Removal of the waterborne parasite Cryptosporidium parvum from drinking water using granular activated carbon

Abstract

Cryptosporidium is a genus of apicomplexan parasites that infect the gastrointestinal tract of a wide range of vertebrate hosts, including humans. These enteropathogens are commonly detected in surface waters and Cryptosporidium is responsible of numerous waterborne outbreaks in industrialised countries. Filters of granular activated carbon (GAC) are mainly used to eliminate emerging micropollutants or control unpleasant odour and taste in drinking water. Recently, GAC has been also employed for removal of microorganisms from different types of water. This work evaluates the capability of GAC in the elimination of the infective forms of Cryptosporidium parvum (oocysts) from drinking water. For this, well water was spiked with oocysts of C. parvum and passed through a chromatographic column filled with fresh GAC at different bed heights (5–50 cm) and a filtration rate of 100 mL/min, approximately. By immunofluorescence microscopy, the number of oocysts in the water samples was determined. The logarithmic reduction (LR) was calculated by comparing the number of oocysts quantified in the filtered samples and the corresponding influent samples. High efficiencies of GAC in removing C. parvum oocysts from water were obtained. Thus, with a bed height of 35 cm, removal efficiencies > 2 LR were achieved. The highest LR (3.47 ± 0.31) was observed when a GAC bed height of 50 cm was used. Taking into account the results obtained, C. parvum oocysts were eliminated remarkably and, therefore, GAC adsorption filters may be considered additional barriers against this waterborne enteropathogen in drinking water at the household level in developing countries.