Silsoe seeks to ease pollution rules burden

20 July 2001

Pollution regulations are set to tighten for large pig

units over the coming years. Marianne Curtis visited the

Silsoe Research Institute to discover how they

may be applied in practice

Silsoe seeks to ease pollution rules burden

RESEARCH to find ways of minimising the financial impact of pollution regulations on large-scale pig producers is underway at the Silsoe Research Institute.

The EU directive on Integrated Pollution Prevention Control (IPPC), which has been in operation since Oct 30 last year, aims to reduce pollutant emissions to air, water and land from industrial processes, including pig and poultry production.

Jane James, technical guidance adviser at the Environment Agency, says the legislation applies to units with more than 40,000 poultry places, 2000 finishing pig places or 750 sow places.

"Anyone building a new unit of this size or substantially changing an existing one requires a permit from the Environment Agency before stocking it." However, it is a good idea to contact the EA before building work commences to check regulations are being adhered to, she advises.

Existing installations will not require a permit until at least 2006. The issue of permits requires producers to follow standard farming installation rules which cover methods of minimising pollution through appropriate management and housing, adds Mrs James.

Work at the Silsoe Research Institute should allow these rules to be refined, providing information on techniques that are suitable under UK conditions. Conducted in collaboration with Norfolk-based ADAS Terrington, it aims to establish best available techniques for reducing ammonia emissions, the pollutant of most concern. Researcher Theo Demmers adds that it also hopes to find the least onerous way for UK pig producers to comply with the regulations.

"A number of techniques exist for reducing ammonia emissions from pig housing. Many have been thoroughly investigated in Denmark, Holland and Germany, but our challenge is to apply them to UK conditions," explains Dr Demmers.

High or low tech?

Solutions can be divided into high tech or low tech, with high tech options finding favour on the Continent. "However, UK buildings tend to be older and lower. Applying high tech solutions can mean an expensive rebuild, so we are concentrating on low tech options."

Reducing slatted areas can help reduce ammonia emissions substantially, says Dr Demmers. "There are two sources of ammonia emissions in a slatted house – the slats themselves and the slurry level in the manure pit beneath. Moving from fully slatted to part-slatted housing can reduce ammonia emissions by 30-50%."

Building types being monitored on farms taking part in the project include fully slatted with automatically controlled natural ventilation (ACNV) and part-slatted and fully slatted with fan ventilation. Other common systems will follow later in the project.

Another system being investigated is known as the Dutch modified part-slatted system with mechanical ventilation. This relies on a V-shaped channel under slats which allows rapid run off of slurry through a narrow channel at the bottom of the V into the slurry pit. This reduces the time slurry is in contact with air and reduces the surface area of the slurry pit emitting ammonia, says Dr Demmers.

Fully slatted housing with ACNV, modified by covering 75% of the slatted areas with a convex concrete lying area is another form of modified housing being examined. "The convex shape of the lying area allows water to run off and through slats. A small slatted area will remain at the front of pens for fouling."

However, refinements to the ACNV system will be required to avoid fouling in solid areas of the pen in hot weather, believes Dr Demmers. "With ACNV there is less control over building ventilation patterns than with mechanical ventilation systems. Unless a cool draught is directed on the solid area, there is a danger of pigs fouling and wallowing in it, defeating the objective of reducing ammonia emissions by increasing the solid area."

Although there may be fewer problems with mechanical ventilation systems when trying to reduce ammonia, there is a balance to be struck in environmental terms, addsSilsoe researcher Roger Phillips.

"These systems use more electricity and one of the IPPCs aims is to reduce consumption of non-renewable energy. There may also be contradictions between reducing both ammonia and dust emissions. Drier buildings, where ammonia emissions are lower, may be more dusty. The government should prioritise pollutants because reducing one may increase another."

There is also a danger of transferring the problem away from buildings to elsewhere on a unit, says Dr Phillips. "Using straw reduces ammonia emissions from buildings, but leads to greater emissions from stored manure.

"It may be necessary to develop a closed system for manure handling and use low emission techniques, such as injection, for spreading."

As well as manure handling, nutrition may have a role in reducing emissions, says Dr Phillips. "Ammonia emissions can be reduced by manipulating diets, such as by using amino acid levels which more specifically meet animal requirements. However, this is too expensive at the moment."

Parts of the project have been delayed due to foot-and-mouth restrictions, with final results expected in 2003.

However, despite efforts to minimise the cost of IPPC implementation on farms, reducing emissions will come at a price, warns Dr Phillips.

"Although there may be slight improvements in animal performance due to lower ammonia emissions, implementing IPPC wont pay for itself. All we can hope to do is minimise the financial pain for producers." &#42


&#8226 Seek guidance from EA.

&#8226 Affects large pig units.

&#8226 Reduce slatted areas.

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