The Experts below are selected from a list of 5127 Experts worldwide ranked by ideXlab platform
Jayantha Kodikara - One of the best experts on this subject based on the ideXlab platform.
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numerical interpretation of pressurized corroded cast Iron Pipe tests
International Journal of Mechanical Sciences, 2017Co-Authors: Chunshun Zhang, Suranji Rathnayaka, Benjamin Shannon, Jian Ji, Jayantha KodikaraAbstract:Abstract Pitting/patch corrosion is a major and common cause of leaks and (or) bursts in cast Iron (CI) Pipes that consist of over 50% of global Pipelines. The determination of the remaining life of a CI Pipe is a major challenge facing water utilities requiring an estimate of the impact of pitting corrosion on the degradation of structural Pipe capacity. This paper uses an efficient finite element analysis (FEA) to model the behaviour of large diameter CI Pipes with natural or simulated corrosion pits and patches. The test results were obtained through laboratory pressure testing. Laser scanning was used to develop three dimensional geometric models of Pipe specimens for direct use in the numerical modelling. The CI material was simulated by a non-linear hyperbolic elastic model (termed MHM-CI) recently developed by the authors for CI Pipe modelling. The numerical results showed that the proposed FEAs with the MHM-CI model are reasonably capable to predict the measured responses with increasing water pressure, importantly at the critical Pipe corrosion patches, such as hoop strains, initiation of leak and burst failures. The initiation of fracture was explained by material failure purely by tension, which can form a crack that could lead to water leakage. Final burst possibility was modelled by using a simplified fracture mechanics approach to determine the critical crack length for spontaneous fast fracture as in a burst. Our numerical findings suggest that the proposed simplified numerical approach may be used to determine whether a corroded cast Iron Pipe would leak before break provided that the corrosion condition of the Pipe and the relevant material properties are available. However, the window of time for leak before break would require further testing since this would be governed by sub critical fracture growth subject to repetitive external and internal Pipe loadings.
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Experimental evaluation of bursting capacity of corroded grey cast Iron water Pipeline
Structure and Infrastructure Engineering, 2017Co-Authors: Suranji Rathnayaka, Benjamin Shannon, Dilan Robert, Jayantha KodikaraAbstract:AbstractCast Iron was used in the water industry prior to 1970 and a large number of cast Iron Pipes still remain as trunk mains. These Pipes have been subjected to different levels of corrosion and variety of loading conditions. This leads cast Iron Pipes to fail in the field without prior warning. Water utilities are seeking solutions to optimise cast Iron Pipe renewal and rehabilitation programs for critical water mains (diameter ≥ 300 mm). A new experimental set-up has been developed at Monash University in order to perform burst testing of large diameter cast Iron Pipes (diameter ≥ 300 mm). A section of cast Iron Pipe, extracted during maintenance in Sydney, was laser scanned to determine the remaining thickness of the Pipe (minimum of 7–8 mm at the most critical patches). Although the Pipe was pressurised to 3.6 MPa, catastrophic failure did not occur. Water leakage from the two critically corroded patches was observed at around 3.25–3.45 MPa internal pressure. Strain results on the outer Pipe surfa...
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Introduction of the leak-before-break (LBB) concept for cast Iron water Pipes on the basis of laboratory experiments
2017Co-Authors: Suranji Rathnayaka, Chunshun Zhang, Benjamin Shannon, Jayantha KodikaraAbstract:Failure of cast Iron water mains in Australia is a common occurrence. Water utilities are seeking solutions to optimise the renewal and rehabilitation of ageing cast Iron critical water mains (diameter ≥ 300 mm). Failure pressures of three large-diameter cast Iron Pipe specimens (600 mm in diameter) were tested. A large corrosion patch was machined onto each Pipe section to initiate Pipe failure. A large corrosion patch and significant reduction (>90%) of Pipe wall thickness were needed to fail the tested Pipe specimens. All three Pipes under test exhibited leaking before bursting, indicating that the concept of leak-before-break (LBB) could be used for Pipe failure prevention. In addition, LBB provides valuable information that could be added to the Pipe asset database to make better management decisions on repair or replacement along with all other asset information. The study also found that small corrosion patches (
Min Yang - One of the best experts on this subject based on the ideXlab platform.
