Effect of rare earth element Y(III) on short-term denitrification performance of anaerobic ammonia oxidized granular sludge

BACKGROUND The ammonia-nitrogen wastewater generated during rare-earth mining poses a serious hazard to the environment around the mine. This type of wastewater is difficult to treat using conventional biological methods due to its low carbon-to-nitrogen ratio. Anaerobic ammonia oxidation (anammox) has become the first choice for treating rare earth mine wastewater. However, the effect of rare earth elements (REEs) in wastewater on anammox bacteria has been insufficiently studied, and this limits the application of this process. Yttrium is a rare earth element present in wastewater, and the study of its effect on anammox can help in the application of this process in rare earth mine wastewater. RESULTS The effect of Y(III) on anammox granular sludge was studied using batch experiments. Anammox activity decreased with increasing Y(III) concentration, from 64.78 +/- 0.28 to 17.15 +/- 2.70 mg g(-1) VSS day(-1). The semi-inhibitory concentration (IC50) of Y(III) for anammox activity was 30.36 mg L-1. Y (III) exhibited low promotion and high inhibition of anammox bacterial extracellular polymer secretion (EPS). Comparing the kinetic models, the Loung model is better suited for describing the kinetic equation of substrate concentration on anammox. CONCLUSION The acute toxicity of Y(III) to anaerobic sludge is influenced by the substrate and Y (III) concentrations. EPS-based defence strategies play an important role in counteracting the toxicity of Y(III). The Edwards model fits the experimental data well and is suitable for predicting the inhibition of anammox activity by the substrate concentration. (c) 2022 Society of Chemical Industry (SCI).

Automated summary

Ammonia-nitrogen wastewater generated during rare-earth mining poses a serious threat to the surrounding environment. Conventional biological methods are ineffective in treating this type of wastewater. Anaerobic ammonia oxidation (anammox) has become the preferred method for treating rare earth mine wastewater. However, the impact of rare earth elements (REEs) on anammox bacteria has not been sufficiently studied, which limits its application.