Green remediation of mixed contaminants using surface-tailored organoclays

Mixed contaminants, such as cadmium (Cd) and polycyclic aromatic hydrocarbons (PAHs) can be released in the environment from gasworks and mine sites (Thavamani et al., 2012). This poses serious environmental and health risk once these compounds/elements are mixed with soil, sediment and water. The remediation of these contaminants is often hard using single adsorbent due to their different immobilizing mechanisms (Biswas et al., 2016). However, incorporating natural and augmented microorganisms into the adsorbent-based remediation techniques could facilitate the biodegradation of PAHs. In this case, the adsorbent should immobilise the toxic Cd without sequestrating the PAHs. Previously, a surface-tailored organoclay was synthesised (Biswas et al.,2016), which showed selective adsorptive properties for Cd and PAH (Biswas et al., 2016), biocompatibility to microorganism in uncontaminated soil and water (Biswas et al., 2015; Mandal et al., 2016). However, the efficiency of the newly developed clay products should be tested with the originally contaminated soil of mixed contaminants for the potential use in the real-world application. In this study, we used a low clay soil from PAH/heavy metal-contaminated mine site and assessed the biocompatibility of the modified organoclay, contaminant's bioavailability and biodegradation over a long-term incubation period. (author)