Research On The Construction Of COD Concentration Model In Sewage Network And Its Application

A lot of sewage treatment plants were constructed in Pearl River Delta in order to reduce the quantity of pollutant discharged and river pollution. However, according to present situation, the sewage network construction as supporting facilities is far more behind than the sewage treatment plant. Sewage treatment plant cannot work normally in this situation. Problems such as deficiency collection of sewage, low influent COD concentration of sewage treatment plant, high influent pollutant concentration are come out in the constructed sewage treatment plants in Pearl River Delta, which have deadly impact on operation of sewage treatment plants, lower the pollutant reduction efficiency and cannot reduce the river pollution. The performance of the sewage network construction is very important and always gets more customer attention because of the huge investment. Therefore, if the sewage network cannot work normally, sewage treatment plant will become energy dissipation and low pollutant reduction, and will bring serious harm to river environment. The research on the construction of COD Model and Online Management System in sewage network can solve the problems of sewage network management, and also has great significance on river pollution reducing, construction and operation of sewage treatment plant, energy saving and emission reduction.The sewage network model of sewage COD was built based on one dimensional diffusing equation and the drainage pipelines were seen as pygmy rivers. On the basis of analysis on different kinds of physical, chemical, biological phenomenon in drainage network, the one dimensional diffusing equation was simplify reasonably and relative parameters were determined. The model predicted the variations of sewage COD concentrations in the process of sewage transmitting along the sewer well in Lecong town, and successfully simulated the influent COD concentration in Lecong sewage treatment plant.This paper concluded present problems of management and construction in sewage network and did the research on online management system. The system can reflect the real time operation of sewage network. It was built on the basis of Geographic Information System(GIS), achieved such functions as drainage network data management, sewage quality online monitoring, drainage network programming. This paper also introduced advice that improved the sewage network management from the institutional level.The paper has come to such conclusions as below:1. Utilize one dimensional diffusing equation to build the sewage pipe water quality (COD) model, then simulate the variation of sewer COD consistency. Simulated value approximates measured value, with the maximum relative error of2.5%.2. For the city which adopts circular cross section drainage pipe, combine the sewage pipeline COD concentration model and the node hybrid model to simulate the influent COD consistency. The relative error between simulated value and measured value is6.6%.3. Sewage network online management system has functions such as collecting data, recording and editing, managing data, converting data, managing drainage facilities, monitoring water quality and quantity of sewage network online, simulate influent COD concentration of sewage treatment plant, assisting planning sewage network. This system can real time monitor the sewage pipe network and show instantly how the sewage network runs.4. For the present sewage network management situation, this paper put forward that the construction, operation, maintenance and management of sewage network should be in charge by one independent department. What’s more, discharge permit system, tendering system, check and accept system must be carried out. Also, the progress of interception, reform and construction of sewage network should be accelerated scientifically. The design and prediction of sewage treatment quantity can be determined by using regional water supply data, and more accurate than the traditional way. The design of influent COD concentration in sewage treatment plant can use the COD concentration Model to determine.