Exhaust air treatment

In wastewater treatment, biological degradation processes, sludge treatment, and the storage of contaminated wastewater can generate unpleasant odors and gaseous emissions. Hydrogen sulfide, ammonia, and volatile organic compounds, in particular, can impact the surrounding environment. Targeted exhaust air treatment reduces these odor emissions, helps ensure compliance with environmental regulations, and improves the acceptance of wastewater treatment plants within their local communities.

Depending on the composition of the exhaust air and the required level of purification, various methods can be employed.

Biofilters:

Biofilters utilize the natural degradation capacity of microorganisms to remove odorous, biodegradable gaseous components from exhaust air. The contaminated air is passed through a filter bed consisting of suitable organic or mineral material, upon which microorganisms colonize. Under appropriate operating conditions, these microorganisms biologically break down the pollutants, converting them into largely harmless substances.

Biofilters are particularly well-suited for treating large volumes of exhaust air containing biodegradable odorous substances—such as those generated at pumping stations, sludge treatment facilities, or via the extraction of exhaust air from wastewater basins. To ensure reliable purification, factors such as moisture, temperature, and the airflow through the filter medium must be carefully adjusted to the specific operating conditions. When designed correctly, this method is characterized by minimal chemical requirements and low operating costs.

Activated Carbon Filters:

Activated carbon filters remove odorous substances and gaseous contaminants through the process of adsorption.

In this process, pollutants contained in the exhaust air accumulate on the highly porous surface of the activated carbon. Due to its large internal surface area, activated carbon possesses a high binding capacity for numerous organic compounds and specific inorganic odorous substances.

This method is particularly well-suited for exhaust air streams with low to medium pollutant concentrations, as well as for applications that require strict limits on residual odor levels. The choice of activated carbon depends on the substances to be removed and the specific operating conditions. Once the adsorption capacity is exhausted, the activated carbon must be replaced or regenerated off-site. Consequently, regular monitoring is essential for reliable operation.