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Ebara Engineering Review No.228

Development of Internal Cooling System for Sewage/Wastewater Pump

by Chikara MAKINO, Junya KAWABATA, & Shunichi AIYOSHIZAWA

An internal cooling system for sewage/wastewater pumps has been developed. The system assures safe operation of the motor even when the pump is not submerged. The system also makes it possible to prevent overheating without using pumped liquid which may contain various foreign matters. In the developed system, a newly designed impeller is located between two mechanical seals, and circulates the coolant through a newly designed passage to the cooling jacket around the motor. Thus, heat generated by the motor is transferred to the coolant and effectively dissipated to the pumped liquid via a heat exchanger.

Internal cooling system, Sewage/wastewater pumps, Duplex mechanical seals, Coolant, Heat exchanger, Heat transfer coefficient, Thermal conductivity, Winding temperature rise

Submerged Type Membrane Filtration System for an Existing Sedimentation Tank

by Shohei OKAGA, Koji SUDA, & Satoru KAWASAKI

Japan's largest-scale submerged type membrane filtration system (filtration capacity: 30000 m3/d) has been installed in the existing sedimentation tank of Sano Water Treatment Plant, Hyogo Prefecture. This unprecedented changeover from rapid sand filtration to membrane filtration was accomplished with no stop in water treatment. This allowed a saving in construction cost with no generation of construction debris. Furthermore, the 2.3 m difference in water levels between the sedimentation and filtration tanks allow a natural downward flow (gravity filtration), making it unnecessary to use electric power to transmit the water from one tank to the other. This is achieving significant energy-saving in the filtration process.

Using existing sedimentation, Submerged type, Membrane filtration system, Height difference for gravity filtration, L-cube, In desiccated keeping, Energy-saving, Sano Water Treatment Plant, Hollow fiber membrane, Hydrophilic PE

Characteristics and Chronology of Development in Aerobic Bio-treatment Technology

by Masayoshi KITAGAWA

Aerobic bio-treatment constitutes as the mainstay for treating wastewater containing organic pollutants. It is also considered as an important method for removing eutrophication causing elements such as nitrogen and phosphorus. The following outlines characteristics and discusses chronological data regarding development in aerobic bio-treatment technology. Also discussed is the combined use of both anaerobic and aerobic treatment, ammonium oxidation, as well as MBR (Membrane Bio Reactor) technology. Progress in these are looked forward to from the viewpoint of energy conservation, reduction in the amount of generated sludge, and the realization of safe and sanitary wastewater treatment.

Biological treatment, Aerobic treatment, Anaerobic treatment, Activated sludge process, Biofilm process, Bulking control, Phosphorus removal and denitrification, Aerobic filtration, Moving-bed biofilm reactor, Anaerobic ammonium oxidation

Application of a Methane Fermentation Plant for Treating Organic Wastes

by Yutaka YONEYAMA, Shinji UEDA, Masaaki NISHIMOTO, Ryoji TSUKUI, Kazuyuki NAKAMURA, & Naoaki KATAOKA

Studies have been made on the basics and application of methane fermentation for treating organic wastes, including the pre-treatment and post-treatment. Investigation at a beverage manufacturer revealed stable methane fermentation of organic wastes constituting coffee grounds and tea leaves. This was being achieved by grinding these organic wastes as pre-treatment. Stable operation was also confirmed at a domestic food waste treatment plant whereby the gas generation per ton of influent waste was found to be 200 - 250 m3/t (NTP).

Methane fermentation treatment, Organic waste, Coffee grounds, Domestic kitchen waste, Tea leaves, Pre-treatment, Post-treatment, Sewage sludge, Thermophilic digestion, Mesophilic digestion