UKWIR Funded Research Project on Sewage Sludge Recycling

Consultancies Team Up to Investigate Threats of Recycling Biosolids to Ground

Environmental consultants, Aqua Enviro, have joined a consortium led by fellow consultancy, ADAS, to deliver a strategic project looking at threats from recycling biosolids to land.

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Environmental consultants, Aqua Enviro, have joined a consortium led by fellow consultancy, ADAS, to deliver a strategic project looking at threats from recycling biosolids to land. 

The project is funded by research programme, UKWIR and also includes Cranfield University, The James Hutton Institute and The Animal and Plant Health Agency (APHA).

Aqua Enviro explained that biosolids, treated sewage sludge, has been beneficially recycled to agricultural land for many decades, supplying plant nutrients and organic matter – contributing to immediate crop nutrient requirements as well as providing long-term benefits to soil structure and fertility. As such, recycling biosolids to land is recognised by the UK government as the best practicable environmental option.

The understanding and management of hazards (such as heavy metals) in biosolids is underpinned by a substantial body of research carried-out over many years. 

A range of regulatory and voluntary controls now limit the crop type, application rate and return period of biosolids applications, but there are a number of emerging hazards for which the evidence is less robust, and increasing interest in understanding whether current controls are adequate to manage these emerging hazards, which include micro-plastics. 

The consultants added that a robust, evidence-based response to these concerns is required to ensure that biosolids can continue to be applied to agricultural land in a safe and sustainable manner.  Project SL01 forms a key part of this response.

The project team will build on the existing information available on biosolids recycling to agricultural land by undertaking a targeted evidence-based review of the new and emerging issues.

The review will take a holistic and systematic approach, and will include the published UK and international scientific literature investigating the range of potential substances that are, or could be, present in biosolids and which may pose a future barrier to its recycling to land.

These include micro- and nano-plastics, fibres, organic chemical compounds, potentially toxic elements, nanoparticles, pathogens (human, animal and plant), transfer of antimicrobial resistance and, importantly, combinations of these.

The team will use their expertise to identify and prioritise key focus areas for further investigation, including an assessment of safe levels and limits in place in the UK and elsewhere, together with information obtained on future trends and signals. Aqua Enviro’s direct practical experience with biosolids’ production and quality control will form a key part of the context within which the scientific evidence will be evaluated.

UKWIR’s Programme Lead for the project is Sarah Legg and the Project Manager is Mandy Fletton. They are supported by an expert steering group drawn from UK water companies.