Enhanced Recovery of Zn(II) on Marine Anammox Bacteria-Based Consortia after Long-Term Multiantibiotic Inhibition in Marine Wastewater Treatment

Marine wastewater (MW) treatment faces a huge challenge due to its high salinity, and marine anammox bacteria (MAB) are currently used because of their good salt tolerance. Besides, most of the MWs contain antibiotics and MAB-based consortia are difficult to recover after long-term multiantibiotic inhibition in MW treatment. Herein, 2 mg/L Zn(II) was added to investigate the fast recovery of MAB-based consortia after long-term multiantibiotic inhibition in MW treatment for the first time. Zn(II) significantly accelerated the microbial recovery, achieving a 100% ammonium removal efficiency 10 days earlier. The stoichiometric ratios (ΔNO2–-N:ΔNH4+-N = 1.22, ΔNO3–-N:ΔNH4+-N = 0.26) of the marine anammox finally stabilized around the theoretical ratios. Besides, MAB (Candidatus Scalindua) abundance increased by 2.07-fold after Zn(II) addition. Moreover, the antibiotic resistance gene (ARG) abundance decreased by 13.48%, and the persistence of quinolone-induced and sulfonamide-induced ARGs was higher than that of tetracycline-induced ARGs. The intI1 abundance generally increased to promote horizontal transfer, but it increased little after Zn(II) addition. Correlations among different ARGs were strengthened by Zn(II), and tetG was positively correlated with sul1. This work clearly demonstrates that Zn(II) can enhance the recovery of MAB-based consortia after long-term multiantibiotic inhibition and promote nitrogen removal in MW treatment.