In the UK, approximately 12 million tonnes of wastewater is processed each day = 140 tonnes per second (on average).
Further to this a considerable amount of rainfall enters the wastewater network.
Sewage Sludge Treatment
“Gas from biosolids production in the UK supplies about 200,000 homes with renewable electricity”
Recycling to Agricultural Land
- Digested cake is around 23% dry solids and can be safely and securely stored in field heaps before application and soil incorporation.
- Lime treated cake is about 25% dry solids and contains quick lime or slaked lime and can also be stacked in field heaps before application.
- Digested liquid at only 4% dry solids is normally injected directly into the soil.
- Granules and pellets at 98% dry solids are broadcast on the land.
Benefits to Soil and the Environment
In addition to valuable nutrients, biosolids also contain organic matter, which further benefits agriculture and the environment as indicated in this table:
The UK Government considers biosolids recycling to agricultural land in most circumstances to be the Best Practicable Environmental Option and it is the most sustainable practice aligning with Government Waste Hierarchy as illustrated below.
“Biosolids recycling to land is consistent with the EC Circular Economy”
Here are some documents that provide further information on biosolids: