Investigation Of The Sewage Outlets Discharging Into The South Lake And Study On The Water Quality Model Near The Outlets

With the development of society and economy in our country, the water consumption and sewage emission of the city increase rapidly, a large amount of untreated municipal sewage is discharged into the water body directly, which pollutes the lake water body greatly. The South Lake is a bigger sealed city landlocked lake. Because the sewage is discharged into the lake long-term, it is seriously polluted and belongs to bad V Kind water body, and it has already lost the basic function of water body. It is necessary to investigate the outlets actuality and the water quality transformation reguality of the South Lake.in order to establish foundations of the South Lake, comprehensive control.The investigation results of outlets indicate that there forty-three sewage outlets around the South Lake. About 212,000 tons sewage are discharged into the South Lake, among them nearly 11.60,000 tons sewage enter into the small South Lake and nearly 9.60,000 tons sewage enter into the big South Lake everyday. The sewage quality characteristics of most outlets is smimiar to municipal sewage of Wuhan, the density of organic matter is on the low side. The high density sewages outlets are Diary-farm,Xionh jia-zui and Huanong area,etc, the density of COD_Cr, TN, TP is relatively high, which cause the South Lake polluted seriously. The outlets sewage is a main point pollution source.The Happy Village outlet is a bigger sewage outlet of the South Lake, the amount of sewage is more than 24,000 tons everyday. The monitor results of outlets indicate that the hour changing coefficient of Happy Village outlet flow about is 1.25; the discharging amount hour changing coefficient of COD(Cr) is 1.58; and the coefficient of TN and TP is 1.65; the COD_Cr density hour coefficient is 1.96;and the coefficient of TN and TP is 1.40 and 1.42 each.so TN and TP have similar discharging regulity.The Water quality model of water body near the happy village is based on the sewage characteristic analysis. The sewage pollutant is divided into two parts: settled matter and unsettled matter. The self-purification of settled matter in the water body is sedimentation and the unsettled's is diffusion by laminar flow and dilution byturbulence flow. The two parts enter into lake and mix with the water in lake altogether. The comprehensive self-purification coefficient of COD_Cr, TN and TP are deduced by the water quality monitor data near the outlet and the coefficient of COD_Cr,TN and TP is 54.67d^-1 45.39 d^-1, 63.42 d^-1 each.