Biofiltration for odor mitigation in water resource recovery facilities.

Odor emissions, primarily from anthropogenic activities like waste treatment and industrial processes, pose significant challenges in urban areas, particularly near water resource recovery facilities. While these emissions are generally not toxic, they can adversely affect community wellbeing and investment, prompting stricter regulations in some regions. For example, New York State's hydrogen sulfide guidelines are more stringent than federal standards. Hydrogen sulfide, along with other reduced sulfur compounds, volatile organic compounds, and nitrogen compounds, are among the key odorants produced by water resource recovery facilities. Various methods have been explored to mitigate these odors, including chemical treatments, operational modifications, and air treatment strategies like biofiltration, activated carbon adsorption, and regenerative incineration. Among these, biofiltration stands out as an environmentally friendly option due to its high efficiency in removing hydrogen sulfide and other odorants without the need for chemicals. Biofiltration systems, including biofilters and biotrickling filters, use microorganisms immobilized in a bed of porous media to degrade odorous compounds. Biofilters, which operate with intermittent water supply, are highly effective at total odor removal. In contrast, biotrickling filters, which use continuous nutrient and water flow, are better suited for higher pollutant loads but struggle with compounds of low solubility. Key factors influencing biofilter performance include the empty bed residence time, media type, moisture content, and microbial diversity. This review explores recent advancements in biofilter technology, with a focus on the removal of hydrogen sulfide and organic sulfur compounds. It also highlights real-world applications in water resource recovery facilities and discusses critical design and operational parameters for improving odor control, such as media selection, residence time, pH regulation, and microbial management. Key studies underscore the importance of media composition and nutrient supply in optimizing biofilter performance, especially at higher pollutant concentrations. Understanding these factors will help inform future improvements in odor management for water resource recovery facilities.