Development of a scalable adsorptive bioremediation approach for perchlorate decontamination in water resources: A step towards process safety and circularity

Abstract

Perchlorate contamination in water sources poses a significant environmental and public health challenge, necessitating efficient, scalable, and sustainable treatment solutions. This study presents an integrated perchlorate treatment approach that combines adsorption and bioremediation, utilizing a retrievable adsorbent substrate (RAS) system developed by imprinting a functionalized montmorillonite clay-chitosan composite (Mt-H-CTS) onto a flexible carbon cloth substrate. The RAS was designed to effectively address the challenges and limitations of conventional methods for the decontamination of toxic perchlorate ions in large volumes of water, while ensuring process safety and circularity. Batch adsorption experiments with the Mt-H-CTS and RAS modules were conducted to optimize key parameters, including pH, contact time, and sorbent dosage, achieving a maximum adsorption efficiency. The developed sorbent system demonstrated excellent perchlorate removal performance in batch-scale experiments, achieving a maximum adsorption capacity of 5 mg g⁻¹ within 45 min under neutral pH. A lab-scale pilot study with 5 L of perchlorate-contaminated water (25 mg L⁻¹) showed > 98 % removal using RAS modules. Furthermore, real-water application using samples collected from a perchlorate-contaminated (5 mg L⁻¹) community pond validated the field applicability of the RAS system. These findings were incorporated, and a conceptual design and theoretical calculations for scaling up are presented to ease the lab-to-field scale applications. Moreover, the study addresses the challenges associated with spent adsorbent materials by presenting a novel approach to decontaminate perchlorate from spent sorbent (RAS) using an integrated bioremediation strategy. This approach is crucial for ensuring the economic feasibility of safe sorbent disposal while enhancing its reusability. The mechanistic perspective of better performance of ex-situ vis-à-vis in-situ bioremediation in terms of % decontamination, reusability, and faster kinetics (12 hr vis-à-vis 5 days) has been illustrated, thereby clearly unveiling the practical application potential of the developed novel RAS-coupled bioremediation strategy.