London - Crossness

Located on the south bank of the river Thames, the Crossness sewage treatment works (STW) was first connected to the London Sewer network in 1850. Today is serves a population of 2 million people and is one of the largest treatment works in the UK. Nearly opposite on the north bank Crossness STW serves 3.5 million people.

The chosen method is to pre-treat the secondary sludge with Cambi thermal hydrolysis and anaerobic digest it before making agricultural grade fertilizer. The upside of this process is that significant renewable energy can be made as well as a safe product for recycling. Initially Thames Water chose to divert some sludge from Beckton to its Riverside plant via an existing pipeline and use the Cambi Digestion process in digesters at that site- this project is complete.

As a further stage to providing sludge treatment capacity, Thames has awarded a project to Imtech Process for refurbishment of existing digesters at the Beckton Crossness sites to treat mainly secondary sludge so that the incinerators will use maily primary sludge that dewaters well and has high energy content. The works incorporates refurbishing 6 digesters at both sites, adding Cambi THP systems reactors and 4 MWs of combined heat and power that only provides some electricity for operations of the STW but also a large amount of the heat required to drive the thermal hydrolysis process.