Newly identified algal strains rich in phosphorus could improve wastewater treatment

The Revolving Algal Biofilm (RAB) system by Gross-Wen Technologies is an emerging technology that does just that. In the RAB system, phosphorus-laden algae are cultivated in wastewater attached to a revolving belt. The grown algal biomass can then be harvested from the belt and dried for use as agricultural fertilizer or as feedstock for the manufacture of biofuels and bioproducts.

The team of researchers examined the unique properties of phosphorus uptake in the algal strains living in RAB systems. They isolated nearly 770 algal strains from biofilm samples collected across eight active RAB systems throughout Iowa and Illinois.

"Many of these were duplicates of the same algal species, and we pared that number down to 101 unique strains using microscopy," Schaedig said. Those 101 unique strains were identified using DNA sequencing, and the polyphosphate content of each was determined using advanced screening techniques.

The results were promising. Seven isolated algal strains possessed at least 50% more polyphosphate by cell dry weight (CDW) compared to a baseline RAB system algal community, which came in at 5.1% polyphosphate by CDW. The top phosphorus-hyperaccumulating strain, Craticula molestiformis TCF-8d, accumulated 14.0% polyphosphate by CDW.

The research team performed follow-up experiments to confirm whether the top hyperaccumulating algal strains would survive and grow in real-world RAB systems. One of the strains, Chlamydomonas pulvinata, showed strong performance, thriving in the system and boosting the phosphorus removal rate of the modified system to 70%, double the removal rate of an unmodified RAB biofilm community.

Image source: Gross-Wen Technologies.