The performance of gravity-driven membrane (GDM) filtration for roofing rainwater reuse: implications of roofing rainwater energy and rainwater purification

Xing Du*, Jiongji Xu, Zhuoyu Mo, Yunlong Luo, Junhao Su, Jinxu Nie, Zhihong Wang, Lifan Liu, Heng Liang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

Rainwater harvesting (RWH) coupled with gravity-driven membrane (GDM) filtration was used to simultaneously treat rainwater and recover energy. A pilot GDM could obtain a relatively stable level of permeate flux (~4.0 L/(m2·h)) under a set water head (ΔH = 0.4 m) over 140 days of operation. An increase water head (ΔH = 0.6 m) did not achieve a sharp increase in stabilized flux (~2.4 L/(m2·h)) over 20 days of operation until the end. It was found that GDM filtration could produce a permeate that was almost free of particles. However, only a small amount of organic matter and trace metals (i.e., Cr, Al, Fe, Cu, Al, Mn and Ca) were removed, as demonstrated by excitation-emission matrix (EEM) and energy dispersive spectrometry (EDS) analysis. Additionally, the bacterial abundance within the permeate ((8.45 ± 0.11) × 102 cells/mL) decreased compared to that within the GDM tank ((1.85 ± 0.14) × 105 cells/mL), revealing that the rejected bacteria might enhance biofilm formation. The presence of extracellular polymeric substances (EPS), adenosine triphosphate (ATP) and assimilable organic carbon (AOC) indicated a high level of microbial activity within the biofilm, which was also demonstrated by the porous cake layer morphology observed by scanning electron microscopy (SEM) and results from confocal laser scanning microscopy (CLSM) imaging of the biofilm. NH3-N was removed by Nitrospira within the biofilm, which was identified by microbial community analysis. Overall, this novel approach has the potential to improve municipal water availability and stormwater management practices.
Original languageEnglish
Article number134187
Pages (from-to)1-11
Number of pages11
JournalScience of the Total Environment
Volume697
Early online date30 Aug 2019
DOIs
Publication statusPublished - 20 Dec 2019
Externally publishedYes

Keywords

  • Roof rainwater treatment
  • Roofing rainwater energy
  • Gravity-driven membrane filtration
  • Stabilized flux
  • Biofilm

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