Dr. ThomasTo ask the Secretary of State for the Environment if, pursuant to his answer to the hon. Member for Dewsbury (Mrs. Taylor),Official Report, 28 June, column 955, he will set out the basis for his statement that incineration of sewage sludge may be the worst environmental option.
§ Mr. HowardIncineration of sewage sludge needs a significant input of energy in the form of oil or gas to achieve the necessary combustion efficiency. The ash which sludge incinerators produce contains relatively high concentrations of heavy metals, up to 50 times the levels in sludges disposed of in liquid form to agricultural land or to sea. Therefore, special protective measures must be taken at the landfill sites where it is deposited to ensure long-term environmental safety. Unlike other sludge treatment processes, incineration carries a risk of 209W uncontrolled discharge of contaminants to the atmosphere if operational breakdown causes faulty combustion or inefficient cleansing of exhaust gases.
For these reasons, incineration is used only where the sludge producer has no practicable alternative available. Only about 10 per cent. of the sludge produced in other EC member states is dealt with by incineration.