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Utilization of Bidirectional Cation Transport in a Thin Film Composite Membrane: Selective Removal and Reclamation of Ammonium from Synthetic Digested Sludge Centrate via an Osmosis–Distillation Hybrid Membrane Process
journal contribution
posted on 2020-08-07, 13:33 authored by Peizhi Wang, Ji Li, Xiaolei Zhang, Xinglin Lu, Qianliang Liu, Tao Zhang, Wei Cheng, Jun MaSelective
removal and resource recovery of ammonium nitrogen (NH4+–N) from high-strength ammonium waste streams
is of practical importance for biological wastewater treatment and
environmental protection. In this study, we demonstrate the simultaneous
removal and reclamation of ammonium from synthetic digested sludge
centrate via a novel osmosis-distillation hybrid membrane (ODHM) process.
Using NaHCO3 as the draw solute, ammonium diffuses from
the synthetic centrate to the draw solution by utilizing the bidirectional
cation transport nature of the thin film composite (TFC) membrane.
Then, NH4+ is converted to gaseous NH3 at 60 °C and recovered by a sweeping gas membrane distillation
(SGMD) process. Herein, the bidirectional transport of monovalent
cations in the osmotic process, selectivity of TFC membranes for different
cations, and recovery of the draw solution following the extraction
of ammonia through the SGMD process were systematically investigated.
The removal of NH4+–N from the synthetic
centrate achieved 21.34% during a 6-h continuous operation of the
ODHM system, with ammonium fluxes through the TFC and SGMD membranes
at 1.39 and 0.57 mol m–2 h–1,
respectively. A secondary interfacial polymerization was proposed
to further enhance ammonium transport through the TFC membrane. Results
reported here highlight the potential of the ODHM process for the
selective removal and reclamation of ammonium from ammonium-rich waste
streams.