Research undertaken over the last 5 years on more than 40,000 reference points has shown a clear link between open air windrows that are too high and the production of unpleasant odours on composting sites.
A recent court case in which a waste operator was found to have insufficiently managed odour production at one of its landfill sites as a result of not adopting best available technology, is likely to have profound implications for composters in England and Wales.
Public pressure on operators who cause nuisance through the creation of unpleasant odours will require an assessment of the real causes of the problems. Historically operators have focussed efforts primarily on the managing of problems by using expensive flavoured sprays.
The research, which is considered to be very forward-thinking, was carried out by Dr Eric Crouch from Compost Manager and it specifically highlights the connection between temperature and windrow height.
Temperature
In essence the higher the windrow, the higher the temperature. When windrow heights exceeded four metres, temperatures were shown to reach levels well beyond 70oC and the microbes specifically needed for composting were significantly inhibited. The microbes happy to exist at these high temperatures are the ones responsible for the non-earthy and therefore unpleasant – compost odours. So when a windrow in this state is turned, release of these odours is inevitable.
As Dr Crouch puts it: High temperatures cause odour. When it gets too high and the good bugs stop doing their job, thats when the problems arise. Reducing windrow heights to around 4 metres will greatly assist. Theres also less chance of the structure collapsing and the chimney effect being undermined, both of which are also significant contributors to bad odours.
But its not good enough just to monitor temperature alone. For the bugs to do what they do best the operator really needs to understand the conditions within the windrows. It is essential to look at moisture levels and respiration (i.e. the relationship between O2 and CO2) as well as temperature. The research undertaken makes this abundantly clear.”
Data
The system Dr Crouch has developed records this data and then gives composters simple instructions to control the composting process. Results on customers sites have shown a marked reduction in complaints from neighbours.
Isnt it time to prevent odour through proper process controls rather than just mask it? All the effort and cost of masking odours dont seem to be reducing the level of complaints being made. The odour-chasing law firms are coming, whether we like it or not.
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