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Nigg Digesters

Anaerobic digestion - recyling and energy generation

What is anaerobic digestion?

Anaerobic digestion (AD) is a process where organic materials such as food waste can be recycled using naturally occurring processes.

The organic material is put into air tight sealed tanks and naturally occurring micro-organisms break the material down generating heat and releasing methane which can then be converted to renewable electricity. Useful, high nutrient by-products such as soil fertilisers can also be created by the process.

Almost any type of organic material can be treated using AD processes including food waste, crop residues and sludge. This means that waste from homes, supermarkets, industry and farms can be processed by AD, and that the biogas which can be converted to 'green electricity' and heat can be used to power local homes and businesses. The digested material can be used as a fertiliser replacement in agriculture providing land with vital nutrients.

By viewing this organic material as a resource we can avoid sending the material to landfill and avoid releasing harmful greenhouse gases into the atmosphere.

The benefits of anaerobic digestion

The facts about landfill

Our experience in anaerobic digestion

Through our operation in Scotland's Grampian region, and working in partnership with Scottish Water, we use the anaerobic digestion (AD) process to treat sludge from residents and businesses in Scotland's North East.   This established ten year operation uses an innovative CAMBI process to treat sludge.

Our sister company, Yorkshire Water, runs significant AD operations throughout Yorkshire, including a hi-tech and large-scale facility in Bradford that produces enough energy to power 3.45 million homes.  We are looking to develop further  AD facilities to support Yorkshire Water and KWS. Typically we look to provide the electricity and heat requirements for energy intensive operational sites, such as waste water treatment works.

Kelda Organic Energy are also working with a number of local authorities to recycle food waste using AD, avoiding costly and unsustainable landfilling. Kelda Organic Energy (Edinburgh) are working with the City of Edinburgh and Midlothian Councils for their flagship project to recycle food waste. Kelda Organic Energy (Cardiff) are working with Cardiff and the Vale of Glamorgan Councils to recycle both their Food and Green Waste. Find Out More