Waste Water Treatment Plant Permit

Waste Water Treatment Plant, Selby

Speaking at the AD In the City event (April 30), senior consultant Dr Adrian Gibbs said that using AD to process food waste collected separately could work out cheaper than processing commingled food and green waste together in an in vessel composting plant.

Dr Gibbs explained that a report by Eunomia had found that sending food waste to AD and green waste to windrow composting cost councils £9.50 in gate fees per household per year whereas sending commingled green and food waste to IVC cost £10.80 per household. He also said that just collecting food waste alone and sending it to AD cost £5.50 per household over the same period.

Dr Gibbs admitted that average gate fees for AD facilities - around £55 per tonne - were higher than IVC, which he quoted as £45 per tonne, but said that “overall AD is cheaper”.

He also claimed that separate food waste collections also worked out cheaper than mixed collections and said that the number of local authorities which were implementing separate collections had risen from 11 in 2007 to 54 in 2008.

He told the London borough council officers who attended the event, which was set up to explore ways to introduce more AD capacity in London, that: “AD is better than IVC, it’s the way to go and it is the one I would watch.”

Anaerobic digestion treats food waste in an oxygen-free environment and produces biogas - which can be converted into energy - and a nutrient rich digestate which can be used on farmland. It also has the potential to provide combined heat and power (CHP).

IVC treats green and/or food waste and sometimes card in an enclosed but oxygenated and aerated environment and produces compost. It does not generate energy.

A number of strengths and weaknesses were highlighted for both separate and mixed collection. The plus side to mixed collections included; only needing to use one vehicle; only one bin required; and quick and cheap collections.

However, Dr Gibbs explained that the seasons significantly affected what was collected, with garden waste levels dropping significantly in the winter, meaning that feedstock was inconsistent. He also said that the waste had to be processed in and enclosed environment due to Animal By-Product Regulations and this ups the cost of green waste.

Dr Gibbs also pointed out that green waste and food wastes required different collection frequencies. In addition to this, not all homes have gardens and collecting green and food waste together prevented councils charging for green waste collection.

Dr Gibbs claimed that separate AD collection reduced net costs for councils, allowed local authorities to charge for garden waste. He added that there is a large quantity of food waste which could potentially be picked up.

He said AD had a number of strengths including:

• Internationally proven technology
• AD has strong government support in the form of ROCs, a Task Group and feed-in tariffs
• It is a carbon positive technology
• Valuable outputs - biogas and digestate
• Leaves green waste to go through the cheaper windrow process

He said AD’s only weakness was the lack of facilities in the UK, adding: “AD wins hands down for organic waste.”

The amount of food we throw away is a major contributor to the production of greenhouse gases in the UK, currently most of our food waste is going to landfill sites.  Once in landfill, food breakdown produces methane - a greenhouse gas 21 times more harmful to the environment than carbon dioxide.  The sealed process used in anaerobic digestion captures the methane produced through food breakdown and converts it to renewable energy and heat.

Selby Renewable Energy Park will have capacity to divert 165,000 tonnes of food waste away from landfill and provide producers of packaged food waste with a solution to help them move towards zero waste to landfill and meet their coporate social responsibility objectives.

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The £20 million project will create 120 new jobs for the town, 40 directly and an additional 80 jobs indirectly.  The project will also generate enough clean, renewable energy to power 10,800 homes for a year (or the whole of Selby).  The plant, which will occupy eight acres of the former Tate & Lyle Citric Acid Plant in the south of the town, will also provide a potential low cost heat source for use by local businesses. An anaerobic digester already exists on the site which is currently being updated and the proposal is to build two new anaerobic digesters.  All the clean renewable electricity generated would be sent via the site’s existing power connection to the National Grid.

Whites Renewable Energy are currently consulting with the local community to take into consideration their views on the proposed redevelopment of the site. The initial response from community representatives has been very positive.  The proposal has already won the support of the government backed WRAP (Waste & Resources Action Program) and Future Energy Yorkshire, which is the organisation set up to help promote renewable energy projects in Yorkshire and Humber.

According to DEFRA’s (Department for Environment, Food and Rural Affairs) Waste Strategy Report published in May 2007, the Government wishes to encourage local authorities and businesses to consider using anaerobic digestion as the preferred technology for treating organic waste in the UK, as it has significant benefits over other technologies in the treatment of food waste.  The process has already become very popular across Europe in countries like Sweden, Switzerland, Denmark and is now the fastest growing renewable technology in Germany, which has the largest number of anaerobic digesters in Europe.

The process of anaerobic digestion occurs when organic material is broken down by micro-organisms in a sealed environment without oxygen present.  The process produces a biogas which can be used to power a combined heat and power plant (CHP) to generate clean, renewable electricity and heat.

In addition to generating a renewable, very low carbon fuel, anaerobic digestion also produces a high nutrient, bio-fertiliser that is a high quality substitute for chemical fertilisers on agricultural land.
David Balderson from Selby Renewable Energy Park comments:
“Anaerobic Digestion is widely recognised by the government, DEFRA and Friends of the Earth as one of the best solutions for disposing of organic waste.  Everyone wins as the waste is treated in a sealed process reducing the generation of greenhouse gases and carbon emissions; a clean, renewable fuel is produced which can be used to create electricity and heat; and we are returning a green, sustainable fertiliser to the land which will in turn grow our crops for food.  Another big advantage is that we are using a sustainable energy source that does not compete with food production, unlike other biofuels.
“The site at Selby is ideal as it is well connected to the local motorway network via Selby bypass, it already has an anaerobic digester and a connection to the National Grid . This project will provide a significant boost to the local economy by creating jobs and will also make available a cheap non fossil fuel heat source that will attract businesses to the area.”
In August 2008, Joan Ruddock, then Minister for Waste visited an anaerobic digestion plant in Ludlow which is part of Defra’s New Technologies Demonstrator Programme to test technology that could offer alternatives to landfill.  Following her visit she said:
“Anaerobic digestion is extremely attractive. Why would we go on throwing food waste into holes in the ground when we could generate our own electricity and end up with a product that can be returned to the soil?”
Jo Adlard, Project Manager with Future Energy Yorkshire, part of Yorkshire Forward comments:
“The Yorkshire and Humber region has an important role to play in helping the UK to reduce its greenhouse gas emissions. The proposed Selby Renewable Energy Park will contribute to our regional emissions reduction targets by generating renewable energy for export to the Grid, while diverting large quantities of waste from landfill.”