Hitachi, Ltd.

Youji Odawara

Masahiko Ishida

Ryooichi Haga

Norio Shimizu

Kazuaki Ichihashi

Azuma Nakaoka

Tetsuo Yamaguchi

Setsuo Saitou

Method for treatment of biochemical waste which comprises adding acid to the biochemical waste to adjust pH (power of hydrogen ion) thereof, heating the adjusted biochemical waste, adding alkali thereto to neutralize the waste, and treating with anaerobic digestion.

Method for treatment of biochemical waste

Waste water containing organic materials is introduced into an aeration tank, and is subjected to aeration treatment in the presence of activated sludge, while supplying oxygen to the aeration tank. The tank provided with an air diffusion pipe at the bottom of the tank, an air dispersion device above the air diffusion pipe and a plurality of inside cylinders above the air dispersion device. An overall circulating stream and partial circulating streams are generated in the aeration tank.

Apparatus for high-efficient microbiological oxidation treatment

Waste water containing organic materials is introduced into an aeration tank, and is subjected to aeration treatment in the presence of activated sludge, while supplying oxygen to the aeration tank. The organic materials contained in the waste water are oxidized by high-efficient activated sludge at a high oxygen transfer rate of 5 to 80 mmol O.sub.2 /l.multidot.hr to the aeration tank.

High-efficient activated sludge method

A process for the tertiary treatment of biochemical waste waters comprising the following 4 main steps; (1) adding milk of lime to waste water from the anaerobic digestion treatment process to render the waste water alkaline and recovering NH.sub.3 by reduced pressure distillation, (2) contacting recovered NH.sub.3 with a weakly acidic ion exchange resin to make NH.sub.3 adsorbed in the ion exchanger resin, (3) adding acid to the adsorbed ammonia to form an ammonia salt, and (4) blowing CO.sub.2 into the treated water from which NH.sub.3 has been removed, to thereby recover P, and subjecting the treated water from which N and P have been removed to the activated sludge treatment to remove BOD.

Process for tertiary treatment of waste waters from anaerobic digestion

In a system for treatment of biochemical waste such as activated sludges, the waste is subjected to anaerobic stabilization processes, which include two phases of an acid fermentation and a methane fermentation effected in separate reactors. The waste after the acid fermentation is then separated into a liquid effluent for the methane fermentation and a waste sludge. The waste sludge which may cause secondary environmental pollution is re-treated within the anaerobic stabilization processes without withdrawing from the system.

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Hitachi, Japan

Youji Odawara