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Ebara Engineering Review No.213

Performance of a High-Rate Sedimentation Process for Combined Sewerage Treatment in Wet Weather

by Sakae KOSANDA, Hirotoshi HINUMA, & Ryosuke HATA

A novel high-rate sedimentation process has been developed for directly treating combined sewer overflows (CSOs). This was done using a test facility at an actual wastewater treatment plant in Tokyo. Pilot test results, carried out 13 times, from December 2002 to July 2003 in wet weather, suggested that the process was suitable for treatment of CSOs. The performance of the process was favorable at 50 m3/(m2·h) up to 880 mg/L influent TSS, removing between 78% and 91% of TSS at loading and between 64% and 85% of BOD5 also at loading.
The pilot testing clarified that a decrease in the influent alkalinity due to rain water caused a drop in the pH after FeCl3 addition and thus improved coagulation, with a significant decrease in the effluent TSS. Mixing, coagulation and flocculation were carried out in a baffling type mixing tank to enable uniform mixing without any short-passes. Coagulation conditions in this mixing method were evaluated and results clarified that rapid mixing was required momentarily after each addition of FeCl3 and polymer, i.e. to diffuse these additives into the influent.

Combined sewer system, Stormwater, Coagulation-sedimentation process, Solid-liquid separator, Baffling mixing, CSOs (Combined Sewer Overflows), Flocculation, Diffusion, Alkalinity, SS

The Impact of Wafer Edge Roll-Off on CMP Performance

by Akira FUKUDA, Hirokuni HIYAMA, Kazuto HIROKAWA, Manabu TSUJIMURA, & Tetsuo FUKUD

The impact of wafer edge roll-off on CMP performance was studied using FEM (Finite Element Method) analysis. It was found that the edge roll-off influenced the removal rate distribution at the wafer edge of both stacked and solo pads. This influence was up to 4 mm from the edge for stacked pads and up to 10 mm from the same for solo pads. The surface pressure in the vicinity of the edge, for cases where the ROA (Roll-Off Amount) was 1.27μm, was about 30% greater than that at the wafer center for stacked pads and about 23% greater than the same for solo pads. The relationship between the retainer ring pressure and allowable ROA was also studied.

Wafer edge roll-off, CMP, FEM analysis, Removal rate, ROA, Stacked pad, Solo pad, Surface pressure

LNG Pumps and Expander Turbine Generator


This report outlines EBARA's pumps for handling LNG, some history and trends, and includes an introduction of a newly developed expander turbine generator.

Submerged motor pump, Expander turbine generator, Natural gas, Liquefaction plant, Carrier, Receiving terminal, Thrust load, Ball bearing, Self-balance, Clearance

Development of Underground Vacuum Station

by Fuyuki OHGAKI

A low-cost and compact underground vacuum station has been developed for use in vacuum sewerage systems. The underground vacuum station uses vacuum pump units capable of reciprocal rotation. Contaminated water becomes discharged by injecting air into the collection tank, thus making it unnecessary to use discharge pumps, such as those equipped in conventional vacuum collection stations. The compactness of the vacuum pumps, which are placed inside small units for enabling easy maintenance, save considerable space and the collection tank can be set underground and accessed by a manhole. Installation is thus low-cost with no need to construct a structure for the vacuum station.

Underground vacuum station, Vacuum sewerage system, Vacuum pump, Vacuum pump unit, Collection tank unit, Discharge pump, Check valve, Deodorizer, Motorized shut valve, Gravity system

Pump Controller for Thawing Snow - Snow Lasta -

by Hideji ISOBE, Hiroshi YAMASHITA, & Toshihiro SASAGAWA

Snow Lasta, a pump controller for thawing snow, effectively thaws snow on road surfaces making use of pumped up groundwater. Its operation thus has relatively small effect by wind. The Snow Lasta's control panel, equipped with a microcomputer, features a design which enables easy groundwater pumping and pump operation control. The development and production of this product was concerted by EBARA, a sensor manufacturer and a control panel manufacturer. This product features technical know-how accumulated through years of experience in the field. Further studies are being made to enhance this product to meet current and future market demands, especially in terms of environmentally feasible aspects, such as the minimization of water and power consumption.

System for thawing snow, Control panel for thawing snow, Snow sensor, Snowflake detection, Snow-fall pulse, Snow temperature detector, Current sensor, Digital indication, Forced backup, Saving water

Newly Developed Integrated CMP F-REX300SⅡ System

by Soichi ISOBE, Takao MITSUKURA, & Tadakazu SONE

The newly developed F-REX300SⅡ is an add-on to the F-REX series CMP (Chemical Mechanical Polishing) systems. It features enhanced performance, functions, operability and maintenance capability, thus satisfying the current demand in the semiconductor manufacturing market. This high throughput system comprises a EFEM (Equipment Front-End Module) unit with 4-FOUPs capability, a polishing unit with four polishing tables and a cleaner unit with three cleaning modules and one drying module. Also featured are highly functional transporters in the polishing and the cleaner units, minimized wafer defect during in transportations.

Chemical Mechanical Polishing, Increase in wafer dia., Throughput, Semiconductor production process, Front-Opening Unified Pod, Swing transporter, Cleaner linear transporter, Robot, Cleaner unit, Top ring