[Thanh Tran]

Hi Anita, recently I had a conversation with a friend who builds ponds and waterfalls and natural water retention systems that can create living, clean water. We’ve been discussing how this type of system could benefit farmers and ranchers. A UV treatment system is a sterilization approach that does kill the algae but isn’t a natural filtration solution. It depends on the size of the UV bulb and how fast your pump is moving the water through; ie you can’t have the water flow thru too fast. It needs time for the radiation to kill the algae. UV kits will likely tell you how much water to move but it’s roughly 1/3 of the total gallons per hour.

Example. A 1500 gallon reservoir would need about 500g per hour flowing through the UV filter. The natural system approaches eliminate harmful contaminants and still keep the good living microbiome in the water; e.g. wetland filter, bog etc. Ed Beaulieu, the pond professor, designed a natural system that I’ve been discussing with my friend. You can reach me at [email protected] if you’d like to explore further.

[Valerie Smith]

Hi Anita,

I’ll be visiting a farm soon that is using a multi-step system for using surface water, to clarify the system details. What I do know from their plan is that their holding tank will get algae without some treatment beyond UV, so they are also using bleach to treat the water followed by periodic water testing. I am definitely interested in what options there are and their effectiveness since many in New Mexico may not have a well or access to municipal water.

Valerie Smith

[Billy Mitchell]

Anita,

Thanks for starting this discussion and interesting to read the replies.

There are a couple of resources I would point towards for UV surface water treatment for food safety considerations:

One research paper (attached) – Evaluation of ultraviolet (UV-C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity.

And another research paper (attached) – Developing a Decision-making Tool for Agricultural Surface Water Decontamination Using Ultraviolet-C Light – and the online calculator they developed (I’ve not used this, but may be helpful) – https://trevorhefley.shinyapps.io/uv-1/.

I’ve also attached the Bridging the GAPs water treatment flipbook. This was released before the updated water rule (I haven’t re-read it since, but it does mention FSMA and some of that info may now be out of date) and provides a nice overview on UV starting around page 26.

My interpretation of those resources is that, yes, UV can be effective and that effectiveness depends on turbidity, UV, and flow rate.

Thanks for this push to dive a little deeper on this topic!

Billy

Evaluation-of-ultraviolet-UV-C-light-treatment-for-microbial-inactivation-in-agricultural-waters-with-different-levels-of-turbidity.pdf 625 KB PDF - Click to view

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Developing-a-Decision-making-Tool-for-Agricultural-Surface-Water-Decontamination-Using-Ultraviolet-C-Light.pdf 2 MB PDF - Click to view

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Bridging_The_Gaps_Final.pdf 2 MB PDF - Click to view

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