While the use of ozone for controlling hydrogen sulfide odors is not a new methodology, there are times when ozone is not totally effective when injected directly into a wet well. For instance, if ozone does not thoroughly fill the headspace or blanket the wastewater, odors can escape through hatch covers and/or vents.
A new approach to odor control that eliminates escaping odors is used in a Savannah, GA., lift station where hydrogen sulfide levels ranged from 66 to 100 ppm.
This turnkey package system was designed and built by Ozonology Inc. and distributed by Parson Environmental Products. It uses a blower to create negative pressure in the wet well, drawing odors into a stainless steel vessel containing vapor phase activated carbon. Odors are adsorbed by the carbon bed, a proven treatment method for hydrogen sulfide and other odor constituents.
In a typical activated carbon system, the carbon has a limited capacity for adsorbing odors and eventually must be replaced with virgin or regenerated carbon. In the Savannah system, ozone is used to continuously regenerate the carbon bed.
Ozone is injected into the incoming odor stream in a contact chamber ahead of the carbon bed. Some oxidation reaction with odors occurs in the contact chamber, which reduces the odor load impacting the carbon bed. However, the primary function of the ozone is its reaction with hydrogen sulfide (and any other oxidizable constituents) adsorbed by the carbon, thus providing continuous regeneration.
The turnkey package system consists of two components: One is a weatherproof building that houses the ozone generator and an oxygen generator with integral air compressor (to provide feed gas for the ozone generator). The other is a stainless steel vessel for the carbon, with an induced-draft blower attached to the clean air exhaust.
With these package systems, installation can be made in a matter of hours, requiring only anchoring of the two components to the pad of the wet well, connection of a 120vAC line to the blower and equipment building, running a 5-in. flexible hose between the wet well vent and carbon vessel. The components may be placed together, or separated, thus accommodating all configurations of wet wells. The system may also be used for treatment plants and other facilities where fugitive odors are a problem.
