Effect of compost aging on zinc adsorption characteristics

• The effect of aging of compost particles on metal adsorption was studied.
• Sorption capacity of compost dropped due to the effect of aging process on compost.
• Physicochemical properties of compost particles were changed due to aging process.
• Kinetics models showed that the rate of zinc sorption decreased due to the compost aging.

One approach to improving the performance of biofiltration based treatment systems is to amend filtration media with compost to improve metal sorption. The effect of aging these amended compost particles on zinc sorption is investigated using batch and column tests. Batch tests showed that aged compost had a lower rate of zinc sorption but a similar zinc sorption capacity compared with fresh compost. Pseudo-second-order kinetics was found to best fit the batch experimental data. The intra-particle diffusion plot shows that there are differences due to the effect of aging of compost and that intra-particle diffusion is the dominant rate controlling mechanism. Column studies show that aging the compost decreased the sorption capacity by 22% (from 16 mg g−1 to 13 mg g−1). It is evident that aging compost media have an effect on the magnitude and kinetics of zinc adsorption. This was also evidenced in the decreased CEC and peak intensities of relevant spectra in the FTIR of the aged compost.