After the successful trial of Salinity Solution’s ultra-efficient RO technology at Wessex Water’s Fivehead Water Recycling Centre, Somerset Council has submitted a bid to the Government’s Nutrient Mitigation Funds hoping to secure £10.5m funding.

As has been hotly discussed, to protect the UK’s watercourses from nutrient pollution – principally nitrates and phosphates – housing developments adjacent to protected sites must demonstrate “nutrient neutrality”. The result, huge backlogs in the housing development. For example, Somerset and Dorset Councils have some 18,000 new homes awaiting the go-ahead until suitable phosphorus mitigation measures are approved.

Ultra-efficient Reverse Osmosis for Nutrient Mitigation

Salinity Solutions, Te-Tech Process Solutions and Wessex Water conducted a no-cost trial to demonstrate SAM50 ultra-efficient reverse osmosis (RO) technology. For the trial period ending on 1 August, a containerised SAM50 unit was provided to treat the final effluent from Wessex Water’s Fivehead Water Recycling Centre near Taunton. The trial plant was installed as a side stream as shown in the diagram below with the waste concentrate stream giving potential for recovery as a fertiliser.

The trial unit, a SAM50-25, used a standard 8040 brackish water RO element producing an average of 1.0 m3/h of permeate. Early indications show promising results with the first verified laboratory results showing over 98% of phosphates and 88% of nitrates removed. The energy consumption of the SAM50-25 unit was 0.23-0.41* kWh/m3 compared with a typical conventional RO energy consumption of around 1 kWh/m3. The waste stream was 8% of the feed compared with about 30% for conventional RO systems.

Somerset Council working in partnership with the Farming and Wildlife Advisory Group (FWAG), Plymouth University, Te-Tech Process Solutions, Salinity Solutions, and Dorset Council, has submitted a bid for £10.5m to the Government’s Nutrient Mitigation Fund. “We need to unlock development in the short term in a way that is aligned with longer-term nature recovery of our waterways,” says Cllr Ros Wyke, Lead Member for Economic Development, Planning, and Assets. “SAM50 can deliver sufficient nutrient credits to 2030 to help unlock all the housing units caught up in Somerset. The early trial results are excellent, exceeding our expectations and we call on the Government to confirm our bid so we can progress without further delay.”

SAM50 Explained

SAM50 is a fully automatic batch RO system developed by University of Birmingham spin out Salinity Solutions1. It consists of a high-pressure feed pump, a recirculation pump, industry standard RO modules and a free-piston pressure exchanger that operate in a cyclic manner using only three automatic valves. SAM50, can typically reduce energy consumption by 50% and with high recovery, reduces wastewater by up to 80%, compared to traditional RO technologies2.

“This interim solution remains just as relevant today despite the recent government announcement to ‘do away with’ certain legacy EU obligations set out in the Habitats Directive which are enshrined in UK law”, says Te-Tech’s Business Development Director, Mike Froom. “This controversial amendment to the Levelling up and regeneration bill will inevitably face legal challenge and will still need to get through parliament before it is enacted.”


Te-Tech Process Solutions


1 Hosseinipour E et al A free-piston batch reverse osmosis (RO) system for brackish water desalination: Experimental study and model validation Desalination 527 (2022) 115524

2 Park K et al Design, modelling and optimisation of a batch reverse osmosis (RO) desalination system using a free piston for brackish water treatment Desalination 494 (2020) 114625

* Electrical SEC inferred from recorded hydraulic SEC and assumed pump efficiency of 80%