§ Mr. Bob RussellTo ask the Secretary of State for the Environment, Transport and the Regions if he will publish a breakdown of the content of unauthorised emissions from United Kingdom commercial aerobic/anaerobic digesters since January 1996. [56747]
§ Mr. MealeAerobic and anaerobic digestion is used throughout the United Kingdom in processes such as the treatment of sewage sludge and biodegradable, industrial, organic effluents (eg from food processing). These processes produce mainly carbon dioxide, methane and ammonia together with trace organic compounds. In the anaerobic digestion of sewage sludge, the methane is normally burnt to produce heat and power. The emissions into air from these processes are not the subject of specific controls. In consequence, it is not feasible to provide a breakdown of the content of unauthorised emissions.
The aerobic digestion (composting) of garden waste etc. is subject to waste management controls. The activity generally takes place in the open and potentially harmful emissions are controlled by operational procedures and conditions on siting.