Cambi has been awarded a contract for the thermal hydrolysis process (THP) scope of the Howdon sewage treatment works advanced digestion project.

Cambi’s Thermal Hydrolysis Process will be installed close to the city of Newcastle, UK
to complete Northumbrian Water’s migration towards advanced digestion methods.

 

 

Cambi UK Ltd has been awarded a contract by GTM, a joint venture between Imtech Process Ltd
and Galliford Try Infrastructure Services Ltd for the thermal hydrolysis process (THP) scope
of the Howdon sewage treatment works advanced digestion project.

 

Following a review of sludge strategy in 2005 – Northumbrian Water (NW) adopted conversion
to advanced digestion at one of their major sites. The aim was to cease using thermal drying
to improve NW’s environmental sustainability, reduce operating costs and its carbon footprint.
This project was completed at Bran Sands (on Teesside) in 2009 and is currently treating over
100 dry tonnes of sludge per day (equivalent to about 1 million population) using Cambi THP.
Based up on the success of Bran Sands, Howdon has now become the sister project in the
north of NW and has many similarities to the Bran Sands project including a capacity of 40,000
dry tonnes. Together Bran Sands and Howdon will then treat most of NW’s sludge.

 

Currently indigenous and imported sludge is dewatered at Howdon sewage treatment works and
treated with quicklime for agricultural recycling.  NW has awarded a contract to GTM to design
and build the new treatment facility. The project entails the building of new digesters with Cambi
pre-treatment, combined heat and power for electricity and steam production will also form part
of the new facility. Cambi and Imtech Process Ltd have worked together before on two projects
in South Wales for the Cardiff and Swansea area. Innovations from those projects on how to best
integrate Cambi THP into the advanced digestion project will be carried forward to Howdon.

 

The main project comprises of pre-dewatering the sludge to make a cake of about 18% dry solids.
This is fed into the Cambi THP that has a configuration of two streams of four reactors that treats
the sludge by the addition of steam to make a hydrolysed (pressure cooked) and sterilized digester
feed at about 10% dry solids.

 

The biogas from the digesters will be used to produce over 4 MWs of renewable electricity, waste
heat is also recycled to steam for Cambi THP and for other uses. Overall it has been estimated
that the two projects using Cambi THP will reduce NW’s carbon footprint by about 50,000 tonnes CO₂ per year.

 

Cambi THP, a Norwegian technology, has a strong presence in the UK and Ireland with eleven THP plants built,
or in design, for over ten million population in the last 12 years. The projects have demonstrated the ability to feed
digesters at 2-3 times conventional load and to make a high quality fertiliser cake product. Cambi has earned
a good reputation for the reliability and it’s support of the THP system.