Detecting the concentration of aldehydes disinfection by-products formed due to the application of the ozonation process in water treatment plants

Abstract

The current study presents, in detail, an experimental investigation for detecting four of high risk aldehyde compounds in water (acetaldehyde, formaldehyde, glyoxal, and methyl glyoxal). These compounds are normally formed in water in micrograms per liter, as by-products, after addition of ozone in the water treatment plants. For this study, 114 samples were taken from the raw and directly from the ozonated water of a drinking water treatment plant in Iraq, between August 2020 (54 samples) and September 2020 (60 samples). The samples were analyzed for their constituents — for aldehyde compounds — using a Gas Chromatography-Electron capture detector (GC-ECD) apparatus. In addition, the concentration of organic matters was measured via total organic carbon (TOC) and chemical oxygen demand (COD) tests, which were measured in accordance with the other technique for the checking of water. The results showed that in all analyzed samples there was a significant increase in the formaldehyde and acetaldehyde concentration in the water, after subjecting it to the ozonation process.In addition to that, noticeable concentrations of glyoxal (6.7 and 9.0 µg/L in August and September, respectively) and methyl glyoxal (12.6 and 12.1 µg/L in August and September, respectively, which were not detected in the raw water samples, appeared in those taken from the treated water. The conclusion obtained from this study was that the level of aldehydes formed in the water was dependent on the raw water characteristics and the amount of ozone added for disinfection purposes.