Sewage sludge is the main solid waste left behind after the sewage treatment process.

All sewage sludge treated in our region is put to beneficial use, with 72 per cent treated and recycled to agricultural land as a nutrient-rich fertiliser - known as biosolids.

The remainder is used to generate renewable energy to help power our sites or used in land restoration.

To ensure we can continue to manage sewage sludge in a safe, sustainable and beneficial way, we need to increase our treatment capacity and find other appropriate uses for sewage sludge in the future. 

25-year Sludge Strategy

Our Sludge Strategy is based upon an assessment of a range of treatment options, which have helped us choose a preferred list of options for each area in our region.

In the medium term, from 2010 to 2015, we will:

• Work to ensure we can continue to recycle sewage sludge to agricultural land where suitable land is available
• Maximise energy recovery and reduce the amount of solids within our sewage sludge so there is less to recycle  

In the long term, from 2015 to 2035, we will:

• Continue to implement a sustainable sludge strategy that makes the best use of our sewage sludge use and considers issues of acceptability, energy, transport, odour, nutrients and local constraints.

Independent consultants (Entec) completed a Strategic Environmental Assessment (SEA) of our draft Sludge Strategy to ensure that environmental, social and economic sustainability aims were central to our decision-making. A SEA Post Adoption Statement was published to explain their findings.

The purpose of the SEA Post Adoption Statement is to explain how the findings of the SEA Environmental Report have been taken into account. It includes our response to comments submitted to the consultation on the SEA and covers our approach to monitoring. 

Recycling of biosolids to agricultural land

Recycling biosolids to agricultural land reduces the need to use chemical fertilisers. Without recycling in this way, these wastewater by-products would need to be disposed of in much less sustainable ways, for example at landfill sites.

Recycling to land is recognised, under most circumstances, as the Best Practical Environmental Option (BPEO) and is supported by the UK Government and European Commission. We aim to encourage the practice wherever possible.

Recycling of biosolids is a carefully regulated activity and we continue to maintain 100 per cent compliance with the Sludge (Use in Agriculture) Regulations 1989.

Safe Sludge Matrix

In 1998, we worked with other water companies and representatives from the food industry to develop the Safe Sludge Matrix. For the first time, this established standards of treatment appropriate for different uses of sewage sludge, including microbiological limits within the product.

The Government supports this approach, and agreed that the Matrix should form the foundation of any new revisions to the regulations for the use of sewage sludge in agriculture.

It is our goal to effectively manage the recycling of biosolids to agricultural land, providing all stakeholders with the reassurance that the environment and the food chain are fully protected.

We aim to do this through continuous improvement and the review of our products, processes and practices to ensure that we are acting in a sustainable way.