One of the major problem areas associated with wastewater, in general, are problems associated with odors. The incoming wastewater carries unpleasant and strong orders of biological (fecal) mater and ammonia. Partially treated or treated wastewater that is allowed to sit without air, reduces carbon, phosphorus and eventually sulfur compounds. These sulfur compounds can then be released causing a rotten egg odor.
A main focus of the wastewater treatment process is to provide sufficient air (oxidation) and mixing to prevent the formation of odor causing compounds and where practical gather foul smelling air and treat it prior to release to the atmosphere.
Influent Odor Control System
The quantification of treatment criteria for odors is often difficult. Perception of odor by the public is difficult to gauge and the sensitivity of the residents surrounding a plant can vary depending on prevailing winds, humidity, operation of the plant, and location relative to the primary odor sources. Although no specific criteria have been discussed, reduction of odors to minimal levels at the fence line is a common goal. This criterion does require a high level of odor treatment – normally above 99% for most constituents. A wet scrubbing (dual stage tower) was installed for the application. This technology has been successfully by many city for to control odors.
The North Olmsted Wastewater Treatment Plant is equipped with 2 standalone wet scrubber odor control systems located at the plant’s PTF and solids handling building.
Odor control in the Preliminary Treatment Facility collect air flow from the screens, channels and grit Headcell. Under this scenario, air is pulled through the Headcell, then through the screenings room and finally exhausted to odor control. The new odor control system is located in the existing Mixing Flocculation Building. The wet scrubber is provided with a sodium hypochlorite and caustic feed system.
Odor control at the solids handling building is located in a separate room, immediately adjacent to the plants’ centrifuge/conveyor equipment. Similar to the preliminary treatment odor control, a two stage, modular wet scrubber was installed. This wet scrubber is also equipped with a sodium hypochlorite and caustic feed systems.