INFLUENCE OF CHEMICAL CONDITIONS AND SOIL CHARACTERISTICS ON THE BEHAVIOR OF CRYPTOSPORIDIUM OOCYSTS IN POROUS MEDIA

The purpose of this study was to investigate the transfer of Cryptosporidium oocysts through alluvial geological formation. To better understand the mechanisms of Cryptosporidium oocysts transfer in porous media, the batch adsorption studies were implemented. These tests were carried out in a mixture at a constant pH of natural soil from an alluvial aquifer and different ranges of pure oocysts concentrations in solutions of 3 mM CaCl₂ and 1 mM NaBr. The contact of chemical solutions containing oocysts with samples of soil provides a concentration of oocysts after equilibrium (Ce) and estimate the amount of retained oocysts (qe) in the solid matrix. The results of these equilibrium showed a total transfer in batch containing NaBr and a partial transfer in batch containing CaCl₂ depend of media concentration oocysts. To confirm the dispersion of oocysts in the soil, confocal microscopy was successfully used (MEB). The monitoring of this dispersion was carried out on two samples showing the greatest concentration of oocysts in the range of tested solution. The results obtained images from microscopy observations confirm the dispersion of oocysts in the solid phase. These observations showed that changing chemical conditions of the environment may have an impact on the transfer of oocysts in porous media, which could make possible adsorption phenomenon.