Research Of Upgrading Process In Urban Wastewater Treatment Plant

The rapid development of heavy industry in the city brings good environmental benefits, but at the same time the environmental issues have emerged, especially the increasingly serious water pollution. In response to this situation, our country regards the water environment pollution as a prevention focus, a variety of appropriate sewage treatment plants are gradually builded in the city to improve the water environment pollution problems. With the aggravation of the pollution problems, the emission standards continue to improve. The implementation of the urban sewage treatment plant emission standards (GB18918-2002) makes most of the sewage treatment plant had to face transformation. This paper taking Liaoyuan City sewage treatment plant for example, explored the study of urban sewage treatment plant upgrade technology. Liaoyuan City sewage treatment plant was designed in1999, the designed effluent standards are the secondary standard in urban sewage treatment plant emission standards (GB18918-1996).With the gradual improvement of the national environmental standards, Liaoyuan City sewage treatment plant effluent standards are required to achieve the A in first grade discharge standard of GB18918-2002.In this context, the current situation of Liaoyuan City sewage treatment plant was understood by the feasibility study of Liaoyuan sewage treatment upgrade and transformation which was compiled by China Northeast Municipal Engineering Design and Research Institute as well as field investigation.We found that there exists several problems, for example, the equipments were aging, the sewer network was imperfect,the effluent quality cound not reach the national standards. On the basis of the sewage treatment situation, the sewage treatment plant were upgraded according to the appropriate standard design, mainly including the design of influent and effluent quality index, treatment capacity and the selection of the main treatment process, etc. The upgrade were as follows:(1) The design capacity for the total amount of water was10.0×104m3/d. Reclaimed water reuse scale was8.0×104m3/d.6.0×104m3/d was reused for the power plants, and the remaining2.O×104m3/d for the nearby industrial zone miscellaneous uses.(2) Design of infuent quality indexes were COD=450mg·L-1, BOD5=200mg·L-1,SS=200mg·L-1,pH=6-9, NH3-N=25mg·L-1,TN=30mg·L-1, and total phosphorus (based on P)4.5=mg·L-1. Effluent quality indexes wereCOD≤50mg·L-1, BOD5≤10mg·L-1,,SS≤10mg·L-1,pH=6～9, NH3-N≦5mg·L-1, total phosphorus (based on P)≦0.5mg·L-1.(3) Through comparisons of the "modified AAO pool+V-filter (Schem One) and "MBBR+V-filter (Scheme Two)",the paper analyzed and demonstrated the main process in terms of technology, economy, as well as advantages and disadvantages of two kinds of processes,"improved the AAO pool+V-filter " was defined as its main process. It also demonstrated sewage pipe network and reclaimed water reuse scheme.(4) In the case of the "improved AAO pool+V type term" biological treatment technology, combining the influent and effluent quality index of sewage treatment plant, it designed corresponding parameters of individual processing unit.