Effects of feed water NOM variation on chloramine demand from chloramine-decaying soluble microbial products during rechloramination.

Effects of feed water NOM variation on chloramine demand from chloramine-decaying soluble microbial products during rechloramination.
Chemosphere. 2018 Dec;212:744-754
Authors: Herath BS, Torres A, Sathasivan A
Abstract
Earlier, we reported on soluble microbial products-mediated chloramine decay in nitrifying waters. However, we neither separated the agent(s) nor identified the factors that enhanced the production of chloramine-decaying soluble microbial products (cSMPs). Experiments were conducted by feeding reactor sets (each consisting of five reactors connected in series) with treated water (3-8 mg-DOC.L-1) obtained from a water treatment plant. The reactors simulated various nitrifying conditions that are experienced in a chloraminated system. In unfiltered samples obtained from nitrified reactors, about 89-93% of the dosed chloramine decayed within 40 h. The cSMP-mediated decay accounted for 21-39% of all chloramine decay in the samples from 0 to 5 mg-C.L-1 fed reactors and 15% in the samples from 7 to 8 mg-C.L-1 fed reactors. Microbial processes (mediated by nitrifiers and/or heterotrophs) and biomass-associated microbial products (BMPs) in insoluble form accounted for 13-21% for the reactors fed with 0-5 mg-C.L-1 and 34% for those fed with 7-8 mg-C.L-1. The cSMPs were separable with a 30 kDa cut-off membrane but not with 50 or 100 kDa membranes, i.e., they were above 30 kDa but below 50 kDa in size, and we...

Source: Chemosphere - November 9, 2018 Category: Chemistry Authors: Herath BS, Torres A, Sathasivan A Tags: Chemosphere Source Type: research