Effects of NaClO shock on MBR performance under continuous operating conditions. Issue 2 (6th January 2021)

• Record Type: Journal Article
• Authors: Sun, Ming; Hou, Bingdong; Wang, Shengli; Zhao, Qiannan; Zhang, Lanhe; Song, Lianfa; Zhang, Haifeng
• Is Part Of: Environmental science. Volume 7:Issue 2(2021)
• Page Start: 396
• Page End: 404
• Publication Date: 2021-01-06
• Subjects: Water-supply -- Periodicals; Water security -- Periodicals; Water resources development -- Periodicals; Water chemistry -- Periodicals; 553.705
• DOI: 10.1039/d0ew00760a
• Languages: English
• ISSNs: 2053-1400

Abstract

Abstract : The NaClO-shocked sludge had a self-recovery ability, and with the gradual improvement of sludge properties, membrane fouling was reduced. Abstract : In situ chemical cleaning with sodium hypochlorite (NaClO) is frequently employed to maintain a constant permeability in membrane bioreactor (MBR) systems. In this study, the effects of NaClO shock on MBR performance under continuous operating conditions were investigated. A lab-scale MBR was operated for three runs with in situ chemical cleaning. Experimental results demonstrate an obvious increase of the membrane fouling rate (13.7, 23.5 and 23.3 kPa d −1 ) on day 1 of cleaning, followed by a rapid reduction (6.4, −0.2 and 3.5 kPa d −1 ) on day 2 of cleaning. This indicates the rapid self-recovery ability of the NaClO-shocked sludge. Furthermore, as the operating time increased, the sludge extracellular polymeric substance (EPS) content initially increased, followed by a subsequent decrease, with the gradual improvement of sludge filterability that consequently reduced membrane fouling. Thermodynamic analysis revealed that the shocked-sludge surface properties, including the surface electron donor component ( γ − ), hydrophobicity, adhesive energy and self-cohesive ability, were gradually restored to the raw sludge level, which reduced the membrane fouling potential.