UKWIR finds commercial promise in sludge recycling options

Findings from a recent UK Water Industry Research (UKWIR) assessment of the market for water treatment surges include recommendations for full-scale demonstrations in:

• the use of ferric sludges in stripping hydrogen sulphide from biogas; and 

• the use of acid digestion for ferric and aluminium sulphate (alum) sludges and their subsequent use in wastewater treatment.

UKWIR recommended collaborative projects for both demonstrations as well as for pilot scale trials of advanced coagulant recovery for reuse. 

Other recommended projects for collaboration included stakeholder engagement with water firms to ensure their needs in coagulant performance and anaerobic digester management are being met, and liaison with regulators to determine the steps needed to extend the reuse of sludge beyond land spreading and discharge to sewers.

The UKWIR study concluded that a number of treatment processes had the potential to increase the value of water treatment sludge, including thermal treatment, granulation and acid treatment.

It noted also that there was limited data on the presence of potentially toxic contaminants in water treatment sludge, “which could influence alternative outlets or uses”. It concluded that the risk of their presence causing an issue was “considered to be low, although it would be prudent to include analysis if any work is undertaken on identified options”.