Managing sewage sludge

Sewage sludge (also known as biosolids) is the solid waste left behind after the sewage treatment process.

Approximately 245,000 dry tonnes of sewage sludge is produced annually, with sludge disposal strictly controlled. All sludge is put to beneficial use, with 70 per cent recycled to agricultural land as a nutrient-rich fertiliser, and the remainder used to generate renewable energy to help power our sites.

To ensure we can continue to manage sludge in a safe, sustainable and beneficial manner, we need to increase treatment capacity and secure appropriate future uses.

In the medium term, from 2010 to 2015, we will work to ensure we can continue to manage sludge in a safe, sustainable and beneficial manner, increasing treatment capacity and securing sustainable future uses.

In the long term, from 2015 to 2035, we will continue to implement a sustainable sludge strategy, maximising beneficial use and considering issues of acceptability, energy, transport, odour, nutrients and local constraints.

Recycling of biosolids to agricultural land

Recycling biosolids to agriculture reduces reliance on chemical fertilisers. Without recycling in this way, these wastewater by-products would need to be disposed of in much less sustainable ways, for example through landfill.

This 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 highly regulated activity. We continue to maintain 100% compliance with the Sludge Use in Agriculture Regulations 1989.

Safe Sludge Matrix

In 1998, Thames Water, along with other water companies, helped to develop the Safe Sludge Matrix with representatives of the food industry. This established for the first time, standards of treatment appropriate for different end uses of sludge.

The Government supported this new approach and agreed that the Safe Sludge Matrix should form the cornerstone of revisions to the regulations for the use of sludge in agriculture. It is our goal to effectively manage the recycling of biosolids to agricultural land thereby providing all stakeholders with the reassurance that the environment and the food chain are being 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.