New insight into sludge digestion mechanism for simultaneous sludge thickening and reduction using flat-sheet membrane-coupled aerobic digesters

Xuefeng Zhu, Wenyi Yuan, Zhichao Wu, Xinhua Wang, Xuedong Zhang

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)

Abstract

Three identical pilot-scale flat-sheet membrane-coupled aerobic digesters for simultaneous sludge thickening and reduction (MSTR) were performed in parallel under a hydraulic retention time (HRT) of 14.6 h for 15 days. In the first 8 days, the stepwise destruction of waste activated sludge (WAS) flocs, i.e., dispersion from the outer to inner part, was observed likely due to the variation of dissolved oxygen concentration (Step 1: from 7.0 to 2.5 mg/L, Step 2: from 2.5 to 0.5 mg/L). During the process, the concentration of extracellular polymeric substances (EPS) first decreased from about 170.0 to 140.8 mg/g volatile suspended solids (VSS), then from 140.8 to 67.7 mg/g VSS, resulting in the much higher concentration of soluble organic matters and small particles (1–20 lm) in Step 2. Meanwhile, the ratio of protein like substances to humic acids in the EPS first increased from 0.5 to 0.7, then decreased from 0.7 to 0.4. After 8 days, the regroupment of sludge fraction and successive increase in fine particle could also correspond to the slight change of EPS concentration. Moreover, the degree of humification of the supernatant could well correspond to the reduction degree of the sludge.
Original languageEnglish
Pages (from-to)41-48
JournalChemical Engineering Journal
Volume309
DOIs
Publication statusPublished - 2017

Keywords

  • Reduction mechanism
  • Aerobic digestion
  • EPS
  • Particle size distribution
  • Flat-sheet membrane

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