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Zhiguo Yuan - One of the best experts on this subject based on the ideXlab platform.
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the rapid chemically induced corrosion of concrete Sewers at high h2s concentration
Water Research, 2019Co-Authors: Xuan Li, Liza Omoore, Yarong Song, Philp L Bond, Simeon Wilkie, Guangming Jiang, Lucija Hanzic, Zhiguo YuanAbstract:Abstract Concrete corrosion in Sewers is primarily caused by H2S in Sewer atmosphere. H2S concentration can vary from several ppm to hundreds of ppm in real Sewers. Our understanding of Sewer corrosion has increased dramatically in recent years, however, there is limited knowledge of the concrete corrosion at high H2S levels. This study examined the corrosion development in Sewers with high H2S concentrations. Fresh concrete coupons, manufactured according to Sewer pipe standards, were exposed to corrosive conditions in a pilot-scale gravity Sewer system with gaseous H2S at 1100 ± 100 ppm. The corrosion process was continuously monitored by measuring the surface pH, corrosion product composition, corrosion loss and the microbial community. The surface pH of concrete was reduced from 10.5 ± 0.3 to 3.1 ± 0.5 within 20 days and this coincided with a rapid corrosion rate of 3.5 ± 0.3 mm year −1. Microbial community analysis based on 16S rRNA gene sequencing indicated the absence of sulfide-oxidizing microorganisms in the corrosion layer. The chemical analysis of corrosion products supported the reaction of cement with sulfuric acid formed by the chemical oxidation of H2S. The rapid corrosion of concrete in the gravity pipe was confirmed to be caused by the chemical oxidation of hydrogen sulfide at high concentrations. This is in contrast to the conventional knowledge that is focused on microbially induced corrosion. This first-ever systematic investigation shows that chemically induced oxidation of H2S leads to the rapid corrosion of new concrete Sewers within a few weeks. These findings contribute novel understanding of in-Sewer corrosion processes and hold profound implications for Sewer operation and corrosion management.
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corrosion of reinforcing steel in concrete Sewers
Science of The Total Environment, 2019Co-Authors: Yarong Song, E M Wightman, Yimei Tian, Huiyun Zhong, Philip L. Bond, Kevin S Jack, Xuan Li, Zhiguo Yuan, Guangming JiangAbstract:Hydrogen sulfide is a controlling factor for concrete corrosion in Sewers, although its impact on Sewer rebar corrosion has not been investigated to date. This study determined the corrosion mechanism of rebar in Sewers by elucidating the roles of chloride ions, apart from the effects of hydrogen sulfide and biogenic sulfuric acid. The nature and distribution of rusts at the steel/concrete interface were delineated using the advanced mineral analytical techniques, including mineral liberation analysis and micro X-ray diffraction which is the first-ever use in such studies. The corrosion products were found to be mainly iron oxides or oxy-hydroxides. HS and biogenic sulfuric acid did not directly participate in the product formation of steel partly covered by concrete or directly exposed to Sewer atmosphere. Instead, chloride ions played an important role in initiating steel corrosion in Sewers, supported by a thin chloride-enriched layer at the steel/rust interface. Away from the chloride-enriched layer, iron oxides accumulated on both sides of the mill-scale to form a corrosion layer and corrosion-filled paste respectively. The corrosion layer around rebar circumference was non-uniform and the rust thickness with respect to polar coordinates followed a Gaussian model. These findings support predictions of Sewer service lifetime and developments of corrosion prevention strategies.
