Following on from Severn Trent Water’s award for Nereda technology at its wastewater treatment works in Barston near Birmingham last year, the water company has now awarded two further contracts for the ground-breaking technology at Walsall Wood Sewage Treatment Works in West Midlands and Radcliffe-on-Trent Sewage Treatment Works in Nottinghamshire.
Severn Trent Water is one of the earliest adopters of Nereda technology in the UK, and when complete, the three new plants will benefit from the most cost-effective solution in terms of CAPEX as well as on OPEX. In addition, the new plants will meet the stringent new standards for phosphorus and ammonia levels.
Barston Sewage Treatment Works required complete new works to significantly reduce the amount of phosphorus and ammonia discharges into the watercourse. It needed to improve the effluent produced, so as to comply with some of the tightest effluent consent requirements in the UK. New inlet works have been designed, and the construction of three new Nereda reactors, each with a volume of 2,900m3, will start in December this year (2017).
Radcliffe-on-Trent Sewage Treatment Works is going to be upgraded to increase its capacity to receive flows from another nearby sewage works. It also needs significant upgrading in order to meet higher environmental standards. Severn Trent Water needed to find a solution that would ensure the treated wastewater complied with more stringent regulations as well as finding a way of increasing treatment capacity as cost effectively as possible. Currently in design, the construction of the three new Nereda reactors, each with a volume of 1,375m3 will start early next year.
Meanwhile, Walsall Wood Sewage Treatment Works also needed to be upgraded in order to comply with stringent new standards for phosphorus and ammonia levels in wastewater. Three Nereda reactors, each with a capacity of 1500m3 are in the design phase and construction is expected to commence early 2018.
Manjit Chadha, Severn Trent programme manager, said: “Installing Nereda will significantly improve the quality of effluent we put back into the water courses in each area. In addition to the system’s efficiency and environmental credentials, which are extremely impressive, its relatively low capital expenditure requirement made it a very straightforward choice for us.”
Developed by Royal HaskoningDHV in the Netherlands, Nereda is the first process to successfully harness the benefits of aerobic granular sludge technology. Nereda naturally selects fast settling granules, allowing higher concentrations of active biomass to be accumulated. The compact plants achieve very high levels of nutrient removal, without chemical dosing. Applications can be new-build or retrofit. The compactness of the site – which typically requires a quarter of the land area that is needed for an equivalent conventional activated sludge – is an important plus factor in its competitiveness, in addition to its relatively low installation and running costs.