Co-inhibition of salinity and Ni(II) in the anammox-UASB reactor

Abstract

Both nickel and salinity are often detected in the environment. Especially electroplating wastewater contains some salt and nickel, which affects microbial activity in biological wastewater treatment process. In this study, the effects of sustaining addition of a high-concentration salinity and Ni(II) on the anaerobic ammonium oxidation (anammox) process were examined. The results indicated that the anammox system had an acclimation ability to <0.2 mg L^-1 Ni(II) and 20 g L^-1 NaCl. After a recovery phase of approximately 70 days, the nitrogen removal efficiency and rate reached at 77.1% and 1.18 kg N m^-3 d^-1, respectively. The three-dimensional excitation-emission matrix fluorescence and Fourier transform infrared spectra results showed that the introduction of NaCl and Ni(II) caused a substantial variation in the quantity and composition of the bound EPS in the surface of anammox granules. The present study is the first to document the long-term effect of co-existence of salinity and Ni(II) on the performance of the freshwater-derived anammox bacteria in the upflow anaerobic sludge blanket reactor and to provide a reference for the stable operation of anammox bioreactors for the treatment of sulfonamide-containing wastewater.

Keywords: Anammox; Co-inhibition; Nickel; Salinity; Sludge characteristics.