Sewaco was contracted by WECS Ltd (Wessex Engineering Construction Services Ltd) to deliver a design and build package as part of the Ratfyn STW improvement scheme.

The site handles a large quantity of imported sludge and sewage flows from Amesbury and the surrounding area.

The contract comprised a 22.475m-diameter Hyrate biofilter structure packed with 2380m3 of 2H Aqua modular media. Effluent is applied to the media surface at up to 60litre/sec by stainless steel, tubular arm distributors.

The Hyrate biofilter and distributor were supplied to reduce ammonia levels and improve effluent quality prior to flows passing through a rapid gravity sand filter system, before final discharge into the river.


Sewaco was contracted by WECS Ltd (Wessex Engineering Construction Services Ltd) to deliver a design and build package as part of the Ratfyn STW improvement scheme.

The site handles a large quantity of imported sludge and sewage flows from Amesbury and the surrounding area.

The contract comprised a 22.475m-diameter Hyrate biofilter structure packed with 2380m3 of 2H Aqua modular media. Effluent is applied to the media surface at up to 60litre/sec by stainless steel, tubular arm distributors.

The Hyrate biofilter and distributor were supplied to reduce ammonia levels and improve effluent quality prior to flows passing through a rapid gravity sand filter system, before final discharge into the river.