Comparison of Methods for Recovery of Cryptosporidium from Water

Methods were evaluated for the recovery of Cryptosporidium oocysts from water. Various types of cartridge filter were tested but proved to be inferior to the standard Cuno Micro-Wynd filter. Laboratory scale sand columns were also evaluated. The retention within the column material was satisfactory at low flow rates. However, the system was judged inadequate for monitoring because of the poor retention of oocysts within the column matrix at realistic flow rates. The continuous flow centrifuges tested were shown not to be capable of yielding satisfactory recoveries, although it is considered more refined machines currently available may warrant investigation. The vortex-flow filtration technique using the Membrex Benchmark device gave fairly consistent recoveries of 30-40%. However, the comparatively long process times would militate against the use of this device for monitoring purposes. A cross-flow filtration module was evaluated and gave relatively good recoveries (approximately 40-80%) at moderately high flow rates (0.9-1.01/min) from clean water samples spiked with Cryptosporidium oocysts.