Aerobic bacterial spores as process indicators for protozoa cysts in water treatment plants

Abstract

The possibility of using aerobic spores as indicators (surrogates) of water treatment efficiency for the removal of Giardia cysts and Cryptosporidium oocysts was evaluated in a water treatment plant that supplies the Barcelona area of Spain. The water treatment consists of pre-chlorination, flocculation-sedimentation, double filtration (sand and granular activated carbon, GAC) with intermediate ozonation and post-chlorination. Aerobic spores significantly increased after GAC filtration, which indicated an active propagation of aerobic spore-formers. However, anaerobic (Clostridium) spores could be a good surrogate for Cryptosporidium oocysts, especially if their detection in samples at low concentrations was improved.

Occurrence of Cryptosporidium spp. oocysts in raw and treated sewage and river water in north-eastern Spain

“…In our study, river water was investigated for the presence of Cryptosporidium and faecal indicators (data not shown). Our results are in the range of values reported by other authors, 100% by Madore et al (1987), 74% by Rose et al (1991) and 100% by Galofré et al (2004). Similar oocyst densities were obtained in river waters throughout the entire sampling period, with the exception of a high concentration of Cryptosporidium oocysts in 2002.…”

Inactivation of indicator organisms in wastewater treated by a high rate algal pond system

“…An alternative, but not mutually exclusive explanation, was that ASFB were propagating in the system. This was supported by reports in the literature of ASFB propagating in wastewater treatment plants (Gale et al 2002;Galofr et al 2004) and of germination of bacterial spores responding positively to increases in temperature (Keynan et al 1964;Rice et al 1996;Leuschner and Lillford 1999;Galofr et al 2004). Initial observations that ASFB concentration in the HRAP was increasing in the warmer summer months, and then decreasing in the colder winter months supported this proposition.…”

“…; Leuschner and Lillford ; Galofr et al . ). Initial observations that ASFB concentration in the HRAP was increasing in the warmer summer months, and then decreasing in the colder winter months supported this proposition.…”

Comparative study between two laser scanning cytometers and epifluorescence microscopy for the detection of Cryptosporidium oocysts in water

“…Laser scanning cytometer technology has already been extensively applied to different scientific studies (40,41), pharmaceutical water analysis (42)(43)(44) and, more recently to Cryptosporidium and Giardia detection in water samples as an attractive alternative to manual microscopy (7,19,22,36). The use of this new technology application yields counts of Cryptosporidium that are at least equivalent to the conventional methods.…”

“…Results are shown as a scan map, with the aid of the motor-driven microscope stage, and each count can be visually confirmed. The ChemScanRDI used in this study is being applied for the Cryptosporidium oocysts and Giardia cysts monitoring in drinking water samples by the drinking water company AGBAR (36).…”