Spreading of sewage sludge to land - impacts on human health and the environment: community concerns

This workshop summary report is part of the research project undertaken by the James Hutton Institute on the impacts on human health and environment arising from the spreading of sewage sludge to land (CR/2016/23).

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Appendix 3

The impacts on human health and the environment (presentation)

The presentation slides, for ‘The impacts on human health and the environment’, are is available from the supporting files as a downloadable PDF. The text below describes what’s on each of the slides. shows the slides from the presentation titled “The impacts on human health and the environment”.

Slide 1 shows the project title “The impacts on human health and the environment” and the names of the representatives of the James Hutton Institute who attended the workshop. (Rupert Hough, David Tomkins, John Williams, and Dominic Duckett).

Slide 2 shows the project overview e.g. to undertake an impartial study into potential negative impacts of sewage sludge on human health; update existing guidance on how sewage sludges are used on land restoration sites; provide evidence based recommendations for better practices.

Slide 3 shows how attendees can assist the project by helping the James Hutton Institute understand where issues have arisen and under what circumstances.

Slide 4 shows the scope of the project e.g. odour investigation, system mapping and a review of literature.
Slide 5 shows the system mapping e.g. that the primary aim is to understand the amounts of different sewage sludges produced in Scotland; who and how these are handled; volumes spread to land (and where).

Slide 6 shows a map of the locations of sludge treatment centres in Scotland.

Slide 7 charts the available markets for sewage sludge in 2017 e.g. farmland, landfill, incineration and land reclamation.

Slide 8 shows the relevant regulations and codes of practice e.g. Sludge use in agriculture regulations; the Safe Sludge Matrix; PEPFAA and SNIFFER (water and air pollution); Biosolids Assurance Scheme).

Slide 9 shows a brief overview of the Safe Sludge Matrix guidelines.

Slide 10 This slide shows a picture of an odour measurement being taken.

Slide 11 This slide shows what a risk modelling/assessment involves e.g. risk assessment estimates the potential for something to happen; approach tends to err on the side of caution; risk assessment flags up where further investigation may be needed or what measures should be taken to reduce risks; cannot advise that harm is actually occurring.

Slide 12 shows a diagram outlining the risk modelling/assessment.

Slide 13 shows the approach (1) taken in terms of commentary i.e. the information is either very poor, incomplete, or missing; it will be based on literature review and expert judgement.

Slide 14 explains the approach (2) of using the Bayesian network e.g., computer models that aid decision making; used where data have large uncertainties, making fully quantitative estimates of risk less meaningful; mixture of “hard” data, judgement, and opinion; explores interaction between different factors; odours.

Slide 15 shows the approach (3) of using Fugacity modelling e.g. based around chemical partitioning; if a chemical is placed in an oil: water mixture, does it partition mainly to oil or water?; this tells us something about how the chemical might move in the environment; lots of assumptions....tends to over-estimate risk; ‘emerging’ contaminants……pharmaceuticals, personal care products etc.

Slide 16 thanks the audience.


Email: gary.gray@gov.scot

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