How to Stop Water Pollution Risks Leading to Water Pollution from Biogas and AD Plants

There was recently quite a serious biogas plant digestate tank failure at Harper Adams University, which we reported on in our last post. It led to digestate leaking into a bunded area, and because the right precautions were taken with containment it is extremely unlikely that any pollution has occurred.

That led us to consider what we could do to help those people who are responsible for Anaerobic Digestion and Biogas Plants to understand the UK legislation on watercourse and groundwater protection. Most will be familiar with their site environmental permitting arrangements anyway, but we wanted to provide an accessible reminder which would also be useful to our international readers who might view it as "good practice" worth following, even if similar local regulations don't exist in their location. 

The idea is that a better appreciation of the law in this area, and what causes most spillages, would ensure that those responsible, such as site managers and plant operators carry out what is in fact their legal duty (in the UK). That is to assess risks from their liquid storage installations and reduce all such risks to their minimum which in most cases (as for anaerobic digestion plants) means providing suitable containment.

The answer, we thought, would be to post the infographic image below which is based upon a UK Chartered Institute of Waste Management Fact File.

It provides the legal basis for compliance by owners/ operators of factories and other potentially polluting sites, making sure that they appreciate their legal liability should they fail to follow the guidance. 

It then provides a summary of some of the most important requirements for minimizing pollution risks from processes like anaerobic digestion, where collapse or even a leak can harm large areas of groundwater, or long stretches of rivers if either the mixed-liquor, stored digestate, or even uncontrolled maturation slab run-off reaches rivers, or soaks into the ground and into the groundwater.

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Here, in text, is what the CIWM said in their Fact File:

OPERATORS OF permitted facilities are responsible for complying with their environmental permit and for preventing pollution of air, land and water.
Waste management facilities have the potential to cause significant environmental harm, which could threaten water supplies, public health and wild life in the event of an environmental incident such as fire, explosion or spillage.
 A facility found guilty of causing a pollution incident could face a fine of up to £50000 in the Magistrates Court.
In order to prevent environmental harm you should be aware of the following:
The source of the contaminant;

• the most common pollutant in the UK is oil 

The pathway 

• this could be the site's surface water drainage system or via off-site surface drainage, direct run-off, foul drainage system or into the atmosphere 

The receptor

• ie a river, groundwater, the local population. 

Potential causes of environmental incidents include: 

• delivery and use of materials 

• plant or equipment failure 

• containment failure 

• fire, explosion or failure to contain fire fighting water 

• wrong connections of sewers and pipes 

• discharge of partially-treated or raw effluent 

• vandalism 

• flooding of part or all of your site.

Those operating waste facilities need to assess the risk from every one of the above listed potential causes, in the context of the source (degree and nature of pollution), the pathway to the permeable ground, river, ditch or stream which would become the receptor.