UK piloting water-polishing using algae

The University of Bath in the UK is running a pilot plant with environmental innovation company Aragreen to demonstrate the effectiveness of algae as a water-polishing technology.

The pilot facility in Gloucestershire will use wastewater from a nearby Welsh Water plant. The algae will then be harvested and used in the production of saleable products.

The first of its kind in the UK, this pilot scheme will be used to trial different techniques and methods, and to experiment with different species of algae to find those suitable for water polishing and biofuel, biochemical and protein production. The team hope to enter commercial production by the end of 2012.

Rod Scott, professor of plant molecular biology and academic lead on the project, says: “There is a large demand for both sustainable water polishing techniques and production methods for renewable fuels and algae biomass which pose less competition to increasingly scarce productive farmland. However, finding a cost-effective method for growing algae in large quantities has historically been difficult.”

Scott has been working with Dr Tom Arnot and Professor Matthew Davidson in the University of Bath’s Chemical Engineering and Chemistry departments respectively.

“We have invested in a multidisciplinary approach to tackle these issues. Nitrates and phosphates are required by algae as nutrients, and the process of growing algae strips them out of the wastewater,” Scott explains. “In the future we may also use waste carbon dioxide from industry to further enhance the process and make use of another waste stream.”

The wastewater for the pilot plant will be piped from a nearby Welsh Water plant into photo-bioreactors, large clear tubes under LED lights, in which the algae will grow. The clean water will be returned to Welsh Water free of cost for the purposes of the pilot scheme, although resale of this product will eventually be essential in reaching commercial viability.

When the algae is ready to be extracted from the photo-bioreactor, it is first concentrated by specialised machinery before being dried into biomass, which can be used for a range of purposes such as biofuel, fertilizers or proteins.

The team is also currently investigating algae – growing in the city’s Roman baths – which can survive at higher temperatures and could cut the cost of cooling the photo-bioreactors.