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stability of illicit drugs as biomarkers in Sewers from lab to reality
Environmental Science & Technology, 2017Co-Authors: Jiaying Li, Phong K Thai, Zhiguo Yuan, Jochen F. Mueller, Guangming JiangAbstract:Systematic sampling and analysis of wastewater samples are increasingly adopted for estimating drug consumption in communities. An understanding of the in-Sewer transportation and transformation of illicit drug biomarkers is critical for reducing the uncertainty of this evidence-based estimation method. In this study, biomarkers stability was investigated in lab-scale Sewer reactors with typical Sewer conditions. Kinetic models using the Bayesian statistics method were developed to simulate biomarkers transformation in reactors. Furthermore, a field-scale study was conducted in a real pressure Sewer pipe with the systematical spiking and sampling of biomarkers and flow tracers. In-Sewer degradation was observed for some spiked biomarkers over typical hydraulic retention time (i.e., a few hours). Results indicated that Sewer biofilms prominently influenced biomarker stability with the retention time in wastewater. The fits between the measured and the simulated biomarkers transformation demonstrated that the lab-based model could be extended to estimate the changes of biomarkers in real Sewers. Results also suggested that the variabilities of biotransformation and analytical accuracy are the two major contributors to the overall estimation uncertainty. Built upon many previous lab-scale studies, this study is one critical step forward in realizing wastewater-based epidemiology by extending biomarker stability investigations from laboratory reactors to real Sewers.
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methane emission from Sewers
Science of The Total Environment, 2015Co-Authors: Bingjie Ni, Keshab Sharma, Zhiguo YuanAbstract:Abstract Recent studies have shown that Sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in Sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in Sewers. No significant methane sinks or methanotrophic activities have been identified in Sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity Sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in Sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in Sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from Sewers, including the production mechanisms, quantification, modeling, and mitigation.
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degradation of methanethiol in anaerobic Sewers and its correlation with methanogenic activities
Water Research, 2015Co-Authors: Shihu Hu, Keshab Sharma, Bingjie Ni, Zhiguo YuanAbstract:Abstract Methanethiol (MT) is considered one of the predominant odorants in Sewer systems. Therefore, understanding MT transformation in Sewers is essential to Sewer odor assessment and abatement. In this study, we investigated the degradation of MT in laboratory anaerobic Sewers. Experiments were carried out in seven anaerobic Sewer reactors with biofilms at different stages of development. MT degradation was found to be strongly dependent on the methanogenic activity of Sewer biofilms. The MT degradation rate accelerated with the increase of methanogenic activity of Sewer biofilms, resulting in MT accumulation (i.e. net production) in Sewer reactors with relatively low methanogenic activities, and MT removal in reactors with higher methanogenic activities. A Monod-type kinetic expression was developed to describe MT degradation kinetics in anaerobic Sewers, in which the maximum degradation rate was modeled as a function of the maximum methane production rate through a power function. It was also found that MT concentration had a linear relationship with acetate concentration, which may be used for preliminary assessment of MT presence in anaerobic Sewers.
Guangming Jiang - One of the best experts on this subject based on the ideXlab platform.
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the rapid chemically induced corrosion of concrete Sewers at high h2s concentration
Water Research, 2019Co-Authors: Xuan Li, Liza Omoore, Yarong Song, Philp L Bond, Simeon Wilkie, Guangming Jiang, Lucija Hanzic, Zhiguo YuanAbstract:Abstract Concrete corrosion in Sewers is primarily caused by H2S in Sewer atmosphere. H2S concentration can vary from several ppm to hundreds of ppm in real Sewers. Our understanding of Sewer corrosion has increased dramatically in recent years, however, there is limited knowledge of the concrete corrosion at high H2S levels. This study examined the corrosion development in Sewers with high H2S concentrations. Fresh concrete coupons, manufactured according to Sewer pipe standards, were exposed to corrosive conditions in a pilot-scale gravity Sewer system with gaseous H2S at 1100 ± 100 ppm. The corrosion process was continuously monitored by measuring the surface pH, corrosion product composition, corrosion loss and the microbial community. The surface pH of concrete was reduced from 10.5 ± 0.3 to 3.1 ± 0.5 within 20 days and this coincided with a rapid corrosion rate of 3.5 ± 0.3 mm year −1. Microbial community analysis based on 16S rRNA gene sequencing indicated the absence of sulfide-oxidizing microorganisms in the corrosion layer. The chemical analysis of corrosion products supported the reaction of cement with sulfuric acid formed by the chemical oxidation of H2S. The rapid corrosion of concrete in the gravity pipe was confirmed to be caused by the chemical oxidation of hydrogen sulfide at high concentrations. This is in contrast to the conventional knowledge that is focused on microbially induced corrosion. This first-ever systematic investigation shows that chemically induced oxidation of H2S leads to the rapid corrosion of new concrete Sewers within a few weeks. These findings contribute novel understanding of in-Sewer corrosion processes and hold profound implications for Sewer operation and corrosion management.
