Dear Tamer, Two forms of ...

Dear Tamer,

Two forms of sulfur are commonly found in drinking water supplies: sulfate and hydrogen sulfide. Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic water supplies

Sulfates are a combination of sulfur and oxygen and are a part of naturally occurring minerals in some soil and rock formations that contain groundwater. The mineral dissolves over time and is released into groundwater.   In addition, this problem may be related to a community hazard, such as a: landfill, leaky fuel tank, pipeline, old septic system, chemical lab, and many other community hazards.  It may be wise to run a Community Hazard Report and Identify the Historic / Active Hazards within Your Neighborhood.

Sulfur-reducing bacteria(SRV), which use sulfur as an energy source, are the primary producers of large quantities of hydrogen sulfide. These bacteria chemically change natural sulfates in water to hydrogen sulfide. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. These bacteria usually flourish on the hot water side of a water distribution system.High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener. When a hydrogen sulfide odor occurs in treated water (softened or filtered) and no hydrogen sulfide is detected in the non-treated water, it usually indicates the presence of some form of sulfate-reducing bacteria in the system. Water softeners provide a convenient environment for these bacteria to grow. A "salt-loving" bacteria, that uses sulfates as an energy source, may produce a black slime inside water softeners.

Sulfates and hydrogen sulfide are both common nuisance contaminants. Although neither is usually a significant health hazard, sulfates can have a temporary laxative effect on humans and young livestock. Sulfates also may clog plumbing and stain clothing.  Hydrogen sulfide produces an offensive "rotten egg" odor and taste in the water, especially when the water is heated. If the odor is stronger in the electric water heater, we recommend the following:

(i)  Turn off the system and drain the tank.  Note any anomalies, such as: the color and odor of the water, coatings, precipitates, or other solid materials.

(ii)  Allow the tank to refill, but raise the temperature setting of the tank to a level above 60 degree Cent.

(iii)  Allow the tank to stay at this level for at least 6 to 10 hours.
d. Turn off the system and reduce system to the normal temperature setting.
(iv) Drain any discolored water and then allow the tank to refill.
(v) If the odor goes away, it was most likely a bacteria growing in the tank that is causing the problem.

(vi)  If the odor returns immediately, it is likely a chemical reaction between the water and the sacrificial anode used in the system.  It would be advisable to check the quality of the water entering the tank.

Water Treatment Methods s to Remove Sulphur Odours

The choice of water treatment method to remove sulphur smells depends on the cause of the problem and its severity. The treatment methods discussed here are listed alphabetically and include comments on the level of sulphur for which the method is suitable.

Chlorine (Bleach) Injection Systems To Remove Sulphur Odors

Higher levels of hydrogen sulfide (H2S) in the water supply in the 7-10 ppm range are often treated by using a chlorine injection system. Controlled by a pump and mixed in a mixing tank, a bleach solution (chlorine) is injected into the water supply by a control that uses a timer or a device that measures water consumption. The mixing tank is required to allow sufficient contact time between the chlorine molecules and the (H2S) (or in some cases also bacteria) in the water supply to oxidize the contaminant.

Because this chlorine/bleach oxidation process produces a sediment (such as sulphur particles or sulphur dioxide particles), a chlorine injection system is almost always combined with a filtering system downstream from the chlorinator. The filter, often combining a sediment filter stage with an activated charcoal stage, removes both particulate sediment and also the residual "chlorine" odor from the water.

Regards,

Prem Baboo