Waste to wealth

JCU’s Dr Andrew Cole says the experiment has been very successful, improving the quality of the discharged water and producing a biomass resource that is high in protein.

“We put three large troughs of the alga Oedogonium intermedium fed by final effluent discharge from the Cleveland Bay wastewater treatment plant in Townsville.

“We wanted to demonstrate that it was a viable approach to ‘polishing’ effluent, so we ran a trial for a whole year to prove this. The algae not only survived but grew well all year round, and through this growth reduced the nutrient concentrations in the effluent.”

Dr Cole said the use of algae to recover otherwise wasted and unwanted nutrients in treated sewage has become a solid commercial proposition over the last decade.

“Sewage treatment plants are very efficient and Cleveland Bay operates well within its environmental authority, but the discharge water still contains a relatively high level of nitrogen and phosphorous compared to fresh water, and algae provides a smart way to recover these resources,” he said.  

Tests on the Cleveland Bay discharge water showed the algae production removed more than 36 percent of the remaining nitrogen and 65 percent of the remaining phosphorous.

The team says with full-scale application of the technique, there is the possibility of reducing nitrogen released into the environment from the Cleveland Bay facility by 10.5 tons per year and phosphorus by 3.8 tons year.

MBD Energy Limited, the algae company that funded the research, are now looking at ways to scale up this process and create commercial applications and products.

The Cleveland Bay wastewater treatment plant is run by Townsville City Council and processes 20,000 kilolitres of sewage a day. The scientists say it could support a four hectare algal production area and produce an annual crop of 181 tons of dried algae. The product would then be processed for use as a premium stock feed.

Dr Cole said smaller rural treatment plants often did not have the resources for filtering wastewater to the degree available at Cleveland Bay and could use algae as a cheaper option.

He said with extra sanitation steps there was also the possibility of using the algae as a human food supplement.

Link to pics and video of algae tanks at Cleveland Bay: http://bit.ly/2eBFmkV