Nutrient-energy-water recovery from synthetic sidestream centrate using a microbial electrolysis cell - forward osmosis hybrid system

Abstract

Recovery of nutrients, water, and energy from high-strength sidestream centrate offers benefits such as reusable resource, minimized discharge and cost-savings in mainstream treatment. Herein, a microbial electrolysis cell-forward osmosis (MEC-FO) hybrid system has been investigated for integrated nutrient-energy-water (NEW) recovery with emphasis on quantified mass balance and energy evaluation. In a closed-loop mode, the hybrid system achieved recovery of 54.2 ± 1.9 % of water (70.4 ± 2.4 mL), 99.7 ± 13.0 % of net ammonium nitrogen (8.99 ± 0.75 mmol, with extended N 2 stripping), and 79.5 ± 0.5 % of phosphorus (as struvite, 0.16 ± 0.01 mmol). Ammonium loss primarily from reverse solute flux was fully compensated by the reclaimed ammonium under 6-h extended N 2 stripping to achieve self-sustained FO process. The generated hydrogen gas could potentially cover up to 28.7 ± 1.5 % of total energy input, rendering a specific energy consumption rate of 1.73 ± 0.08 kWh m-3 treated centrate, 0.57 ± 0.04 kWh kg-1 COD, 1.10 ± 0.05 kWh kg-1 removed NH 4 +-N, 1.17 ± 0.06 kWh kg-1 recovered NH 4 +-N, or 5.75 ± 0.54 kWh kg-1 struvite. Recycling of excess Mg 2+ reduced its dosage to 0.08 kg Mg 2+ /kg struvite. These results have demonstrated the successful synergy between MEC and FO to achieve multi-resource recovery, and encouraged further investigation to address the challenges such as enhanced hydrogen production, reducing nutrient loss, and optimizing MEC-FO coordination towards an energy-efficient NEW recovery process.

Resource recovery by osmotic bioelectrochemical systems towards sustainable wastewater treatment

“…Overall, the OsMFC had a negative energy balance of 0.717 kWh m -3 . (Qin et al 2015) In the coupled OsBES (MEC-FO), energy was recovered as hydrogen gas, which could be converted to a NER of 0.36 kWh m -3 treated water (Figure 2.5B) (Zou et al 2017). The energy consumption of this system was 1.26 kWh m -3 treated water, 94.4% by the MEC external power supply, 4.8% due to the MEC electrolyte recirculation, and 0.8% by the FO process.…”

“…In a coupled OsBES (MEC+FO), the recovered ammonia in the MEC was applied as a draw solute for water recovery in the FO process (Qin and He 2014), and this system was further studied to include phosphorus recovery as struvite (MgNH4PO4•6H2O) (Zou et al 2017). In a closed-loop mode, this coupled OsBES achieved the recovery of 54.2 ± 1.9 % of water, 99.7 ± 13.0 % of net ammonium nitrogen, and 79.5 ± 0.5 % of phosphorus as struvite (Zou et al 2017). Ammonium loss primarily from RSF in the FO was fully compensated by the reclaimed ammonium under extended N2…”

“…A prior study has examined the NEW recovery from a synthetic sidestream and achieved effective recovery of water, ammonium nitrogen, and phosphorus (Zou et al 2017). A challenge of treating high strength wastewater by using an OsBES is the potential competition with anaerobic digestion, which is a mature and efficient technology for biogas production.…”

Bioelectrochemical Systems for Removal of Selected Metals and Perchlorate from Groundwater: A Review

“…In BESs, both oxidation and reduction reactions can occur, respectively at the anode and at the cathode [45][46][47], and thus oxidized contaminants such as nitrate, vanadium, perchlorate or chromium can be reduced in the cathodic environment, while arsenic and/or organic matter can be oxidized in the anodic environment (Figure 1), with possible complete groundwater remediation due to the integration in a single treatment sequence. Energies 2018, 11, x FOR PEER REVIEW 2 of 22 as being able to produce energy from more complex substrates such as domestic and industrial wastewater: dairy [15-18], food-processing [19], leachate [20,21], pharmaceutical [22], brewery [23,24], winery [25], oil [26] and petroleum refinery wastewater [27] are amongst the principal examples.After the initial exclusive interest as possible net energy producers from organic matter degradation, which had somehow disappointed researchers' initial development expectations [28][29][30][31][32], BES technology has been used as a flexible platform for fulfilling several other tasks: brackish water desalination in microbial desalination cells (MDC) [33,34], hydrogen production in the microbial electrolysis cell (MEC) setup [35,36], microbial electrosynthesis (MES) of valuable chemicals and commodities [37,38], power-to-gas energy storage [39], nutrient recovery [40,41], and biosensing [42,43] are some notable examples.Due to the intrinsic characteristics of the technology, BES has been identified as a promising technology for groundwater bioremediation [44]. In BESs, both oxidation and reduction reactions can occur, respectively at the anode and at the cathode [45][46][47], and thus oxidized contaminants such as nitrate, vanadium, perchlorate or chromium can be reduced in the cathodic environment, while arsenic and/or organic matter can be oxidized in the anodic environment (Figure 1), with possible complete groundwater remediation due to the integration in a single treatment sequence.…”

“…After the initial exclusive interest as possible net energy producers from organic matter degradation, which had somehow disappointed researchers' initial development expectations [28][29][30][31][32], BES technology has been used as a flexible platform for fulfilling several other tasks: brackish water desalination in microbial desalination cells (MDC) [33,34], hydrogen production in the microbial electrolysis cell (MEC) setup [35,36], microbial electrosynthesis (MES) of valuable chemicals and commodities [37,38], power-to-gas energy storage [39], nutrient recovery [40,41], and biosensing [42,43] are some notable examples.…”