Simple and effective remediation strategies of Martian perchlorates

Abstract Martian surface minerals have abundant perchlorate salts existing in both solid and liquid phases that will impair agricultural operations, biological life‐support systems, and in situ resource utilization due to their toxicity. Thus, simple and effective perchlorate remediation strategies will be necessary for the successful use of Martian surface minerals as a plant growth substrate among other uses. The low thermal decomposition, high solubility, reluctant nature to sorb to minerals, and biological metabolism of perchlorate offer attractive solutions for remediation. Using JSC Mars‐1 simulant spiked with varying concentrations (1–10 g kg −1 ) of magnesium perchlorate, it was found that a 470°C thermal decomposition in a furnace led to near elimination of perchlorate. Additionally, three leaching events at a 1:5 (solid:liquid) ratio followed by distillation of leachate also eliminated magnesium perchlorate from simulated Martian surface minerals and leachate water. For biological perchlorate reduction, a native soil microbiome was bio‐prospected from agricultural fields. A directed evolution of the native soil microbiome proved successful in increasing perchlorate reduction rates from 35% to 52%. The directed evolution microbiome was compared to pure cultures of six bacteria and one fungus known to be capable of perchlorate reduction, with the directed evolution microbiome having similar perchlorate reduction rates to the pure cultures. Overall, the thermal decomposition and leaching with distillation approaches were considered low technology, highly effective options to remediate perchlorate from Martian surface minerals, although their energy inputs and alteration of soils may be undesirable in certain circumstances.