environmental impact statement kilmainhamwood compost facility ...

5361- Kilmainhamwood Compost Facility Extension- EIS
microbial activity and hence oxygen consumption are highest. Each composting bay is approximately
5.75m wide and 11.57m long. The feedstock is piled to a height of approximately 3m within the bays.
The composting process is a forced aeration temperature feedback system. The composting bays
feature an automated forced aeration system. There is an aeration fan behind each composting bay to
blow air up through the pile and control temperature. These fans are located in tunnels/corridors behind
the composting bays. Air is blown from the underside of the static pile of composting material towards
the exterior of the mixture. The system maintains a temperature ceiling of 60°C by means of the ondemand
removal of heat by ventilation through temperature feedback control. This encourages a high
decomposition rate as significantly higher temperatures inhibit and slow down decomposition by
reducing microbial activity. In addition the interior of the composting facility building is a controlled
environment, where an atmosphere of negative pressure is maintained.
Temperature probes inserted into the composting mixture can generate a control signal used to adjust
the air/oxygen supply and maintain a set point temperature. Temperature is the controlled variable and
aeration rate is the manipulated variable during the process. Aeration fans linked to a pre-programmed
control panel operate according to the temperature of the individual bays.
Throughout all stages of the composting process, temperature is monitored by use of temperature
probes. This helps to ensure that the bays are being adequately aerated. Moisture is checked by
means of a "squeeze" test which is a non-quantitative method of estimating moisture.
The high temperatures generated in all stages of the composting process, in combination with the
measures taken during feedstock blending/mixing to include sufficient dry amendment to adjust the
moisture content to within an optimal range, ensures that no leachate is produced by the process under
normal conditions. Any leachate produced including leachate from incoming feedstock is contained and
reintroduced in the blending/mixing stage of the process.
For inspection purposes only.
Consent of copyright owner required for any other use.
After the initial phase of high rate composting, the material is moved by loading shovel to composting
bays in the maturation area of the facility where the compost is matured by aerating the compost for
another 10-12 days.
Following this stage, the compost is processed through a trommel screen fitted with 12mm and 40mm
screens. The minus 12mm fraction produced by the screening process is placed in a bulking tunnel
which allows enough material to be bulked in order to fill the pasteurisation tunnel. This normally takes
approximately 3 weeks. The material is then transferred in to an Animal By-product (ABP) treatment
tunnel No.2 where the temperature of the material is maintained at 70 o C for a minimum of 1 hour, in line
with the requirements of DAFF. Samples of compost product are subsequently taken from the ABP
treatment tunnel and sent for testing (E. Coli and Salmonella) to a DAFF approved laboratory and
compost is left in situ until analysis results are returned from the laboratory. This process from when
material enters the ABP tunnel and receipt of final results may take up to 3 weeks. Following a
successful outcome to laboratory testing, the compost product is removed from the ABP treatment
tunnel for delivery to a customer.
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