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corrosion of reinforcing steel in concrete Sewers
Science of The Total Environment, 2019Co-Authors: Yarong Song, E M Wightman, Yimei Tian, Huiyun Zhong, Philip L. Bond, Kevin S Jack, Xuan Li, Zhiguo Yuan, Guangming JiangAbstract:Hydrogen sulfide is a controlling factor for concrete corrosion in Sewers, although its impact on Sewer rebar corrosion has not been investigated to date. This study determined the corrosion mechanism of rebar in Sewers by elucidating the roles of chloride ions, apart from the effects of hydrogen sulfide and biogenic sulfuric acid. The nature and distribution of rusts at the steel/concrete interface were delineated using the advanced mineral analytical techniques, including mineral liberation analysis and micro X-ray diffraction which is the first-ever use in such studies. The corrosion products were found to be mainly iron oxides or oxy-hydroxides. HS and biogenic sulfuric acid did not directly participate in the product formation of steel partly covered by concrete or directly exposed to Sewer atmosphere. Instead, chloride ions played an important role in initiating steel corrosion in Sewers, supported by a thin chloride-enriched layer at the steel/rust interface. Away from the chloride-enriched layer, iron oxides accumulated on both sides of the mill-scale to form a corrosion layer and corrosion-filled paste respectively. The corrosion layer around rebar circumference was non-uniform and the rust thickness with respect to polar coordinates followed a Gaussian model. These findings support predictions of Sewer service lifetime and developments of corrosion prevention strategies.
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stability of illicit drugs as biomarkers in Sewers from lab to reality
Environmental Science & Technology, 2017Co-Authors: Jiaying Li, Phong K Thai, Zhiguo Yuan, Jochen F. Mueller, Guangming JiangAbstract:Systematic sampling and analysis of wastewater samples are increasingly adopted for estimating drug consumption in communities. An understanding of the in-Sewer transportation and transformation of illicit drug biomarkers is critical for reducing the uncertainty of this evidence-based estimation method. In this study, biomarkers stability was investigated in lab-scale Sewer reactors with typical Sewer conditions. Kinetic models using the Bayesian statistics method were developed to simulate biomarkers transformation in reactors. Furthermore, a field-scale study was conducted in a real pressure Sewer pipe with the systematical spiking and sampling of biomarkers and flow tracers. In-Sewer degradation was observed for some spiked biomarkers over typical hydraulic retention time (i.e., a few hours). Results indicated that Sewer biofilms prominently influenced biomarker stability with the retention time in wastewater. The fits between the measured and the simulated biomarkers transformation demonstrated that the lab-based model could be extended to estimate the changes of biomarkers in real Sewers. Results also suggested that the variabilities of biotransformation and analytical accuracy are the two major contributors to the overall estimation uncertainty. Built upon many previous lab-scale studies, this study is one critical step forward in realizing wastewater-based epidemiology by extending biomarker stability investigations from laboratory reactors to real Sewers.
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prediction of concrete corrosion in Sewers with hybrid gaussian processes regression model
RSC Advances, 2017Co-Authors: Yarong Song, Philip L. Bond, Jurg Keller, Guangming JiangAbstract:Concrete corrosion is a major concern for Sewer authorities due to the significantly shortened service life, which is governed by the corrosion rate and the corrosion initiation time. This paper proposes a hybrid Gaussian Processes Regression (GPR) model to approach the evolution of the corrosion rate and corrosion initiation time, thereby supporting the calculation of service life of Sewers. A major challenge in practice is the limited availability of reliable corrosion data obtained in well-defined Sewer environments. To enhance the predictability of the hybrid GPR model, an interpolation technique was implemented to extend the limited dataset. The trained model was able to estimate the corrosion initiation time and corrosion rates very close to those measured in Australian Sewers.
