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Howdon, UK

Plant sheet: Printable pdf


Plant capacity and expected performance:

• 40,000 metric tonnes DS/year • Reduced energy for drying and transport

• 3 x 6,300 m³ digesters

• High performance digestion

• 8 reactor Cambi THP

• 4.7 MW electricity + cogen steam

Cambi’s process by Newcastle  to double Northumbrian Water’s
conversion to advanced digestion.

Following a review of sludge strategy in 2005 – Northumbrian Water Ltd (NWL)
adopted conversion to advanced digestion at 2 major sites that would treat about
80% of all NWLs sludge. The aim was to cease using thermal drying and lime
stabilization treatment as both have high operation costs and high carbon footprint.
The first project was built at Bran Sands (Middlesborough and southern towns of NWL)
in 2009 and is currently treating over 100 dry tonnes of sludge per day (equivalent to
about 1 million population) using Cambi THP. Howdon is the sister project in the north
of NWL and has many similarities to the Bran Sands project including a capacity of
40,000 dry tonnes. 
Currently indigenous and imported sludge is dewatered at Howdon and treated with
quicklime for agricultural recycling.  NWL have awarded Imtech Process Ltd the
contract to build the new plant.
The project entails building new digesters with Cambi pre-treatment and combined
heat and power for electricity and steam production. Cambi and Imtech have worked
together before on 2 projects in South Wales for the Cardiff and Swansea area.
Lessons learnt from those projects on how to best integrate Cambi THP into the
advanced digestion project will be carried forward.
The main project comprises reception of sludge from areas in the North of NWL
and blending with Newcastle sludge followed by pre-dewatering of the sludge to
make a cake of about 18% dry solids. This is fed into Cambi THP in 2 streams of
4 reactors that convert 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 and waste heat recycled to steam for Cambi TH and other uses. Overall
it has been estimated that the two projects with Cambi reduce NWLs 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 10 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.

Where to find the plant:
Howdon STW
Northumberland Dock Road
Tyne & Wear
NE28 0QD

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