Effects of early biofilm formation on water quality during commissioning of new polyethylene pipes

Abstract

Mature biofilms are considered beneficial to non-chlorinated Danish drinking water distribution systems, as they increase the microbiological stability of the water. During commissioning of new pipes in the distribution network,...

Chemical and microbiological safety of drinking water in distribution networks made of plastic pipes

“…García-Timermans et al (2023) noted that after just 8 days of running the model system, the number of bacteria in the water leaving the model increased by an order of magnitude, from 10 5 cells/mL at the feed to 10 6 cells/mL at the exit of the system. Similar results have been obtained by other authors (Papciak et al, 2022;Skovhus et al, 2022;Zhao et al, 2022), but Skovhus et al (2022) showed that initially the number of bacterial cells determined in the water at the exit of the test system increases and then decreases, which correlates with an increase in the number of biofilm-building cells associated with the pipe surface. Other modeling studies mimicking conditions in indoor networks (in buildings), taking into account periods of water stagnation, have also shown that the biofilm in PVC pipes does not contain mineral deposits and is based on densely dispersed, single cells of Pseudomonas aeruginosa bacteria.…”

“…A similar relationship was observed in a study on the susceptibility of polymeric materials to colonization by microscopic fungi (Eerkes‐Medrano et al, 2015). The type of pipe material also influences the phylogenetic diversity of bacteria included in biofilms (Papciak et al, 2022; Rożej et al, 2015; Schwartz et al, 2003; Skovhus et al, 2022; Zhao et al, 2022). Unfortunately, the vast majority of studies in this area were conducted in model systems simulating conditions in DWDNs and/or in so‐called indoor networks in buildings, which, according to the authors, may have yielded results that do not fully coincide with the actual composition of biofilms in real water supply networks.…”

“…The compositions of the biofilms characterized so far, growing on PE and PVC surfaces, indicate a high phylogenetic diversity of the microorganisms inhabiting them. The most abundant bacterial phyla were Proteobacteria (26.7%–60%), Bacteroidetes (2.3%–3.4%), and Actinobacteria (0.7%–1.9%) (Goraj et al, 2021; Rożej et al, 2015; Skovhus et al, 2022; Zhao et al, 2022). In contrast, Pseudomonas , Bacillus , Aquabacterium , and Lactococcus dominated among the identified genera (Skovhus et al, 2022; Zhao et al, 2022).…”

“…The most abundant bacterial phyla were Proteobacteria (26.7%–60%), Bacteroidetes (2.3%–3.4%), and Actinobacteria (0.7%–1.9%) (Goraj et al, 2021; Rożej et al, 2015; Skovhus et al, 2022; Zhao et al, 2022). In contrast, Pseudomonas , Bacillus , Aquabacterium , and Lactococcus dominated among the identified genera (Skovhus et al, 2022; Zhao et al, 2022). The high percentages of Bacillus , Pseudomonas , and Lactococcus in the biofilms collected from PE and PVC, compared to the biofilms present on the other pipe materials tested, are, according to Zhao et al (2022), a direct consequence of the release of large amounts of organic compounds from plastics acting as a medium for these particular microorganisms.…”

Biodegradable Dissolved Organic Carbon (BDOC) Removal from Micro-Polluted Water Source Using Ultrafiltration: Comparison with Conventional Processes, Operation Conditions and Membrane Fouling Control

“…The occurrence of biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) in drinking water produced by waterworks provides potential nutrient substrates in the water distribution system for the re-growth and reproduction of heterotrophic bacteria that have not been killed when not enough chlorine is left in the pipes [ 1 , 2 , 3 , 4 ]. Bacteria can use the BDOC and AOC in the water as a nutrient matrix to re-grow, threatening drinking water safety, and attach to the water supply pipe’s inner surface to form biofilms, causing corrosion and scaling of the pipe [ 5 , 6 ]. The existence of a biofilm is further conducive to the growth and spread of pathogenic microorganisms in the water of the pipe network, posing a threat to public health [ 7 ].…”