AECOM awards contract to Cambi in Kent, England

Asker, 16 September 2013


The Long Reach project is a first of its kind in the UK. Thames Water has selected AECOM as the main contractor with Cambi as its specialist sub-contractor to build and upgrade to its sludge digestion plant at Long Reach STW, in NW Kent. The plant has a sewage treatment design capacity for 840,000 people equivalent and digests its sludge for agriculture as a fertiliser.

The project aims to make the site more self-sufficient in energy and produce a lower volume of final biosolids that can meet a higher treated standard and have superior storage qualities without further digesters. To do this, Thames Water devised a system of hydrolysing mainly the secondary sludge from the treatment process and feeding this in admixture to the existing digesters. This has many advantages:

  • the volume of digester feed is reduced to about 70% of the current volume, therefore, extending the digestion time;
  • the effect of Cambi's thermal hydrolysis process (CambiTHP) will make the sludge much more digestible and thus produce more biogas;
  • the dewaterability of the biosolids product will reduce final quantities by about 1/3 and increasing final product quality;
  • the CambiTHP™ system will operate on the waste heat from two 1MW Caterpillar engine generators that will supply the Thermal Hydrolysis Process, which will, in turn, be mainly responsible for the digester heating.

Thames Water has tested this system rigorously in their research labs and has devised a system of serial digestion that will dramatically reduce the pathogen content of the sludge. At full scale, this will comprise feed the mixed, heated sludge to a bank of existing primary digesters and then over spilling in series to 3 of the existing digesters, in turn, to give an extended period of pathogen die-off and secondary biogas production.

The CambiTHP system will comprise a second-generation Cambi B6-3 continuous batch system that is extremely compact and can be assembled on-site in a matter of days. The system is designed to operate on steady steam consumption from the engine waste heat boilers.

Cambi is the leading provider of technologies for converting biodegradable material to renewable energy, bio-fertilizer resource,s and biofuel, based on Cambi’s patented thermal hydrolysis process (CambiTHP™).

Media Contact: Norman Weisz, EVP Operations
Email:, Phone: +47 90474194