Product category:
Sludge Handling and treatment
News Release from: Biwater Treatment | Subject: Isle of Mull sludge
Edited by the Processingtalk Editorial
Team on 13 March 2008
'Island wide sludge strategy' on Mull
Whilst working on a GBP6.8M scheme to provide Tobermory on the Isle of Mull with new waste treatment facilities, the Biwater Leslie JV was also able to provide a solution to an on-going sludge problem
Two of the main communities along the west coast of Scotland include the Islands of Mull and Islay Previously these islands have had no method of treating and disposing of sludge
This article was originally published on Processingtalk on 12 Aug 2003 at 8.00am (UK)
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The existing disposal routes for the sludge consisted of either dewatering and disposal to existing landfill sites on the islands, or transporting to the mainland for disposal at a regional sludge treatment centre.
These methods were not sustainable and a new strategy had to be put in place that looked at the impact on the environment, long term sustainability and a whole life cost solution.
The process identified was to use facultative lagoons at Tobermory on the Isle of Mull and at Bowmore on the Isle of Islay thus providing an 'Islands Sludge Strategy'.
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The use of the 'Aero Fac' facultative lagoons process on each island meant that a sustainable solution providing a long term disposal route for the islands sludge had been found.
Imported sludge from across the island is handled by a sludge reception facility consisting of sludge screening, transfer pumps, 350cu.m storage tanks and dedicated odour control.
The sludge is then fed into the facultative lagoon at a controlled rate.
Sludge ''self-digestion'' is an integral part of the system and provides the benefits of internally digested sludge.
The very small amount of accumulated materials generally never need be removed from the system; historical data shows that some plants in America have not been desludged during their 30 year life.
Jim McGroarty of Biwater Treatment said, 'We have calculated that this solution has reduced the Scottish Water Carbon Footprint by over 25 tonnes of CO2 per annum.
This is mainly due to the fact that, as a result of this project, the need for large sludge tankers on the Island of Mull and between Oban and Glasgow has been eliminated.
All that is now required is smaller tankers working locally to deliver to the sludge reception centre at Tobermory several times a year'.
In addition to this the aerators for the facultative lagoons are wind driven.
This reduces both the size of the back-up blowers required and the power requirements of the scheme overall thus further reducing the Scottish Water carbon footprint.
Finally the re-use of all of the peat excavated in the construction of the lagoons as organic capping material for the municipal landfill site adjacent to the works again reduced the carbon footprint of disposing offsite and turned a potential 'waste' material into a valuable re-used material.
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