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Ebara Engineering Review No.217

Behavior of Nitrogen during Ozonation in an Excess Sludge Removal Process

by Kiyomi ARAKAWA, & Toshihiro TANAKA

The effects of sludge-reducing ozonation conditions on nitrogen in the effluent of an activated sludge process were studied through continuous bench-scale tests. The nitrogen concentration in the effluent and that in the produced sludge were monitored under different ozone injection rates. It was revealed that although ozonation was effective for reducing the amount of excess sludge produced, it increased the T-N in the effluent. The amount of nitrogen in the reduced sludge was found to be almost identical to amount of T-N (most of which was NOx-N) in the effluent. The results of this study suggest the possibility of a nitrification-denitrification process which would enable a large part of effluent nitrogen, produced by sludge reduction, to be removed, also that biological denitrification was practical for sludge reduction in activated sludge processes.

Sludge reduction, Nitrification-denitrification process, Ozonation, Nitrogen removal, Activated sludge treatment

Development of Fluidized-bed Gasification System for Sewage Sludge

by Yusuke TAMARI, Takashi IMAIZUMI, Satoshi ASANO, & Tatsuya HASEGAWA

A new gasification system for the pyrolysis of sewage sludge has been developed. This system features a gasifier for producing product gas for gas engine power generation. A pilot plant, capable of treating 15 tons/day of dehydrated sewage sludge, had been used since 2005 and continuous performance tests (over 3400 hours) had been carried out. The stability and environmental feasibility, as well as its practicality had been proven by the tests. Replacing a conventional sewage sludge incineration plant with this system enables a 25% saving in primary energy consumption and a 65% reduction in the emission of greenhouse gases. The use of this novel system is looked forward to as an effective measure towards the prevention of global warming.

Gasification, Fluidized-bed, Sewage sludge, Gas engine, Power generation, Pyrolysis, ICFG, Biomass

Fluidized-bed Gasification for Recovering Energy from Waste

by Kohei MATSUNAGA, Takayuki IHARA, Kei MATSUOKA, Kenichi SEMITANI, Tatsuya HASEGAWA, & Takayoshi KAWAGISHI

R&D is underway for a novel ICFG (Internally Circulating Fluidized-bed Gasifier) for converting biomass and wastes into higher calorific product gas. This gas is for use as alternative fuel for power generation and liquid fuel synthesis by industries. A performance test of the ICFG had been done at a test facility for over 6700 hours and results confirmed that it was a feasible system for recovering energy from biomass and wastes.

Fluidized-bed, Gasification, Pyrolysis, Biomass, Waste, Energy, Power generation, Liquid fuel synthesis

Evaluating Wind Conditions and Power Generation of Wind Turbine Generators using Weibull Distribution Data

by Satoshi SEKIZUKA, Hiroshi OKAZAKI, & Sumio SAITO

Wind conditions and power generation were evaluated for two wind turbine generator systems to clarify Weibull distribution effects, namely by changes in shape parameters. The systems had the same nominal rated power but their control methods were different. Shape parameter effects were also studied using measured wind condition data of prototype wind turbines operating at a site.

Wind turbine, Wind turbine generator system, Propeller type wind turbine, Power control, Wind speed, Frequency distribution of wind speed, Power performance, Power curve , Weibull distribution, Rayleigh distribution

New Vertical Pump Released into the Market

by Yoshihiro UCHIDA, Toru ISHIDO, & Sakae SHIMIZU

A new vertical pump has been developed and released into the market. The pump's submerged bearing, which constitutes a consumable part, is set below the pump impeller and not inside the pump bowl. This allows inspection on wearing or erosion of the bearing, and exchanging the bearing when necessary, without hoisting the pump. This pump design (patent pending) has revolutionized the maintenance and inspection of vertical pumps and is notably contributing to labor and cost saving.

Submerged bearing, Impeller, Discharge bowl, Full-speed stand-by operation at any suction water level, Ceramic bearing, Tungsten carbide sleeve, Brittleness, Axial flow pumps, Mixed flow pumps, Maintenance management

Pulsed Discharge Water-Bloom Prevention System

by Shinta KUNITOMO, Kenichi SASAKI, Masao AYUKAWA, & Hisamichi FUJIWARA

A pulsed discharge water-bloom prevention system had been developed for the removal and propagation-prevention of water-bloom (free-floating algae such as Microcystis) in closed-water bodies. This system uses shock waves from electric discharge to specifically collapse gas vesicles inside water-bloom cells, making them sink to the aphotic and low temperature bottom of a water body, thus inhibiting their growth by reducing their activity. Neither cell membranes nor colonies of water-bloom become scattered, resulting in no water pollution. Another feature is that only water bloom with gas vesicles are targeted and effects on other aquatic life are minimized. As treatment effectiveness is not dependant on turbidity elements and water-bloom concentration, it is possible to conduct treatment per miscellaneous matter such as dead leaves and twigs. The system is shaped like a pontoon so it can be easily transported to an area of water-bloom growth, thus enabling its use at dams and inlets of lakes and marshes, as well as in shallow water reservoirs.

