Treatability evaluation of fourteen aldehyde odorants in drinking water by powdered activated carbon: Influence of odorant's properties on adsorption characteristics

Abstract

Powdered activated carbon (PAC) was frequently used for removing musty and septic odor-causing compounds in water matrix. However, it is not known if PAC is effective on removing various aldehyde odorants. In this study, the treatability of fourteen aldehyde odorants by PAC adsorption was evaluated comprehensively. The results indicated that most aldehyde odorants' removal rates could reach 90 % after 0.5 h exposure, while adsorption kinetic was better fitted for pseudo second-order model, and adsorption capacity was better fitted with Freundlich model. However, adsorption predictions from these models, which neglected olfactory threshold concentration (OTC), were unsuitable for evaluating that odor caused by aldehyde odorant could be controlled effectively or not. Therefore, treatability value, which considered residual concentration and OTC, was calculated, the result of 0.3– 0.67 suggested they could be removed below OTC effectively by PAC adsorption. Furthermore, the effect of aldehyde odorant's property on adsorption and treatability was studied through Pearson and Spearman correlation analysis. The results indicated that there were not significant correlations between adsorption capacity and aldehyde odorants' properties. Comparatively speaking, treatability had significant and positive correlations with aldehyde odorants' properties including molar refractivity (MR), octanal and water (LogKW), parachar, polarizability and volume (r: 0.860– 0.942, p: 0.000), suggesting that odorant with larger volume, more hydrophobic, higher MR and polarizability would be adsorbed by PAC easily. This is the first study for evaluating adsorption of multiple aldehyde odorants onto PAC completely, which would supply more understanding for controlling aldehyde odorants in drinking water treatment plant (DWTP).