Comparison of methodologies for determination of residual peracetic acid in wastewater disinfection.

The use of peracetic acid (PAA) in the disinfection of sanitary effluents provides an opportunity for the study of analytic methods that permit the determination of the residual concentration of the disinfectant in the effluent. The object of the present study is to compare different methodologies for the determination of residual PAA in concentrations recommended for disinfection of wastewater. The methodologies adopted in this study include three redox titration methods and one spectrophotometric method. Preliminary tests were performed by adding PAA (0.1; 0.5; 1.0; 5.0 and 10.0 mg L−1) to distilled water, and later reevaluated by applying the same concentrations of the disinfectant in wastewater. The results obtained were statistically evaluated and showed that the concentrations between 0.5 and 10 mg L−1of PAA could be determined both by the cerimetric/iodometric titration method and by the spectrophotometric method using DPD chromophore with catalase. For concentrations between 0.1 and 0.5 mg L−1, only the spectrophotometric method provided satisfactory results. [ABSTRACT FROM AUTHOR]