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Corrosion and odor management in Sewer systems
2015Co-Authors: Guangming Jiang, Keshab Sharma, Jing Sun, Zhiguo YuanAbstract:Sewers emit hydrogen sulfide and various volatile organic sulfur and carbon compounds, which require control and mitigation. In the last 5-10 years, extensive research was conducted to optimize existing sulfide abatement technologies based on newly developed in-depth understanding of the in-Sewer processes. Recent advances have also led to low-cost novel solutions targeting Sewer biofilms. Online control has been demonstrated to greatly reduce the chemical usage. Dynamic models for both the water, air and solid (concrete) phases have been developed and used for the planning and maintenance of Sewer systems. Existing technologies primarily focused on 'hotspots' in Sewers. Future research should aim to achieve network-wide corrosion and emission control and management of Sewers as an integrated component of an urban water system.
Keshab Sharma - One of the best experts on this subject based on the ideXlab platform.
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methane emission from Sewers
Science of The Total Environment, 2015Co-Authors: Bingjie Ni, Keshab Sharma, Zhiguo YuanAbstract:Abstract Recent studies have shown that Sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in Sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in Sewers. No significant methane sinks or methanotrophic activities have been identified in Sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity Sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in Sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in Sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from Sewers, including the production mechanisms, quantification, modeling, and mitigation.
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degradation of methanethiol in anaerobic Sewers and its correlation with methanogenic activities
Water Research, 2015Co-Authors: Shihu Hu, Keshab Sharma, Bingjie Ni, Zhiguo YuanAbstract:Abstract Methanethiol (MT) is considered one of the predominant odorants in Sewer systems. Therefore, understanding MT transformation in Sewers is essential to Sewer odor assessment and abatement. In this study, we investigated the degradation of MT in laboratory anaerobic Sewers. Experiments were carried out in seven anaerobic Sewer reactors with biofilms at different stages of development. MT degradation was found to be strongly dependent on the methanogenic activity of Sewer biofilms. The MT degradation rate accelerated with the increase of methanogenic activity of Sewer biofilms, resulting in MT accumulation (i.e. net production) in Sewer reactors with relatively low methanogenic activities, and MT removal in reactors with higher methanogenic activities. A Monod-type kinetic expression was developed to describe MT degradation kinetics in anaerobic Sewers, in which the maximum degradation rate was modeled as a function of the maximum methane production rate through a power function. It was also found that MT concentration had a linear relationship with acetate concentration, which may be used for preliminary assessment of MT presence in anaerobic Sewers.
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Corrosion and odor management in Sewer systems
2015Co-Authors: Guangming Jiang, Keshab Sharma, Jing Sun, Zhiguo YuanAbstract:Sewers emit hydrogen sulfide and various volatile organic sulfur and carbon compounds, which require control and mitigation. In the last 5-10 years, extensive research was conducted to optimize existing sulfide abatement technologies based on newly developed in-depth understanding of the in-Sewer processes. Recent advances have also led to low-cost novel solutions targeting Sewer biofilms. Online control has been demonstrated to greatly reduce the chemical usage. Dynamic models for both the water, air and solid (concrete) phases have been developed and used for the planning and maintenance of Sewer systems. Existing technologies primarily focused on 'hotspots' in Sewers. Future research should aim to achieve network-wide corrosion and emission control and management of Sewers as an integrated component of an urban water system.
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Sulfide and methane production in Sewer sediments
Water Research, 2014Co-Authors: Bingjie Ni, Ursula Werner, Keshab Sharma, Ramon Ganigué, Zhiguo YuanAbstract:Recent studies have demonstrated significant sulfide and methane production by Sewer biofilms, particularly in rising mains. Sewer sediments in gravity Sewers are also biologically active; however, their contribution to biological transformations in Sewers is poorly understood at present. In this study, sediments collected from a gravity Sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 +/- 0.39 g S/m(2).d from the sediments, which is significantly higher than the areal rate of Sewer biofilms. In contrast, the average methane production rate is 1.56 +/- 0.14 g CH4/m(2).d at 20 degrees C, which is comparable to the areal rate of Sewer biofilms. These results clearly show that the contributions of Sewer sediments to sulfide and methane production cannot be ignored when evaluating Sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics. (C) 2014 Elsevier Ltd. All rights reserved.
