Waste water treatment

Claim 1

A process for facilitating the separation of fat from a waste stream composition comprising water, fat, fatty aids, and solids produced in food processed plants and rendering plants, said process comprising the steps of: (a) adding an aqueous flocculant composition comprsing an aluminum salt the waste stream composition in an amount to maintain from about 5 ppm to about 100 ppm of the aluminum salt in the waste stream composition prior to subsequent addition of an aqueous alkaline pH control composition to said waste stream; (b) subsequently adding the aqueous alkaline pH control composition to the resulting waste stream composition of (a), said pH control composition comprising an alkali metal hydroxide in a sufficient amount to produce an equivalent alkalinity thereto of from about 20% to about 50% by weight of sodium hydroxide to produce a pH of from about 6.0 to about 6.5 in the resulting waste stream composition, and further comprising a surfactant in an amount of from about 0.1% to about 5.0% by weight of the pH control composition; and (c) subsequently holding the resulting waste stream composition of (b) in a clarifier for a period of time sufficient for formation of an aluminum hydroxide fatty acid complex which floats to thereby effect separation of the waste stream composition into three layers, the bottom layer thereof comprising essentially solids, the middle layer thereof comprising essentially water, and the top layer thereof comprising essentially fat which can be recovered by skimming for further processing.