Closing the chloride loop: Halophyte biomass for circular road salt management

Road salt contamination is an increasing environmental concern in cold-climate cities, where repeated applications lead to long-term chloride accumulation in soils and waterways. Salt-tolerant vegetation (i.e., halophytes) can help intercept this chloride, but the resulting salt-laden biomass presents a secondary management challenge. This study evaluates the feasibility of recovering chloride from the biomass of the grasses Panicum virgatum and Sporobolus michauxianus using two water-based leaching approaches. Passive rinsing removed up to 70% of chloride at high water volumes, while active leaching achieved near complete (≈100%) recovery with fourfold less water. Based on plant densities and tissue chloride concentrations measured at a Canadian field site, preliminary estimates indicate that halophyte stands could recover 4-21 g Cl^-/m² annually, comparable to the salt applied during a single winter road treatment. To our knowledge, this study is the first to demonstrate a scalable approach to reclaim road salt from phytoremediation biomass. Scaling considerations-including biomass collection and transport, volume reduction, dewatering, pre-treatment, water reuse, and brine concentration-suggest that the system could be integrated into existing vegetation management infrastructure. Life-cycle assessment and cost-benefit analysis are significant next steps. Implementing circular biomass-based salt recovery could reduce salt procurement, improve resilience to supply disruptions, and support more sustainable winter maintenance practices.