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An Experimental Study Of Dewatering Of Alum Sludge, Uday G. Kelkar

Civil & Environmental Engineering Theses & Dissertations

The use of aluminum sulfate (Alum) as a coagulant for treating surface water was introduced in 1884. When this salt is added to water, the aluminum Ion hydrolyzes by reaction that consumes alkalinity in water. The gelatinous hydroxide thus formed in the reaction, carries suspended material with it as it settles. In addition, however, it is likely that positively charged hydroxyl-bridge dimmers and higher polymers are formed which interact specifically with the colloidal particles, bringing about coagulation. These gelatinous floes settle by gravity, called sludge, consists of relatively large quantities of suspended and colloidal inorganic and organic materials.

The disposal …