Water industry supports development of anaerobic digestion

Jul 30, 2008

Water UK welcomes today’s announcement by Defra to boost support for anaerobic digestion (AD) in the UK.

The water industry has used AD for many years to extract valuable energy from the sewage treatment process. The technology offers a wide range of benefits including:
  • renewable energy
  • diversion of organic waste from landfill
  • reduction of methane emissions from waste, and
  • provision of fertiliser.

There is also significant potential for expansion by co-digesting sewage with biodegradable material from other sectors.

Water companies will cooperate actively with other sectors to remove the barriers to AD and build on the water industry’s existing infrastructure, experience and expertise in support of the Government’s vision.

Anaerobic Digestion is a biological process that happens naturally when bacteria break down organic matter in environments with little or no oxygen. Almost any organic material can be processed with AD, including waste paper and cardboard (which is of too low a grade to recycle for example because of food contamination), grass clippings, food, agricultural, industrial effluents, sewage and animal waste.

'Conventional' AD has been used by the water industry for decades as a sludge stabilisation process. Conventional AD can be converted to advanced AD by the addition of a pre-treatment stage. This effectively doubles the gas production per unit volume of the digester and reduces the volume of digestate (sludge).

Of the 1.6 million tonnes of sewage sludge produced annually by the industry, 66% is treated by AD and 60% of the biogas produced by this process is used to generate renewable heat and power by Combined Heat and Power (CHP) engines. Other methods of treating sewage sludge include liming, drying and incineration.

Water UK head office
1 Queen Anne's Gate
London SW1H 9BT
Tel +44 (0)20 7344 1844
Fax +44 (0)20 7344 1853

Internet: www.water.org.uk

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