Process solutions provider ACWA Services has installed new bio-filters at the Pencaitland maltings plant near Edinburgh, one of five plants operated by major UK maltster Bairds Malt. The new bio-filters are now operating to full capacity, treating an effluent flow of 550m3 per day.
With an annual malt production capacity of 47,000 tonnes, the majority destined for the distilling industry, the Pencaitland Maltings Plant uses significant quantities of water in the steeping and germination processes.
Minimising its environmental impact is crucial and the new bio-filtration system plays a key role in reducing the pollutant load in wastewater discharged from production processes. ACWA designed the system to reduce the BOD (Biological Oxygen Demand) load by more than 90%, which has directly reduced the plant’s trade effluent charges.
ACWA Services was the principal contractor for all aspects of the project including the decommissioning and demolition of the existing biofilters which had reached the end of their useful life and the design, supply, installation and commissioning of the new bio-filtration solution.
The new system
This incorporates two identical bio-filters complete with structured media and effluent distribution systems ensuring the effluent is evenly distributed through the bio-filters to promote biological growth and hence effective treatment, recirculation pumps, together with electrical and minor civil works. The project was completed in eight months.
Ensuring the Pencaitland plant remained fully operational while the wastewater biofilters were replaced was a key challenge, said the firm. This was achieved by installing a temporary Submerged Aerated Filter (SAF) unit to operate in parallel with the existing biofilters to enable each one to be replaced in turn.
Peter Brewer, ACWA Services’ UK General Manager said: “Wastewater bio-filtration solutions to reduce trade effluent loads from production processes are crucial to a range of industries to minimise their environmental impact, ensure compliance and reduce costs. With a growing range of wastewater treatment solutions to choose from, combined with changing water industry directives, it is important to select the right engineering partner to deliver durable, future proof solutions.”