Occurrence and removal of amino acids during drinking water treatment

Abstract

Amino acids (AAs) have been identified as precursors to disinfection by‐products—some more cytotoxic than the currently regulated disinfection by‐products. This study measured occurrences and removals of AAs, amino sugars, and bulk organic matter surrogates (dissolved organic carbon [DOC], dissolved organic nitrogen [DON]) in raw water and filter effluents of 16 full‐scale water treatment plants influenced by algal activity or wastewater discharge. In raw waters, the average concentration of free AAs—those not bound in larger molecules—was very low, 0.69 μg/L N (< 0.5% of the DON). The average concentration of total AAs—those bound and unbound—was 41.1 μg/L N (15% of the DON). The most dominant (on a molar basis) AA species detected were serine, alanine, and glycine. Water treatment removed, on average, 30, 30, 25, and 65% of DOC, DON, free AAs, and total AAs, respectively. This study was the first large‐scale occurrence survey of free and total AAs in United States drinking waters.