Proceedings

The Biosolids Assurance Scheme (BAS) was soft-launched in 2013, with the aim of coalescing
various regulatory and best practice requirements into a single, auditable standard for biosolids. This
was intended to provide additional market confidence in the safety and value of the material, the
majority of which is applied to agricultural land in the UK, as a biofertiliser. A key requirement of the
scheme is that biological hazards are managed through adoption of HACCP (Hazard Analysis and
Critical Control Points) planning approaches, since these ensure ongoing product quality when Critical
Limits are appropriately set, monitored and implemented. Since launch, sludge treatment centres
have been audited against the standard, and all have passed – despite (confidential) evidence of
ongoing failures in microbiological compliance. In the resulting atmosphere of public positivity and
private uncertainty, there is a risk that the fine aspirations and credibility of the BAS will be
undermined. A small number of changes to the scheme – including an explicit requirement that the
HACCP approach consider product storage – should deliver more consistent microbiological
compliance and further improve market confidence in biosolids.