A Cyanobacteria-Based Biofilm System for Advanced Brewery Wastewater Treatment

Featured Application: Post-treatment of brewery wastewater through an attached cyanobacterial growth system with simultaneous production of bioethanol. Algal/cyanobacterial biofilm photobioreactors provide an alternative technology to conventional photosynthetic systems for wastewater treatment based on high biomass production and easy biomass harvesting at low cost. This study introduces a novel cyanobacteria-based biofilm photobioreactor and assesses its performance in post-treatment of brewery wastewater and biomass production. Two different supporting materials (glass/polyurethane) were tested to investigate the effect of surface hydrophobicity on biomass attachment and overall reactor performance. The reactor exhibited high removal efficiency (over 65%) of the wastewater's pollutants (chemical oxygen demand, nitrate, nitrite, ammonium, orthophosphate, and total Kjeldahl nitrogen), while biomass per reactor surface reached 13.1 and 12.8 g center dot m(-2) corresponding to 406 and 392 mg center dot L-1 for glass and polyurethane, respectively, after 15 days of cultivation. The hydrophilic glass surface favored initial biomass adhesion, although eventually both materials yielded complete biomass attachment, highlighting that cell-to-cell interactions are the dominant adhesion mechanism in mature biofilms. It was also found that the biofilm accumulated up to 61% of its dry weight in carbohydrates at the end of cultivation, thus making the produced biomass a suitable feedstock for bioethanol production.

Automated summary

This study successfully conducted post-treatment of brewery wastewater through a novel cyanobacteria-based biofilm photobioreactor, while also producing biomass suitable for bioethanol production. The results showed that surface hydrophobicity of supporting materials affected biomass attachment and overall reactor performance, but cell-to-cell interactions were identified as the dominant adhesion mechanism in mature biofilms.