Potential of anthracite, dolomite, limestone and pozzolan as reactive media for de-icing salt removal from road runoff

Abstract

De-icing salt (NaCl) application is a common practice during winter road maintenance in northern countries, compromising ecosystem services. Ecoengineering facilities, including reactive filter beds, are becoming an effective strategy for road runoff management. Different materials (anthracite coal, dolomite, limestone, and pozzolan) were tested as reactive media of filter beds. Characterization showed that dolomite has the best physical properties (resistance to fragmentation, porosity) for filter bed construction and maintenance, followed by limestone. NaCl removal efficiency was investigated in batch at different concentrations (150-5000 mg L -1 Cl). Removal efficiency substantially varied depending on the element (Cl or Na), the material, and the added NaCl concentration. At the lowest NaCl concentration, Cl removal was higher onto anthracite (48 %) and dolomite (59 %); but greater Na removal was reached onto limestone (54 %) and pozzolan (67 %). At higher concentrations, Cl removal was similar (anthracite), decreased (dolomite), or increased (limestone, pozzolan); and Na removal increased (anthracite) or decreased (dolomite, limestone, pozzolan). Parallel experiments at 4°C showed lower NaCl removal, anthracite being the most efficient. Practical applicability was evaluated in columns using synthetic runoff solution (NaCl and metals). NaCl removal efficiency was much lower in column assays with respect to batch. The highest NaCl removal was reached onto dolomite, followed by limestone. Metals were successfully removed, generally remaining over time in a wide range (41-89 % Cd, 78-97 % Ni, 44-88 % Cu, and 3-83 % Zn) depending on the material, being pozzolan the least efficient. Further studies including a combination of materials would be of high interest.

Archives of Environmental Protection

“…The necessity of salinity reduction has led to the search for a substance or dosing method which will decrease the negative impact of readily soluble salts entering the soil environment. Currently, many research is being conducted throughout the world to determine the essential features of such a universal and environmentally friendly material, characterized by: naturalness, physical and chemical stability, as well as low costs (de Santiago-Martín et al 2016). The results presented in this paper are a continuation of an environmental study initiated by Kochanowska and Kusza (2010), which dealt with changes of the physico-chemical properties of soils as a result of readily soluble salts used in the winter maintenance of streets in the city of Opole.…”

Runoff water loaded with road de‐icing salts: Occurrence, environmental impact and treatment processes

“…Notably, biofilters have shown the capability of reducing suspended solids, carbon, total organic matter, BOD5, ammoniacal nitrogen and nitrates (Basu et al, 2016). In a study conducted by de Santiago-Martín et al (2016), different materials such as anthracite coal, dolomite, limestone and pozzolan were assessed as reactive media for filter beds. According to their results, dolomite was introduced as an appropriate candidate for filter bed construction and maintenance owing to its physical properties such as fragmentation resistance and porosity.…”