REMOVAL OF PHARMACEUTICALS BY IRON OXIDE AND MANGANESE OXIDE COATED SANDS IN BIORENTENTION COLUMN REACTORS

Abstract

This study is designed to investigate performance and mechanism of bioretention facilities in Pharmaceuticals and Personal Care Products (PPCPs) reduction. In batch experiments, iron oxide coated sands (IOCS) and manganese oxide coated sands (MOCS) showed better removal efficiency than silicon sands. Adsorption isotherms were well fitted using Langmuir model. PPCP removal decreased when pH higher than pHPZC, suggesting it was mainly controlled by adsorbent surface charge. The dominant contribution of removal was attributed to oxidation process. In bioretention column experiments, adsorption sites on adsorbent surface got saturated when concentrations of Caffeine (CF) and Ibuprofen (IBP) were up to 10 mg/L. Lower flow rates were demonstrated to increase removal by extending contact time. Breakthrough curves were well fitted using bed depth service time model. For CF and IBP removal by IOCS, the critical bed depths were 32.05 and 28.67 cm, while for MOCS they were 27.80 and 30.86 cm, respectively.