Sewage Water Treatment

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CHAPTER II LITERATURE REVIEW 2.1 IRON Quality of water depends on its physical, chemical, microbiological and radiochemical characteristics. Drinking water or other usage always need desired quality of water often need treatment. There are certain elements or compounds in raw water which are not removable by conventional processes of water treatment. The elements include sodium, magnesium, nitrate, sulphate, chloride, iron, mangenese etc. Iron is found in most raw waters in numerous forms: in true solution, as a colloid, in suspension, or as a complex with other mineral or organic substance. It can impart a bitter taste when present in large amounts, marking the water unpalatable (Corbitt, 2009). Iron is generally present in the soluble ferrous state and water containing a lot of iron takes up oxygen on exposure to air. In ferric state, it will be precipitated and causing brown stains on laundry and plumbing fixtures. Even small amounts of iron can lead to the accumulation of large deposits in a distribution system. These deposits also can give a good condition for iron bacteria growth, which in turn cause further deterioration in the quality of the water by producing slimes, or objectionable odors. Levels of iron are in the range of 1 to 5 mg/l in large percentage of Malaysian river waters (MWA, 2006). A high level also exits in some ground waters. If iron level is high than 0.3 mg/l the water should be treated (Smathurst, 2008). Current treatment such as prechlorination and/or aeration followed by adequate coagulation, flocculation, sedimentation, filtration and pH control are always applied. If iron concentration greater than 1.0 mg/l it will be need special processes and the cost to treat the water will be increased. 2.2 MANGANESE Manganese resembles with iron in its chemical behavior and occurs in

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