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effects of microbial redox cycling of Iron on cast Iron Pipe corrosion in drinking water distribution systems
Water Research, 2014Co-Authors: Haibo Wang, Xiaoxiao Li, Lili Zhang, Chun Hu, Min YangAbstract:Abstract Bacterial characteristics in corrosion products and their effect on the formation of dense corrosion scales on cast Iron coupons were studied in drinking water, with sterile water acting as a reference. The corrosion process and corrosion scales were characterized by electrochemical and physico-chemical measurements. The results indicated that the corrosion was more rapidly inhibited and Iron release was lower due to formation of more dense protective corrosion scales in drinking water than in sterile water. The microbial community and denitrifying functional genes were analyzed by pyrosequencing and quantitative polymerase chain reactions (qPCR), respectively. Principal component analysis (PCA) showed that the bacteria in corrosion products played an important role in the corrosion process in drinking water. Nitrate-reducing bacteria (NRB) Acidovorax and Hydrogenophaga enhanced Iron corrosion before 6 days. After 20 days, the dominant bacteria became NRB Dechloromonas (40.08%) with the protective corrosion layer formation. The Dechloromonas exhibited the stronger corrosion inhibition by inducing the redox cycling of Iron, to enhance the precipitation of Iron oxides and formation of Fe3O4. Subsequently, other minor bacteria appeared in the corrosion scales, including Iron-respiring bacteria and Rhizobium which captured Iron by the produced siderophores, having a weaker corrosion-inhibition effect. Therefore, the microbially-driven redox cycling of Iron with associated microbial capture of Iron caused more compact corrosion scales formation and lower Iron release.
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effects of disinfectant and biofilm on the corrosion of cast Iron Pipes in a reclaimed water distribution system
Water Research, 2012Co-Authors: Haibo Wang, Min YangAbstract:The effects of disinfection and biofilm on the corrosion of cast Iron Pipe in a model reclaimed water distribution system were studied using annular reactors (ARs). The corrosion scales formed under different conditions were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), while the bacterial characteristics of biofilm on the surface were determined using several molecular methods. The corrosion scales from the ARs with chlorine included predominantly α-FeOOH and Fe2O3, while CaPO3(OH)·2H2O and α-FeOOH were the predominant phases after chloramines replaced chlorine. Studies of the consumption of chlorine and Iron release indicated that the formation of dense oxide layers and biofilm inhibited Iron corrosion, causing stable lower chlorine decay. It was verified that Iron-oxidizing bacteria (IOB) such as Sediminibacterium sp., and Iron-reducing bacteria (IRB) such as Shewanella sp., synergistically interacted with the corrosion product to prevent further corrosion. For the ARs without disinfection, α-FeOOH was the predominant phase at the primary stage, while CaCO3 and α-FeOOH were predominant with increasing time. The mixed corrosion-inducing bacteria, including the IRB Shewanella sp., the IOB Sediminibacterium sp., and the sulfur-oxidizing bacteria (SOB) Limnobacter thioxidans strain, promoted Iron corrosion by synergistic interactions in the primary period, while anaerobic IRB became the predominant corrosion bacteria, preventing further corrosion via the formation of protective layers.
Suranji Rathnayaka - One of the best experts on this subject based on the ideXlab platform.
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numerical interpretation of pressurized corroded cast Iron Pipe tests
International Journal of Mechanical Sciences, 2017Co-Authors: Chunshun Zhang, Suranji Rathnayaka, Benjamin Shannon, Jian Ji, Jayantha KodikaraAbstract:Abstract Pitting/patch corrosion is a major and common cause of leaks and (or) bursts in cast Iron (CI) Pipes that consist of over 50% of global Pipelines. The determination of the remaining life of a CI Pipe is a major challenge facing water utilities requiring an estimate of the impact of pitting corrosion on the degradation of structural Pipe capacity. This paper uses an efficient finite element analysis (FEA) to model the behaviour of large diameter CI Pipes with natural or simulated corrosion pits and patches. The test results were obtained through laboratory pressure testing. Laser scanning was used to develop three dimensional geometric models of Pipe specimens for direct use in the numerical modelling. The CI material was simulated by a non-linear hyperbolic elastic model (termed MHM-CI) recently developed by the authors for CI Pipe modelling. The numerical results showed that the proposed FEAs with the MHM-CI model are reasonably capable to predict the measured responses with increasing water pressure, importantly at the critical Pipe corrosion patches, such as hoop strains, initiation of leak and burst failures. The initiation of fracture was explained by material failure purely by tension, which can form a crack that could lead to water leakage. Final burst possibility was modelled by using a simplified fracture mechanics approach to determine the critical crack length for spontaneous fast fracture as in a burst. Our numerical findings suggest that the proposed simplified numerical approach may be used to determine whether a corroded cast Iron Pipe would leak before break provided that the corrosion condition of the Pipe and the relevant material properties are available. However, the window of time for leak before break would require further testing since this would be governed by sub critical fracture growth subject to repetitive external and internal Pipe loadings.
