Technologies

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Ebara Engineering Review No.229

Up-flow Anaerobic Sludge Blanket (UASB) Treatment of Municipal Wastewater under an Unheated Condition

by Yutaka YONEYAMA, Shigemi OKADA, Naohide MATSUMOTO, Ayako IGARASHI, & Akihiro NAKAMURA

In order to establish the feasibility of methane fermentation for treating low organic concentration wastewater, a pilot-scale UASB reactor was operated under an unheated condition over 631 days by seeding mesophilic sewage digested sludge and by feeding with a municipal wastewater. The pilot-scale UASB reactor had a treatment capacity of 50 m3/d, an effective capacity of 20.2 m3 and a net depth of 5 m. The result obtained from a continuous experiment indicated a stable treatment, i.e. , between 397-631 days after the startup. The mean values obtained during this time indicated a biogas generation of 2.4 m3/d, methane gas composition of 70.5%, CODCr removal of 63.8% at water temperature of 23.8℃, CODCr volumetric load of 0.99 kg-CODCr / (m3·d), and CODCr sludge load of 0.12 kg-CODCr /(kg-MLVSS·d).

Keywords
UASB, Unheated condition, Municipal wastewater, Sewage, HRT (Hydraulic Retention Time), CODCr (Chemical Oxygen Demand), Methane, Biogas production rate, Granule

Model SSLD In-line Pump equipped with an All-in-one Controller and Permanent Magnet Synchronous Motor

by So KUROIWA, Shoji ITOH, & Masaki WATANABE

This newly developed pump, equipped with an all-in-one controller and PM motor, realizes a Max. 50% plus saving in energy consumption as compared to that of an equivalent conventional pump made by Ebara. Features which make this possible are an upgrade in pump performance by optimized rotational speed control and flow analysis by computational fluid dynamics. This pump model has been introduced into the market in May 2010.

Keywords
Energy saving, Satndard pump, High efficiency, Pump controller, Permanent magnet synchronous motor, High speed, Hydro-design, Noise reduction, Cooling, Maintenance-free

Construction and Handover of a Next-generation Stoker Type Incineration Plant to the Kariya-Chiryu Environment Association

by Kiyoyuki SAKURAI, Tomoyuki SONE, Takehiro OKA, & Junichi ICHIKAWA

A next-generation stoker type incineration plant, the second of its kind Ebara, has been constructed and handed over to the Kariya-Chiryu Environment Association. Development targets included minimized impact on the environment and a visual blending with the landscape. This plant is capable of not only advanced treatment of flue gas but also production of reusable slag by melting incineration ash and fly ash. Another feature is the effective use of incinerator heat to generate electricity which is used in the plant and in other facilities. Moreover, wastewater is treated by a closed system, thus preventing any contamination outside the plant. The previous administration building had been modified for this plant so there was no need to construct a new building. A greening wall had been erected for visual betterment of the landscape. In this way not only the betterment of incineration/treatment performances but also of environmental and landscape factors had been achieved.

Keywords
Next generation stoker technology, Incineration plant, Exhaust gas recirculation, Power plant, Slag, Closed cycle system, Heat supply, Dioxins, Greening wall, Reuse

A Fluidized-bed Gasification and Slagging Combustion Plant - Ecotopia Ikehara -

by Kazuaki WATANABE, Daisuke SAKU, & Katsutoshi NARUSE

A novel fluidized-bed gasification and slagging combustion plant has been successfully installed at Ecotopia Ikehara, run by the Kurahama Sanitary Facilities Association, Okinawa. This plant has a capacity of 103 t/d×3 lines (total of 309 t/d) and furnace flue gas is effectively used in a waste heat recovery boiler which generates a max. of 6000 kW via a steam turbine generator. Dioxins in fly ash is kept below 0.25 ng-TEQ/g, without the use of fly ash dechlorination process, significantly lower than the national standard which is 3 ng-TEQ/g. Slag generated at this plant sufficiently meets 2 Japan Industrial Standards stipulations, namely JIS A 5032:2006 (slag material for road construction) and JIS A 5031:2006 (slag aggregate for concrete). Test results are showing favorable steam flow controllability and expectations are great for this plant's use not only as a waste treatment system, but also as a PPS (Power Producer and Supplier).

Keywords
Fluidized-bed, Gasification, Ash melting, Slag, Fly ash, Dioxins, Power generation, Japanese Industrial Standard, Slag aggregete quality, Steam flow contorollability

Characteristics and Development Chronology of Anaerobic Biotreatment Technology

by Naoaki KATAOKA

In anaerobic biotreatment organic matter becomes degraded into methane and carbon gas by catabolization of anaerobic bacteria propagating in an oxygen-less/anaerobic environment. This treatment method had started to be applied in Europe between the end of the 19th Century and the beginning of the 20th Century. In the 1950s heating and mechanical agitation techniques were developed for this method. In Japan, the use of anaerobic digestion for reducing and stabilizing sludge in sewage sludge and night soil treatment became widespread around this time. In the 1980s high-load anaerobic biotreatment featuring microbial immobilization was developed and its use became widespread mainly for treating industrial wastewater. At present, focal attention is being directed at anaerobic biotreatment as a source of unused energy for achieving a low-carbon social and economic structure, by producing biomass from domestic waste, food processing refuse, sludge and other such refuse.

Keywords
Anaerobic treatment, Anaerobic digestion, Methane fermentation, Biomass, Methane, Digester, Anaerobic bacteria, Microbial immobilization, UASB, Sludge