Cryptosporidium, often found in surface waters used as drinking water supplies, is a waterborne protozoan pathogen that can cause gastrointestinal illnesses. In drinking water treatment plant, rapid granular filtration usually serves as an important barrier against the passage of Cryptosporidium oocysts; however, the interactions between oocysts and filter media during the rapid granular filtration process is still ambiguous. Non-genotoxic fluorescent polystyrene microspheres with sizes similar to oocysts have been extensively reported as surrogates to evaluate the filter removal performance on Cryptosporidium. Still, there is little known about the correlation of the changes of microspheres surface properties with particle removal during the filtration process.  Here, we prepared three different types of Cryptosporidium surrogates by chemical modification of polystyrene microspheres with glycoprotein and synthetic glyco(co)polymer. The interactions between surrogates and filter media were compared with living oocysts on a quartz crystal microbalance with dissipation (QCM-D) using silica coated sensors to mimic the sand surfaces. The results showed that oocysts/microspheres-filter media interactions are governed by both the electrostatic interactions and the oocysts/microspheres’ surface hydrophobicity. Glycoprotein or glycopolymer coated microspheres that without hydrophilic coating were highly aggregated and showed significantly different QCM-D signals at higher ionic strength (10Mm of NaCl) as compared to living oocysts adhering to the same surface. The hydrophilic zwitterionic-/glyco-polymer coated microspheres were found to be the best surrogate in terms of similar surface charge, QCM-D signals, numbers of particles adhering to silica sensor surfaces, and a low cost of preparation. Our study has demonstrated that the synthesized zwitterionic-/glycol-polymer coated polystyrene microspheres can be good surrogates for filtration operation optimization studies and filter performance assessments.<br/>

Zwitterionic-/glycol-polymers coated polystyrene microspheres as surrogates for studying the interactions between <i>Cryptosporidium </i>oocysts and silica surface

253rd National Meeting (2017)

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Zwitterionic-/glycol-polymers coated polystyrene microspheres as surrogates for studying the interactions between Cryptosporidium oocysts and silica surface