Environment Climate change Environmental management Waste management Conservation Integrated water cycle management Plastic pollution

Waste management

Sewage sludge is formed at every stage of the wastewater treatment process. As early as 1995, we committed to recycling all sludge as treated biosolids. 

Biosolids are usually treated in large tanks called digesters and much of the water is removed to produce a material that can be spread on fields used for growing crops. Biosolids provide nutrients to soil and plants, enabling farmers to replace some man-made fertilisers. This saves not only money but also the energy and environmental impacts associated with fertiliser production.

Recycling biosolids to agricultural soil plays an important role in replacing the loss of organic matter that can arise from intensive farming, causing soil erosion.

Untapping new energy and resources from urban sanitation - Nereus

We've joined forces with several other European companies as part of a multi-million pound project to focus on creating New Energy and Resources from Urban Sanitation (Nereus).

Involving eight partners and a total of €8 million of EU funding from the Interreg 2 Seas Regional Development Fund, the Nereus project will help us improve how we recover nutrients (such as phosphates and nitrogen) at wastewater treatment works.

The overall objective of the project is to increase the recovery and reuse of resources (energy, water and nutrients) from wastewater by boosting and investing in new technology from wastewater in urban areas. 

Our work will continue until September 2020 – the video below explains how this will help us become more efficient and resilient.


The multi-national Nereus partnership enables Southern Water to work closely with others and access crucial data, technical results and provide market-leading information on nutrient recovery technology.

This includes water, wastewater and academic institutes from across Belgium, France, the Netherlands and the UK.

This Europe-wide learning will help support wider trials with studies, technology assessment and selection, monitoring and analysis of all site trials.

Results from five of the partners carrying out trials will feed into an online support tool which will be developed by three academic institutes, including the University of Portsmouth.

The final tool will help decision-makers on technologies, policies, regulations and locations when considering options for energy, water and nutrient recovery at decentralised urban wastewater sites.