Reform biosolid treatment could create a sustainable future

The report, Biosolids and Sustainability, by the Natural Step (TNS) is supported by four UK water companies and the Environment Agency. It points out how the approach to sewage sludge treatment practised today is unsustainable, gives a vision of how the charity, chaired by Jonathan Porritt, sees a fully sustainable routine working and highlights the key challenges society would face in making the transition.

Today’s biosolids system is unsustainable for a variety of reasons according to TNS authors. Complex organic compounds entering the system that cannot be treated make beneficial reuse difficult and pathogenic organisms, like bacteria and fungi, which can survive sewerage treatment and give rise to health fears are some of the problems today’s system cited in the analysis.

Although there is concern amongst consumers and retailers over the safety of sewage used to fertilise land crops, amid food scares like E.coli, this remains the “best practicable environmental option”, says the report.

“The lack of a vision of the system as a whole, and the consequent fragmentation of decisions reflecting different interests in isolated parts of the system, present obstacles to the achievement of sustainability,” says Dr Mark Everard, co author of the report and Director of Science at TNS.

In a society with a fully sustainable sewage sludge system TNS predict waste to be utilised in production systems like farms, larger infrastructure will be reduced to meet local need in an efficient manner and people will assume responsibility for what they put into the sewer system.

“The TNS plan is looking at the challenge in a different light – this is always useful,” Rupert Kruger from Water UK told edie.

In order to make the change from present society to the ideal one TNS envisages the study highlights challenges that must be overcome. These include:

• creating the perception of ‘waste’ as a valuable resource;
• further investigation of potential health hazards;
• decreasing volume and inappropriate content entering the sewage system;
• creating localised treatment facilities over larger centralised ones; and
• more sustainable regulations.

“We agree that biosolid reuse in agriculture is the best sustainable option, as does DEFRA and the EU Commission,” says Kruger. The Commission is well aware of the challenges highlighted in the report such as the need to control what inputs to the sewage system, he says. However the issue of decentralising wastewater treatments is a difficult direction to go in. “Take London for example – urbanisation calls for centralised water plants.”

On 21 October, Water Minister Elliot Morley announced changes to the sewage sludge treatment regulations intended to encourage the recycling of sludge to agricultural land and to improve enforcement and monitoring by the Environment Agency. The regulations include the banning of the use of untreated sludge to arable agricultural land, which has been subject to a voluntary ban since 1999.