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effects of nitrate dosing on methanogenic activity in a sulfide producing Sewer biofilm reactor
Water Research, 2013Co-Authors: Guangming Jiang, Keshab Sharma, Zhiguo YuanAbstract:Nitrate dosing is widely used by water industry to control hydrogen sulfide production in Sewers. This study assessed the impact of nitrate addition on methane generation by Sewer biofilms using a lab-scale rising main Sewer reactor. It was found that methanogenesis could coexist with denitrification and sulfate reduction in Sewers dosed with nitrate. However, methane production was substantially reduced by nitrate addition. Methanogenic rates remained below 10% of its baseline level, with 30 mg-N/L of nitrate dosing for each pump event. By calculating the substrate penetration depth in biofilms, it is suggested that methanogenesis may persist in deeper biofilms due to the limited penetration of nitrate and sulfate, and better penetration of soluble organic substrates. The control of methane and sulfide production was found to be determined by the nitrate penetration depth in biofilms and nitrate presence time in Sewers, respectively. The presence of nitrous oxide after nitrate addition was transient, with a negligible discharge of nitrous oxide from the Sewer reactor due to its further reduction by denitrifiers after nitrate depletion.
Tsangjung Chang - One of the best experts on this subject based on the ideXlab platform.
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inundation simulation for urban drainage basin with storm Sewer system
Journal of Hydrology, 2000Co-Authors: Shiuanhung Chen, Tsangjung ChangAbstract:An urban inundation model, combining a storm Sewer model SWMM, two-dimensional (2D) diffusive overland-flow model and operations of pumping stations, has been developed to simulate inundation in urban areas caused by the surcharge of storm Sewers and outlet pumping stations. The movement of water in the studied urban watershed is characterized by two components, namely, the storm Sewer flow component and the surcharge-induced inundation component. SWMM is employed to solve the storm Sewer flow component and to provide the surcharged flow hydrographs for surface runoff exceeding the capacity of the storm Sewers. The 2D diffusive overland-flow model considering the non-inertia equation with Alternative Direction Explicit numerical scheme is then used to calculate the detailed inundation zones and depths due to the surcharged water on overland surface. Drainage by pumping stations at outlets of the storm Sewer system has also been taken into consideration. The parameters of the model are calibrated and verified for discrete storms. The combined model is suitable for analysis of inundation on urban areas due to overflow of storm Sewers and flooding caused by failure of pumping stations. Simulated results can be applied to establish flood-mitigation measures.
Mohammad Anbari - One of the best experts on this subject based on the ideXlab platform.
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risk assessment model to prioritize Sewer pipes inspection in wastewater collection networks
Journal of Environmental Management, 2017Co-Authors: Mohammad Anbari, Massoud Tabesh, Abbas RoozbahaniAbstract:In wastewater systems as one of the most important urban infrastructures, the adverse consequences and effects of unsuitable performance and failure event can sometimes lead to disrupt part of a city functioning. By identifying high failure risk areas, inspections can be implemented based on the system status and thus can significantly increase the Sewer network performance. In this study, a new risk assessment model is developed to prioritize Sewer pipes inspection using Bayesian Networks (BNs) as a probabilistic approach for computing probability of failure and weighted average method to calculate the consequences of failure values. Finally to consider uncertainties, risk of a Sewer pipe is obtained from integration of probability and consequences of failure values using a fuzzy inference system (FIS). As a case study, Sewer pipes of a local wastewater collection network in Iran are prioritized to inspect based on their criticality. Results show that majority of Sewers (about 62%) has moderate risk, but 12%of Sewers are in a critical situation. Regarding the budgetary constraints, the proposed model and resultant risk values are expected to assist wastewater agencies to repair or replace risky Sewer pipelines especially in dealing with incomplete and uncertain datasets.
