Application of isotherm models to combined filter systems for the prediction of iron and lead removal from automobile workshop stormwater runoff

Langmuir and Freundlich isotherm adsorption models were used to predict iron lead removal from automobile workshop stormwater runoff. Combined low-cost filter systems consisting of granular activated carbon–rice husk (GAC–RH) river gravel–granular carbon (GR–GAC) in this study. The effects adsorbent dosage contact time on the capacity adsorbents, as well efficiencies systems, also investigated. results for model generally showed favourable processes., with all RL values < 1 (in range 0.358–0.518). gave better predictions removal, high R2 0.842–0.969), while root mean square error (RMSE) ranged 0.002 2.366. parameters indicated chemisorption processes n 0.1296–0.4675). 0.634–0.916 RMSE 0.1765. Additionally, using GAC–RH system (54% 48%, respectively) found be higher than those obtained GR–GAC (35% 25%, respectively). capacities adsorbents decreased increased dosages adsorbent, optimum 0.5 g equilibrium 80 min combined adsorbents. Further research towards modifying oil grease polluted runoff are warranted.