Main content area

Pathogen reduction in an algal-based wastewater treatment system employing Galdieria sulphuraria

Delanka-Pedige, Himali M.K., Munasinghe-Arachchige, Srimali P., Cornelius, Jackson, Henkanatte-Gedera, Shanka M., Tchinda, Duplex, Zhang, Yanyan, Nirmalakhandan, Nagamany
Algal research 2019 pp. 101423
Acidobacteria, Arcobacter, Enterococcus faecalis, Escherichia coli, algae, coliform bacteria, dissolved organic carbon, fecal bacteria, nutrients, pathogens, quantitative polymerase chain reaction, wastewater, wastewater treatment
The feasibility of an algal-based wastewater treatment system employing an extremophilic alga, Galdieria sulphuraria, in removing dissolved organic carbon and nutrients from primary-settled wastewater has been demonstrated at pilot scale. Here, pathogen-reduction capability of this system was assessed and compared against that of an existing traditional wastewater treatment system (WWTS). While total coliform in the influent (2.3 × 107 CFU/100 mL) was reduced by 3.3 log units in the WWTS, no total or fecal coliform were detected in the algal effluent. Results of qPCR analysis confirmed 98% removal of total bacteria and complete removal of Enterococcus faecalis and Escherichia coli in the algal system. Illumina MiSeq sequencing showed diverse bacteria phyla (>10 classifications) in the WWTS-effluent; but, only two classifications in the algal effluent. Bacteria kingdom relative to the entire microbial population declined from 99% to 83% in the WWTS; and to 17% in the algal system. Proteobacteria phylum (which includes mostly putative pathogenic bacterial genera) dominated the WWTS-effluent (abundance = 35%). Substantial alteration of the bacterial profile was observed in the algal system: Acidobacteria phylum being the most dominant (98%), and Proteobacteria, the least (2%). At the genus level, enteritis-causing Arcobacter species were detected only in the WWTS-effluent with a relative abundance of 0.9%.