Analysis and occurrence of odorous disinfection by-products from chlorination of amino acids in three different drinking water treatment plants and corresponding distribution networks

Abstract

Previous studies have established that odorous and stable chloraldimines are formed during amino acid chlorination in drinking water treatment. In order to identify at low level (10 −8 M) the presence of these odorous disinfection by-products in drinking water matrixes an analytical method was developed by using head space apparatus (HS) combined with a sorbent trap system linked to a GC with a mass spectrometer detector (HS/Trap/GC/MS). The analyses were carried out in three different drinking water supplies from the Paris area, during the four seasons. Free amino acids were monitored at the inlet of the plant. The odorous disinfection by-products were analyzed at the outlet of each drinking water treatment plant and the different distribution networks were connected to the corresponding plant. The results confirmed that the odorous chloraldimines are produced during chlorination of free amino acids in three different matrixes in different seasons throughout the year (N-chloroisobutaldimine; N-chloromethyl-2-butaldimine; N-chloromethyl-3-butaldimine (6–10 nM). The analytical method (HS/Trap/GC/MS) used to monitor odorous disinfection by-products appeared to be adapted for the detection of these by-products at nM level.