Donnan Dialysis-Osmotic Distillation (DD-OD) Hybrid Process for Selective Ammonium Recovery Driven by Waste Alkali

Abstract

This work proposed an innovative and energy-efficient Donnan Dialysis (DD) and Osmotic Distillation (OD) hybrid process for alkali-driven ammonium recovery from wastewater. The efficiency and feasibility of ammonium removal and recovery from synthetic and real wastewater using NaOH and waste alkali were investigated. Ammonium in the feed first transported across the cation exchange membrane and accumulated in the receiver chamber. It is then deprotonated as ammonia, passing through the gas permeable membrane and finally is fixed as ammonium salt in the acid chamber. Our results indicated that employing waste alkali (red mud leachate) as driving solution led to excellent ammonium recovery performances (recovery efficiency of >80%), comparable to those of NaOH solution. When the initial ammonium concentration was 5 and 50 mM, the waste alkali driven DD-OD process achieved acceptable NH4 +-N flux density of 16.8 and 169 g N m–2 d–1, at energy cost as low as 8.38 and 2.06 kWh kg–1 N, respectively. Since this alkali driven DD-OD hybrid process is based on solute concentration (or partial pressure) gradient, it could be an energy-effective technology capable of treating wastewaters containing ammonium using waste alkali to realize nutrients recovery in a sustainable manner.

Armor-Structured Interconnected-Porous Membranes for Corrosion-Resistant and Highly Permeable Waste Ammonium Resource Recycling

“…As shown in Figure d, we found that the removal efficiency of NH 4 + -N reached 90% after acid absorption for 12 h and almost 100% when the run time was increased to 24 h. This means that the recovery efficiency of NH 4 + -N was close to 100% during the whole GMAR process, which had a stable pH value to ensure that the armor-structured NFM was not wetting. The energy consumption of this technique was estimated at 2.24 kWh kg –1 N by Method S10, lower than 10.3 kWh kg –1 N for the Haber–Bosch process . The total NH 4 + -N concentration in the illustration further confirmed that NH 4 + -N in the feed solution was almost completely recovered.…”

“…The energy consumption of this technique was estimated at 2.24 kWh kg −1 N by Method S10, lower than 10.3 kWh kg −1 N for the Haber−Bosch process. 27 The total NH 4 + -N concentration in the illustration further confirmed that NH 4 + -N in the feed solution was almost completely recovered. In addition, negligible CODcr was observed in the absorbent solution and no TP was detected (Figure 5e), which ensured the high purity of the recovered ammonium solution.…”

“…At present, ever-growing measures have been developed for ammonium recovery, mainly including chemical precipitation, , thermal stripping, and membrane processes. , Especially, the gas-permeable membrane (GM) technique using a hydrophobic microporous membrane has emerged as the most competitive method because of the high recovery efficiency, low energy consumption, and highly compact configuration of equipment. , Gas-permeable membrane ammonium recovery (GMAR) is driven by a partial pressure gradient of ammonia between the feed and the collect side. The hydrophobic membrane aims at resisting the permeation of liquid water and only allowing the transmission of ammonia, thus achieving the purpose of recycling ammonium and simultaneously purifying wastewater . Right now, various kinds of membrane-based processes based on hydrophobic membranes have also been developed, e.g., dialysis–distillation, , electrochemical-membrane stripping, − gas-permeable membrane-coupled aeration, catalytic hydrogenation–membrane distillation, and so on.…”

“…The hydrophobic membrane aims at resisting the permeation of liquid water and only allowing the transmission of ammonia, thus achieving the purpose of recycling ammonium and simultaneously purifying wastewater . Right now, various kinds of membrane-based processes based on hydrophobic membranes have also been developed, e.g., dialysis–distillation, , electrochemical-membrane stripping, − gas-permeable membrane-coupled aeration, catalytic hydrogenation–membrane distillation, and so on.…”

Transport characterization and modelling of Donnan dialysis for ammonium recovery from aqueous solutions

“…Breytus [9] showed the recovery of nitrate at 3 mM using Selemion, Neosepta and Fumatech membranes. Furthermore, Chen [10] studied the feasibility of ammonium recovery at 5-50 mM using using Selemion and Neosepta membranes and developed the process further by integrating Osmotic Distillation with a Donnan dialysis process [11]. Rodriguez [12] used Donnan dialysis to enhance the recovery of ammonia by electrodialysis and reduce energy consumption at 140 mM using Nafion membranes.…”