Research On Design Process Of The Third Sewage Treatment Plant Of Laiwu City

In recent years, the economy and society of the city Laiwu have been developingrapidly. With the gradual increase of population and industry, gradually waterconsumption has become increased gradually, and the emission of waste water isincreased sharply. This is true particular to areas such as Sima River in the north ofthe city and the watershed at the south bank of Lianhe River. The riverway of the cityhas been severely polluted due to lack of perfect waste water collection andmanagement system. Environmental problems have become worse and worse.Therefore, sewage treatment plants and related waste water pipelines are in urgentneed.In accordance with practical needs, Laiwu municipal government decided toestablish Laiwu3rd Sewage Treatment Plant in the south of Ciyao-Laiwu Railwayand the junctions of Sima River and Lianhe River. This project aims to provideservice to south region and north region around Lianhe River, north region of SimaRiver and the Power Plant region. The scale of the project in the short term is20000m3/d and is expected to reach40000m3/d in the long term. The inlet water quality isreferred to the East and West Biolak Sewage Treatment Plant.The quality of inflow water is BOD5≤180mg/L,CODCr≤380mg/L,SS≤250mg/L,TN≤40mg/L,TP≤4.0mg/L and pH6～9. SBR process is finally selected bycomparing A2/O, SBR process and oxidation ditch process. Water treated with thistechnology will meet with standard A according to the present “Discharge standard ofpollutants for municipal wastewater treatment plant”(GB18918-2002). Wastewaterwill be poured into the Lianhe River after being sterilized by ClO2, and sludge,dewatered by machines in treatment plant, will be burnt in local power plant.This project has made Lianhe River and Sima River less polluted to a largeextent and has improved the local environment effectively. It has also protected wastewater form pouring directly into Lianhe River and polluting Dongping Lake, and hasguaranteed the quality of the South-to-north water diversion project. It can alsoimprove the local environmental capacity and promote the all-round development oflocal economy, trade and tourism, laying a solid foundation for the project of clearwater and blue sky, building the model area of watershed management and building ecological city.