Patent ID: 7258791
Filing Date: 2007-08-21
Classification: C02F,Y02W

Abstract:
1. A method for reducing the volume of sludge comprising the steps of: taking out at least a fraction of sludge from a biological oxidizing tank, receiving a sludge from a sewage water treatment device, said sludge being generated by aerobic treatment of an organic sewage water in the sewage water treatment device; adjusting the pH of said taken out sludge to 8 to 14; heating the pH-adjusted sludge to 110° C. to 250° C. at a pressure equal to or higher than saturated steam pressure to solubilize the sludge to a state readily degradable by microorganisms; returning a preset amount of the solubilized sludge into said biological oxidizing tank; and adjusting the pH of the sludge in said biological oxidizing tank to 5 to 9.