Removal of protozoan (oo)cysts and bacteria during microalgae harvesting: Outcomes from a lab-scale experiment. (January 2022)

• Record Type: Journal Article
• Authors: Oliveira, Gabriela Laila de; Sueitt, Ana Paula Erbetta; dos Santos, Priscila Ribeiro; Leite, Luan de Souza; Daniel, Luiz Antonio
• Is Part Of: Chemosphere. Volume 286:Part 3(2022)
• Publication Date: 2022-01
• Subjects: Flocculation -- pH modulation -- Dissolved air flotation -- Chlorella sorokiniana -- Microbiological safety -- Giardia spp; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.131767
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The efficiency of microalgae harvesting on the removal of Giardia spp. cysts, Cryptosporidium spp. oocysts, total coliforms, Escherichia coli, Enterococcus spp. and Clostridium spp. was assessed in lab-scale experiments (Jartest and Flotatest) using effluent from a flat panel photobioreactor used for Chlorella sorokiniana cultivation. Three harvesting methods were evaluated: (1) flocculation induced by pH modulation followed by sedimentation (pH-SED), (2) flocculation induced by pH modulation followed by dissolved air flotation (pH-DAF), and (3) coagulation using an organic coagulant (Tanfloc SG) followed by dissolved air flotation (Coag-DAF). The results indicated that the three harvesting methods were efficient in removing protozoan (oo)cysts and bacteria, achieving percentages of removal higher than 97% for all the analyzed pathogens. Among the three methods, pH-SED showed the best removal performance: 99.60% (2.5 log) for Giardia spp. cysts, 100% (>6.3 log) for total coliforms, 100% (>4.6 log) for Escherichia coli, 100% (>5.8 log) for Enterococcus spp. and 99.96% (3.6 log) for Clostridium spp. Clostridium spp. seemed to be more tolerant to the harvesting methods than the other groups of bacteria analyzed in the study, and its presence was positively correlated to the presence of Giardia spp. cysts. Graphical abstract: Image 1 Highlights: Microalgae harvesting methods efficiently removed protozoan cysts and bacteria. pH - SED achieved the best performance related to pathogen removal. A significant correlation between Clostridium spp. and Giardia spp. was observed. Escherichia coli was more sensitive to the harvesting methods than total coliforms.