Scottish Water Horizons food digester arrives  

Scottish Water Horizons, the commercial arm of Scottish Water, has welcomed the delivery of a cutting-edge anaerobic digestion tank that will turn food waste into energy at their Deerdykes Organics Recycling facility in Cumbernauld.

From Spring 2010, the £7million food recycling unit will turn 30,000 tonnes of solid and liquid food waste into around 8,000 megawatts of power each year - enough electricity to power up to 2,000 homes.

A massive 16 metre-high, 20.5 metre diameter tank is in the process of being erected on the site. This tank will hold food waste for 15-20 days and convert it to biogas.

Once the glass coated steel tank is erected it will be surrounded with insulation and profiled sheet cladding to maintain process temperatures within the tank.

The next stages are to complete installation of the mechanical and electrical features such as instrumentation and control works. Once these are completed the facility can be commissioned and enter active service.

The anaerobic digestion unit is being constructed by Henry Boot Scotland and Monsal. The digester tank is being supplied and erected by UK-based Kirk Environmental.

Chris Banks, Commercial Director, Scottish Water, said: “The unit harnesses biogas produced by the break down of organic materials. The biogas will then be used in a combined heat and power engine to produce electricity and heat.

“This electricity will be used at the Deerdykes facility and any surplus will either be used to power the neighbouring industrial estate or sold back to the national grid. A scheme to export the heat to local homes and businesses is also being investigated.”

The process also produces nutrient rich digestate which can be used as a liquid fertiliser to improve the nutritional content of Scotland’s soil resources.

WRAP, which is part funding developments at the Deerdykes site, recently found that Scottish households throw away a billion pounds worth of food every year – amounting to a staggering 570,000 tonnes of discarded food and drink.

Iain Gulland, WRAP Director for Scotland, who visited the site this month said:

“Having invested £1.7m in the Deerdykes Anaerobic Digestion project, it is great to see that it is on track. This is clearly going to be an impressive, high-quality facility which will play a key role in diverting food waste from landfill and reducing greenhouse gas emissions.”

The facility will also take in food waste from supermarkets and food manufacturers who are also becoming more enthusiastic about the waste sector because of recent changes in market conditions. Landfill tax will escalate by £8 per tonne each year until at least 2013, taking it to £72 per tonne excluding processing fees.

Food waste collections trials from customers in North Lanarkshire, Glasgow, Argyll and Bute and East Renfrewshire have already been conducted and composted into pod soil improver.

The anaerobic digestion process will run alongside the existing pod composting facility at Deerdykes which has turned more than 100,000 tonnes of grass cuttings, tree trimmings and shrub prunings into 50,000 tonnes of environmentally friendly compost since 2006.

Anaerobic digestion is seen by the government as the preferred technology for recycling because it already produces renewable energy. It is not a new treatment process, it has been used in Europe for over 20 years. The technology also has wide support in environmental circles. Duncan McLaren, Chief Executive of Friends of the Earth Scotland, is among the supporters:

"This is an example of a big company taking sound initiative to help address the twin problems of climate change and excessive organic waste being sent to landfill."

Food waste recycling trials from householders in North Lanarkshire, Glasgow, Argyll and Bute and East Renfrewshire, as well as from supermarkets and food manufacturers, are already taking place at Deerdykes with the waste currently composted into pod soil improver.

Donald MacBrayne, Business Development Manager for Scottish Water Horizons, is hailing the food waste trials a massive success: “We’ve had a fantastic start to these and local residents have been incredibly supportive, showing a real ‘green’ streak.”

The project is encouraging all Scottish householders, food manufacturers and food processors to play their part and help put Scotland at the forefront of environmental stewardship.