Related Experiment Video
Updated: Oct 23, 2025
Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae
Published on: July 10, 2015
Removal of protozoan (oo)cysts and bacteria during microalgae harvesting: Outcomes from a lab-scale experiment
Gabriela Laila de Oliveira1, Ana Paula Erbetta Sueitt1, Priscila Ribeiro Dos Santos1
1Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Avenida Trabalhador São-Carlense, 400, 13566-590, São Carlos, São Paulo, Brazil.
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.
