Formation and release behavior of iron corrosion products under the influence of bacterial communities in a simulated water distribution system

Abstract

To understand the formation and release behavior of iron corrosion products in a drinking water distribution system, annular reactors (ARs) were used to investigate the development processes of corrosion products and biofilm community as well as the concomitant iron release behavior. Results showed that the formation and transformation of corrosion products and bacterial community are closely related to each other. The presence of sulfate-reducing bacteria (SRB, e.g. Desulfovibrio and Desulfotomaculum), sulfur-oxidizing bacteria (SOB, e.g. Sulfuricella), and iron-oxidizing bacteria (IOB, e.g. Acidovorax, Gallionella, Leptothrix, and Sphaerotilus) in biofilms could speed up iron corrosion; however, iron-reducing bacteria (IRB, e.g. Bacillus, Clostridium, and Pseudomonas) could inhibit iron corrosion and iron release. Corrosion scales on iron coupons could develop into a two-layered structure (top layer and inner layer) with time. The relatively stable constituents such as goethite (a-FeOOH) and magnetite (Fe 3 O 4 ) mainly existed in the top layers, while green rust (Fe 6 (OH) 12 CO 3 ) mainly existed in the inner layers. The IOB (especially Acidovorax) contributed to the formation of a-FeOOH, while IRB and the anaerobic conditions could facilitate the formation of Fe 3 O 4 . Compared with the AR test without biofilms, the iron corrosion rate with biofilms was relatively higher (p < 0.05) during the whole experimental period, but the iron release with biofilms was obviously lower both at the initial stage and after 3 months. Biofilm and corrosion scale samples formed under different water supply conditions in an actual drinking water distribution system verified the relationships between the bacterial community and corrosion products. Environmental impactIron pipe corrosion and the release of corrosion products could greatly affect the integrity of water distribution infrastructure and the safety of drinking water at consumer ends. Corrosion scales formed by the accumulation of corrosion products under different water supply conditions had different morphological and compositional characteristics, which are closely associated with the processes of iron corrosion and release. Biolms developed on the internal surface of distribution pipes could play crucial roles in corrosion reactions and the composition of corrosion scales. Therefore, understanding the effects of bacterial community structure on the iron corrosion, iron release and associated corrosion by-products could provide scientic support for drinking water quality and distribution infrastructure maintenance.

Long-term spatial and temporal microbial community dynamics in a large-scale drinking water distribution system with multiple disinfectant regimes

“…The effect of disinfection on the community composition has previously been reported, indicating that Alphaproteobacteria are typically dominant in both chlorinated and chloraminated water, whereas Betaproteobacteria were found to have increased abundance in chloraminated water as opposed to chlorinated water (Berry, 2006;Wang et al, 2014). This was consistent with the observed changes in Alpha-and Betaproteobacteria in this study.…”

“…However, it is difficult to separate the effect of a single parameter on the bacterial community in a fullscale DWDS. For example, Wang et al (2014) reported on the combined effects of disinfectant, water age and pipe material creating different physicochemical conditions and ecological niches, which can then select and promote the growth of various microbes.…”

“…Microbial growth in drinking water has been observed in the form of higher particle counts and increased turbidity (Liu et al, 2016), higher cell counts (Hammes et al, 2008) and increase in the presence of indicator organisms in the final tap water compared to the water leaving the treatment plant (van der Wielen et al, 2016). The water leaving the treatment plant may therefore be impacted by the distribution system itself through processes such as pipe corrosion (Sun et al, 2014), the detachment of biofilms (Chaves Simões and Simões, 2013) and suspension of loose deposits (Liu et al, 2013;Liu et al, 2017;Liu et al, 2018). These processes together in combination with increasing contact time with the disinfectant may explain the observed spatial dissimilarity observed in the bacterial community as bulk water moves away from the DWDP and through the DWDS.…”

Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

“…Unwanted changes in microbial quality of drinking water can have adverse effects on distribution system and consumers. For example, during distribution, excessive growth of bacteria can lead to deterioration of drinking water quality in terms of safety (e.g., pathogens), consumer’s perception (e.g., discolouration) and operational aspects (e.g., biocorrosion; Szewzyk et al, 2000 ; Vreeburg et al, 2004 ; Sun et al, 2014 ). Changes in microbial water quality are a result of complex interactions between various organisms (bacteria, viruses, protozoa, higher organisms) regulated by: access to available growth-limiting nutrients, response to environmental conditions, such as water temperature, presence of potential residual disinfectant and other inhibitory substances, attachment of bacteria to pipe walls, particle deposition, sediment re-suspension and biofilm formation.…”

Iron to Gas: Versatile Multiport Flow-Column Revealed Extremely High Corrosion Potential by Methanogen-Induced Microbiologically Influenced Corrosion (Mi-MIC)

“…In addition to SRB, acetogens, iron-reducers/oxidizers, sulfide-oxidizers and methanogenic archaea (MA) are also corrosive (Dinh et al, 2004;Mori et al, 2010;Park et al, 2011;Sun et al, 2014;Kato et al, 2015;Mand et al, 2016). MA can metabolize limited substrates for growth, including H 2 /CO 2 , acetate, methanol and methylamines (Youssef et al, 2009;Tucker et al, 2015).…”