Reverse osmosis membrane rejection for ersatz space mission wastewaters

Yeomin Yoon, Richard M. Lueptow*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Adequate rejection of a variety of inorganic and organic compounds is necessary if reverse osmosis (RO) and nanofiltration (NF) membranes are to be used for space mission wastewater reuse. Three ersatz space mission wastewaters defined by NASA having different pH (2.6-8.9), conductivities (3980-12,640 μS/cm), and amounts of organic compounds (50-2400 mg/L as carbon) were tested to determine the membrane flux and the solute rejection for five RO and two NF membranes that are commercially available. The results show that the rejection of ions depends upon the solution pH which influences electrostatic repulsion. However, the rejection of dissolved organic carbon (DOC) depends upon the composition of the wastewater. The DOC rejection (80-95%) was the highest for the wastewater containing dextran (molecular weight 15-20 k) compared with the other ersatz wastewaters having detergent and urea as the major carbon sources (31-83%). The wastewater having the greatest conductivity (12,640 μS/cm) and DOC (2400 mg/L) showed a greater flux decline (71-96%) than the other ersatz wastewaters (37-82%) having lower conductivities (3980-6980 μS/cm) and DOC (50-660 mg/L) for the RO and NF membranes. The ratio of solute radius (r i,s) to effective membrane pore radius (rp) was employed to compare ion rejection. For ionic compounds, the rejection is higher than 70% when the ri,s/rp ratio is greater than 0.5 for both the RO and NF membranes with all wastewaters.

Original languageEnglish (US)
Pages (from-to)3298-3308
Number of pages11
JournalWater Research
Volume39
Issue number14
DOIs
StatePublished - Sep 2005

Keywords

  • Membrane flux
  • Nanofiltration
  • Rejection
  • Reverse osmosis
  • Water treatment

ASJC Scopus subject areas

  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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