Study On The Formative Cause Of Black Flocculus In Tap Water And Treatment Measures In XiShui SouthCity Waterworks Of Hubei Province

Tap water of South City waterworks in XiShui County of Hubei Province is quality and good production from the end of 2006 after remodeled .But since the 2007 summer, a large number of black flocculus appears in the water, and this winter the content of black flocculus dropped or even disappeared. This thing has also appeared and gradually increased in May 2008.The phenomenon brings seriously affected to the hundreds and thousands of residents` living in XiShui County. It is a sever problem which urgently needed to solve.This article based on the water source area's environmental conditions, using scanning electron microscopy and energy dispersive spectroscopy, atomic spectrophotometer special testing, chemical analysis and other means to detect the compositions of black flocculus, and combined with South City Water quality characteristics and water process to study the reasons for its formation. Get the following conclusions:(1) The black flocculus is composed of carbohydrates, iron and manganese. The carbohydrates are ferromanganese-oxidation bacteria. The sort of bacteria transformed Fe²⁺ and Mn²⁺ into iron and manganese oxides which deposited around thmeselves and formed the black flocculus.(2) The cause of formation of black flocculus are the raw water quality, riverbed sludge blanket and filter layer of water-rock interaction. The sludge blanket plays a decisive role for it. High content of iron in raw water is the intensification factor. The water pH value of 6.8 7.8 provides the best pH conditions for the black flocculus's formation. Filter layer of water-rock interaction provides sufficient nutrients for ferromanganese-oxidation bacteria. The key factor of formation of black flocculus is sludge layer which riches in organic matter and iron and manganese. (3) The root cause of black flocculus's formation in water is environmental pollution.Not only black flocculus growth in tap water, but also throughout the total process. To completely solve problems of water quality and eradicate the black flocculus, it must clear the black sludge layer on the riverbed, and take the entire filter bed and intake facilities comprehensive disinfection. Engineering practice shows that tap water quality greatly improved and the water black flocculus reduced or even disappears after dredged. From long-term interests, we must establish water protection areas.Through the black flocculus's forming reason in tap water and treatment research, not only timely deal with the problems of XiShui water quality, but also it can provides some reference value for the similar water problems in the future.