Having no public restrooms within a 15 minute walk is worse than having no public benches. Cities shouldn't be allowed to exist without either of them. Also, ground-level restaurants and supermarkets should not be allowed to reject non-customers from using them.
Bulk urine is a good source of urea/ammonia which has commercial value, especially considering the global fertilizer shortage.
> Also, ground-level restaurants and supermarkets should not be allowed to reject non-customers from using them.
The single biggest reason why there are no public restrooms within a 15 minute walk in many American cities is because the visibly homeless fuck them up, through crazy vandalism, deliberately dirtying them with their bodily fluids, doing drugs in them, etc. Businesses being legally compelled to let non-customers use their bathrooms would exacerbate this problem.
> Bulk urine is a good source of urea/ammonia which has commercial value, especially considering the global fertilizer shortage.
It's not cost effective to set up systems to capture the ammonia from the urine of people using public restrooms in urban areas, or else people would be doing that. There are municipal sewage treatment plants that sell some of the byproducts from treating human wastewater as fertilizers, because that is cost-effective at their scale and level of centralization.
The mulch fertilizer from sewage is an impure toxic mess contaminated with PFAS that permanently destroys farmland. It should be banned and never be used. It has already destroyed a significant chunk of American farmland.
It is wholly different from urine diversion and ammonia recovery. The two concepts have little in common. It shouldn't require a municipal facility if the residual liquid can be drained into the sewage. It is meant to be a commercial endeavor.
Once the urine is contaminated and diluted with regular wastewater, it's already too late to extract urea/ammonia from it.
Even this concept is predicated on being able to extract ammonia with sufficient purity without PFAS, pharmaceuticals, and other residue.
Perhaps in urban settings it does. In the suburbs it is not an issue. Also, it is not an issue if someone looks after the toilet every hour, vacating anyone who doesn't belong.
This made me go down a rabbit hole of techniques for separating sodium and chloride from urea/ammonium/ammonia solutions. I wonder if it could ever be made viable when compared to the Haber process for ammonia production.
Also, phosphorus is the more scarce fertilizer, I think. I remember reading a paper from a Chinese lab that was trying to figure out how to cheaply isolate phosphorus fertilizer from commercial pig farm feces. They decided it wouldn't be cost effective.
Filtration tchnology is evolving by virtue of nanotech evolving. What was cost prohibitive yesterday shouldn't necessarily remain so tomorrow. Someone does have to chase it though for it to get there.
Bulk urine is a good source of urea/ammonia which has commercial value, especially considering the global fertilizer shortage.