Feammox Bacterial Biofilms as an Alternative Biological Process for the Removal of Nitrogen from Agricultural Wastewater

The excessive deposition of ammonium (reactive nitrogen) in the environment has led to losses of biodiversity and the eutrophication of ecosystems. Anthropogenic sources contribute twice the natural rate of terrestrial reactive nitrogen and provide about 45% of the total amount of it produced annually on Earth. Recently, a biological process that anaerobically metabolizes ammonium and facilitates iron reduction, termed Feammox, was discovered. The use of Feammox activity together with hollow fiber membrane bioreactors (HFMB), for which the latter are based on the formation of biofilms of bacterial communities, constitutes an efficient and sustainable method for the removal of ammonium from agriculturally derived wastewater. To implement the use of HFMB with Feammox activity, the formation of Feammox bacterial biofilms from wastewater sludge samples from a brewery was evaluated. The cultures were enriched with two different carbon sources, namely, sodium acetate and sodium bicarbonate; then, ferrous iron and ammonium concentrations, which were used as indicators of reactive nitrogen removal, were measured. The measurements revealed that the ammonium removal level reaches 20.4% when sodium acetate is used as carbon source. Moreover, an increase in the ferrous iron concentration of +Delta 84.6 mg/L was observed, indicating that Feammox activity had been generated. Biofilm formation was observed under Feammox conditions on the hollow fibers. These results showed that Feammox bacteria can form biofilms and efficiently remove ammonium from wastewater, constituting an essential feature with which to scale up the process to HFMBs. Overall, these results contribute to a better understanding of the Feammox process that can be used to implement these processes in agriculture and thus progress towards a more sustainable industry.

Automated summary

The excessive deposition of ammonium in the environment has negative impacts on biodiversity and ecosystem eutrophication. Anthropogenic sources are responsible for the majority of terrestrial reactive nitrogen, contributing to 45% of the total annual production on Earth. The Feammox process, a biological method that anaerobically metabolizes ammonium, coupled with hollow fiber membrane bioreactors (HFMBs), shows promise for the removal of ammonium from agriculturally derived wastewater. This study evaluated the formation of Feammox bacterial biofilms and demonstrated their efficiency in ammonium removal, providing valuable insights for scaling up the HFMBs process.