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We report a kinetic and equilibrium study in which we examined the removal of perchlorate anions from water by adsorption onto modified reed (MR), an adsorption material constituted by giant reed (GR) particles whose anion adsorption properties have been enhanced by quaternary amine (QA) crosslinking. In particular, we examined how MR adsorption of perchlorate interacts competitively with concomitant adsorption of agriculture-derived phosphate and nitrate contaminants. Equilibrium and pH experiments were first conducted in single-component systems, the results of which were best described by the Langmuir-Freundlich (L-F) isotherm. Subsequent analyses of competitive effects on adsorption showed that although MR had a higher adsorption capacity for perchlorate alone than for nitrate or phosphate alone, the addition of either phosphate or nitrate to a perchlorate solution had a diminishing effect on MR adsorption of perchlorate within a natural-water pH range, with phosphate having the stronger competitive effect. Perchlorate adsorption on MR varied inversely with competing ion concentrations, providing direct evidence of the perchlorate diminution effect being attributable to anion competition. Finally, we developed a multicomponent isotherm model that describes the binary adsorption of perchlorate in the presence of each of these competing anions. The results of this work provide perchlorate removal efficiency information that is directly applicable to the design of water treatment systems.

Disposal of untreated perchlorate-laden modified reed (MR) generated in the treatment of contaminated water risks further contamination issues. The primary aim of this study was to assess the enriched microbial culture (EMC)-mediated biodegradation of perchlorate bound to spent quaternary amine-MR adsorbent. The culture was enriched to utilize perchlorate as an electron acceptor and brewer’s yeast as an electron donor. Kinetics experiments were performed to determine biodegradation rates and the total time for complete removal. The secondary aim of this research was the development and testing of a microwave-assisted extraction (MAE)-facilitated accurate perchlorate quantitation method. Extraction efficiency was optimized by adjusting the nitric acid concentration, resulting in 90 ± 5% recovery. Results show that EMC can degrade aqueous perchlorate effectively and consistently. EMC can also effectively degrade adsorbed perchlorate from spent MR. In conclusion, anaerobic biodegradation of perchlorate from spent MR can be used as an efficient, cost-effective, and environmentally friendly alternative or supplement to other treatment options, such as ion exchange and incineration. This approach can also be an effective solution to the waste generated by using MR to remove perchlorate from contaminated water.