Roundup — Sludge Treatment

April 1, 2006
The Centriquip AS Range centrifuges separate solids from oily sludges continuously, without manual intervention, 24 hours a day.

New centrifuges help Torbay cope with busy tourist season

The Centriquip AS Range centrifuges separate solids from oily sludges continuously, without manual intervention, 24 hours a day. The solid matter is removed from the sludge for disposal to landfill, the resulting mixture of oil and water then readily separates in a gravity separator.

Centriquip centrifuges help improve coastal water quality during the summer season in Torbay.
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For most separators, oily sludge is a tough assignment. The high amount of irregular and abrasive solids cause wear making economic operation difficult or impossible. The AS range machines, however, are designed specifically to handle heavy slurries containing coarse, irregular solids that would damage ordinary decanters or separators.

No polymers or heat treatments are necessary to cause separation. Nor will the machine become blocked by debris when it is used in conjunction with a sludge macerator, which ensures oversize material is cut down to an acceptable size.

The AS Range separators operate by feeding the sludge vertically into the separator bowl where the solids are deposited on its internal wall as a relatively moisture-free cake. When the solids holding space is full, the machine stops automatically and plough blades scrape the surfaces clean into a hopper placed under the unit.

The liquid phase, normally oil and water, is sent to a holding tank to separate under gravity. Oil and water may then be drawn off later for safe disposal, further treatment or, in some cases, reuse.

This mechanism ensures very little friction created inside the separator during normal operation, which allows it to handle abrasive feeds that would quickly damage other types of equipment.

The AS Range comprises three model sizes with a processing capacity of up to 6 tonnes per hour depending on the solids content. Centriquip provides a free bench test for evaluation, which may then be followed by an on-site demonstration at a nominal charge.

Centriquip is a leading UK manufacturer of decanter centrifuges, especially for handling wastewater streams. The AS Range complements the company’s core products and is rapidly becoming a key product in its own right.

Centriquip centrifuges were installed at the Brokenbury Works at Churston near Torbay in Devon, UK, to provide the area with its first comprehensive sewage treatment system. The new system is designed to cope with the massive influx of tourists visiting the area in summer and keep the local beaches clean for families to enjoy all year round.

The CQ5000 centrifuges in Derbyshire are an important feature of the US$ 77-million (£44m) investment made in Churston to prevent 10 million gallons of sewage being pumped out to sea every day. The centrifuges dewater the sewage sludge by separating out the water to produce a dry cake. The decanted water is then ready to be disposed safely through the works system. The dry cake is sent to the landfill or used as a valuable fertilizer for local farmers.

Because of the increasing popularity of Torbay as a tourist destination, the sewage works runs twenty-four hours a day and uses both CQ5000 machines continuously. The machines can be shut down independently for essential maintenance allowing the plant to continue. A separate rotating assembly is on hand that can be transferred to either machine at short notice if major work is required.

The project was designed with the environment considerations; the processing system helps keep the beaches clean and the entire plant was built largely below ground level to help maintain the much-loved beauty of the surrounding area. "Centriquip machinery was used to reduce the number of sludge tankers required and as a result has prevented increased traffic congestion in this premier holiday resort," explained Peter Brooks, program leader of Asset Development Planned Projects for the Torbay Sewage Works.

The project is part of a US$ 166-million (£95m) Clean Sweep scheme in Torbay to replace outdated sewage outlets and improve the environment. More than 223 of the 250 raw sewage outlets on the southwest coast have been closed down permanently, with all but four scheduled for shut down by the end of 2006.

Centriquip Ltd.
Clay Cross, Derbyshire, UK

Screw pump lining wear resistant

Abresist custom-engineered tile linings extend the life of screw pump troughs handling wastewater, especially from combined systems. Tile harder than the sand and other solids entrained in sewage and storm water resist the wear they cause, maintaining the proper gap between the screw and trough, keeping the lifting capacity constant. Installed on steel or concrete, they are designed to account for the bend in the screw.

Abresist Corporation
Urbana, Indiana, USA

Annihilator improves grinder for maximum shredding strength

The Moyno® Annihilator™ is a twin shaft solids reduction unit designed to perform in industrial and municipal installations including sewage lift stations, head works and sludge processing systems. The Annihilator’s counter-rotating, hexagonal shaft design coupled with its five-tooth, hardened steel cutters provide the maximum shredding strength necessary to process from 300 to 4,250 gpm (.43 to 6.12 mgd) of influent. When properly specified, the Annihilator prolongs the service life of downstream equipment such as pumps, sensors, monitors and valves.

The unit is fitted with patented, toothed cutting spacers that increase the unit’s efficiency, further decrease particle size and reduce the risk of failure from ragging. A seal/bearing cartridge assembly eliminates the need to disassemble the entire grinder when servicing seals and bearings.

Moyno, Inc.
Springfield, Ohio, USA

Centriquip centrifuges help improve coastal water quality during the summer season in Torbay.

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