Mechanisms of virus removal in waste stabilisation ponds
Annual Conference
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Globally waste stabilisation ponds (WSP) offer a sustainable and economical method of treatment for wastewater. The pathogen removal mechanisms occurring within ponds are largely unknown and only a few studies have been conducted on virus removal. While it is clear that sunlight (UV) and temperature play a major role in removal of pathogens in WSP’s there are other mechanisms present in these complex systems that also play their part in removal of pathogens such as viruses.
The virus (and indicator organisms) removal efficiencies of WSP in the presence and absence of sunlight was investigated. The effect of controlled pH and DO was also studied.
The results demonstrated that by increasing pH and DO levels, even in the absence of light, efficient removal of viruses was achieved: die off rate (k) ln -5.5 to -9.5 day-1 . Results over two summers showed a similar removal rate for virus (4-5 log) but lower for indicator organisms when the temperature was lower during the second summer. Only E. coli showed a significant negative correlation between sunlight and removal rate.
By maintaining WSP with high pH and DO levels efficient removal of virus can be achieved using these sustainable, economic treatment methods.