Cambi AS has been chosen by Imtech Process to provide thermal hydrolysis pre-treatment
(THP) of sludge for two advanced sludge treatment centres for Dwr Cymru Welsh Water
(DCWW) located in Cardiff and Afan in Wales.
Following a review of energy policy DCWW has decided to reduce its reliance on energy intensive
thermal drying of sludge at 3 plants in South Wales in favour of anaerobic digestion (AD) and
power generation. The aim is to be able to generate 5 MW of green power by March 2011
in order to grandfather the value of Renewable Obligation Credits (ROCs). After start-up
the plants will play an important role in reducing Dwr Cymru Welsh Water’s carbon
footprint (a measure of a company's contribution to the greenhouse gas effect) by
35,000 tons of CO2 equivalent per year. This is equivalent to 15% of the total carbon footprint
of Dwr Cymru Welsh Water.
The key challenge for the new AD plants was to build them within the existing site boundaries
at the two sites that are being converted to regional sludge centres. This required very
compact design and maximum productivity. Following a review of pre-treatment technologies
for AD, Imtech Process selected Cambi AS to provide THP pre-treatment. Cambi THP is
already used for 6 compact digestion plants at Dublin, Aberdeen and other sites in the UK.
Cambi THP entails the sludge being heated up to 170 degrees Celsius, sterilized and is
then anaerobically digested at digester loading rates that are two to three times that of conventional.
An added advantage of this sludge treatment process is that a high volume of biogas is yielded
(mainly methane), even with the secondary biological sludge produced at Cardiff from the SBR process.
The treated sludge will be dewatered and processed into a high quality sludge cake that
is free of pathogens and will be used across South Wales as an agricultural fertiliser.
The Cambi THP process encourages a well dewatered digested product in excess of 30% dry
solids that is non smelly and easy to store and use.
When complete the 8 Cambi plants in UK and Ireland will be treating sludge from the equivalent
of approximately 6 million population.
Cambi AS provides pre-treatment and biogas systems for organic waste and sludge. The compact
Cambi plants are designed for high organic loading and enhanced biogas production, and a low
volume pathogen-free biosolids product. Cambi has thus far delivered a total of 17 plants to Norway,
Denmark, the UK, Belgium, Poland, Ireland, Finland, Germany, Australia and Japan.