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Experimental evaluation of bursting capacity of corroded grey cast Iron water Pipeline
Structure and Infrastructure Engineering, 2017Co-Authors: Suranji Rathnayaka, Benjamin Shannon, Dilan Robert, Jayantha KodikaraAbstract:AbstractCast Iron was used in the water industry prior to 1970 and a large number of cast Iron Pipes still remain as trunk mains. These Pipes have been subjected to different levels of corrosion and variety of loading conditions. This leads cast Iron Pipes to fail in the field without prior warning. Water utilities are seeking solutions to optimise cast Iron Pipe renewal and rehabilitation programs for critical water mains (diameter ≥ 300 mm). A new experimental set-up has been developed at Monash University in order to perform burst testing of large diameter cast Iron Pipes (diameter ≥ 300 mm). A section of cast Iron Pipe, extracted during maintenance in Sydney, was laser scanned to determine the remaining thickness of the Pipe (minimum of 7–8 mm at the most critical patches). Although the Pipe was pressurised to 3.6 MPa, catastrophic failure did not occur. Water leakage from the two critically corroded patches was observed at around 3.25–3.45 MPa internal pressure. Strain results on the outer Pipe surfa...
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Introduction of the leak-before-break (LBB) concept for cast Iron water Pipes on the basis of laboratory experiments
2017Co-Authors: Suranji Rathnayaka, Chunshun Zhang, Benjamin Shannon, Jayantha KodikaraAbstract:Failure of cast Iron water mains in Australia is a common occurrence. Water utilities are seeking solutions to optimise the renewal and rehabilitation of ageing cast Iron critical water mains (diameter ≥ 300 mm). Failure pressures of three large-diameter cast Iron Pipe specimens (600 mm in diameter) were tested. A large corrosion patch was machined onto each Pipe section to initiate Pipe failure. A large corrosion patch and significant reduction (>90%) of Pipe wall thickness were needed to fail the tested Pipe specimens. All three Pipes under test exhibited leaking before bursting, indicating that the concept of leak-before-break (LBB) could be used for Pipe failure prevention. In addition, LBB provides valuable information that could be added to the Pipe asset database to make better management decisions on repair or replacement along with all other asset information. The study also found that small corrosion patches (
Gerard T. Pittard - One of the best experts on this subject based on the ideXlab platform.
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SEALING LARGE-DIAMETER CAST-Iron Pipe JOINTS UNDER LIVE CONDITIONS
2005Co-Authors: Kiran M. Kothari, Gerard T. PittardAbstract:Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-Iron Pipes for gas distribution. The bell-and-spigot joints that connect Pipe sections together tend to leak as these Pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-Iron bell and spigot joints from a single Pipe entry point. The proposed system will perform repairs while the Pipe remains in service by traveling through the Pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of old cast-Iron Pipes; (2) the assembly must travel long distances through Pipes containing debris; (3) the Pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed previously. Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in test cast-Iron Pipe segments. Efforts in the current quarter continued to be focused on Tasks 4-8. Highly valuable lessons were learned from field tests of the 4-inch gas Pipe repair robot in cast-Iron Pipe at Public Service Electric & Gas. (These field tests were conducted and reported previously.) Several design issues were identified which need to be implemented in both the small- and large-diameter repair robots for cast-Iron Pipe to assure their commercial success. For Task 4 (Design, Fabricate and Test Patch Setting Robotic Train), previous problems with bladder design and elastomeric material expansion in the large mains were addressed. A new bladder based on a commercially available design was obtained and tested with success. Minor improvements were highlighted during patch-setting tests and are now being pursued. For Task 5 (Design and Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera), the previous field tests showed clearly that, in mains with low gas velocities, it will be necessary to improve the system's capacity to remove debris from the immediate vicinity of the bell and spigot joints. Otherwise, material removed by the cleaning flails (the flails were found to be very effective in cleaning bell and spigot joints) falls directly to the low side of the Pipe and accumulates in a pile. This accumulation can prevent the sleeve from achieving a leak-free repair. Similarly, it is also deemed necessary to design an assembly to capture existing servicetap coupons and allow their removal from the inside of the Pipe. Task 6 (Design and Build Surface Control and Monitoring System) was previously completed with the control and computer display functions being operated through LabVIEW. However, this