Reflection on ozonation within a wastewater biotreatment process for synthetics degradation

Authors: VAN LEEUWEN, J - Iowa State University; BARNARD, JAMES - Black And Veatch; Koziel, Jacek; ELLIS, TIMOTHY - Iowa State University

Submitted to: Frontiers in Environmental Chemistry
Publication Type: Review Article
Publication Acceptance Date: 2/19/2025
Publication Date: 3/13/2025
Citation: Van Leeuwen, J., Barnard, J.L., Koziel, J.A., Ellis, T.G. 2025. Reflection on ozonation within a wastewater biotreatment process for synthetics degradation. Frontiers in Environmental Chemistry. 6:Article 1534405. Available: https://doi.org/10.3389/fenvc.2025.1534405.
DOI: https://doi.org/10.3389/fenvc.2025.1534405

Interpretive Summary: The 8-billion human population produces 700,000 m3 (18.5 million gallons) of wastewater per minute. Wastewater treatment plants mostly use a bacterial process, but substances such as agrochemicals are difficult to break down during such treatment. These substances degrade the environment, discolor water, and kill or inhibit aquatic organisms. Removal involves advanced and more expensive technologies than just biological treatment. In this article, researchers from ARS (Bushland, TX), Iowa State University, and industrial partners reviewed earlier research on using ozone to make such synthetic compounds more biodegradable. What is novel is that the oxidation and breakdown is achieved within a biological treatment process, whereas earlier attempts used ozone treatment before or after biological treatments. It was found that ozone treatment could be done during biological treatment without undue disturbance of the process microbes. The benefits of adding the ozone inside the bioreactor is that the biodegradables, and even potential toxicants, can be removed directly by the bioprocess. The approaches investigated at bench scale showed much promise in using an integrated biotreatment with chemical oxidation to further purify wastewater from industrial processes.

Technical Abstract: The 8-billion human population on this planet produces 700,000 m3 wastewater per minute, most of which is treated, usually with a bacterial process, to lower environmental impact. Synthetic substances in wastewater from industry, e.g. agrochemicals, pesticides, and textile dyes are difficult to degrade during such biological treatment. These substances degrade the environment, discolor water, and kill or inhibit aquatic organisms. Removal of synthetic compounds involves advanced and more expensive technologies than just biological treatment. Current technology needs improvement to become cost-effective. The body of work summarized in this article was aimed at improving biological wastewater treatment by breaking down non-biodegradable substances with ozone. What was found novel is that the ozone was not introduced conventionally either before or after, but during biological treatment. Research focused on removing dyes, methylene blue & Orange II, cyanide as test substances, and using ozonation within an activated sludge process was found to be novel and significant. There is growing evidence that a powerful disinfectant such as ozone does not necessarily inhibit beneficial organisms in a biological process. The review showed that it was indeed possible to degrade certain undesirable compounds by combined ozone oxidation and biodegradation within the bioprocess, all without serious inhibition of useful organisms, even protecting these by lowering the toxicity of some target compounds.