So I thought I'd share a bit of an experiment I did in my freshwater 75-gallon in regards to Nitrates that I hope other people will find helpful. I am going to try to share this in as many places as I can, as I think I'm the only one who's tried it, and it has been by far the most successful method in significantly reducing Nitrates. It's long, sorry, but I think it's really important. Basic point is that methanol is the best option if you are serious about reducing Nitrates in your freshwater aquarium long-term. So I have a pretty heavily stocked goldfish aquarium that is also planted. I was doing ok with Nitrates for a while, since the fish were small, I was siphoning out the waste about every other day, and the tank wasn't as heavily planted as it is now (contrary to popular opinion, a planted aquarium can in certain instances INCREASE Nitrates, since rooted plants are very efficient at trapping sediment and waste, thus making it difficult to siphon and for the filters to capture it). However, the fish have grown quickly, and I had to keep them well-fed, because they kept picking at the plants. I eventually moved a couple of the big ones out into the stock tank with the pond fish, but Nitrates were still way too high (like 80 ppm+). Some of you may have seen my previous argument about whether plants, water changes, or anaerobic bacteria are more efficient/effective for reducing Nitrates, and I said the anaerobic bacteria is what is most important. Going off of that, I attempted to increase my anaerobic bacteria population, both by creating more appropriate media for them to grow on, and more importantly, adding Red Sea NO3/Po4 Remover (methanol). I was using this in my reef aquarium, and it worked really well, almost too well (I lowered the dose, even though my bioload is bigger now). The idea behind methanol dosing is it gives the bacteria a source of inorganic carbon, which is often a limiting nutrient for them. It is used in wastewater treatment, and is the most effective and safe compound to use. Everywhere I read on forums said they either didn't know if it could be used in freshwater or said not to do it (but as usual, couldn't back up their statements with legitimate research). I read; however, that most fish and plants are quite tolerant of it, and plants even usually perform better with reasonable doses. If you are having a Nitrate problem, I can tell you this is by far the best way to reduce it. Aquariums are all about recreating natural processes as closely as possible. Most freshwater ecosystems have very effective Nitrate absorbtion through anaerobic bacteria found in the anoxic soils of wetlands. We need to try to recreate this as closely as possible.
My intention was not to say you where lying about it being used in waste water treatment, quiet the opposite in fact. I am very familiar with the waste water treatment process and used to work for a company designing waste water treatment facilities. I understand what you are saying completely, I was simply supplying reasons as to why it does work in water treatment. Reasons why it is much safer to use in large scale waste water treatment. There is a lot of chemistry behind it, I do not know what your chemistry background is, I presume some based on your work history, chlorine (which is used very often in waste water management) or high intensity UV light, reacts to break down or "neutralize" lots of "heavy" organic matter. Large organic molecules that make it thruough all of the biological filtration and even the settling tanks are neutralized on the way out of the waste water facility.
A very interesting post (and experiment), along with some interesting comments. I guess I should keep my response to my opening sentence - but 'what the hey' - for what it is worth (hopefully my comments will not be misconstrued or considered disrespectful by anyone):
Most advanced Wastewater Treatment facilities (and their associated treatment processes) are based on desired goals. Removing (that important trio of initials) "TKN", is usually the main goal... along with the other goal of meeting permit compliance. In most instances, conventional secondary treatment (e.g., activated sludge basin & secondary clarifiers - biological nitrification in the activated sludge basin and suspended solids via the secondary clarifiers) provide adequate BOD and Suspended Solids removal. A well designed secondary treatment process will remove about 85-95% of the Biological Oxygen Demand & Suspended Solids, and about 65% Chemical Oxygen Demand from the original influent stream. Even though "considered adequate", the treated effluent still contains organic/inorganic materials, nitrogen, and phosphorus (and because of the nitrogen still present there is additional oxygen demand as a result). This could cause a Wastewater Treatment Plant to "not" meet basic compliance standards/regulations, along with permit violations.
If a higher quality effluent is needed to meet/exceed regulations, additional treatment is needed beyond secondary treatment (e.g., nutrient removal/ denitrification, tertiary). This is where methanol
comes into play. Denitrification processes, usually incorporating some type of anoxic zone (e.g., basins/filters/reactors that can also include a fixed packing), are usually supplemented with a carbon source (more than often a dilute methanol solution is used, although ethanol is often used in anoxic rock tanks). Denitrification processes can become real 'gnarly' (in a hurry) for an operator. It's a difficult process and there are a lot of factors that come into play: like ph, temperature, methanol feed, etc.). Usually a well designed (municipal) wastewater treatment plant uses tertiary treatment for removing SS, COD, phosphorus, metals... while chlorine and UV are usually used for disinfection (Fecal Coliform).
I've got a lot of respect for the OP thinking outside of the box (with your methanol experiment and giving it a try), but more importantly: sharing your observations and results.