Bench-scale assessment of the formation and control of disinfection byproducts from human endogenous organic precursors in swimming pools

Abstract

In this study, a bench-scale system was utilized to assess the disinfection byproduct (DBP) formation from human endogenous organic matter. Perspiration and urine, constituting the main organic substances in swimming pools, were selected to represent the major human endogenous organics. Results revealed that the continuous input of body fluids into the reactor led to rapid accumulation of endogenous organic matter, which contributed to high concentrations of DBPs in the swimming pool. The increase in nonpurgeable organic carbon (NPDOC) concentration from the perspiration precursor was lower than that from urine during the operation. Moreover, the accumulation of swimmers' body fluids leads to increased DBP precursors, as well as increased chlorine demand and DBP formation in swimming pool water. The concentration of the trihalomethanes (THMs) and haloacetic acids (HAAs) consistently increased during the reaction. More THMs were generated in urine solution, whereas more HAAs were found in perspiration solution. To improve the water quality in swimming pools, ozonation, UV/Chlorine, and UV/H2O2 treatments were evaluated for their efficacy in reducing the DBP precursors. Results revealed that all of the three treatment processes can degrade the DBP precursors in perspiration and urine, eventually decreasing the DBP concentrations. However, only the UV/H2O2 treatment can decrease the formation of DBPs in perspiration and urine. In addition, the results revealed that UV/Chlorine and UV/H2O2 treatments should be operated for a sufficient contact time to prevent the increased production of DBP precursors in water at the early stage of the treatment.