Viruses present a major challenge to the array of point-of-use disinfection approaches currently applied in developing regions. For many POU disinfection systems, the goal of fully controlling viruses is sacrificed due to the stringent constraints relating to economics and sustainability.
The objective of this research was to improve the performance of some commonly prescribed POU technologies against viruses without comprising their prospects for sustainability. The POU systems explored were coagulation with Moringa seeds, biosand filtration, chlorination, and solar disinfection.
When applied alone, most of these systems provided inadequate removal of viruses in representative water types. Chlorination had the greatest efficacy amongst the group, but its performance was inhibited by ammonia, a contaminant commonly associated with human and animal waste pollution. Despite
the shortcomings of each technology, enhanced control of viruses was achievable through strategic multi-barrier approaches. Applying Moringa seed coagulation upstream of biosand filtration consistently yielded more than a three-log removal of viruses over a one-month testing period. In
this approach, the settling step, which is often ineffective with moringa seeds, was bypassed. Incorporation of clinoptilolite, a natural zeolite, into the biosand matrix yielded a high level of ammonia control. This system, named the Green Machine, was developed and tested by a team of students
within WaterCAMPWS with the goal of achieving sustainability through reliance on materials local and familiar to the target populations, which may enhance user acceptance and stimulate local economic development. Combining solar and chlorine disinfection in waters contaminated with ammonia
proved to be much more effective than either technology alone. A synergistic effect between sunlight and monochloramine produced a six-log reduction of virus viability within a two-hour exposure time, compared to a timescale of days required for either technology alone. This novel process,
named SoChlor, provided enhanced control of viruses in 20% wastewater using two of the most affordable POU technologies currently available in developing regions.
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