Removal of pathogens from domestic wastewater by microalgal-bacterial systems under different cultivation conditions

The present work assessed the removal of Pseudomonas aeruginosa , Escherichia coli and Enterococcus faecalis in algae-bacterial systems. The influence of the presence of microalgae ( Chlorella vulgaris ) and bacteria (activated sludge), aeration (O 2 ), supplementation of carbon dioxide (CO 2 ), photoperiod, and the system being open or closed were studied. The use of a consortium of microalgae and bacteria increased the removal of Escherichia coli , Pseudomonas aeruginosa and Enterococcus faecalis by 56, 59 and 55%, when compared to using only activated sludge. Also, addition of CO 2 or O 2 increased the removal of Escherichia coli by 11 and 14% and of Pseudomonas aeruginosa by 10 and 20%, respectively, but decreased the removal of Enterococcus faecalis by 24 and 28%, when compared to no gas addition. In general, a 24:0 light:dark photoperiod decreased removal of Escherichia coli and Pseudomonas aeruginosa , while increasing the removal of Enterococcus faecalis, when compared to a “normal” 16:8 light:dark photoperiod, for all conditions. Finally, aeration promoted a maximum ammonium removal of ≈ 99.4% and a maximum biomass productivity of ≈ 388.8 mg L −1 d −1 . Graphical abstract