Severn Trent’s £60 million thermal hydrolysis plant becomes operational

The utility’s new thermal hydrolysis plant (THP) is now processing 100 tonnes of sludge daily.

The £60m project changes the way the company treats waste before it’s used to generate green power. It’s designed to make the process considerably more efficient and increasing the amount of clean energy produced by almost a third.

More than half of the plant is now up and running, the company hopes to see it fully operational by the end of summer 2018.

According to Severn Trent, the Minworth site already generates enough clean electricity to power the equivalent of 11,000 homes and enough gas to heat 4,800 homes every year. Those numbers are set to increase with THP coming online.

The process heats sewage sludge to 170°C before putting it under pressure. The treated sludge is then fed into huge digesters which biodegrade the volatile solid matter within the sludge and produce methane rich bio-gas.

Once that part of the process is complete, the sludge is then passed forward to the dewatering process where it is thickened, ready to be recycled as fertiliser for agricultural land. The thermal hydrolysis process allows the leftover solids to be classified as ‘enhanced’ fertiliser that can potentially be used in the production of crops for human consumption.

David Nyul, who is leading the project for Severn Trent, says: “Minworth is our biggest sewage works and treats waste water from more than 1.6 million homes and businesses across Birmingham and the Black Country. The technology we have already generates both power for use in the works and gas for injection into the national grid.

“The bio-gas we create through this process will both be used to generate electricity and to be treated at our gas to grid plant on site to make it suitable for domestic use before being injected into the grid where it will be used by local homes and businesses.”

By generating renewable energy Severn Trent is hopes to reduce costs and keep customer bills down.