Investigation Of Water Bloom Control And Water Quality Service Of Shichahai Water System In Beijing

Shichahai River system ,an important part of Beijing city' water system,is known as the heart of Beijing. Recently the development of economy and the increase of urban population in Beijing accelerate the process of the entrophication,so the water quality aggravates and water bloom of blue algae, Shichahai River system microsysis is the dominant specie, occurs in every summer and autumn of recent year in Shichahai River system. All these seriously affect the lives of resident surrounding and are disadvantage ous to the development of the tourism. This search analyse the relation between the water bloom and the main index of the water body by sampling in field work and test in the lab.Shichahai river system water body has low transparency (0.23m)and high level nutrient salts(with TN2.457mg/L,TP:0.134mg/L),TSI_M of five targets(TN,TP,COD_cr,SD,Chla)are from 57 to 59,which indicated entrophication of Shichahai River system. The main controlling factors of water bloom are physical factors,chemical factors and biological factors. Water temperature is the main factor among physical factors such as water temperature, illumination and water requirement of ecological environment. Chemical factors are TN and TP, which are the main restriction facor of the algae growth. And Chla,which is the index of phytoplankton biomass and parameter to estimate the phytoplankton biomass,has relativity with the index above.The research screened out some effective medicaments by fieldwork experiment when water bloom exploded and did the experiments in the lab with them to determine the optimal time and quantity. The research chose ClO₂(oxidant), CTAB and Methyichloroisothiazolinone (antioxidant),BSE and allelochemical(biological medicament) as the algae-killing medicaments. The results showed that among chemicals CTAB had the best effect of algae-killing,then did ClO₂,the worst isMethylchloroisothiazolinone. Between the two kinds of biological medicaments,BSE had the better effect,when it was added on the lag time,25ppm could inhibit the algae growth absolutely and the mechanism of allelochemical should be studied more,it can accelerate the growth of algae when it was added on the logarithm time.