Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater

Abstract

The ion desorption behavior from carbon electrodes onto high concentration brine was examined in this work because the ionic resources in brine are accumulated to attain high concentration in membrane capacitive deionization (MCDI) during mineral resource recovery. Several major issues were explored to demonstrate the suitability of MCDI for mineral recovery: ion discharge behavior using different solution chemistries (0 to 10 mM of NaCl, KCl, and MgCl2) of feed and brine, desorption efficiencies of various electrode regeneration methods (reverse polarity, short-circuiting and power disconnection) for enrichment of ions, and ion desorption selectivity among selected cations (Na, K, and Mg). The desorption efficiency was inversely proportional to ionic strength of aqueous brine solution as the ions from electrodes migrate toward the brine solution against ionic-strength gradient. Furthermore, the desorption onto brine was constrained by utilizing energy-efficient short-circuiting, whereas the electrochemically adsorbed ions were well discharged by reversing the polarity compensating for its cost. The ions were preferentially released from the electrodes in order of Na>K>Mg in the results, showing a reverse trend with the selectivity of electrosorption. From ammonium recovery tests, a high concentration of ammonium in brine (78.54 mg/L) was obtained from the synthetic wastewater through continuous operation of five cycles, attributing to its selective desorption over sodium ions present. However, it must be noted that its incomplete discharge from the electrodes is a challenging issue to overcome the limitations of MCDI as a mineral recovery process, and to attain highly concentrated ammonium.

Physico‐chemical processes

“…By putting the environmentally friendly factors into life cycle assessment consideration, on average MCDI system had 5,641 fewer values for damage assessment categories than RO system. Kim et al (2019a) tested the behavior of cations desorption from the cathode into the brine stream using solutions with different chemical compositions; efficiency of the desorption using different regeneration methods; cations desorption selectivity. With the ionic-strength gradient increases in the brine, the cation desorption efficiency was retarded during the recovery.…”

Food‐processing wastes

“…Kim et al (2019) and Kim, Nakhla, and Keleman (2019) studied the binding and transport of cations in membrane capacitive deionization (MCDI) using a cation exchange membrane (CEM) to recover minerals and found that the order of release of cations was potassium, followed by sodium and magnesium. They reported that the diffusion rate of the cations and their valence were the primary factors governing their release.…”

“…BioWin software was used to predict the impact of food waste on nutrient removal, biogas generation, and energy balance for 114 scenarios using various technologies (Kim et al, 2019; Kim et al, 2019). Addition of food waste produced effluents with lower effluent nitrogen (3.6–7.9.g/L for BNR; 0.6–1.3 mg/L for A2O; 1.0–2.3 mg/L for Bardenpho), reduced operating costs of between 25% and 78% for various processes analyzed, and produced a net energy gain of 3,300–3,700 kWh/day for a 10 MGD plant.…”

Green Synthesis of Fe3O4@Carbon Filter Media for Simultaneous Phosphate Recovery and Nitrogen Removal from Domestic Wastewater in Biological Aerated Filters

“…The domestic wastewater depth processing for secondary effluent is required to meet effluent quality standards and reuse wastewater resources. 4,5 The efficiency of a secondary effluent treatment depends on the performance of biological aerated filters (BAFs) that are most commonly employed for secondary effluent treatment. 6 BAF was developed in Europe in the late 1980s using the principle of filter media.…”

“…6 Various cost-effective materials have been utilized to bridge this gap. However, the existing literature on BAF is primarily focused on the removal of either nitrogen alone 4,8 or both phosphate and nitrogen. 9 Nonetheless, to the best of the authors' knowledge, limited work is focused on the simultaneous phosphate recovery and nitrogen removal (SPN) in BAF, which is an urgent requirement for resource recovery from wastewater.…”