Removal of Giardia spp. cysts and Cryptosporididum spp. oocysts from anaerobic effluent by dissolved air flotation.

Lab-scale studies were carried out to investigate the efficiency of dissolved air flotation (DAF) for the removal of Giardia spp. cysts and Cryptosporidium spp. oocysts from anaerobic effluent from the pilot UASB reactor. Raw wastewater, UASB and DAF effluent samples were collected weekly and protozoan (oo)cysts were concentrated using IMS followed by protozoa detection using immunofluorescense assay (IFA). The number of Cryptosporidium spp. oocysts in the raw wastewater was always lower than that of Giardia spp. cysts with 28-33 oocysts L-1 and 3177-4267 cysts L-1, respectively. Log10 removal of Giardia cysts utilising polyaluminium chloride (PACl) was higher than that with FeCl3, but no statistically significant difference between the two coagulants was observed. Cryptosporidium was absent in most of the treated effluent samples. The results indicate that DAF reached more than 2 log of cyst removal. In addition, the results demonstrated that these parasites are prevalent in the study area and E. coli and total coliforms were not good indicator microorganisms in terms of cyst and oocysts numbers.