Simple Method for Quantifying Microbiologically Assisted Chloramine Decay in Drinking Water

Abstract

In a chloraminated drinking water distribution system, monochloramine decays due to chemical and microbiological reactions. For modeling and operational control purposes, it is necessary to know the relative contribution of each type of reaction, but there was no method to quantify these contributions separately. A simple method was developed to do so. It compares monochloramine decay rates of processed (0.2 microm filtered or microbiologically inhibited by adding 100 microg of silver/L as silver nitrate) and unprocessed samples under controlled temperature conditions. The term microbial decay factor (Fm) was defined and derived from this method, to characterize the relative contribution of microbiologically assisted monochloramine decay to the total monochloramine decay observed in bulk water. Fm is the ratio between microbiologically assisted monochloramine decay and chemical decay of a given water sample measured at 20 degrees C. One possible use of the method is illustrated, where a service reservoir's bulk and inlet waters were sampled twice and analyzed for both the traditional indicators and the microbial decay factor. The microbial decay factor values alone indicated that more microbiologically assisted monochloramine decay was occurring in one bulk water than the other. In contrast, traditional nitrification indicators failed to show any difference. Further analysis showed that the microbial decay factor is more sensitive and that it alone can provide an early warning.

Continuous Left Atrial Pressure Monitoring During MitraClip

“…Earlier findings (Sathasivan et al, 2005(Sathasivan et al, , 2008Bal Krishna et al, 2013) showed that the behavior (mild nitrification mediated by CDOs) under high chloramine residual is noticed until the onset of nitrification. Earlier findings (Sathasivan et al, 2005(Sathasivan et al, , 2008Bal Krishna et al, 2013) showed that the behavior (mild nitrification mediated by CDOs) under high chloramine residual is noticed until the onset of nitrification.…”

A selection framework for NOM removal process for drinking water treatment

“…Chemical decay of chloramine is described by a complex set of reactions in the US EPANET MSX and Innovyze H 2 OMap MSX software [27]. Chemical stability of chloramine is not a limiting factor because chloramine (as formed for water disinfection) decays by less than 5% per day [28]. Therefore, after 10 d, there would still be more than 50% of chloramine available.…”

Monochloramine Decay for Two Chlorine to Ammonia Ratios in Bulk Water

“…Nitrite is not typically found in tap water, but it can build up to significant concentrations in the distribution system because of nitrification (Kirmeyer et al, 1995). Some research indicates that the chloramines loss could be caused principally by nitrite when nitrification occurs (Sathasivan et al, 2005;Yang et al, 2008). Under water treatment conditions, it has been indicated that the direct nitrite oxidation of chloramines could result in the chloramines loss (Lieu and Roy, 1993;Margerum et al, 1994).…”