Supported gas membrane-based ammonia removal and recovery for a pH-dependent sink: Effect of water vapor transport

Philip A. Aligwe, Kamalesh K. Sirkar, Christian J. Canlas, Wu Cheng Cheng

Research output: Contribution to journalArticlepeer-review

Abstract

Sometimes NH3 is stripped from process/effluent streams through hydrophobic porous hollow-fiber-membranes (HFMs) via a supported-gas-membrane (SGM) process and recovered in concentrated H2SO4 solution as (NH4)2SO4. To recover relatively purified (NH4)2SO4, one can avoid excess H2SO4 with a more dilute H2SO4 strip solution. Neglect of strip-side mass-transfer resistance for low-pH strip H2SO4 solutions is not desirable with higher-pH H2SO4 strip solutions. Small hollow-fiber membrane modules (HFMMs) were used with a higher-pH H2SO4 strip solution. Mass transfer was successfully modeled using reaction-enhanced mass transport in higher-pH H2SO4 solution. Employing larger-scale crossflow HFMMs, time-dependent ammonia removal from a large tank having ammonia-containing process effluent was modeled for batch recirculation operation. The larger-scale modules employ shell-side feed liquid in crossflow with an overall countercurrent flow pattern and acid flow in the tube side. Modeling ammonia transport without water vapor transfer can cause substantial errors in batch recirculation method. Water vapor transport was considered here for low-pH and high-pH H2SO4 strip solutions for ammonia-containing feed in a large tank. Model results describe literature-based experimentally observed mass transfer behavior in industrial-treatment systems well. Model calculations were also made for continuous ammonia recovery from industrial effluents by a number of series-connected HFMMs without any batch recirculation.

Original languageEnglish (US)
Article number118308
JournalJournal of Membrane Science
Volume611
DOIs
StatePublished - Oct 1 2020

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

Keywords

  • Ammonia removal
  • Experiments and models
  • Hollow fiber membranes
  • Mass transfer coefficient
  • Strip-side pH dependence

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