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Microbial desalination cells are considered a low-energy-consumption, clean technology to simultaneously purify wastewater and desalinate saline water by utilizing the in situ energy source contained in wastewater. To enhance desalination performance and achieve an optimal membrane stack configuration, an enlarged stacked microbial desalination cell (SMDC) has been developed and tested with 6–14 desalination cells. The cross-membrane area of the enlarged SMDC is 100 cm 2 . The anode and cathode volumes are both 200 mL. To reduce internal resistance, the width of desalination cells is kept as <0.5 mm. The optimal configuration with 10 desalination cells achieves the highest total desalination rate (TDR) of 423 mg/h and the highest charge transfer efficiency (CTE) of 836% when treating the 20 g/L NaCl solution. During this process, the junction potential across membranes increases from 0 to 374 mV, and occupies up to 74% of the total potential loss inside the SMDC. This shows that the SMDC used in this work achieves the highest TDR and CTE among the reported studies, and the junction potential should be effectively controlled to achieve the desired desalination performance in future practical applications. [ABSTRACT FROM AUTHOR]

In this study, a hollow fiber microfiltration membrane (HFM) coupled biocathode microbial desalination cell (MDC) was fabricated. With real wastewater flowing serially from anaerobic anode to oxic biocathode, filtered by the HFM and finally to the central membrane stack, the HFM-MDC took advantages of conventional anaerobic/oxic process, membrane biofilm reactor, and eletrodeionization technology, realizing advanced removal of organics, suspended solids, and salinity during 105 days of operation. The produced diluate was 86.1 v%, with final conductivity, chemical oxygen demand, total nitrogen, and total phosphorus (TP) reaching 59.2 ± 12.2 μS/cm, 35.5 ± 4.0 mg/L, 1.65 ± 0.39 mg/L, and 0.14 ± 0.05 mg/L respectively. The corresponding concentrate (13.9 v%) concentrated 6.7 times the initial conductivity (6044 ± 168 μS/cm), recovered 98.7% of phosphorous (TP of 40.9 ± 4.9 mg/L) and part of nitrogen. In addition, the HFM was stably operated for 105 days due to coefficient aeration flushing and regular chemical backwashing, with trans-membrane pressure keeping at ≤ 15 kPa for most of time. Moreover, this integrated process only needs wastewater as sole water input, and possesses a relative cheap HFM coupled biocathode compared with conventional Pt cathode, providing a promising solution for practical application of MDC in wastewater purification. [ABSTRACT FROM AUTHOR]

Nitrogen exists in municipal wastewater in the form of ammonia/ammonium which is a recoverable resource. Recovering nitrogen to improve nitrogen-use efficiency should be carefully considered to promote global environmental sustainability. However, ammonia/ammonium is always not well recovered but removed as one of the main pathways for nitrogen release into the environment, which is due to ineffective ammonia capture. In this study, a new method of ion-exchange resin ammonium recovery combined with membrane capacitive deionization (MCDI + IE process) pretreatment is proposed. Selective ion removal by MCDI is demonstrated and ammonium ratio to the total prior ion (K + , Ca 2+ and Mg 2+ ) in outflow of MCDI cell is respectively increased from ∼15% to over 30% and 45% after 3 and 5 MCDI cycles. The MCDI + IE process could deal with 2.48 and 3.89 times of inflow, respectively, compared with the single IE process after 3 and 5 MCDI charge–discharge cycles and recover more than 65% of ammonium in a resin regeneration cycle after 3 MCDI cycles. It ascribes to MCDI desalination eliminating the negative effects of divalent cations, such as Ca 2+ and Mg 2+ , on the IE absorb–desorb process. [ABSTRACT FROM AUTHOR]