Like many coastal communities, Huntington Beach has a very effective storm drain collection system. During the rainy days the storm water passes through this collection basin directly to the flood control channel, and during the non-rainy days, nuisance water is collected by the drainage system in wet wells.

One particular storm drain wet well recorded level of Total Sulfides as high as 6 mg/l, which incidentally generated H2S gas (nuisance odor that smells like rotten eggs).

At this point a licensed Civil Engineer with the City of Huntington Beach investigated bottom aeration with air stones as a way to reduce the level of Total Sulfides, Dissolved sulfides, Dissolved H2S, and H2S gas odor. His research indicated the possibility of such reductions.

The City of Huntington Beach then purchased two of the Koenders electric pond aeration systems, with 4 aeration stones ($1000+) and began aerating the wet well 24/7. The monthly cost in electricity for each of the 1/4 hp units is minimal. The engineer's study also indicated that alternative solutions, such as injection with Hydrogen Peroxide, would have been substantially higher in cost (as high as $10,000 per month in chemicals).

The water in the wet well was re-tested about 6 weeks after the installation and activation of the of the aeration stone system, the results were zero for Total Sulfide and Dissolved Sulfides, zero for Dissolved H2S, and no H2S odor was detected. The City is currently very pleased with the result of the aeration stones, and further testing is continuing.

Why does bottom aeration work?

Sulfur is more soluble in air than water. With continuous bottom aeration, the sulfur is transferred into each of the rising air bubbles, brought to the water's surface and into the atmosphere.

The key factors are:

1. Bottom aeration - continuously rotates the water from bottom to the top of the basin.
2. The size of each rising bubble has to be big enough to rotate the water to the surface.... but not too big for the transfer of sulfur into the bubble.

The Koenders Air Stone diffuser produces the perfect sized bubble for this process.

Bottom aeration also removes nitrogen, phosphorous, nitrites, and other gasses.