Earlier guidance on other sectors contains limits on pollutant releases from new processes. Existing processes are expected to meet these by a set deadline, other than in "exceptional circumstances" or "where a major change in process configuration is required".
However, the draft guidance on metals processes stressed that "achievable release levels" should not be viewed as uniform emission standards, and may not be achievable by existing plant. Furthermore, the concepts of "best available techniques not entailing excessive cost" (BATNEEC) and "best practicable environmental option" (BPEO) were to be applied on a site-specific basis only, in line with HMIP's moves towards a BPEO assessment procedure (see pp 38-40 ).
The policy shift has received a frosty welcome from the National Society for Clean Air (NSCA). The earlier guidance, it says, offers a "consistent benchmark" and firm timetables which acted as a "key element in creating a level playing-field, assisting long-term investment planning and ensuring that similar demands are made of competing producers".
The NSCA sympathises with the need for "a degree of flexibility to tailor emissions requirements to locality", but says that this should operate only "over and above the agreed minimum standards" in the guidance. It fears that the new approach "could produce competitive distortion both within and between industrial sectors", and "is hardly likely to enhance the rate of uptake of clean technologies".
However, ENDS understands that HMIP may now be considering removing upgrading deadlines from its guidance notes altogether. An important factor in its thinking is the impact of the recession on industry. Equally, its guidance carries no statutory force, unlike that for processes under local authority air pollution control. HMIP is concerned that if inspectors lift authorisation conditions directly from the notes, it may be subjected to a welter of appeals.
HMIP's moves in this direction are signalled in the newly published draft guidance for organotin coating processes (see below) - and are expected to become standard in other guidance. Inspectors are informed that it "may be possible to make improvements to existing processes" using techniques described in the note. Applicants should identify areas of the process in need of upgrading, and submit a programme for improvement. However, the inspector himself "must determine the date by which the scope and detailed timetable for the improvement programmes should be submitted by the applicant" - taking into account the "complexity of the issues to be addressed".
Dr Len Hales, Head of HMIP's technical guidance branch, told a recent conference on the non-ferrous metals sector that "the key is to force the pace of improvement at a rate which can be justified under BATNEEC". Where a "whole-hearted change" to a process is required, such as "re-planting", he expects "the timetable to be more elastic".
Quite where the shifting policy leaves operators whose processes are already authorised is unclear. Many authorisations contain a general condition requiring upgrading to new plant standards by the relevant deadline for the sector. It may be that such conditions will be removed when authorisations and guidance notes come up for their routine four-yearly review.
Meanwhile, HMIP has produced the second draft of its first six guidance notes for iron and steel processes and some non-ferrous metals processes.1 Applications for the former group are due in by 31 March 1995, with an "aim" of upgrading "generally no later than" 1 January 1999. The deadlines for non-ferrous metals processes run five months behind.
The drafts are substantially unchanged from the first versions, covered in ENDS Report 227, pp 30-31 . The British Non-ferrous Metals Federation (BNMF) is particularly concerned about the release limit for dioxins of 1ng/m3 which appears in most of the notes. Its Technical Secretary, Joe Heaton, described the limit as "a political number" derived from EC legislation on hazardous waste incineration. However, Dr Hales said that the limit is "quite sensible", and can readily be met by control of combustion conditions and feedstock quality.
The first covers the manufacture of cadmium alloys, recovery of cadmium from nickel/cadmium batteries, and refining and recovery of mercury. Achievable release limits to air have been put at 0.05mg/m3 for both metals. Wet collectors and oil-based pumps are not recommended as they can lead to metal contamination of liquid effluent. Fabric filters are generally the favoured abatement technique, typically with upstream condensation of mercury vapour and downstream polishing with a cartridge/HEPA filter.
The second note covers tin and bismuth processes. Only secondary and recovery processes are currently operating in the UK. This note makes no mention of dioxin formation or abatement, but a high temperature afterburner may still be necessary to remove odorous organic compounds.