Short- and long-term effects of manganese, zinc and copper ions on nitrogen removal in nitritation-anammox process

Abstract

This study provided a deep insight into the impacts of trace elements (Mn, Zn and Cu) on nitritation-anammox process. For short-term exposure, all the three elements could improve the nitrogen removal rate (NRR) and the optimal concentrations were 2.0 mg/L, 2.0 mg/L and 0.5 mg/L for Mn, Zn and Cu, respectively. Accordingly, the NRRs were enhanced 54.62%, 45.93% and 44.09%. The long-term experiments were carried out in lab-scale sequencing batch reactors. The surprising results showed that only Mn addition could enhance the long-term nitritation-anammox process, and the NRR increased from 0.35 ± 0.01 kg N/m/d (control, no extra trace element addition) to 0.49 ± 0.03 kg N/m/d. Vice versa, the amendment of Zn reduced the NRR to 0.28 ± 0.02 kg N/m/d, and Cu had no significant effect on the NRR (0.36 ± 0.01 kg N/m/d). From the analysis of microbial community structure, it was explained by the increasing abundance of anaerobic ammonium oxidizing bacteria (AnAOB) only in Mn treatment, whereas Zn predominantly promoted ammonium oxidizing bacteria (AOB). Additionally, the majority of Mn was identified inside AnAOB cells, and Zn and Cu were mainly located in AOB. Our results indicated the synergistic effects of trace elements on nitritation-anammox, both short-term encouraging activities of AnAOB and long-term altering microbial community structure. This work implies the importance of trace elements addition in nitritation-anammox process.

Feasibility of CANON process for treating nitrogenous wastewater containing heavy metals

“…2(b). It indicated that short‐term exposure to Zn (II) slightly improved nitrogen removal ability, which coincided with previous studies 3,24 . The higher abundance of AOB also confirmed this speculation, as shown in Fig.…”

“…However, heavy metals lead to a persistent pollution due to their non-degradable and cumulative nature, so they are frequently detected in many kinds of wastewater. 2,3 The appearance of heavy metals in wastewater has become a major burden to wastewater treatment plants due to its high toxicity to microorganisms. 4,5 Anaerobic ammonium oxidation (Anammox) process converts ammonium to nitrogen gas with nitrite as terminal electron acceptor.…”

“…Some kinds of pollutants, such as organic and inorganic salts, can be easily removed by wastewater treatment processes. However, heavy metals lead to a persistent pollution due to their non‐degradable and cumulative nature, so they are frequently detected in many kinds of wastewater 2,3 . The appearance of heavy metals in wastewater has become a major burden to wastewater treatment plants due to its high toxicity to microorganisms 4,5 …”

Long‐term domestication to Mn stresses alleviates the inhibition on anammox process

“…In other word, the results from long‐term operation clearly demonstrated that the inhibition effect of Mn 2+ on anammox was exaggerated when using batch test as evaluation indicator. Besides, Li et al (2018) found that among Mn 2+ , Zn 2+ , and Cu 2+ , only Mn 2+ enhanced nitrogen removal capacity of nitritation‐anammox process after long‐term addition as a trace element. The majority of Mn 2+ was detected inside anammox bacterial cells, while Zn 2+ and Cu 2+ were mainly found in nitrifying bacterial cells.…”

Operational impacts of heavy metals on activated sludge systems: the need for improved monitoring

“…Zhang et al (2016) reported that simultaneous presence of copper and zinc in wastewater resulted in more severe consequences to nitrification (Zhang et al 2016). Li et al (2018) also reported synergistic effects of copper, manganese, and zinc on nitritation with long-term exposures altering community structure.…”