Spatio-temporal variability of halogenated disinfection by-products in a large-scale two-source water distribution system with enhanced chlorination

Review of Ice Slurry Pigging Techniques for the Water Supply Industry: Engineering Design and Application

“…The study shows that ice pigs with initial lengths of 10 m can remove 99.99% (4 log units) of biofilm bacteria on pipeline surfaces, which is more than the other two methods . In a practice project, microbial parameters such as residual chlorine, colonies number, and number of coliforms have been intended for representing water quality performance as a result of ice pigging. ,, The changes in heterotrophic bacteria content coincided well with those of turbidity before, during, and after the ice pigging process, which is a sharp increase, followed by a rapid reduction, and finally lower than before pigging . On the basis of bacteria analysis of sediments taken from 16 ice pigging projects, iron or manganese is the predominant mineral in 30 samples, and 26 of them are positive for iron-related bacteria.…”

Disinfection Byproducts in Intermittent Piped Water Supplies

“…As mentioned previously, high water ages have been shown to result in higher concentrations of regulated THMs and lower concentrations of some HAAs and unregulated DBPs. 22,23 3.2. Natural Organic Matter (NOM) and Other Organic Constituents.…”

“…There have been significant advancements in our knowledge of DBPs since their discovery in the 1970s . DBP formation in drinking water systems is today understood as a function of many water quality parameters, including disinfectant type and dose, dissolved constituents (including organic matter), contact time, pH, temperature, – and many factors influencing the secondary formation of DBPs in drinking water distribution networks (DWDNs). – However, our understanding of these factors in IWS is extremely limited. Although IWS is widely variable across systems, ranging from a few hours per week of supply to an almost continuous supply, certain features of IWS are common and central to this practice: (1) supply-driven low pressures and pressure transients that can lead to low or negative pressures in the distribution system, inducing intrusion of contaminants, (2) water stagnation in sections of the pipe that do not fully drain between supply cycles, (3) drained (empty) pipes between supply cycles due to demand by consumers or system losses, (4) repressurization of pipes when supply is restarted, creating flushing of pipes at the beginning of the supply (known as “first flush”), and (5) the need for household water storage to hedge against discontinuous water availability (Figure ).…”

“…As chlorine residual decreases with water age, the level of formation of THMs may also decrease. Additionally, depending on the degree of intermittency in IWS systems, metastable intermediate DBPs, such as HANs, can degrade into more stable DBPs such as HAMs and HAAs, shifting the speciation of DBPs in the DWDN. – Some of these DBP intermediates are generated in short time frames (e.g., <2 h), while more stable DBPs may take much longer to form. ,,, Because of the complexity of IWS, short and long water ages can be experienced depending on the duration of the supply and among supplies, the size of drinking water systems (DWSs), and stagnation. Understanding how residence times impact DBPs in IWS necessitates DBP monitoring throughout the entire supply cycle.…”

Trace determination of disinfection by-products in drinking water by cyclic ion chromatography with large-volume direct injection

“…Drinking water disinfection is an indispensable measure to guarantee public health, and can remove viruses, bacteria, and other micro-pollutants as well as provide puried water for human consumption. [1][2][3] Disinfection by-products (DBPs) are a series of contaminants produced by the reaction of disinfectants (chlorine, chlorine dioxide, ozone, etc.) with natural compounds in water during the disinfection process.…”