Developing A New Class Of Pathogen Surrogates For Water Applications

In the last a few years, we have conducted multidisciplinary research in developing a new class of surrogates for studying pathogen removal and transport in subsurface media and engineered water systems. This innovation has progressively advanced from developing protozoan surrogates (polystyrene microspheres coated with protein or vitamin), to virus surrogates (DNA-labelled silica nanoparticles with/without protein-coating), and currently bacterial surrogates (food-grade biopolymer microparticles). The new surrogates are harmless, user-friendly and inexpensive.

So far, surrogates for Cryptosporidium parvum, rotavirus, adenovirus and norovirus have been developed by mimicking the physiochemical properties and surface characteristics of the target pathogens. Experiments demonstrated that these new surrogates significantly outperformed the most used existing surrogates, which are unmodified microspheres for Cryptosporidium oocysts and MS2 phage for viruses. The Cryptosporidium surrogates have also been satisfactorily validated by overseas collaborators in filtration processes and water treatment (rapid sand filtration and coagulation).

The “micro mimics” approach has opened up a new avenue for understanding and assessing pathogen removal and transport in water systems, without the risk and expense involved in working with pathogens. Working with the water industry, we have been demonstrating the new surrogate technology in real-world settings, including pilot-scale sand filters in a drinking-water treatment plant and point-of-use domestic filters. For the first time, NZ’s drinking-water filtration systems (also commonly used overseas) are being assessed for their efficacies in protozoan and virus removal. Our research findings will help implement preventive measures to reduce drinking-waterborne infection risks. Research outcomes will promote uptake of new surrogate technology for better protection of vital freshwater resources and drinking water supplies.