Method of treating excess sludge

摘要

A method for treating excess sludge, which comprises the steps of mixing an inlet stream of waste water with activated sludge, aerating the resulting mixture, separating the effluent water from the activated sludge to be recycled to the mixing step, passing the resulting excess sludge to a conversion stage, treating therein the cells of microorganisms composing suspended solids in said excess sludge to convert them to an organic liquid by a physical and/or physico-chemical means, passing the resulting organic liquid to a digesting stage in which activated sludge takes the organic liquid as a nutrient, aerobically digesting therein the organic liquid and discharging an effluent from the digesting stage.