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That makes me wonder… where does the Covid in the wastewater go? Do we successfully filter it out of the wastewater before recycling it back into the ecosystem?

That makes me wonder… where does the Covid in the wastewater go? Do we successfully filter it out of the wastewater before recycling it back into the ecosystem? Where specifically does filtered wastewater go, and how confident are we in the filtering process?

revicon 5y ago
I am not at all an authority on this but I think they use UV light to kill it during one of the treatment steps.
- beerandt 5y ago
  Only in a relatively few places. But it's not really necessary most of the time. It's often done more for political reasons than technical ones, because it's easier for the public to understand and trust UV disinfection than the other, much more complex processes that are typically used. Cobb County GA is an example of a plant that has large scale UV treatment right before discharge into the Chattahoochee River. But it's effluent is cleaner than the water getting pumped into their water supply.
dredmorbius 5y ago
A significant goal of wastewater treatment is reducing or eliminating pathogenic load. For a methods overview, see: https://www.filtsep.com/water-and-wastewater/features/pathogen-removal-from-water-technologies-and/ https://www.filtsep.com/water-and-wastewater/features/pathog... This paper discusses treatment and emergent pathogens: "The Role of Wastewater Treatment in Protecting Water Supplies Against Emerging Pathogens" https://www.jstor.org/stable/23803199 https://www.jstor.org/stable/23803199 I thought direct chlorination played a larger role, it seems it doesn't. (Heavy chlorination of water does result in post-treatment chlorine compounds being present, these are themselves an environmental concern. The bulk of the chlorine evaporates or is reacted relatively quickly. Chlorine also negatively impacts "digestors" which process residual organic matter in wastewater.) UV, oxygenation, sunlight, filtration, and dilution are all utilised as well. Viruses tend not to survive long periods of environmental exposure outside a host in most circumstances, though I'm not knowledgeable on specifics or exceptions.
aardvark92 5y ago
Not sure what the water treatment plant steps are downstream, but I can tell you I've been processing SARS-CoV-2 positive wastewater samples for ages and managed not to catch COVID. Most of the gene fragments tested for in these studies are just that, fragments. The virus itself degrades pretty quickly under environmental stress (UV, heat, evaporation, etc). I wouldn't be too worried about catching COVID from the water.

revicon 5y ago

I am not at all an authority on this but I think they use UV light to kill it during one of the treatment steps.

beerandt 5y ago
Only in a relatively few places. But it's not really necessary most of the time. It's often done more for political reasons than technical ones, because it's easier for the public to understand and trust UV disinfection than the other, much more complex processes that are typically used. Cobb County GA is an example of a plant that has large scale UV treatment right before discharge into the Chattahoochee River. But it's effluent is cleaner than the water getting pumped into their water supply.

dredmorbius 5y ago

A significant goal of wastewater treatment is reducing or eliminating pathogenic load. For a methods overview, see: https://www.filtsep.com/water-and-wastewater/features/pathogen-removal-from-water-technologies-and/ https://www.filtsep.com/water-and-wastewater/features/pathog... This paper discusses treatment and emergent pathogens: "The Role of Wastewater Treatment in Protecting Water Supplies Against Emerging Pathogens" https://www.jstor.org/stable/23803199 https://www.jstor.org/stable/23803199 I thought direct chlorination played a larger role, it seems it doesn't. (Heavy chlorination of water does result in post-treatment chlorine compounds being present, these are themselves an environmental concern. The bulk of the chlorine evaporates or is reacted relatively quickly. Chlorine also negatively impacts "digestors" which process residual organic matter in wastewater.) UV, oxygenation, sunlight, filtration, and dilution are all utilised as well. Viruses tend not to survive long periods of environmental exposure outside a host in most circumstances, though I'm not knowledgeable on specifics or exceptions.

aardvark92 5y ago

Not sure what the water treatment plant steps are downstream, but I can tell you I've been processing SARS-CoV-2 positive wastewater samples for ages and managed not to catch COVID. Most of the gene fragments tested for in these studies are just that, fragments. The virus itself degrades pretty quickly under environmental stress (UV, heat, evaporation, etc). I wouldn't be too worried about catching COVID from the water.