Comparison of Toxicity-Weighted Disinfection Byproduct Concentrations in Potable Reuse Waters and Conventional Drinking Waters as a New Approach to Assessing the Quality of Advanced Treatment Train Waters

Abstract

Advanced treatment trains based on oxidation, biofiltration, and/or granular activated carbon (Ox/BAF/GAC) are an attractive alternative to those based on microfiltration, reverse osmosis, and advanced oxidation (MF/RO/AOP) for the potable reuse of municipal wastewater effluents, but their effluent quality is difficult to validate with respect to chemical contaminants. This study evaluated the sum of the concentrations of 46 disinfection byproducts (DBPs) after treatment by chlorine or chloramines weighted by metrics of toxic potency in 10 full- or pilot-scale reuse trains to estimate the DBP-associated toxicity of their effluents. These total toxicity-weighted DBP concentrations were compared to those measured in their local, conventional drinking waters as a benchmark for water quality receiving regulatory and widespread public acceptance. The results indicated that while the DBP-associated quality of MF/RO/AOP-based reuse waters can readily exceed that of drinking waters, that of Ox/BAF/GAC-based reuse waters can approach or exceed that of drinking waters, particularly when they are chloraminated. Unregulated, halogenated DBPs were the dominant contributors to the estimated DBP-associated toxicity. While RO/AOP treatment preferentially reduced the concentrations of the more toxic brominated DBP species, BAC and GAC treatment favored brominated DBP species by removing DOC but not bromide. Comparing the total toxicity-weighted DBP concentration between reuse and drinking waters provides drinking water as a rational benchmark for water quality comparison, explicitly recognizes that contaminants occur as mixtures, provides utilities flexibility in selecting the most efficient treatment trains to reduce estimated toxicity, and can be expanded to encompass new contaminants as toxic potency data become available.

Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C4-Dicarbonyl Ring Cleavage Products

“…4,5 More than 700 DBPs have been identified, including suspected and known carcinogens, including haloacetaldehydes and haloacetonitriles. [6][7][8] However, despite decades of research, researchers have only been able to account for 40% of the halogenated DBP mass balance. 9,10 Among the chemical moieties that serve as DBP precursors, phenols are of particular importance due to their widespread occurrence in natural organic matter (NOM) and anthropogenic chemicals (e.g., consumer products such as triclosan, additives that are released by plastic pipes like bisphenols and nonylphenol) coupled with their relatively high reactivity with hypochlorous acid (HOCl).…”

Degradation of contaminants of emerging concern by UV/H2O2 for water reuse: Kinetics, mechanisms, and cytotoxicity analysis

“…In future work, CECs at lower, environmentally relevant levels (100e200 ng L À1 ) should be treated by UV/H 2 O 2 (700e1000 mJ cm À2 UV fluence) and the toxicity should be assessed in order to determine whether there is any detectable toxicity and whether the trends observed in the present study are maintained. In general, little toxicity of MF/RO/UV-AOP product waters (non-spiked CECs) in potable reuse facilities was detected in other studies by measuring disinfection byproducts-associated toxicity (Chuang et al, 2019). Nevertheless, improvements in UV/ H 2 O 2 treatment may be beneficial to further reduce any measurable response from bioanalytical tools (which are highly sensitive indicators of cytotoxicity) during CEC degradation, as the formed TPs during UV/H 2 O 2 are more toxic relative to their parent compounds.…”

Disinfection byproducts formed during drinking water treatment reveal an export control point for dissolved organic matter in a subalpine headwater stream

“…The second reacted 250 mL vial was quenched to achieve a concentration of 33 mg/L ascorbic acid and acidified with 5% v/v sulfuric acid to reach a pH of 3.7. The DBP samples were stored headspace free at 4 °C and shipped overnight on ice to Stanford University where the DBPs were extracted according to EPA Methods 551.1 ( U.S. EPA, 1995 ) and 552.3 ( U.S. EPA, 2003 ) and analyzed using gas chromatography-mass spectrometry as described previously ( Chuang et al., 2019 ). A suite of known DBP compounds was analyzed including THMs (chloroform, bromodichloromethane, dibromochloromethane, bromoform), the 5 regulated HAAs (dibromoacetic acid, dichloroacetic acid, bromoacetic acid, chloroacetic acid, trichloroacetic acid), additional HAAs (bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid, idoacetic acid, tribromoacetic acid), haloacetonitriles, haloacetaldehydes, iodinated trihalomethanes, chloropicrin, and haloketones.…”