Construction has recently begun on one of the largest tertiary wastewater treatment plants in the U.K. The plant, to be built at Severn Trent Water’s Strongford Sewage Treatment Works, will use Severn Trent Services’ TETRA NSAF (Nitrifying Submerged Aerated Filter) technology to reduce the ammonia in the plant’s effluent from 15 mg/l to 3 mg/l. The facility is scheduled for completion in the fall of 2008.
The TETRA NSAF, an up-flow, fixed film biological reactor, is a proven, robust system that generates minimal additional solids requiring post-treatment handling and disposal. Its effectiveness in ammonia removal has been demonstrated at several plant installations throughout the U.K. over the past 10 years. A new process – NSAF+ – has been developed to control the very large Strongford plant and will provide significant savings in electricity costs over a conventional NSAF plant.
The total plant area for the Strongford NSAF will be 1,400m2, which will accommodate a flow to the plant of 10,000m3/hr. The technology is extremely flexible and is available in a range of sizes from small modular units suitable for above or below ground construction to custom-made configurations for large plants.
The Strongford facility will be constructed using 10 rectangular concrete cells, each measuring six meters wide and 22.75 meters in length. There will be 10,700 T-Blocks in the facility, which will measure 5½km when placed end to end.