Protesters packed the council offices at Preston to hear the debate on the proposed Farington waste technology park, but were disappointed when consent was given by the Planning Committee. The £40m plant is to be constructed on the former Leyland vehicles test track.
Approval was given to the proposals despite numerous objection and also rejection by South Ribble Council. Nevertheless the facility will be welcomed by the Lancashire WDA in its efforts to achieve its sustainable waste management objectives.
Representatives of the protesters were allowed to give oral presentations to councillors at the meeting and proceedings were also watched on big screens by the "overflow" from the council meeting room.
In addition to perceived problems with smells and traffic, the proximity of housing was discussed. Though some property was described as being around 30m for the site perimeter, it was pointed out that the nearest property was in fact 70m from operational areas of the site.
Cllr Miles Parkinson said that conditions would be put on the consent to mitigate any potential effects on residents in the area.
Cllr Christine Harrison thought the decision was "absolutely outrageous".
The waste technology park is expected to handle approaching 300,000 tonnes of waste per annum and the applicant, Global Renewables, expects the plant to be operational in 2008. Global were appointed preferred bidder for the Lancashire PFI contract in September 2005 on the basis of MBT technology to avoid the need for mass burn incineration.
Global's MBT technology is tried and tested in Australia where an operational plant is located near Sydney.
The location of facilities
The PFI contract is based on the provision of plants at Leyland and Thornton. The Leyland waste technology park is to be provided with a Global's MBT plant of 170,000 tonnes capacity together with a 55,000 tonne in-vessel composting plant and a 55,000 tonne MRF together with a community education centre.
The plant at Thornton will have a similar capacity, but is expected to have a transfer station instead of a MRF.
Summary of Global Renewables UR-3R process
The reception hall for Global Renewables UR-3R MBT process is a fully enclosed building and is maintained at negative air pressure to prevent the escape of fugitive odours.
In the UR-3R process, the residual materials after separating out recyclables are washed to control any odours and reduce volume. The water, solutes and fines are then subjected to anaerobic digestion which results in biogas production from which energy is derived. The energy is likely to be mainly used to power the plant itself though some may be exported.
The percolator
The Percolator and associated equipment, including the anaerobic digester, sand separator, sludge screen and water denitrifier form part of the patented ISKA® Percolation unit process.
This process reduces odour, reduces the 'mass' of organic matter, cleans the organic matter of contaminants such as fine glass, sand/silt, and ceramics, makes the waste stream homogeneous and importantly recovers energy from the material through anaerobic digestion.
Wash water is sprayed over the organic material in the Percolator. During the process the bulk waste is stirred and the organics, fines and sands are passed to a sand washing unit. Following sand washing and sludge removal, the resulting organic rich percolate is subjected to anaerobic digestion to produce biogas and excess water is used in the composting operation.
Anaerobic Digestion
Anaerobic digestion is used to treat high chemical oxygen demand (COD) and high biochemical oxygen demand (BOD) organic streams.
The Percolation system uses an anaerobic, packed bed digester for conversion of the liquefied and soluble volatile solids in the circulating water into biogas.
The digester utilises a hybrid upflow design with a high biological conversion capability which is effective across a range of variable feed conditions. Methanogenic bacteria are encouraged and retained through the process.
The organic solutions (percolate) is circulated and re-circulated through the digester and is mixed with fresh percolate. The large recirculating load effectively provides a buffer to any potential shock loadings in volatile concentration which might otherwise hit the bacterial population. Biomass eventually recirculates to the Percolator where volatile solids are released in acidic conditions for further digestion.
Biogas
Biogas produced from the anaerobic digestion process typically contains 60% to 70% methane and 20% to 30% CO2. In addition a range of trace gasses are present including H2S, known for its strong odour though the concentration depends on the mix of MSW being processed.
The biogas is scrubbed to remove the H2S before use for electricity generation , and for process heat generation in gas fired water heaters.
Solid outputs
Solid outputs from the process can be composted or alternatively can be refined, dried and used as a refuse derived fuel. Global indicate that the material would have a calorific value in excess of 12 MJ/kg or can be combined with non-recyclable plastic, paper and textile waste fractions to produce a fuel with a calorific value in excess of 18 MJ/kg.
Enclosed composting
Composting takes place in a fully enclosed composting building under negative pressure. Compost conditions are controlled to maintained it in the thermophilic temperature range (45ºC to 75ºC).
Turning and aeration are achieved using a patented auger bridge crane running above the compost bay. A trolley fitted with twin, inclined, counter rotating augers traverses the bridge crane for turning purposes. Compost materials migrate from the input end to the output end of the bay through the auger agitation.
The output is maturated for a few weeks before screening and refining.