Odour Management for Composting Facilities
Composting is essentially a controlled decomposition process of organic materials. Source materials include grass clippings, food waste, wood chips and branches. Because this process is a biological one involving bacteria, the conditions of the compost pile must be suitable for decomposition. Temperature, moisture, and oxygen all play a role in creating the ideal environment for microbial activity.
Commercial composting sites use a process called aerated windrow composting. Windrows are compost piles of 1.25 metre to 2.5 metres high which are turned regularly to aerate the material. Composting produces liquid leachate, as well as the compost product itself. The nature of microbial activity means that the potential for producing odours is high.
Some composting companies have fallen foul of residential neighbours as well as the law because of the odours they generate. One Melbourne company was fined $40,000 for releasing pungent odours into the community resulting in significant discomfort for neighbours.
However, there are practical ways and technological solutions for odour management for composting facilities.
Practical steps for odour management for composting facilities
1. Keep tight control over composting process
Composting can be optimised, and odours can be minimised by keeping ideal microbial conditions. Balancing the different feedstocks will keep the carbon to nitrogen ratio in the correct range. Aerobic conditions can be maintained by controlling moisture and oxygen content as well as pH. The porosity of the mixture and the processing temperature also play a role.
2. Control transport and storage conditions
Feedstocks for composting processes may begin decomposing before their delivery to site. Using water and air sealed containers prevent odours from escaping. Food waste, digestate and biosolids are the primary odour culprits. Where possible, these should be handled and stored indoors and sealed from the outside.
3. Cover post processing piles
Fresh compost piles are often stored outdoors once the composting process is complete. Covering these piles with 15 centimetres of mature compost will prevent any residual microbial activity from generating odours.
4. Minimise leachate production
Leachate is another source of odour from composting facilities. Keep all other water (e.g. rainwater runoff, water used for non-composting activities) separate from leachate. The higher the volume of leachate a site produces the greater the potential odour problem.
Odour control solutions
Due to the microbial activity in generating compost, it is not possible to treat compost piles directly and eliminate odours that way. Odours must be treated in the air to prevent odour compounds from reaching neighbours, resulting in complaints. Technology in the form of misting systems or vapour systems can eliminate odours dispersed in the air.
Active ingredients for misting systems are made from essential oils and organic plant compounds. The system uses potable water to generate a mist spray through nozzles. Misting systems work by chemically binding with the odour compound and neutralising it. Permanent fixtures at a boundary fence can be installed or mobile units can be moved to problem areas as needed.
VapourGuard is a newer technology than misting systems with some advantages. It does not use potable water as a carrier and therefore is a more environmentally sustainable solution. The reactant for vapour systems is made up of an ester, a ketone and a cineole, with citric acid and amino sucroates. This formulation has been found to be effective on all common forms of odour. A vaporiser distributes the reactant directly into the air by holed tubing which can be laid around the composting facility perimeter.
While it is not common to use surface treatment on compost sites, it is a possible solution for short term incidents. Outdoor post composting piles could be covered with a surface treatment to limit odours. However, these products can interfere with microbial activity therefore negatively impacting on the compost process if used incorrectly. Biofiltration is another technology that can be used if an area of storage or compost production is contained. Air can be drawn from the contained area and treated through biofilters before being released into the atmosphere.
Contact OdourPro for odour management for composting facilities
OdourPro is the supplier of choice for odour management for composting facilities. We have the technical expertise and industry experience to identify sources of odour and the most effective solutions. OdourPro provides ongoing services to maintain odour control equipment and to monitor performance.
OdourPro on 21 November 2016
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