A new state of the art biosolids processing plant in north Norfolk is claimed to be delivering improved energy efficiency for its operator and a better quality product for farmers.

Anglian Water brought the high-tech plant at King’s Lynn on stream in May, replacing an older plant.

The new £28million sludge digestion plant, the first of its kind in the country, employs mesophilic digestion to transform dirty water and food waste from King’s Lynn and the surrounding area into ‘enhanced treated sludge’ or biosolids for application to farmland as a fertiliser.

The waste material is heated to 55degC using injected steam and held at this temperature for a minimum of five hours, which kills 99.9 per cent of required pathogens and ensures a zero salmonella bacteria count.

The process also incorporates a mixing and aeration stage that stops the digestion process and leaves the biosolid material in an aerobic state.

In comparison to the biosolids produced by the old plant, which used lime and hot water to kill pathogens, the new material has less odour, spreads better and has a slightly better nutrient quality, says Anglian Water biosolids communications manager Tim Burch.

Methane gas produced during the treatment process is harvested, stored and used as a power source for the plant, which is self-sufficient in terms of energy for heat generation. Any surplus energy is exported back to the National Grid.