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Cake day: January 7th, 2024

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  • R with the tidyverse package is amazing once you get over the learning curve. It’s so much easier to simply type a few lines of code then to fiddle with the Excel GUI, plus the ability to customize the plot is much, much better in R.

    Yes making a simple plot in Excel is relatively easy, but try making something evening remotely complex and it’s terrible. A box plot is a great example of this, 2 lines of plotting code in R for a basic plot but an absolute nightmare to create in Excel.


  • The US is a massive country friend, there are lots of places with combined sewers (domestic wastewater and stormwater) that will bypass treatment when there is a big rain event, especially in coastal cities that discharge wastewater to the ocean. It’s not ideal but the alternative is massively oversized treatment plants or replacing all of the existing sewer infrastructure to separate the sewers. Both options would cost tens of billions of dollars in any of the large east coast cities. People are not willing to pay for that.









  • This is very interesting. Currently, most ion exchange systems that remove PFAS have to dispose of their brine as hazardous waste, which is very costly and doesn’t necessarily destroy PFAS - in Florida, for example, they inject the brine into a deep aquifer.

    A lot of novel technologies target PFAS destruction in these concentrated waste streams, but often further concentration is required before you can effectively destroy PFAS with advanced oxidation processes. If they could use low-UV to destroy it without further concentration or additional chemicals (beside the salt already used to regenerate the resin), ion exchange would become a much better solution for treated PFAS contaminated water.






  • There are lots of things dissolved in our water that give it “flavour”, but the goal of all utilities is to minimize this as much as possible. Some water objectively tastes better than others, and a common segment of local drinking water conferences is a taste test. That said, for normal people usually the water they prefer is what their palette is used to. Someone who grew up drinking groundwater with very high alkalinity and pH will prefer that over surface water that is actually more “pure”. Similarly, if you normally drink water from a private well that you don’t add chlorine to, you likely dislike the taste of “city water”.

    The common offenders for bad tasting water are excessive chlorine and some specific organic compounds. Both of these flavours can be removed using a granular activated carbon filter (e.g., a Britta), but you can actually remove the chlorine by just letting your water sit in the fridge for a while.


  • Some facts I posted in another thread about this topic;

    Background info.

    • PFAS is a class of chemical substances with varying properties, but in general act as surfactants.

    • PFAS are considered carcinogenic and impact birth weight.

    • PFAS contain a carbon-fluorine bond, which is a very strong bond that does not naturally degrade.

    • Some PFAS will naturally decrease concentration over time, but only to be transformed into other compounds that will not (often PFOS).

    Regulation.

    • The US EPA has taken the approach of regulating a select few PFAS, generally based on their known toxicity. PFOA and PFOS will essentially be limited to a concentration of zero.

    • The US EPA has been working on this for years. Mr. Biden did not snap his fingers and make a regulation. These things move much slower than that, and the industry generally feels that this process moved too quickly because there is limited understanding of how much PFAS exists in drinking water.

    • Health Canada has proposed a guideline which limits PFAS to 30 ng/L (ppt) as a total sum of all compounds that can be accurately measured. Currently their guidelines limit PFOA to 200 ng/L and PFOS to 600 ng/L. Health Canada does not regulate your water provider through, that is up to your provincial/territorial government, which may have different guidelines than this.

    PFAS in the environment.

    • PFAS is ubiquitous in the environment due to its travel through the water cycle. It exists in Antarctic ice and on top of Mount Everest.

    • Usually the largest sources of PFAS in drinking water are firefighting training areas that used PFAS containing foams (airports and military bases), landfills, certain manufacturers (metal plating, paper, semiconductors), and municipal wastewater. There are many more sources than this though.

    • Landfills and municipal wastewater tend to be the highest mass loading of PFAS because of the ubiquity of PFAS in consumer products.

    Treatment.

    • PFAS can be destroyed using electrochemical and thermal methods, but these are not feasible for drinking water treatment.

    • The current approach for drinking water treatment is adsorption to either granular activated carbon (GAC) or ion exchange resin.

    • Treating PFAS at the source is always the goal instead of treating it at a water treatment plant.

    Feel free to ask questions, I will do my best to answer them!


  • Some facts:

    Background info.

    • PFAS is a class of chemical substances with varying properties, but in general act as surfactants.

    • PFAS are considered carcinogenic and impact birth weight.

    • PFAS contain a carbon-fluorine bond, which is a very strong bond that does not naturally degrade.

    • Some PFAS will naturally decrease concentration over time, but only to be transformed into other compounds that will not (often PFOS).

    Regulation.

    • The US EPA has taken the approach of regulating a select few PFAS, generally based on their known toxicity. PFOA and PFOS will essentially be limited to a concentration of zero.

    • The US EPA has been working on this for years. Mr. Biden did not snap his fingers and make a regulation. These things move much slower than that, and the industry generally feels that this process moved too quickly because there is limited understanding of how much PFAS exists in drinking water.

    • Health Canada has proposed a guideline which limits PFAS to 30 ng/L (ppt) as a total sum of all compounds that can be accurately measured. Currently their guidelines limit PFOA to 200 ng/L and PFOS to 600 ng/L. Health Canada does not regulate your water provider through, that is up to your provincial/territorial government, which may have different guidelines than this.

    PFAS in the environment.

    • PFAS is ubiquitous in the environment due to its travel through the water cycle. It exists in Antarctic ice and on top of Mount Everest.

    • Usually the largest sources of PFAS in drinking water are firefighting training areas that used PFAS containing foams (airports and military bases), landfills, certain manufacturers (metal plating, paper, semiconductors), and municipal wastewater. There are many more sources than this though.

    • Landfills and municipal wastewater tend to be the highest mass loading of PFAS because of the ubiquity of PFAS in consumer products.

    Treatment.

    • PFAS can be destroyed using electrochemical and thermal methods, but these are not feasible for drinking water treatment.

    • The current approach for drinking water treatment is adsorption to either granular activated carbon (GAC) or ion exchange resin.

    • Treating PFAS at the source is always the goal instead of treating it at a water treatment plant.

    Feel free to ask questions, I will do my best to answer them!