There are various ways to control wastewater treatment plant odors — chemical scrubbers, biofilters, carbon adsorption systems and others. They involve varying levels of capital, operation and maintenance costs.

An alternate approach promises effective odor control at lower total cost of ownership while creating healthier work environments. The system, from Aerisa, is engineered to address a wide range of airflows and to suit applications that include headworks buildings, dewatering rooms, truck loading facilities, process tank headspaces and pump stations.

The Aerisa technology pushes ionized air containing positively and negatively charged oxygen molecules (O₂⁺ and O₂^-) into the spaces where the odors are released. These ions attack contaminants there; the resulting odorless air is then discharged to the outside. The company says the technology can be easily retrofitted in most municipal wastewater treatment facilities. It has a compact footprint, is energy-efficient and leaves no chemicals or spent carbon to regenerate or dispose of.

While traditional odor-control systems treat air after it has been exhausted from a space, the ionization treats the odorous air in place. It creates a highly ionized airflow, delivers it to the space and destroys the offensive gases as they are produced. That means workers inside the spaces are not exposed to the odors.  

The equipment consists of an air-handling unit that contains a blower, a bank of ion generators and a particulate filter to protect the ion generators. Ambient outside air is blown across the ion generators, which strip electrons from oxygen (O₂) molecules to produce clusters of positive and negative oxygen ions. These clusters are delivered to the space through specialized ductwork, and there they react with the odorous gases.

For example, when the ion clusters come in contact with ammonia, which is NH₃, the ammonia molecule is converted to the byproducts of nitrogen gas (N₂) and water. In the case of hydrogen sulfide (H₂S) the byproducts are hydrogen, oxygen, water vapor and elemental sulfur, a non-odorous particle that falls out of the air.

In northern climates, to mitigate the impact of drawing cold outside air indoors, the technology can be augmented with a gas-fired heater inside the air handler. The system needs minimal maintenance; only the ion generators need periodic replacement. For more information, visit www.aerisa.com.