Continuing our discussion of applications for ozone in water treatment, we will briefly cover the topic of hydrogen sulfide. Hydrogen sulfide is found in ground water around the world. It is perceived as the odor of rotten eggs and can be smelled in air with a concentration as low as 0.001 ppm. It can also cause water to have an unpleasant taste. It can also be corrosive and result in teh discoloration of water fixtures, silverware and clothing. Aeration can be used to strip some of the sulfide out of the water, but this simply turns a water issue into and air pollution issue.
Ozone on the other hand quickly reacts with sulfides to convert them to sulfates. The first reaction is to sulfur to sulfite to sulfate. Without sufficient oxidation, solid sulfur can be formed as a colloidal suspension.
According to the stoichiometry of the ozone sulfide reaction, a ratio of 3 mg of ozone to 1 mg of sulfide to sulfate is required. In practice, the actual ratio is adjusted to 4:1. This ratio is chosen to insure a small ozone residual which will insure complete oxidation of the sulfide. In addition, a small excess will allow for some variability in the in coming sulfide concentration.
As noted above, sulfide can be stripped from the water by aeration. If fine bubble diffusers are employed to mix the water and ozone care should be taken in the location for the diffusers in a multi chamber contact vessel. The ozone should only be introduced in the first chamber to prevent stripping the sulfide. If a catalytic ozone destroyer is used, the stripped sulfide could poison the catalyst.
If you have water contaminated with hydrogen sulfide contact Spartan Environmental Technologies about an ozone based solution.