Systems that were already using activated carbon or ion exchange for organics removal may have some treatment capacity, but otherwise the first systems specifically for treating drinking water are being designed and constructed now. There are contaminated sites that already have treatment or containment in place.
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.
It’s “forever” in the environmental sense that they don’t break down naturally (or at least very, very slowly). That said, “forever chemicals” is more of a media buzzword than a term that scientists use.
Water is disinfected with either chlorine, chloramine (ammonia + chlorine), ozone, or UV light. In North America chlorine is almost universal because it provides disinfection residual, which keeps water safe while it is travelling from the treatment plant to the consumer. Fluoride is added solely as a supplement to improve dental health.
Groundwater does not typically contain many particles because (a) water moving through the ground gets naturally filtered and (b) groundwater is typically anoxic, which causes certain things to dissolve. Accordingly, most filtration systems for well waters are focused on removing those dissolved contaminants.
The most common well water treatment is water softening. These systems remove hardness from your water (cations, typically calcium and magnesium). Water softeners are usually ion exchange based, so basically you are swapping out the calcium or magnesium for sodium or potassium.
Some wells have dissolved metals (manganese or iron are common) that can stain fixtures and laundry (manganese can also cause health problems for children). Arsenic is also common in some regions, which causes cancer, and hydrogen sulfide, which causes a rotten egg smell. All of these can be removed using a special filter system, which uses catalytic oxidation to oxidize and remove these contaminants. These systems typically use manganese oxide (often called greensand) and chlorine.
To remove salts or microbial contaminants it is common to use a reverse osmosis (RO) membrane filtration system. These systems reject salt ions and microorganisms by a combination of small pore sizes and charged surfaces - the salt ions can’t pass through a positively charged surface because of electromagnetic repulsion.
If you have well water you should get it tested regularly and make sure your treatment system is appropriate for your water!
There are two approaches here. First, if you have a well, you can get a pressure filter system installed. Different systems achieve different things, such as reducing the hardness or removing iron and manganese or sulfur.
Second, if you have municipal water, you could get a tap filter. This type of filter goes directly on your tap and is used to remove particles. Usually these are overkill, but they use them in areas with lead pipes to reduce lead exposure (they will remove the pipes eventually, but it will probably take a decade or more in some cities). Your classic pour over Britta doesn’t do anything for particles, instead it adsorbs certain dissolved contaminates and removes residual chlorine. This may make your water taste better, but it won’t protect you from lead if you have lead pipes.
Unfortunately there really isn’t a replacement for these types of adsorptive filters because they work using activated carbon. Activated carbon comes from natural products (primarily coal, but also coconut shell and other materials), but it has to undergo a heating process to “activate” it, which goes well beyond what you can do at home. That said, other than the improved taste there is likely no benefit to using it, and you can dechlorinate your water by simply leaving a jug in the fridge for a few hours.
If you are on a well I can explain some of the other options!
That’s certainly unusual. Does this occur after having water sit, or is it after cleaning them? You should call your water provider to report it and ask for their advice. If it isn’t something your neighbours are dealing with then it’s probably (a) something to do with your dish soap, or (b) the plumbing in your home. Regardless, that’s not normal and you should call your water provider.
Water infrastructure is very expensive and the industry is dealing with more problems than ever before (impacts of climate change, PFAS, aging infrastructure). Lots of money and effort is needed to fix these problems, but it is worth remembering that tap water is safe for the overwhelming majority of consumers in developed countries. It is worth knowing more about your drinking water, but don’t assume that your water is dangerous because of headlines like this.
Feel free to ask any specific questions you might have about your water!
Most toilet papers are fine, although some systems struggle with Costco’s stuff. Toilet paper is designed to break apart in water. That said, you shouldn’t flush any other products. Paper towels don’t break down the same way, and wipes will almost certainly cause damage, even if they are marketed as flushable!!
Math using janky excel spreadsheets, tell drafters what we want drawings to look like, but mostly a lot of reading and writing. The secret to engineering (at least in my area) is that communication skills are just as important as technical understanding.
I don’t know the details about alum production (assuming that is what you are referring to), but there are many alternative coagulants available now. Sure the supply logistics would be incredibly challenging and many people would have to boil their water or use point-of-use filters, but this take is pretty doomer in my opinion. Most plants use alum because it’s cheap and easy, not because it’s their only option.