posted on 2024-02-01, 12:04authored byYunfei He, Tie Gao, Ao Gong, Peng Liang
In
this study, we used a membrane capacitive deionization
device
with a reservoir (R-MCDI) to enrich phosphorus (P) from synthetic
wastewater. This R-MCDI had two small-volume electrode chambers, and
most of the electrolyte was contained in the reservoir, which was
circulated along the electrode chambers. Compared with conventional
MCDI, R-MCDI exhibited a phosphate removal rate of 0.052 μmol/(cm2·min), approximately double that of MCDI. This was attributed
to R-MCDI’s utilization of OH– alternative
adsorption to remove phosphate from the influent. Noticing that around
73.9% of the removed phosphate was stored in the electrolyte in R-MCDI,
we proposed a novel off-flow desorption operation to enrich the removed
phosphate in the reservoir. Exciting results from the multicycle experiment
(∼8 h) of R-MCDI showed that the PO43–-P concentration in the reservoir increased all the way from the
initial 152 mg/L to the final 361 mg/L, with the increase in the P
charge efficiency from 5.5 to 22.9% and the decrease in the energy
consumption from 28.2 to 6.8 kW h/kg P. The P recovery performance
of R-MCDI was evaluated by viewing other similar studies, which revealed
that R-MCDI in this study achieved superior P enrichment with low
energy consumption and that the off-flow desorption proposed here
considerably simplified the operation and enabled continuous P enrichment.