Formation and Fate of Carbonyls in Potable Water Reuse Systems

• Published in: Environmental science & technology Vol. 54; no. 17; pp. 10895 - 10903
• Main Authors: Marron, Emily L, Prasse, Carsten, Buren, Jean Van, Sedlak, David L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.09.2020
• Subjects: Acetone; Acrolein; Aldehydes; analytical methods; Biofiltration; Carbonyl compounds; Carbonyls; Dissolved organic carbon; Drinking Water; Filtration; formaldehyde; Free radicals; Genetic transformation; Hydroxyl radicals; Ketones; Low molecular weights; Molecular weight; Osmosis; Oxidation; Ozonation; Rate constants; Reverse osmosis; Treated water; Treatment and Resource Recovery; Waste Water; Wastewater; Water Pollutants, Chemical; Water Purification; Water quality; Water reuse; Water treatment; Water treatment plants
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/acs.est.0c02793

Low molecular weight, uncharged compounds have been the subject of considerable study at advanced treatment plants employed for potable water reuse. However, previously identified compounds only account for a small fraction of the total dissolved organic carbon remaining after reverse osmosis treatment. Uncharged carbonyl compounds (e.g., aldehydes and ketones) formed during oxidation have rarely been monitored in potable water reuse systems. To determine the relative importance of these compounds to final product water quality, samples were collected from six potable water reuse facilities and one conventional drinking water treatment plant. Saturated carbonyl compounds (e.g., formaldehyde, acetone) and α,β-unsaturated aldehydes (e.g., acrolein, crotonaldehyde) were quantified with a sensitive new analytical method. Relatively high concentrations of carbonyls (i.e., above 7 μM) were observed after ozonation of wastewater effluent. Biological filtration reduced concentrations of carbonyls by over 90%. Rejection of the carbonyls during reverse osmosis was correlated with molecular weight, with concentrations decreasing by 33% to 58%. Transformation of carbonyls resulted in decreases in concentration of 10% to 90% during advanced oxidation, with observed decreases consistent with rate constants for reactions of the compounds with hydroxyl radicals. Overall, carbonyl compounds accounted for 19% to 38% of the dissolved organic carbon in reverse osmosis-treated water.