A sustainable future . . .
Northumbrian Water operates over 400 sewage treatment works in the north east of England, to clean industrial and domestic effluents (i.e. dirty or waste water) and return clean water to the environment. A bi-product of this process is sewage sludge.
The sludge contains many useful nutrients, and Northumbrian Water has invested over £60 million to transform this sludge into a nutrient rich, environmentally sustainable fertiliser than can be used on agricultural land - this product is called biosolids.
NWGROW is Northumbrian Water’s bioresources operation. It focuses on the treatment and recycling of biosolids to agricultural land.
What are Biosolids?
Biosolids is the name given to nutrient rich organic materials resulting from the treatment of sewage sludge as part of the waste water treatment process.
They contain nitrogen, phosphorous, organic matter, trace elements and small quantities of potassium and have been recycled to agricultural land for many decades in the UK.
The amount of organic matter and levels of specific nutrients contained in the biosolids, along with their sustainability for crop type or rotation, is determined by the particular processes used at the waste water treatment works.
In most circumstances, this is recognised as the environmental best practical option by the European Union (EU) and the UK government.
How are Biosolids produced?
Sewage sludge is produced during the treatment of waste water. Sludge is transformed into biosolids using a number of complex treatments including screening, water removal and advanced anaerobic digestion (AAD).
We have invested over £60 million building two advanced anaerobic digesters on Teesside and Tyneside. These work by creating extreme conditions, rather like a pressure cooker. The gas or ‘biogas’ given off is collected and used to create renewable energy, and what is left is a valuable natural agricultural fertiliser.
All of our sewage sludge is treated this way before recycling to land as biosolids and converted to energy as biogas.
The treatment process makes sure that 99.9999% of the organism E.Coli has been destroyed in biosolids. In addition, biosolids which have gone through an enhanced treatment process are also free of salmonella.
Our service to agriculture - NWGROW
Recycling biosolids (treated sewage sludge) for use on agricultural land is a sustainable and well regulated process that has been carried out for many decades.
Biosolids supplied to farmers provide nutrients and organic matter for soil and crops.
Where are Biosolids used?
We provide biosolids to suitable locations following comprehensive site and environmental risk assessments. The product may be applied to grassland or to arable land post-harvest, where it is incorporated following application.
Before biosolids can be applied to new land, soil samples are taken, analysed and then cross referenced with the risk assessments to ensure the correct application of the product.
Good agricultural practice requires that the use of biosolids takes account of the nitrogen and phosphate content of both the soil and biosolids, as well as the nutrient requirements of the crop.
Northumbrian Water Bioresources Market Information 2018
(Please note: this is an Excel file, which may need saving before being opened).
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