IPPC guidance highlights impacts of surface treatment sector

Draft European guidance on the "best available techniques" companies in the surface treatment sector should use to control pollution has been published by the EU bureau on integrated pollution prevention and control (IPPC). The guidance highlights water consumption and effluent emissions as the main issues.

The guidance applies to companies which operate metal and plastic surface treatment processes regulated under the IPPC Directive. Some 120 sites in the UK carry out activities such as electroplating. The guidance also applies to manufacturers of plastic printed circuit boards.

The guidance is the latest to be produced by the EU's IPPC Bureau. The final draft of the document, containing recommendations on the "best available techniques" (BAT), took more than three years to produce and came too late to inform the Environment Agency's guidance for firms which fell under the regime in July 2004.

To meet the challenges of IPPC, in 2003 the Surface Engineering Association and consultants Environ formed a permitting club to support members' applications. The club also produced valuable information on BAT, which influenced the Agency's guidance (ENDS Report 350, pp 53-54 ).

The BAT reference document (BREF) says the main environmental impacts from surface treatment are energy and water consumption, the use of raw materials such as metals and acids, and emissions of effluent containing metals and other chemicals. For instance, the sector produces some 300,000 tonnes of hazardous waste per year in the EU, mainly as a sludge from wastewater treatment processes.

The BREF describes some 200 pollution control techniques reviewed by industry experts. Unlike some other BREFs, the Bureau says there were no substantial disagreements on its recommendations.

The BREF says that having an environmental management system, preferably certified to international standard ISO14011 or its European equivalent EMAS, is central to BAT. An EMS can provide a systematic and demonstrable framework for managing the impact of an industrial site, it says. The SEA/Environ permitting club found that many sites in the sector, often smaller companies, have yet to implement an EMS.

The BREF says that controlling "drag-out" losses of plating solutions - when items are removed from the treatment vats and rinsed - is one the main areas for potential improvement.

For instance, items should be suspended from racks in such a way as to facilitate the drainage of solution. Items should also be removed from the tanks slowly to minimise drag-out.

Multiple stage rinsing is recommended to conserve water and enable the recovery of raw materials. Cascade technology, counterflow rinsing and multiple static rinsing are named as BAT options. These techniques can help reduce wastewater by up to 90%.

The BREF says emissions levels associated with plants using BAT are typically 0.1-0.5mg/l for cadmium, 0.1-2mg/l for total chromium and 0.2-2mg/l for zinc.

IPPC also requires operators to consider alternative raw materials with a reduced impact.

The BREF says that the chelating agent EDTA, used by printed circuit board manufacturers, should be substituted by biodegradable alternatives, such as those based on gluconic acid.

Chemical company Octel believes its biodegradable chelating agent, EDDS, could also be considered by operators, although it is not named in the BREF (see p 34 ).

The BREF process has an important role in identifying emerging techniques which may represent BAT in future, although they have yet to be used commercially.

One example is a hard chromium plating technique using a modified pulse current - a potential replacement for hexavalent chromium which is carcinogenic. The BREF says the process has been patented and is being evaluated in three industrial applications.

The BREF makes only a passing reference to ink jet technology as an alternative to the complex photolithographic process for manufacturing specialist printed circuit boards.

Experience in the UK suggests ink jets can simplify the process, cutting waste and chemical use (ENDS Report 356, pp 28-29 ).

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