics of strong coupling of multiple variables, strong nonlinearity, time-varying parameters, frequent changes in operating conditions, and difficulty in online detection of effluent quality in the sewage treatment process, traditional control systems cannot achieve optimized control, operation, and management of the sewage treatment process, resulting in large fluctuations in effluent discharge indicators, low opening and compliance rates, and high treatment costs after sewage treatment. Whether the control and operation of the sewage treatment process are successfully implemented is a design issue of the control system, that is, how to organically integrate the operation and management of the sewage treatment process with the control system, so that it has a high degree of autonomy, flexibility, and reliability. Reducing production costs, improving product quality, minimizing environmental pollution and resource consumption can only be achieved through the optimized design of a full process automatic control system.

③ The formulation of production operation plans and production scheduling relies on manual means, which is inefficient and not adjusted in a timely manner. Although the water quality and quantity of sewage inlet are greatly affected by external environmental factors such as season, climate, lifestyle habits, and industrial wastewater invasion events, the effluent indicators of treated sewage must meet the prescribed discharge standards. Therefore, the input of sewage treatment process is non selective, and the output is mandatory. Any malfunction in any link will affect the normal operation of the entire processing process. Therefore, it is necessary to develop a reasonable production operation plan and production scheduling, especially when the process flow, equipment type, and size have been determined. The scheduling of key process parameters is particularly important. In the production process of sewage treatment, it is necessary to ensure the continuous operation of the entire treatment process, and the close connection between the various treatment units before and after. There are issues with flow load balance and time balance in the operation plan and scheduling. Flow load balancing includes determining the production load of each process, adjusting and starting/stopping the production line, etc; Time balance includes hydraulic retention time in water treatment primary sedimentation tanks, biological aeration tanks, secondary sedimentation tanks, sludge age in biological aeration tanks, and sludge digestion time. Sewage production operation plan. Implement the calculation of each process with production scheduling. Manage to balance the load, reduce medication costs, energy consumption, and other losses, thereby lowering production costs. Currently, the majoritysewage treatment plant*It is the manual preparation of production plans for production scheduling, which results in low efficiency and untimely plan adjustments, leading to low production efficiency, opening rate, and compliance rate in the sewage treatment process.

Currently, domestic citiessewage treatment plantThe automatic control system only handles the automatic control of equipment opening and closing, data acquisition and storage, and automatic display functions, and lacks automatic control of the process, making it impossible to use water quality monitoring instruments（pH meter）Integrating modern computer control technology with the characteristics of biochemical reactions to achieve monitoring and control of biochemical systems. Therefore, a comprehensive automation system for urban sewage treatment with production data collection, transmission, analysis, storage, and management functions should be established to optimize the sludge concentration and pH value of the distributed computer control system for the sewage treatment process（PH meter）The set values of circuits such as dissolved oxygen concentration and the number of competing agents are set to achieve the key water quality parameters (BOD, COD, NH, 3-N) that meet the discharge standards and minimize the operating costs of sewage treatment plants. This has become an important development trend for urban sewage treatment plants and an effective means to solve the above problems.