Monochloramine Advanced Oxidation for Removal of Trace Organics in Wastewater

Abstract

Monochloramine and free chlorine are both common disinfectants and candidates for Advanced Oxidation Processes (AOP). Results from this study show that free chlorine in the form of HOCl and OCl- has faster degradation kinetics for emerging pollutants. Unfortunately, free chlorine only becomes stable after chlorine demand is satisfied. Monochloramine on the other hand, forms instantaneously upon the addition of chlorine in the presence of ammonia and is a relatively stable compound. Advanced Oxidation Processes using UV 254 light with monochloramine has not been thoroughly investigated. In this study, monochloramine AOP is used to degrade p-cresol to illustrate its oxidative effectiveness. Monochloramine AOP is then compared to chlorine AOP; Chlorine AOP can achieve 90% p-cresol degradation after 15 minutes while monochloramine AOP degraded approximately 65% p-cresol after 15 minutes; both results operated at concentrations of 100 µM oxidant, under UV 254 light with an incident irradiance of 10.38 W/m2 , with an initial p-cresol concentration of 10 µM, and using deionized water buffered with 10 mM phosphate buffer at pH 7. The viability of Monochloramine AOP in wastewater is tested in this study; unfortunately, monochloramine AOP only achieves 10% p-cresol reduction in 15 minutes under UV 254 irradiation for wastewater experiments. Lastly, breakpoint curves are generated while under 15 minutes of UV 254 irradiation to directly compare how the molar ratio of Cl2:NH3 affects AOP degradation of p-cresol.