Keywords: compost, particle size, rate–limited sorption, sorption capacity, stormwater biofiltration, zinc removal
Occurrence of rate limited sorption in stormwater biofiltration systems
Batch and column studies were conducted using synthetic stormwater with mixtures of 0.6 mm glass beads and compost particles of either 1.18 or 4.75 mm. Batch tests showed that rate limited uptake of zinc occurred onto both particle sizes. The column containing the 1.18 mm particles could be fitted by a Freundlich sorption isotherm while the other column exhibited a diffuse front and tailing and could not be modelled using equilibrium isotherms. The sorption capacity of the compost for zinc was estimated at 12.5 mg/g and 9.1 mg/g for the 1.18 mm and 4.75 mm particle size fractions, respectively.