DRIVEN by government targets, commercial composting is now turning into big business as a convenient way of dealing with the millions of tonnes of organic waste produced by Scottish households and companies every year. However, there are fears that the bioaerosols produced by such waste could be damaging to health.
In Scotland, sites that deal with organic waste have multiplied in recent years with some commercial operators able to cope with up to 40,000 tonnes on sites among the largest in the world.
Green waste is shredded down, laid out in open rows and turned regularly, reaching high temperatures. After several weeks, the waste is filtered to remove any rubbish and sold as compost.
Food waste is mixed with lime and woodchips and left to rot down in large containers before it too is sold as a soil improver.
Bioaerosols can contain fungal spores and bacteria are harmful to human health, and some people seem to be more susceptible than others.
According to the Health Protection Agency, complaints from people exposed to the particles include breathing problems, headaches, nausea and fatigue.
They could cause infection in people with low immune systems.Those working at plants and those living within 250 metres of the area could be most at risk.
Food waste recycling may pose less of an environmental risk because it takes place in closed containers – however it is still put out in the air to dry once it has been heat treated.
The Scottish Environmental Protection Agency (SEPA) says the shredding and turning process involved in treating green waste may “give rise to bioaerosol emissions”. However, so far there has been a lack of scientific research on the problem and SEPA is treating both processes with equal concern.