Algae, Water-bloom, Pulsed discharge, Shock wave, Water treatment, Microcystis, Microcystin, Gas vesicle, Closed water area

New Internally Circulating Fluidized-bed Gasifier and its Feasibility

by Masayuki KAI, & Satoshi ASANO

A novel internally circulating fluidized-bed gasifier (ICFG), Model TWINRec, has made it possible to efficiently obtain high calorific gas from biomass and wastes. Demonstration tests carried at Ebara's Sodegaura Plant confirmed that the quality of the product gas from this ICFG was sufficient for this gas to be used as alternative fuel for gas engines and gas burners. As the ICFG is capable of gasifying various wastes and biomass, its product gas can be refined and used as gas fuel and liquid fuel by other facilities in the proximity. The versatility of this ICFG model makes it possible to recover energy under various influent waste conditions.

Fluidized bed, Gasification, Biomass, Sewage sludge, Waste plastics, Alternative fuel, Gas engine, Reduction of primary energy consumption, Reduction of green house gas emission, Methanol

Kerosene Type Home-use Fuel Cell Co-generation System

by Takashi KAWANISHI

Ebara's Kerosene Type Home-use Fuel Cell Co-generation System has been released into the market. This energy-and cost-efficient system, comprising a polymer electrolyte fuel cell unit and a heat recovery hot water storage unit, features a performance which equals to those of city gas and LPG type such systems. The following touches on fuel cell systems and discusses our kerosene type fuel cell co-generation system, specially designed for home use.

Kerosene, Fuel cell, Cogeneration, Reformation, Catalyst, System, Re former, Generation, Hot water tank, Polymer electrolyte fuel cell

Advanced Resin Cleaning System (ARCS)

by Shinji MIURA, Kaoru KIKUCHI, & Syuichi UENO

Ebara's novel and unprecedented ion exchange resin cleaning system, for use in BWR plants and featuring a vibration separator and basic design factors of Radiological Solutions, Inc., had been delivered to Tokai No. 2 Power Station, Japan Atomic Power Company, in October 2005. This compactly-designed system effectively separates crud and resin fines from ion exchange resins, with no clogging of separation screens. It generates minimized waste liquid and has a specially designed over-pack cleaning tank. The system has been in operation for about a year now and favorable operational data and evaluation results are being reported from the owner-side.

Condensate demineralizer, Ion exchange resin, Crud, Resin fines, Vibration separator, Back wash, Separation efficiency, Spray, Liquid phase radioactive waste

Fly-ash and Bottom-ash Recycling Technology for Chubu Recycle Co., Ltd.

by Shogo MATSUOKA, Ikuhisa YOKOTA, & Hideaki AOYAMA

Ebara's fly-ash and bottom-ash treatment system, core components comprising a submerged arc furnace (off-gas electric resistance furnace) and a dechlorination process, is contributing to the Zero Emission standard of Chubu Recycling Co., Ltd. This system is enabling treatment and resource recovery of fly-ash and bottom-ash from various incineration facilities, including molten fly-ash with highly concentrated chlorine content which is normally land-filled. Products from melting processes (e.g. sorted ferrous matter, molten metal, slag and molten fly-ash) are being recovered as added-value resources. The total amount of influent bottom-ash and fly-ash at the Chubu Recycling facility between 2004-2006 had been about 64000 tons. Out of this, about 35000 tons of slow cooling slag, about 3700 tons of molten metals, and about 700 tons of zinc resource had been recovered.

Bottom ash, Fly ash, Recycle, Submerged electric arc furnace, Dechlorination, Slow cooling slag, Off-gas electric resistance furnace, Zinc, Lead, Copper, Rare metal, Resource depletion

Wind Turbine Systems for Choshi Wind Farm


The construction of Choshi Wind Farm, located in Chiba Prefecture and featuring the use of seven Ebara-Pfleiderer 1500 kW wind turbine generator systems (Model EPW1570), had been completed in February 2007. This project is noteworthy in that it is Ebara-Pfleiderer's first execution of it's Wind Farm Plan which proposes the use of multiple wind turbine generators in a single wind farm.

Wind turbine generator system, Wind farm, Global warming, New and renewable energy, Choshi