Simultaneous removal of nitrate, phosphate, and fluoride using a ZVI-packed bed electrolytic cell

Abstract

A B S T R A C TThe present study aims to treat wastewater containing anionic contaminants such as nitrate, phosphate, and fluoride generated by the etching process of the semiconductor industry. The ZVI-packed bed electrolytic cell was developed to treat the contaminants using reduction, adsorption, and precipitation by electrochemical reactions. The 1 L reactor was operated with a voltage of 600 V, a flow rate of 30 mL/min (HRT: 12 min, EBCT: 33 min), and a packing ratio of 2:1 (v/v, silica sand to ZVI). Synthetic wastewater consisting of 30 mg/L as N, 10-50 mg/L as PO 4 3À , and 5-30 mg/L F À was used for the experiment. Different combinations of anionic contaminants were tested in the experimental setup. Results indicated that nitrate, phosphate, and fluoride were removed at greater than 90%. When the reactor was operated without nitrate to act as a support electrolyte, phosphate, and fluoride removal efficiencies dropped drastically. Ammonia was produced during nitrate reduction, which led to iron oxidation. The FESEM and EDX analyses were performed to further investigate the electrochemical behavior in the ZVI-packed bed electrolytic cell.

Metallic iron for environmental remediation: A review of reviews

“…Perhaps a negative example is best indicated here for comprehension: fluoride is the reduced species in the redox couple F 2 /F À (E 0 ¼ 2.87 V) and cannot be reduced (by Fe 0 ). However, F À quantitative removal by Fe 0 has been documented (Jahin, 2014;Jeong et al, 2014). The results of Jahin (2014) further negate the validity of the reductive transformation concept (Matheson and Tratnyek, 1994;Roberts et al, 1996;Weber, 1996;O'Hannesin and Gillham, 1998).…”

Restoring the Nitrogen Cycle by Electrochemical Reduction of Nitrate: Progress and Prospects

“…In the reactor set up mentioned above, a high voltage (≈600 V) was applied to drive nitrate removal. [ 167,168,170 ] To reduce the operational cost, one effective strategy is to construct an electrolytic cell with a close gap between the key components. Cheng et al., for the first time, reported a zero‐gap solid polymer electrolyte (ZGSPE) reactor for simultaneous reduction of nitrates and oxidation of ammonia in aqueous solutions.…”