The use of sewage sludge as fertiliser – politely called ‘biosolids’ – and its role in the circular economy is currently being scrutinised to address important ecological and chemical concerns.
94% of the sludge remaining after sewage has been processed is recycled as fertiliser on agricultural land, mostly for arable crops in East Anglia and the East Midlands.
Residents of Uttlesford will be familiar with the unpleasant smell that drifts across the countryside in the autumn. Smell is one thing and only temporary; but there is mounting evidence of unseen and persistent dangers.
First, a little history …… using human excrement as fertiliser has been practised since the Middle Ages. In Tudor England, removing human excrement from privies and cesspits became a source of employment. As the population grew, especially in cities, it became a business. Before the Victorians created the underground sewage system, ‘Night soil’ was collected by ‘nightmen’ and transported to farming areas.
Back then, there was a high risk of spreading disease-causing pathogens. Today’s mechanised processing of sewage sludge has removed almost all the pathogen risk; BUT since the Industrial Revolution, an increasing number of toxic pollutants are entering the sewage process that are not being removed.
The rules governing the use of sewage sludge as fertiliser date from 1989 and have not kept pace.
There is mounting evidence of risks from PFAS (Per- and Polyfluoroalkyl substances) commonly known as forever chemicals and microplastics; and continuing concern surrounding antibiotics and antibiotic resistance, brominated flame retardants, and heavy metals. The latter, while traditionally monitored, still pose risks due to long-term accumulation.
That it has taken more than 35 years for the government to take the dangers seriously is a sad indictment of ministerial complacency and the ease with which the water industry has been able to lobby against significant changes in regulation.
Selling dried sewage sludge to farmers has been a convenient way of disposing of a 1.5 million-tonne headache for the water companies. How much longer this can continue without massive investment in more advanced sewage treatment is the big question. Whatever happens, there has to be a far stricter regulatory regime for the manufacture, use, and disposal of problem chemicals, pharmaceuticals, and plastics.
These links tell you more:
https://proudlyindependent.uk/2024/10/02/forever-chemicals-danger/