How to Treat Hydrogen Sulfide

Although the name "Hydrogen Sulfide" may be unfamiliar, the smell likely is not. When present in water supplies, hydrogen sulfide produces a very distinctive "rotten egg" smell. Even 1 part per million of hydrogen sulfide in the water supply is enough to tarnish silverware, stain laundry, and discolor porcelain fittings. Although it doesn't present a major health risk, there is clearly reason to treat water to remove hydrogen sulfide before allowing it into a home's plumbing. There are several common strategies to do so.

Instructions

• 1

  Aerate the water. This is the simplest solution and requires no added chemicals. In an aeration system, incoming water is sprayed into a large tank, or air is sprayed into the water. In either case, the sulfide gas separates from the water as it is sprayed, and can then be vented out of the tank. This may not remove all the hydrogen sulfide from water and is best used when it is present in concentrations of 2 milligrams per liter or less.

• 2

  Pump the water through an ion exchange unit. These units work on the same principle as a water softener, passing the water through a resin that swaps charged particles (ions) for the sulfide molecules in the water. When removing hydrogen sulfide, these units replace it with sodium chloride (salt) which may lead to overly salty tap water.

• 3

  Add chlorine. This can treat hydrogen sulfide in two different ways. First, the chlorine can be added in a concentrated dose to the water source. This is called a "chlorine shock" and kills the bacteria that produce the hydrogen sulfide in the first place. They do, however, naturally regenerate quite quickly in most cases. Chlorine can also be used to oxidize the sulfide into solid hydrogen sulfate, which can then be removed from the water with a filter. This is the most common way of treating water with hydrogen sulfide contamination, especially if levels are above 6 milligrams per liter. The chlorine needs to mix with the water for at least 20 minutes, and the water must then be passed through an activated carbon filter to remove the chlorine and left over hydrogen sulfide.

• 4

  Pass the water through an oxidizing filter. These filters use either manganese oxide (called manganese greensand), zeolite or ozone to turn the hydrogen sulfide into solid sulfates. Manganese greensand filters must be regularly regenerated by the addition of potassium permanganate. This is a dangerous chemical that must be handled carefully. Adding ozone gas or hydrogen peroxide also works well, but both are less often used than greensand filters.

• 5

  Use a carbon filter. Traditional activated carbon filters, used to remove all sorts of mineral contamination from drinking water, are only useful on lower concentrations of hydrogen sulfide (below 1 milligram per liter). Newer "carbon catalyst" units, however, first filter and then oxidize the sulfide and can handle higher concentrations. They only work with at least 4 milligrams per liter of dissolved oxygen in the water; this may have to be added separately. In many treatment systems, carbon filters are used downstream from other oxidizing filters to remove the last little bit of hydrogen sulfide.