Wastewater disinfection for reclaimed water production and distribution – a lab study for assessing the chlorine reactivity

Abstract

This paper describes a laboratory study on chlorination of a treated effluent from a wastewater treatment plant in Lisbon, assessing the changes in water composition promoted by the chlorine reaction, including the formation of trihalomethanes (THM). For this purpose, chlorination breakpoint curves were determined and the effects the chlorine concentration dosing on chlorine decay trend and on THM formation were evaluated. Absorbance and fluorescence spectroscopy methods were also used to characterize the chlorinated water samples and to search for correlations between absorbance spectra, fluorescence excitation-emission matrices and THM formation. Finally, a chlorine disinfection chamber was dimensioned as an alternative approach to that adopted by the Beirolas treatment plant for wastewater treated for reuse.