Title: Mg2+ distribution in activated sludge and its effects on the nitrifying activity and the characteristics of extracellular polymeric substances and sludge flocs
Abstract: Divalent cations act as bridges among extracellular polymeric substances (EPS) and form cross-linkage for the self-immobilization of microbial biomass. However, their effects on the nitrification performance during the biological nitrogen removal are still unclear. In the present study, the effects of Mg2+ on the nitrifying activity, EPS and floc characteristics were investigated using a lab-scale sequencing batch reactor. The distribution of Mg2+ was quantified at different level of sludge floc. The results indicated that the nitrification activity was significantly improved when influent Mg2+ was below 1.1 mmol/L, but suppressed at 3 mmol/L. The overall performance characterized by COD, NH4+-N and TN, the particle size and sludge flocculation ability rapidly increased with the increase of Mg2+ concentration. Mg2+ was mainly distributed in the pellet and changed slightly in supernatant, LB-EPS and TB-EPS. The four fluorescence peaks detected by three-dimensional excitation-emission matrix spectra were attributed to PN-like substances and humic acid-like substances in the LB-EPS and TB-EPS. The results of XPS analysis demonstrated that LB-EPS and TB-EPS comprised similar elements. Therefore, the types of EPS functional groups was unchanged under varied Mg2+ concentrations, while their proportions changed and LB-EPS/EPS was key factor for the changes of bioflocculation.
Publication Year: 2019
Publication Date: 2019-10-05
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 27
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