Attenuation of Trace Organic Compounds by Physical and Chemical Processes in Water Reuse

Abstract

Realized and potential threats of water scarcity due in part to global climate change have increased the interest in potable reuse of municipal wastewater. Recalcitrant trace organic compounds (TOrCs), including pharmaceuticals, steroid hormones and industrial compounds in wastewater are often not efficiently removed by conventional wastewater treatment processes, thereby ubiquitously occurs in natural and wastewater effluents. Advanced water treatment processes including advanced oxidation processes (AOPs), activated carbon adsorption and membrane separation processes have been demonstrated to efficaciously attenuate many classes of TOrCs. In this dissertation, attenuation of TOrCs by ozone oxidation, powdered activated carbon (PAC) and nanofiltration membrane and their monitoring strategies were demonstrated in water reuse applications. Particularly, the first main chapter attempted to elucidate the use of indicator/surrogate for predicting TOrC attenuation by ozone oxidation in a theoretical basis. A semi-empirical model was developed, which successfully predicted many TOrCs with various oxidation kinetics simultaneously. The following chapter was pertaining to development of exploratory models to predict TOrC abatement by ozone. It was concluded that principal component (PC) analysis in conjunction with artificial neural network (ANN) resulted in precise and robust prediction of TOrC attenuation. In addition to oxidation process, kinetic of TOrC adsorption by PAC was scrutinized subsequently. It was found that the initial-phase adsorption was controlled by surface reaction due to hydrophobic interaction. In addition, correlation between surrogate reduction and TOrC attenuation was independent upon water quality at the early phase of adsorption, which was explained theoretically. In the last chapter, synergistic effects of NF membrane in conjunction with pre-ozonation was investigated for TOrC abatement in brine. As a result, all the tested TOrCs were efficaciously attenuated and not quantifiable due to their concentration below limit of quantification. In addition, ozonation also alleviated organic fouling potential substantially.