must now be revisited to add control routines for the coupon catcher that will be added. This will most likely include a lift-off/place-on magnet translation function. Task 7 (Design and Fabricate Large Diameter Live Access System) progressed to completing the detailed design for a bolt-on entry fitting for 12-inch diameter cast-Iron Pipe in the current quarter. The drilling assembly for cutting an access hole through the wall of the gas main was also designed, along with a plug assembly to allow removing all tools from the live main and setting a blind flange on the entry fitting prior to burial. These designs are described in detail in the report. Task 8 (System Integration and Laboratory Validation) continued with the development of the robot module inter-connects and of a master LabVIEW-based system display and control software
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SEALING LARGE-DIAMETER CAST-Iron Pipe JOINTS UNDER LIVE CONDITIONS
2005Co-Authors: Kiran M. Kothari, Gerard T. PittardAbstract:Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-Iron Pipes for gas distribution. The bell-and-spigot joints that connect Pipe sections together tend to leak as these Pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-Iron bell and spigot joints from a single Pipe entry point. The proposed system will perform repairs while the Pipe remains in service by traveling through the Pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-Iron Pipes; (2) the assembly must travel long distances through Pipes containing debris; (3) the Pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed in prior quarters while Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in cast-Iron test Pipe segments. Efforts in the current quarter continued to focus on Tasks 4-8. Highly valuable lessons were learned from field tests of the 4-inch gas Pipe repair robot in cast-Iron Pipe at Public Service Electric & Gas. (These field tests were conducted and reported last quarter.) These tests identified several design issues which need to be implemented in both the small- and large-diameter repair robots for cast-Iron Pipe to assure their commercial success. For Task 4 (Design, Fabricate and Test Patch Setting Robotic Train), work has been directed on increasing the nitrogen bladder reservoir volume to allow at least two complete patch inflation/patch setting cycles in the event the sleeve does not set all ratchets in the same row on the first attempt. This problem was observed on a few of the repair sleeves that were recently installed during field tests with the small-diameter robotic system. For Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera), the recent field tests showed clearly that, in mains with low gas velocities, it will be necessary to improve the system's capacity to remove debris from the immediate vicinity of the bell and spigot joints. Otherwise, material removed by the cleaning flails (the flails were found to be very effective in cleaning bell and spigot joints) falls directly to the low side of the Pipe and accumulates in a pile. This accumulation can prevent the sleeve from achieving a leak-free repair. Similarly, it is also deemed necessary to design an assembly to capture existing service-tap coupons and allow their removal from the inside of the Pipe. These coupons were found to cause difficulty in launching and retrieving the small Pipe repair robot; for example, one coupon lodged beneath the end of the guide shoe. Designs for new features to accomplish these goals for the large robotic system were pursued and are presented in this report. Task 6 (Design & Build Surface Control and Monitoring System) was previously completed with the control and computer display functions being operated through LabVIEW. However, this must now be revisited to add control routines for the coupon catcher to be added. This will most likely include a lift-off/place-on magnet translation function. Task 7 (Design & Fabricate Large Diameter Live Access System) progressed to completing the detailed design of the entry fitting for 12-inch diameter cast Iron Pipe in the previous quarter. Field tests with the 4-inch size fitting were completely successful and did not reveal any significant design issues. The primary suggestion from the PSE&G field crew was to produce a version which completely bolts together and does not require a long seam weld. This could be used in low-pressure cast Iron mains to reduce installation time. A bolt-on version is being designed based on this recommendation. Task 8 (System Integration and Laboratory Validation) continued with the development of the robot module inter-connects and of a master LabVIEW-based system display and control software
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SEALING LARGE-DIAMETER CAST-Iron Pipe JOINTS UNDER LIVE CONDITIONS
