A good deal for scraping

Thames Water is spending £24m on sludge handling equipment for its major sewage works in London.
A deal with Hydro International will see the Zickert continuous bottom scraping and surface scum removal technology collect sludge from 53 primary settlement tanks at Beckton, Crossness and Mogden sewage works. The projects will increase sewage treatment capacity, improve operating efficiency and reduce odour.
In the largest project, at Beckton STW, a total of 24 existing sedimentation tanks will use new Zickert sludge scrapers, joining the eight existing primary tanks already converted to the Zickert system. The complete £16.5m installation will cover more than 56,000 sq. metres.
Zickert equipment is claimed to have significant advantages over conventional sludge scraping technology and with lower operating and infrastructure costs. And the gentle action is said to produce a higher yield of sludge. Its higher throughput reduces the amount of secondary treatment required and produces more primary sludge with a higher calorific value for incineration.
Because the tank design requires a much lower headroom than other sludge collection equipment, the low profile reduces the volume of air to be treated for odour removal in the tank enclosures.
Work has also begun at Mogden to retrofit eight primary settlement tanks and to equip five new tanks. This forms part of Thames Water’s £140m upgrade to increase sewage treatment capacity at the site by 50 per cent. The contract was awarded by Black and Veatch.
At Crossness STW, eight new primary settlement tanks are being built as part of the £220m upgrade increase sewage treatment capacity by 44%. The Zickert equipment will be installed early in 2012 to provide energy-efficient odour control and deliver sludge to provide 20% of the plant’s energy needs. The contract here is from Tamesis, the Laing O’Rourke and Imtech Process Joint Venture.
The Beckton Zickert project was awarded to Hydro by main contractor GBM, the joint venture of Galliford Try, MWH Treatment and Mott Macdonald.
“These contracts together are a record breaker, the largest ever placed with Hydro,” said Chris Day, operations director at Hydro International’s Wastewater division.
“Already the first Scottish installation of Zickert sludge treatment technology is underway at Hamilton WWTW, South of Glasgow as part of Scottish Water Solutions upgrade there.”