SOURCE AND IMPACT OF METHANE IN DRINKING WATER
Methane (CH4), often called marsh gas, is the primary component of natural gas. It is commonly found where landfills once existed and is generated from decaying of plants or other carbon based matter. It can also be found in and around oil fields. Methane is colorless, odorless, nearly invisible, highly flammable, and often found in conjunction with other gases such as hydrogen sulfide. Methane in groundwater also may be the result of contamination caused by leaks from underground methane storage fields or landfills. Elevated levels of methane released into a building may lower oxygen levels and produce a fire or explosion hazard. Even though methane gas gives water a milky appearance which makes it aesthetically unpleasant, there are no known health effects. Methane is not considered toxic, but it is an asphyxiant at a concentration of over 50 percent in air (it displaces oxygen). Therefore, the primary risks for methane would be asphyxiation in a confined or poorly vented area or a potential explosion hazard. As a safety measure, the natural gas industry adds mercaptans to the produced methane gas that enters the pipeline and inside home. The mercaptans produce a very pungent odor so that gas leaks will be noticed, but unprocessed methane gas tends to have no odor. It is critical to note that some unprocessed methane gas may contain long chain hydrocarbon molecules that can create an odor.
There are two main ways methane can get into drinking water. Methane can be naturally produced by subsurface bacteria and the decay of organic matter. Methane also can leak from deep underground storage fields or landfills. As the methane works upward from the source to the surface it may dissolve in groundwater. If this groundwater is used as a source of well water, then the dissolved methane can enter the customer’s home.
TREATMENT OF METHANE IN RESIDENTIAL WELL-WATER
Aeration or degasification is the only way to eliminate the problem of methane gas. Venting the casing and/or the cap of the well will reduce the problem of methane in the water, but may not completely eliminate it. Another method is to provide an atmospheric holding tank where the methane laden water cap be vented to allow the gas to dissipate. This method may not be 100% effective either. An aerator or de-gasifier is the proper piece of equipment to utilize for the removal of methane. Water is introduced through the top, sometimes through spray nozzles, and allowed to percolate through a packing material. Air is forced in the opposite direction to the water flow. The water is then collected in the bottom of the unit and repressurized.
When considering installation of aeration units, other water quality issues must be taken into account as well, such as levels of iron, manganese and other contaminants. Water with high levels of these types of contaminants may need to be pre-treated in order to prevent clogging the aeration unit. Disinfection equipment may also be recommended since some aeration units can allow bacterial contamination into the water system. A reverse osmosis system followed by a closed-tank aeration unit can help achieve desired removal of heavy metals AND dissolved gases such as Radon, Carbon dioxide, Methane, and Hydrogen Sulfide.
3M Under-Sink Reverse Osmosis Water Filter System 3MRO501
Some of the product features of this Reverse Osmosis System include:
- Reduces: particulate, chlorine taste and odor, arsenic, barium, cadmium chromium (hexavalent), chromium (trivalent), copper, parasitic protozoan cysts, fluoride, lead, radium, selenium, p-dichlorobenzene & toxaphene (both VOCs), TDS, turbidity, and nitrate/nitrate
- Membrane rated daily production rate of up to 36.8 gallons per day (GPD)/139.2 liters per day (LPD)*
- Sanitary Quick Change (SQC) cartridge design helps provide fast & easy cartridge change-out
- Advanced multi-stage reverse osmosis water filtration process helps provide cleaner, better tasting drinking water
- Advanced automatic shut-off helps promote peak efficiency and water conservation
- System includes compact booster pump design, which can be installed centrally in a home with lines run to multiple faucets and appliances
Figure 1 describes the product specification for this system:
Figure 1 – Product Specifications
Methane and other dissolved gases such as Hydrogen Sulfide, Carbon dioxide, etc. can cause unaesthetic impacts in drinking water such as taste and odor, and pose fire or explosion hazard. These gases are mostly found in well water which could also have other contaminants such as heavy metals and radionuclides. Therefore, a Reverse Osmosis System followed by Aeration is the best treatment to resolve this issue.
Saniwater consultants are experts in drinking water filtration systems and will provide the necessary guidance to their customers with regards to selection, installation, and maintenance of Reverse Osmosis Units. The technicians at Sani Water are skilled to assist with the installation and maintenance of the 3M Under-Sink Reverse Osmosis Water Filter System (3MRO501).