2004Co-Authors: Kiran M. Kothari, Gerard T. PittardAbstract:Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-Iron Pipes for gas distribution. The bell-and-spigot joints that connect Pipe sections together tend to leak as these Pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple castIron bell and spigot joints from a single Pipe entry point. The proposed system will perform repairs while the Pipe remains in service by traveling through the Pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-Iron Pipes; (2) the assembly must travel long distances through Pipes containing debris; (3) the Pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed in prior quarters while Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in cast Iron test Pipe segments. Efforts in this quarter continued to focus on Tasks 4-8, with significant progress made in each. Task 4 (Design, Fabricate and Test Patch Setting Robotic Train) progressed to the design of the control electronics and pneumatic system to inflate the bladder robotic patch setting module. Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera) continued with additional in-Pipe testing required to optimize the design of the robot elements and surface control electronics and software. Task 6 (Design & Build Surface Control and Monitoring System) has been completed with the control and computer display functions being operated through LabView. Task 7 (Design & Fabricate Large Diameter Live Access System) progressed to completing the detailed design of the entry fitting for 12-inch diameter cast Iron Pipe. The fitting is now being manufactured. The 12-inch ball valve for allowing no-blow access was also procured. Task 8 (System Integration and Laboratory Validation) continued with the development of the robot module inter-connects and of a master LabView-based system display and control software
Haibo Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of microbial redox cycling of Iron on cast Iron Pipe corrosion in drinking water distribution systems
Water Research, 2014Co-Authors: Haibo Wang, Xiaoxiao Li, Lili Zhang, Chun Hu, Min YangAbstract:Abstract Bacterial characteristics in corrosion products and their effect on the formation of dense corrosion scales on cast Iron coupons were studied in drinking water, with sterile water acting as a reference. The corrosion process and corrosion scales were characterized by electrochemical and physico-chemical measurements. The results indicated that the corrosion was more rapidly inhibited and Iron release was lower due to formation of more dense protective corrosion scales in drinking water than in sterile water. The microbial community and denitrifying functional genes were analyzed by pyrosequencing and quantitative polymerase chain reactions (qPCR), respectively. Principal component analysis (PCA) showed that the bacteria in corrosion products played an important role in the corrosion process in drinking water. Nitrate-reducing bacteria (NRB) Acidovorax and Hydrogenophaga enhanced Iron corrosion before 6 days. After 20 days, the dominant bacteria became NRB Dechloromonas (40.08%) with the protective corrosion layer formation. The Dechloromonas exhibited the stronger corrosion inhibition by inducing the redox cycling of Iron, to enhance the precipitation of Iron oxides and formation of Fe3O4. Subsequently, other minor bacteria appeared in the corrosion scales, including Iron-respiring bacteria and Rhizobium which captured Iron by the produced siderophores, having a weaker corrosion-inhibition effect. Therefore, the microbially-driven redox cycling of Iron with associated microbial capture of Iron caused more compact corrosion scales formation and lower Iron release.
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effects of disinfectant and biofilm on the corrosion of cast Iron Pipes in a reclaimed water distribution system
Water Research, 2012Co-Authors: Haibo Wang, Min YangAbstract:The effects of disinfection and biofilm on the corrosion of cast Iron Pipe in a model reclaimed water distribution system were studied using annular reactors (ARs). The corrosion scales formed under different conditions were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), while the bacterial characteristics of biofilm on the surface were determined using several molecular methods. The corrosion scales from the ARs with chlorine included predominantly α-FeOOH and Fe2O3, while CaPO3(OH)·2H2O and α-FeOOH were the predominant phases after chloramines replaced chlorine. Studies of the consumption of chlorine and Iron release indicated that the formation of dense oxide layers and biofilm inhibited Iron corrosion, causing stable lower chlorine decay. It was verified that Iron-oxidizing bacteria (IOB) such as Sediminibacterium sp., and Iron-reducing bacteria (IRB) such as Shewanella sp., synergistically interacted with the corrosion product to prevent further corrosion. For the ARs without disinfection, α-FeOOH was the predominant phase at the primary stage, while CaCO3 and α-FeOOH were predominant with increasing time. The mixed corrosion-inducing bacteria, including the IRB Shewanella sp., the IOB Sediminibacterium sp., and the sulfur-oxidizing bacteria (SOB) Limnobacter thioxidans strain, promoted Iron corrosion by synergistic interactions in the primary period, while anaerobic IRB became the predominant corrosion bacteria, preventing further corrosion via the formation of protective layers.
