Characterization of biofilm and corrosion of cast iron pipes in drinking water distribution system with UV/Cl2 disinfection

Abstract

Corrosion DisinfectionWater quality Drinking water distribution system a b s t r a c tThe effect of UV/Cl 2 disinfection on the biofilm and corrosion of cast iron pipes in drinking water distribution system were studied using annular reactors (ARs). Passivation occurred more rapidly in the AR with UV/Cl 2 than in the one with Cl 2 alone, decreasing iron release for higher corrosivity of water. Based on functional gene, pyrosequencing assays and principal component analysis, UV disinfection not only reduced the required initial chlorine dose, but also enhanced denitrifying functional bacteria advantage in the biofilm of corrosion scales. The nitrate-reducing bacteria (NRB) Dechloromonas exhibited the greatest corrosion inhibition by inducing the redox cycling of iron to enhance the precipitation of iron oxides and formation of Fe 3 O 4 in the AR with UV/Cl 2 , while the rhizobia Bradyrhizobium and Rhizobium, and the NRB Sphingomonas, Brucella producing siderophores had weaker corrosion-inhibition effect by capturing iron in the AR with Cl 2 . These results indicated that the microbial redox cycling of iron was possibly responsible for higher corrosion inhibition and lower effect of water LarsoneSkold Index (LI) changes on corrosion. This finding could be applied toward the control of water quality in drinking water distribution systems. ª 2014 Elsevier Ltd. All rights reserved. IntroductionIron and steel pipes have been used in water distribution systems for several centuries throughout the world, and are subjected to corrosion, causing deterioration of potable water quality due to unwanted chemical and biochemical reactions (McNeill and Edwards, 2001; Husband and Boxall, 2011). In the corrosion processes of iron pipes, iron ions were released into distributed water, and can re-precipitate forming corrosion scales, also referred to as tubercles (Gerke et al., 2008). The processes can greatly affect water quality in distribution system, not only by releasing iron oxyhydroxides (red water), but also by reactions with e.g. chlorinated disinfection byproducts (Chun et al., 2005), nitrates (Hansen et al., 1996) or natural organic matter (NOM) (Nawrocki et al., 2010 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.else vier.com/locate /wa tres w a t e r r e s e a r c h 6 0 ( 2 0 1 4 ) 1 7 4 e1 8 1http://dx

Characteristics of corrosion sales and biofilm in aged pipe distribution systems with switching water source

“…Previous studies have verified that the redox cycling of iron induced by IRB and NRB enhanced the precipitation of iron oxides and formation of Fe 3 O 4 [27,28]. IOB Sediminibacterium could convert ferrous iron to ferric forms, which could be deposited on their cell walls to create voluminous sheaths of iron metabolites [29].…”

“…Bacillus species belonging to NRB also could affect iron corrosion and modify the corrosion products [29]. Some studies found that the oxidation and reduction of iron occurred simultaneously by the respiration of Azospira and Dechloromonas at nitrate-N concentrations less than 7 mg/L, resulting in Fe 3 O 4 formation [10,27,31]. In SW and GW, the nitrate-N concentrations were 5.1-7.9 and 0.87-2.2 mg/L, respectively.…”

Characteristics of biofilms and iron corrosion scales with ground and surface waters in drinking water distribution systems

“…Recently, Xu et al [23] found that a nitrate reducer was more corrosive than typical SRB by pitting data under strict anaerobic conditions. On the other hand, the nitrate-dependent Fe(II) oxidation from nitrate-reducing bacteria (NRB) metabolism has the potential to contribute to a dynamic iron redox cycle in freshwater sediments [16], which has been proven inhibiting iron corrosion [24]. Additionally, more and more studies have begun to show protective effects against corrosion by some bacterial biofilms on metal.…”

Assessing biofilm development in drinking water distribution systems by Machine Learning methods

“…The ability of pipe materials to support drinking water biofilm varies dramatically from plastic to metal pipes as they exhibit different degrees of surface roughness and chemical activity [21]. Three main groups of materials have been specified.…”

“…Most of biofilm research in DWDSs is based on studying the influence of the hydraulic conditions, the physical characteristics of the distribution system and the physico-chemical characteristics of the circulating water, among others, on biofilm development, besides from the interactions among microorganisms [19]. Although numerous studies have been carried out in relation to the influence that a number of characteristics of the DWDSs have on biofilm development [10,[20][21][22], in most cases, these characteristics are studied individually or in pairs, at most. Distribution systems are the major components of water utilities.…”