Research on air purification methods began in the later 1980s and systems have been implemented at an increasing rate on livestock farms across northern Europe ever since, said Dr Nico Ogink, senior scientist at Wageningen University Research in the Netherlands, speaking at the EPP Congress in Vilnius, Lithuania, earlier this year.

The main incentive of the original work was to mitigate the odour nuisance from pig farms in densely populated areas, he said, adding that in areas of high production, around 10 per cent of residents report experiencing odour problems at least once a year. However, the research objectives were later extended to include the reduction of ammonia emissions to prevent nitrogen deposition and the also to control dust emissions – particularly fine dusts with Particulate Matter under 10µm (PM10) – to improve ambient air quality around farms.

From the technical point of view, the systems have improved greatly over 30 years. Current scrubber systems use biological and/or chemical removal principles and are able to remove between 75 and 90 per cent of ammonia and between 40 and 80 per cent of dust. When properly installed and maintained, these scrubbers have proven to be both reliable and effective, and economically viable in areas with challenging environmental limitations.

There are several specialised manufacturers in the Netherlands, Germany and Denmark, which produce air purification systems for pig houses and, more recently, also for poultry facilities. It is estimated that 15 per cent of Dutch pig production is now connected to air purification and this proportion is likely to grow steadily in the coming years.

Only by installing air purification systems can producers increase animal numbers in some of the areas of high pig numbers and dense human population. In such areas, the high level of concern over odour nuisance – as well as the possible impact of bioaerosols on human health – have raised public awareness of these issues and, as a result, also the demands of the regulatory authorities.

Installing air purification is seen by many farmers as a one-off investment and ‘production licence’. Unfortunately, because these systems are seen as increasing energy without bringing clear benefits in terms of improved animal performance, producers often do not feel motivated to manage and maintain them properly, said Dr Ogink.

A lack of field inspectors and their sometimes limited technical knowledge mean that verification of systems on farm is not carried out as well as it should be, issues highlighted by inventories carried out in 2009 and 2010 in Denmark and the Netherlands. Many of the installations were not being properly maintained and, in some cases, the systems had not even been installed.

This attitude, warned Dr Ogink, put at risk the relationship between between producers and the general public, and he recommended that farming organisations and authorities recognise the mutual interest in restoring public confidence by making sure that air purification systems on farm are reliable and operating effectively.

More effective verification systems, such as mandatory electronic monitoring of the systems, would help in this goal, he said. This would involve the electronic logging of essential operational parameters on a secure database, which is always accessible by the farmer, manufacturer and inspectors. Such automatic systems have been shown to work at farm level and help to ensure proper maintenance, acceptable performance and reliable verification of the air purification systems.

However, Dr Ogink stressed that more technology is not the answer to issue of waste air purification. There needs to be a clear understanding of the long-term relationships between all the stakeholders in this area.

August 2012