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

Waste management

Sewage sludge (biosolids) 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.