1. 2012 Water Quality Technology Conference and Exposition (WQTC): Abstract Submission
Comparative Study of Disinfection By-products (DBPs) Formation during Wastewater
Disinfection with Peracetic Acid (PAA) versus Sodium Hypochlorite (NaClO)
Miaoyi Yan, Onita D. Basu, and Jeffery Manthorpe
Peracetic acid (PAA) is gaining increased acceptance in recent years as an alternative
disinfectant to chlorine, and preliminary studies by others have identified its relatively harmless
disinfection by-products (DBPs). However, research on PAA disinfection, especially on its DBPs
formation, is still relatively new in the field of water and wastewater treatment.
The primary goals of this project are to (1) investigate and identify potential genotoxic
and mutagenic DBPs formed from wastewater disinfection with PAA and compare them with the
corresponding DBPs from NaClO at the same experimental conditions; (2) compare reduction
and potential DBPs formation of selected Endocrine Disrupting Compounds (EDCs)/
Pharmaceuticals (PhAC) from PAA and NaClO oxidation. Among the extensive suite of various
EDCs/PhAC found in water, 17 β-Estradiol (E2), Clofibric Acid, and Ketoprofen have been
chosen and focused on in this research, since these t chemicals are frequently measured but not
easily removed by chlorination or ozone oxidation in WWTP, and their high degree of
persistence in environment has lead to long-lasting effects on various water matrices, aquatic
wildlife, farm animals, and even food chain. Comparison of these three chemicals reacted by
PAA versus NaClO can help us to further assess PAA oxidation efficiency and their
corresponding toxicity. Experimental parameters including PAA/NaClO dosage, pH, hydraulic
contact time and their effect on DBPs formation are also studied to investigate conditions that
minimize DBPs formation.

2. In this research, Jar testing study at laboratory scale is used to simulate contact chamber
conditions. Gas Chromatography and Mass Spectrometry (GC/MS) analyzer is used for DBPs
identification and quantification. Experimental desigh and sample preparation procedures are as
follows: 1) Sample Preparation by Jar Testing at different dosages (0, 1, 2, 4, 6, 10mg/L) and
different contact time (0, 10, 15, 30, 60 min); 2) Quenching by sodium thiosulfate and catalase,
acidification by 98% sulfuric acid at pH=2-2.5; 3) Liquid-liquid extraction by dichloromethane;
4) Evaporation/Drying by rotating evaporator; 5) Appropriate gas chromatography and mass
spectrometry (GC/MS) analysis for a certain DBP’s identification. Possible DBPs can be found
by comparing Full-Scan Mass Spectrums before and after disinfection for both PAA and NaClO
disinfection. By combination of various techniques including comparison of experimental mass
spectrum against a fragmentation library that contains published patterns of known
decomposition reaction, software assisted interpretation, and structure elucidation, an unknown
DBP can be identified. The corresponding different disinfection efficiency of PAA versus NaClO
can be demonstrated, and the influence of PAA/NaClO dosages, contact time on each DBP
formation can be also illustrated.
EDC/PhAC at 1 ppm 17 β-Estradiol (E2), Clofibric Acid, and Ketoprofen were reacted
with 10 ppm PAA/NaClO. Comparisons of the various mass spectrums: before and after
treatment with the two disinfectants, identify new peaks in the disinfected samples may be
considered to be DBPs or degradation products. For 17 β-Estradiol (E2) +NaClO, it was shown
that NaClO decomposed 17 β-Estradiol (E2) significantly, which means it may reduce 17 β-
Estradiol (E2) estrogenic effects as well. However, three DBPs were formed: 4-chloro-E2/ 2-
chloro-E2, 4-chloro-E1/ 2-chloro-E1, and one unknown peak needed to be further identified.

3. 2012 Water Quality Technology Conference and Exposition (WQTC): Abstract Submission
These chlorinated 17 β-Estradiol (E2)/ Estrone (E1) might be more toxic than 17 β-Estradiol
(E2) itself and have more estrogenic effects on environment. PAA did not appear to significantly
decompose 17β-Estradiol (E2). However, two DBPs still noted post PAA disinfection: We
propose CH3O-E2 for one DBP, and the other one is still unknown. They will be further
identified and their toxicity will be analyzed in future work. Neither Clofibric acid or Ketoprofen
were oxidized by exposure to PAA/NaClO and no DBPs were found.
Preliminary wastewater disinfection with PAA/NaClO indicates a variety of DBPs from
both PAA/NaClO. The corresponding conclusion from this research will draw some light on the
potential DBPs formation during wastewater disinfection with PAA. It could provide reference
for PAA dosage applied in the field scale and benefit researchers to further study the methods to
reduce the genotoxic, carcinogenic, and/or mutagenic DBPs in order to minimize human and
environmental exposure to noxious pollutants.
!
!
!