Occurrence of Cryptosporidium, Giardia, and Cyclospora in influent and effluent water at wastewater treatment plants in Arizona.
We investigated the occurrence of Cryptosporidium, Giardia, and Cyclospora at two wastewater treatment plants (WWTPs) in Arizona over a 12-month period, from August 2011 to July 2012. Influent and effluent wastewater samples were collected monthly, and protozoan (oo)cysts were concentrated using an electronegative filter, followed by the detection of protozoa using fluorescent microscopy (Cryptosporidium oocysts and Giardia cysts) and PCR-based methods (Cryptosporidium spp., Giardia intestinalis, and Cyclospora cayetanensis). The concentration of Giardia cysts in the influent was always higher than that of Cryptosporidium oocysts (mean concentration of 4.8-6.4×10(3) versus 7.4×10(1)-1.0×10(2)(oo)cysts/l) with no clear seasonality, and log10 reduction of Giardia cysts was significantly higher than that of Cryptosporidium oocysts for both WWTPs (P<0.05). Log10 reduction of Giardia cysts at the WWTP utilizing activated sludge was significantly higher than the other WWTP using trickling filter (P=0.014), while no statistically significant difference between the two WWTPs was observed for the log10 reduction of Cryptosporidium oocysts (P=0.207). Phylogenetic analysis revealed that G. intestinalis strains identified in wastewater belonged to two assemblages, AII and B, which are potentially infectious to humans. C. cayetanensis was also detected from both influent and effluent using a newly developed quantitative PCR, with the highest influent concentration of 1.2×10(4)copies/l. Our results demonstrated that these protozoan pathogens are prevalent in the study area and that efficacy of the conventional wastewater treatment processes at physically removing (oo)cysts is limited.
Department of Soil, Water and Environmental Science, The University of Arizona, Tucson, AZ 85721, USA. Electronic address: kitajima@smart.mit.edu.
Masaaki
M
Kitajima
International Research Center for River Basin Environment, University of Yamanashi, Yamanashi 400-8511, Japan. Electronic address: eharamoto@yamanashi.ac.jp.
Eiji
E
Haramoto
Department of Soil, Water and Environmental Science, The University of Arizona, Tucson, AZ 85721, USA. Electronic address: ikerb@email.arizona.edu.
Brandon C
BC
Iker
Department of Soil, Water and Environmental Science, The University of Arizona, Tucson, AZ 85721, USA. Electronic address: gerba@ag.arizona.edu.
Charles P
CP
Gerba
D001130:Arizona; D003458:Cryptosporidium / Q000254:growth & development* / Q000302:isolation & purification; D021744:Cyclospora / Q000254:growth & development* / Q000302:isolation & purification; D004784:Environmental Monitoring; D005872:Giardia / Q000254:growth & development* / Q000302:isolation & purification; D033761:Spores, Protozoan / Q000302:isolation & purification; D014865:Waste Disposal, Fluid / Q000706:statistics & numerical data*; D062065:Wastewater / Q000469:parasitology*
D062065:Wastewater
PCR; Phylogenetic analysis; Protozoa; Removal; SYBR Green; Wastewater