Grundon's existing incinerator was commissioned early in 1990, and is now running at 75% of its 7,000 tonnes per year capacity. The plant is burning roughly 80 tonnes of clinical waste each week, of which 15 tonnes are imported from Germany.
The imports began last year due to the lack of UK demand (ENDS Report 197, pp 10-11). The move ran contrary to the Government's policy that developed nations should be self-sufficient in waste disposal capacity, but legislative powers were too weak to block the imports.
Grundon's Managing Director, Tony Mitchell, does not expect the imports from Germany to continue for long, although the contract is likely to be renewed for 1993. Demand in the UK has grown strongly over the past year, although "contractors are still suffering from health authorities' poor appreciation of environmental law," he says. "But we would much rather concentrate our efforts in the UK market."
The new incinerator is due to start up in mid-1994, and will probably be of a similar design to the existing stepped-grate unit. Grundon says that it will meet the standards set out in the draft EC Directive on hazardous waste incineration, which are considerably tougher than those required under UK rules (ENDS Report 208, pp 36-37 ).
Gas clean-up will be by a two-stage wet and dry scrubber. It is unlikely that the new incinerator will have a heat exchanger unit after the secondary combustion chamber. The existing plant has this type of heat exchanger, but the slow cooling of the gases in the boiler is leading to significant dioxin formation at levels of up to 11.7ng/m3. The problem was revealed in a recent report by Warren Spring Laboratory (ENDS Report 212, pp 14-15 ), and Grundon admits that the incinerator described in the report is the Colnbrook unit.
Once the new unit is on stream, the company will shut down and upgrade the existing incinerator, which must meet a dioxin emission limit of 1ng/m3 by December 1996. The upgrading is likely to include the removal of the heat exchanger.