WORK has begun on a £17m improvement scheme at Swindon sewage treatment works.

The scheme by Thames Water is expected to boost the quality of the water discharged into the River Ray using a biological nutrient removal process to reduce the amount phosphates usually found in products such as washing powder.

The works treats sewage for 190,000 people in Swindon and Wroughton, but the capacity will be increased by 25 per cent to meet population growth.

Improvements are being made to the screening process, which removes plastic and rag material from the sewage before it is treated.

A new treatment lane and settlement tank are also being added. But the work is being done without extending on to surrounding land, part of which Thames Water has made into a wildlife sanctuary.

Margaret Skivington, catchment manager for Swindon, said: "There will be many benefits arising from the improvements to the works."

Engineers expect the work to be completed in time to meet the Environment Agency's new standards in April 2005.