A team of Waterloo researchers have published a preprint article on the activities of complete ammonia oxidizing bacteria, better known as “comammox”, in a wastewater treatment plant.
The team includes Waterloo Biology Profs. Laura Hug, Andrew Doxey and Josh Neufeld; Engineering Prof. Wayne Parker; Biology graduate students Emilie Spasov and Jackson Tsuji and Waterloo alumna Laura Sauder.
Municipal wastewater contains ammonia that is removed by wastewater treatment plants in order to prevent eutrophication, oxygen depletion, and toxicity to aquatic animals in receiving waters.
Historically, the two enzymatic steps of nitrification, the process that removes ammonia, were thought to be mediated by two distinct groups of microorganisms, but a new group of microorganisms that can complete both steps of nitrification was hypothesized to exist: comammox bacteria.
In 2015, comammox bacteria were finally identified, although little is known about the abundance and diversity of comammox bacteria in engineered aquatic environments and no studies have investigated comammox bacteria in the final tertiary stages of wastewater treatment systems.
In Guelph Ontario, the tertiary treatment system includes rotating biological contactors, with 440,000 m2 of biofilm surface area. Due to their design and consistent accessibility for sampling, they present a valuable opportunity to study comammox bacteria “in the wild”.
This study showed how comammox bacteria are dominant ammonia oxidizers in the Guelph tertiary treatment system, and arguably the most abundant bacteria in the biofilm overall. Future research will investigate the contributions of comammox bacteria to nitrification in the treatment system environment and attempt to cultivate these newly discovered bacteria.
Understanding the role of microorganisms in the context of water treatment is important in the improvement of effluent quality of municipal, industrial, and aquaculture-associated water treatment systems. How do comammox bacteria contribute to this process? The Neufeld lab hopes to answer this question soon.