Sand Filtration Refits for Scottish Water

As part of Scottish Water’s capital investment into its sewage treatment works to meet tighter consent requirements, an extensive refitting programme is being undertaken. At the works in Ashgill and Coalburn (South Lanarkshire) and Blackridge (West Lothian), Hydro International’s (UK) Dynasand and Dynasand Oxy vertical sand filters have been installed to ensure improved tertiary treatment and final water quality to river catchments.

“At Ashgill, Scottish Water Solutions’ requirement was to reduce the ammonia content and BOD, so the two new Dynasand Oxy sand filters are installed to promote nitrification, as well as removing solids,” comments Project Engineer Duncan Smith for engineering consultant Grontmij UK. “We have installed one filter at Coalburn, for final polishing through solids removal.”

At Blackridge, the task is ammonia removal using two Dynasand Oxy sand filters. Reducing ammonia pollution is important as part of the improvement of the River Forth catchment area.

“Dynasand and Dynasand Oxy vertical sand filters have been recommended on several projects in Scotland since 2009,” adds Duncan. “They are highly effective and versatile as a ‘bolt-on’ treatment for improving water quality, and have a very small footprint for the volume of effluent treated which is extremely useful in the constrained space available at long established STWs.”

The extensive programmes at Ashgill, Coalburn and Blackridge, which include Suspended Air Flotation for improved aerobic secondary treatment followed by tertiary treatment by the sand filters, are being undertaken by Jacobs Engineering Services. The programme is contributing to the need to improve water standards as part of the Clyde River Basin Management (Ashgill and Coalburn) and Forth Estuary Catchment (Blackridge) plans, and meet overall obligations under the EU’s Water Framework Directive.