Though large-scale water treatment plants are poised to comply with the As drinking water standard, small systems and residential wells are facing bigger challenges in treating As-contaminated water effectively. For small and decentralized treatment systems using sorption for As removal, a key challenge is how to maintain a sufficiently high As uptake rate to accommodate the short hydraulic contact times. A new remove-and-relocate sorption technique with a two-material composite packed in a sorptive column is reported here. A fast-sorbing Fe-based mesoporous carbon (FeMC) was used to extract As(V) rapidly from running water during the daytime (e.g., 10 h per day); while a second sorbent (i.e., Fe-based activated carbon (FeAC)), with a large compacity, facilitated As(V) desorption from FeMC. The desorption occurred especially during pump-off periods that are consistent with residential uses with day-night shift, thus regenerating the sorption sites on FeMC. By this approach, we could capitalize on the rapid sorption kinetics of the first medium, which is often too expensive to be used alone, and the second inexpensive medium with a slow sorption kinetics but a large compacity. Our results demonstrated that during the 44 days’ operation with a &lt;1 min empty bed contact time and a 102-<i>μ</i>g-As/L influent concentration, the fast-sorbing FeMC and the FeAC collaborated to capture As(V), resulting in 20,022 bed volumes of the treated water at 10-<i>μ</i>g-As/L breakthrough. A sorption density of 2.36 mg As/g was observed. This remove-and-relocate sorption approach may help integrate sorption kinetics and capacity with the day-night shift in decentralized systems for fast uptake of As(V).

Developing a new remove-and-relocate technique for rapid arsenate uptake in residential application settings

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.