Methane again!

Hi All,

I still haven't resolved my methane problem with the new drilled well, I've put a lot of thought into the problem and I'm finding out that most plumbers/plumbing supply outlets look the other way when a question regarding methane removal is asked.

As a recap, I have methane, and sulfur. I am using an existing chlorination system to erradicate the sulfur, and it works. The chlorine (actually household bleach) is then removed by an activated carbon filter. Unfortunately, but I can't get any hard yes or no answer, methane and chlorine combine to form chloroform, a carcinogen.

My questions:

1) Bleach I'm assuming acts as chlorine in this respect?
2) Is the bleach removed from the water by the activated carbon filter thus no chloroform is formed, or has the bond to produce chloroform already happened before the bleach gets removed and the chloroform exists?
3) There are methane removal systems available as evidenced by the replies on this forum to my original question, but I have a little concern on the venting of the methane from these systems. I have an idea, maybe somebody can tell me if it will work. If I put in say a 200 gallon tank in the ground near the house, pump the water from the drilled well directly into it, and use an aerator stone - the same principle as used in fish aquariums, would this erradicate the methane? (Of course the tank would have to be vented, but it's away from the house and of less concern).
4) When I draw a glass of water from the faucet, the methane fizzles out from bottom to top, when the water clears is all the methane presumed now gone?

Thanks again, if anybody has any insight to answer these I'd appreciate it.

Gary

First your questions:
1) Bleach I'm assuming acts as chlorine in this respect?
Yes, bleach contains sodiumn hypochlorite which provides free chlorine.

2) Is the bleach removed from the water by the activated carbon filter thus no chloroform is formed, or has the bond to produce chloroform already happened before the bleach gets removed and the chloroform exists?
The disinfectant byproducts (more than just chloroform) are produced when the chlorine reacts with organic compounds in the water. The activated carbon will remove much (but not all) of both the chlorine and the byproducts, if you change the carbon filter when it is depleted.

3) There are methane removal systems available as evidenced by the replies on this forum to my original question, but I have a little concern on the venting of the methane from these systems. I have an idea, maybe somebody can tell me if it will work. If I put in say a 200 gallon tank in the ground near the house, pump the water from the drilled well directly into it, and use an aerator stone - the same principle as used in fish aquariums, would this erradicate the methane? (Of course the tank would have to be vented, but it's away from the house and of less concern).
An aerator stone is intended to ADD air to the water. It would not be my choice to removed gas from the water. All of the systems to remove methane must be properly and safely vented to the outdoors.

4) When I draw a glass of water from the faucet, the methane fizzles out from bottom to top, when the water clears is all the methane presumed now gone?
Some but not all is removed. That is a form of "stripping". The effectiveness will be increased if you have a good aerator on your faucet and you let the water fall some distance before it hits the glass. The bubbles are probably a misture of air and methane.

Comments on systems:
Removing gasses from water by "stripping" with air in a "packed column" is a standard chemical engineering process. That is what I described in a reply to your earlier post of several weeks ago. Spraying into the atmosphere is also a stripping process that would probably meet your requirements. Methane, hydrogen sulfide, and radon can all be removed to various degrees by stripping.

The "spray it into a tank with air and vent the mixture" process described by another poster (I think "Speedbump" but I'm not sure) is a stripping process that also works. It is usually used for small systems where the avoidance of an added pump is economically significant, or where compactness is important. You can do a cost comparison to pick the system you want.

Your "aerator stone" is designed to ADD gas (air) to the water. It is not likely to do what you want.

Chlorine and some of the disinfectant byproducts can be removed by activated carbon. Some chlorine can also be removed by stripping. Of course, that removes the disinfecting qualities of the chlorine but you shouldn't need it with a deep well. Since you are not likely to have giardia or cryptosporidium in a deep well you don't need much contact time even if you want chlorine to kill bacteria and viruses.

Adding oxidants such as air or chlorine to the water will result in oxidation of iron and some sulphur compounds, resulting in precipitates (suspended solids, stuff you can see). Suspended solids can be removed by a filter.

If you have and want to remove suspended solids, you have two practical choices of fitlers; the backwashable filters that look like a water softener without the salt system, and cartridge filters.

Backwashable filters will remove large particles and some small particles that may produce a large floc that can be filtered. Large versions of granular backwashable filters are used in water treatment plants with special chemicals that promote flocculation.

Cartridge filters cost less to start with but the cartrtidges must be changed. They can be used to remove smaller particles than home-type granular filters, down to about 1 micron (1 millimeter = 1000 microns). You need a good filter if you are going to use an activated carbon filter to remove chlorine and chlorine byproducts because otherwise the particles will plug the carbon filter.

If you are in an area where you get radon in the water, the carbon will remove it. The cartridge will collect enough radon to become mildly radioactive so you should be careful when disposing of it. The low-energy radioactive particles will be confined by the filter housing.

The appropriate way to select, design, and install a system is to:
1. Define what you want to accomplish (performance requirements).
2. Put concepts on paper that might accomplish your requirements.
3. Analyze the systems (figure out if they will meet your requiremenmts).
4. Estimate the cost of the systems (initial and operating costs).
5. Select and install the selected system.
6. Monitor performance and adjust parameters to get the performance you need.
7. Maintain the system to keep getting the performance you need.

If money is not an issue, you can hire someone to do all of that for you.

If you have the time and inclination, you can do it yourself and probably save half the cost.

That might have been me. I am not sure if my system would take care of the methane or not. If air stripping would work just as it does for sulphur then it would.

My system uses a small galvanized tank along with an air compressor which injects air into the water stream just before entering the top of the galvanized tank. This is all done under pressure as opposed to an open vessel. The air and gas is let out of the tank by means of a air volume control (air release valve) when the water gets to that level. The only additional thing may be to vent the air release valve to atmosphere if this tank has to be in doors. My system does not require another pump either, just the well pump.



bob...

Gary, IMO you need to talk to water treatment dealers. We know water and the equipment to solve water quality problems. As you have found, most plumbers and supply houses don't get into much more than selling softeners and common filters.

BobNH has answered your questions but I don't agree with a backwashed carbon filter removing much DPBs/THMs. There will not be proper contact time but... The use of chlorine in any form is not advised with methane in the water.

Speedpumb's system will work although it may not get all the methane but if it gets H2S out of water, it should get all the methane too.

IMO sprayed aeration with atmospheric storage is the best way to treat methane. That is not true air stripping, and you don't need air stripping type equipment. The sprayed atmospheric aeration insures total removal of all dissolved gases. I have used one type that is made for residential/commercial use and can fit through regular house size doors or be installed outside in non-freeze environments; two different models. The indoor model requires forced venting to up and away from the building windows/doors etc. while the outdoor model does not have a blower. You'd use 3" PVC pipe.

A stone bubbler requires an air compressor. Why bother with burying a tank and a compressor and running power to it when there is a system designed to treat dissolved gases without those needs and extra expense and maintenance?

I have experience with buried water tanks as you want to use. A buried tank is not going to meet the venting requirement; which means an opening to the tank that will probably be at ground level with the tank containing your supposedly "potable" water. Of course you can have a vent pipe standing up out in the yard. Also, you'll be dealing with cleaning that tank and that can be difficult to impossible. And usually you'll have an algae problem in a buried tank with a manhole to enable cleaning and the required sanitation. That may require more water treatment equipment in the house; especially disinfectant type equipment. That's more expense and maintenance. If you want to, you can contact me for more information.