Virus removal in wastewater

The Virus Removal in Wastewater project is an ESR-led research group that aims to advance knowledge of the efficiency and relative importance of processes involved in virus removal in natural wastewater systems such as oxidation ponds.

The research has grown from an initial project started back in 2009 aimed at optimising virus removal in wastewater systems through a sustainable and low cost approach. The current project expands upon this research by focusing on enhancing the understanding of the complex mechanisms existing in wastewater that have the potential for virus (and other microbial pathogens) removal. In particular, the research is focused on those mechanisms that act independently of light (the main driver of natural virus removal).

The behaviour of wastewater associated viruses (and other pathogens) in the absence of sunlight is not fully understood. By advancing understanding of “dark” removal mechanisms, opportunities for optimising pathogen removal can be evaluated.

Other removal mechanisms such as the sedimentation of particle-associated pathogens will vary depending on the properties of microbes (viruses in particular); varients such as surface characteristics, size and mobility of the microbe in question. Experiments are currently being conducted to extend  knowledge of the attachment and/or aggregation and settlement behaviour of a range of viruses and other pathogens in wastewater.

The research project involves NIWA to develop a detailed model of virus removal in wastewater. The model will be used to aid management and optimisation of wastewater treatment systems for virus removal. NIWA (Dr Rebecca Stott) are also leading the research into the potential for viral grazing to occur in these systems. Protozoa naturally graze on microbes including viruses (and other particulate matter) present in wastewater. Dr Stott’s research has shown that higher virus removal can be achieved in the presence of protozoa and it can be the dominant removal mechanism in the absence of light. Her research has shown 80-95% removal of bacterial and viral microbes by protozoan grazing can occur. This is an important finding as the protozoa are found in wastewater naturally and so can offer a low cost solution to viral loading issues in receiving waters.

For further information contact Louise Weaver.