|M.Sc Student||Khshiboun Kifah|
|Subject||Transport and Survival of Protozoa Parasites in Soils|
Irrigated with Effluents
|Department||Department of Agricultural Engineering||Supervisors||Professor Robert Armon|
|Professor Emeritus Abraham Shaviv|
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 C. perfringens
spores from sediments and soil samples with minor modifications. The range
recovery achieved by this method was 64% to 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 Cryptosporidium
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.
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.