Study on the removal of aesthetic indicators by ozone during advanced treatment of water reuse

Abstract

Aesthetics and water quality are primary issues of concern for sustainable water reuse since aesthetically unpleasant color and odor are likely to induce public misgiving. This study utilizes aesthetic indicators and other bulk water quality parameters for evaluation. It is found that ozonation during advanced treatment processes in a full-scale water reclamation plant (WRP) could achieve satisfactory performance in decolorization and oxidation of aromatic and humic contents. As limited efficacy on odor removal was detected in the WRP, this study further researched the removal of the main odorant substances 2-methylisokanol (2-MIB) and geosmin (GSM) with different ozone dosage using solid-phase extraction (SPE) and gas phase mass spectrometry (GC–MS) techniques. According to the first-order reaction kinetics, it is inferred that competitive reactions during ozonation by organic matters and restricted CT values are major factors affecting the odor removal. As such, additional treatment approaches such as nanofiltration (NF) are suggested to be consider for aesthetic control towards sustainable and long-term reclaimed water use.