The Fate of Cryptosporidium Parvum Oocysts in Reclaimed Water Irrigation-history and Non-history Soils Irrigated with Various Effluent Qualities

The present study aimed to look at the fate of protozoan parasite Cryptosporidium parvum oocysts applied through surface drip irrigation on reclaimed water irrigation-history and non-history sandy-loam (Hamra) soil columns. A new and simple isolation method for recovery of oocysts from soil samples was developed and used along this study. The new soil isolation method of oocysts is based on the “two phase separation method” formerly used to recover Clostridium perfringens spores from sediments and soil samples with minor modifications. The range recovery achieved by this method was 64-95% (mean 61.2 ± 17.4). The objectives of the second part of this study were to investigate several physical and chemical factors governing transport and survival of C. parvum oocysts in sandy-loam soil columns by breakthrough curves. Comparison of fresh water and reclaimed water irrigation revealed that reclaimed water irrigated-history soil was more hydrophobic allowing water flow through channels with poor oocysts retention and fast flow. Examination of the organic matter effect (originating from reclaimed water irrigation) on oocysts breakthrough revealed that their soil infiltration increased. Calculations of oocysts concentration at different columns depths showed that most of the oocysts were retained in the first 5 cm of soil column. In the present study, comparing the two soil types (history and non-history of effluents irrigation) beside the surface electrostatic charge, one of the main elements found to affect oocysts infiltration and transport in soil columns was soil hydrophobicity caused by soluble organic matter originating from reclaimed water irrigation. Therefore, prior to application in soil irrigation, reclaimed water should be treated to high quality (i.e. membrane technology as the best option) to prevent enhanced transport of various pathogens through those irrigated soils.