Evaluation of geotextile-based adsorption system in a pilot scale test simulating runoff contaminated with petroleum products and heavy metals

Traffic and transportation are the sources of pollution in roadside soil-groundwater systems by petroleum products and heavy metals. In this study, geotextile systems were used as adsorption layers for petroleum substances and heavy metals in a pilot scale test that simulates runoff from the petroleum station and roads under moderate and heavy rainfall. Two new types of geotextiles filled with (1) activated carbon and (2) composite mineral sorbent consisted of halloysite, recycled rubber and fly ash were used. Geotextiles were installed in the base layer below the pavement. Diesel oil, E95 petrol, motor oil, zinc and copper were dosed on the pavement under routine and accidental leak scenarios. The performance of the geotextiles was assessed on pollutant concentrations measured in the outflow from the column system. Despite the high cumulative load of fuels (diesel oil and E95 petrol, each 2x180 g/m²), copper (500 mg/m²) and zinc (500 mg/m²) applied during the routine leakage test, the concentrations of copper and zinc from petroleum products in the outflow did not exceed 1.3 mg/L 0.9 mg/L, and 0.24 mg/L, respectively. The geotextiles also effectively trapped petroleum products during simulations of large accidental spill events. Despite substantial loads of spilt fuels (948 g/m²) and motor oil (1044 g/m²), the concentration of petroleum products in the outlet remained below 0.26 mg/L and 0.31 mg/L, respectively. Petroleum products originating from motor oil were retained more effectively by the geotextile containing the mineral sorbent, whereas petroleum products from fuels were more efficiently adsorbed by the geotextile-activated carbon system. This was because smaller fuel molecules more easily penetrating the microporous structure of activated carbon was more easily adsorbed, while motor oil-characterised by higher viscosity and larger particle size-was more effectively adsorbed by the mineral sorbent with a mesoporous structure.