Reduction of Oil in Sludges From Light Petroleum Separators

A flotation treatment for reducing the oil content of sludges accumulated in light petroleum separators and grit traps is described. Hydrocarbon content of the sludge can be reduced to less than 3% of the dry solids by air flotation assisted by appropriate surfactants. There is a corresponding reduction in Polychlorinated Biphenyls (PCBs) and Polyaromatic Hydrocarbons (PAHs). Air escaping from the flotation cells is scrubbed in a bio-filter and water is purified by activated sludge or a further flotation method. Recovered oil can be further dewatered to produce a useful fuel.