RECOVERY OF CRYPTOSPORIDIUM FROM WATER
Report No FR0189
T N Whitmore
The objective of this work was to evaluate the efficiency of the standard recovery technique for Cryptosporidium oocysts from water based on their entrapment in polypropylene cartridge filters. Any deficiencies in the technique would be evaluated and attempts made to overcome them. Other methods would also be evaluated based on the entrapment of oocysts in sand filters. Other potential methodologies would also be identified.
The standard technique for the recovery of Cryptosporidium oocysts from water is quite tedious and time consuming: another drawback is its low net recovery efficiency. Hence it would be advantageous to enhance the recovery efficiency and evaluate alternative techniques.
Experiments quantified the net loss of Cryptosporidium oocysts employing the standard cartridge filtration technique at around 87%. It was ascertained that the elution step resulted in the greatest percentage loss. Attempts to improve the efficiency of this step were, however, unsuccessful. An alternative procedure demonstrated that oocysts were retained by a laboratory-scale slow sand column filtration procedure and elution of the oocysts from the sand was readily accomplished.
It is recommended that studies on the recovery of Cryptosporidium oocysts from water are continued using alternative recovery techniques, particularly the use of sand columns.
V RESUME OF CONTENTS
This work was undertaken to evaluate techniques for the recovery of Cryptosporidium oocysts from water. The standard technique based on the filtration through polypropylene cartridge filters was shown to be quite inefficient: net recoveries being around 13%. The various steps of the procedure were evaluated and the greatest loss shown to occur during the elution of the oocyst from the filter matrix. Attempts to minimise this loss were not successful. Alternative procedures based on filtration through laboratory scale rapid sand columns, slow sand columns and granular activated carbon columns were assessed. Of these only the slow sand technique was shown to possess the capacity to retain Cryptosporidium oocysts.
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