Modelling chlorine wall decay in a full-scale water supply system

Monteiro, Laura; Carneiro, Joana; Covas, Dídia

doi:10.1080/1573062x.2020.1804595

Cited by 28 publications

(10 citation statements)

References 25 publications

(41 reference statements)

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“…For the usually much more complex distribution systems, which often involve booster doses or multiple dosed sources, more systematic search procedures, such as genetic algorithms or particle swarm methods (Peirovi Minaee et al, 2019), are needed to ensure that the optimization is most likely to find a global optimum with high efficiency. However, this requires embedding EPANET and MSX in a broader supervisory software environment such as MATLAB, as Monteiro et al (2020) did. Alternatively, some commercial derivatives of EPANET and MSX (such as InfoWorks MSQ or WaterGEMS MSX) provide optimization procedures for fitting model parameters, which may be adaptable to optimizing inputs.…”

Section: Resultsmentioning

confidence: 99%

Integrated EPANET‐MSX process models of chlorine and its by‐products in drinking water distribution systems

Fisher

2023

Water Environment Research

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EPANET and its commercial derivatives are the most widely‐used software packages for modeling free chlorine and its by‐products in drinking water distribution systems. Yet, they are not sufficiently accurate, general, or efficient for deriving optimal chlorine dosing strategies at different seasonal temperatures. To overcome EPANET's limitations, an integrated set of rigorously validated multispecies process models are proposed for application within the EPANET‐MSX environment. An executable (command‐line) version of these MSX models is supplied for use either within the MSX environment or embedded in commercial versions of MSX. A new general method was devised to obtain output of any intermediate coefficient or variable involved in the simulation. This overcomes MSX's limited output options. When the debugged models were applied to a real distribution system, the optimal chlorine dose for summer required almost double the chlorine dose needed in winter. A lower initial dose combined with a downstream booster dose required less chlorine in total. Formal optimization techniques are needed to efficiently obtain similar strategies in more complex systems.Practitioner Points EPANET water quality models are not accurate or general enough for deriving optimal chlorine dosing strategies in distribution systems. Integrated EPNET‐MSX models of chlorine reactions in bulk water and at pipe walls, and associated by‐product formation, overcome EPANET’s limitations. To verify model authenticity, a general technique was developed to obtain values of coefficients and variables within an EPANET‐MSX simulation. EPANET‐MSX command lines implementing these integrated EPANET‐MSX models are presented with verified results for optimal initial and booster dosing strategies. Optimal summer dosing in a real system of rough pipes was almost double that required in winter.

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Section: Resultsmentioning

confidence: 99%

Integrated EPANET‐MSX process models of chlorine and its by‐products in drinking water distribution systems

Fisher

2023

Water Environment Research

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“…, denoting the number of previous time steps from which information is needed to evaluate this function Here we note that the aforementioned modeling of chlorine reactions and kinetics in WDN is a simplified model which approximates the actual chemistry and physics of chlorine in these networks and has been shown to work reasonably well (Monteiro et al, 2020). Some aspects of modeling water-quality in WDN however are more complex, such as the effect of water stagnation on chlorine residuals at dead-end sections where water demand can be zero (Abokifa et al, 2016(Abokifa et al, , 2020.…”

Section: Water-quality Modelingmentioning

confidence: 99%

Calculating Chlorine Concentration Bounds in Water Distribution Networks: A Backtracking Uncertainty Bounding Approach

Vrachimis

Ηλιάδης

Polycarpou

2021

Water Resources Research

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The most recent EU directive on the quality of water intended for human consumption (European Commission, 2018) emphasizes the importance of water-quality monitoring for reducing the risks to health from drinking water, with chlorine by-products being among the quality parameters recommended for monitoring. Chlorine is commonly used by water utilities as a disinfectant in Water Distribution Networks (WDN). According to the World Health Organization (WHO), a chlorine residual needs to be sustained throughout the drinking water network which should be sufficient to deactivate waterborne pathogens and, at the same time, small enough to reduce the formation of harmful chlorine by-products (Mouly et al., 2010). Additionally, due to the fact that certain contaminants will affect chlorine residuals in a specific way (e.g., a bacterial toxin may decrease the concentration of free chlorine due to its reaction dynamics) (Helbling & Van-Briesen, 2009), chlorine residuals can be used as key indicators of contamination events (Hall et al., 2007).The installation of online chlorine sensors can enhance monitoring capabilities of chlorine residuals and enable more timely control actions. For contamination event detection, water-quality sensors may be installed which can monitor multiple parameters (e.g., pH, free chlorine, total organic carbon) and detect changes in water-quality. The placement of such sensors in WDN in order to detect a contamination event has been a subject of research for years (Eliades & Polycarpou, 2010;Hart & Murray, 2010). The problem is posed as a multiobjective optimization, with one of the objectives being the minimization of the number of sensors due to their high capital and maintenance costs (Zeng et al., 2016), while addressing the uncertainty present in these real-world systems is also a crucial component of these methodologies (Sankary & Ostfeld, 2018). Single-parameter sensors (such as free chlorine concentration sensors) are cheaper than multiparameter sensors, and using them not only for chlorine residual monitoring but also for contamination event detection, could significantly reduce the health risks from contaminated drinking water. However, in order to determine whether a sensor reading is abnormal (e.g., due to a contamination), it needs to be compared with an estimate of the expected concentration at the sensor location. The estimated concentration can be calculated using water-quality models (Rossman & Boulos, 1996). These are mathematical representations

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“…Residual chlorine degradation due to the physico-chemical reactions takes place in the bulk volume and at the pipe walls throughout a WDS (McGrath et al 2021). Bulk degradation is mainly a function of natural organic and inorganic matter, water temperature, and disinfectant concentration, while pipe wall degradation depends mainly on pipe age, the presence of corrosion and/or biofilm and pipe material (Monteiro et al 2020). Biofilm and corrosion, specifically in metallic pipes, can accelerate chlorine degradation, so pipe physical characteristics and ageing need to be closely studied and understood (Pasha & Lansey 2009).…”

Section: Introductionmentioning

confidence: 99%

Full-scale determination of pipe wall and bulk chlorine degradation coefficients for different pipe categories

et al. 2023

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Having good information about the parameters that impact water quality can improve the management of water distribution systems in the short term (optimizing disinfection) and the long term (planning rehabilitation). Full-scale data on the degradation of the residual disinfectant for various pipe characteristics are difficult to obtain but necessary. As the most common disinfectant is chlorine, this paper aims to determine the most important pipe and/or hydraulic system characteristics in the chlorine degradation coefficients. Such characteristics were identified based on statistical analyses that relate them with range values of bulk (kb) and pipe wall (kw) degradation coefficients estimated in full-scale conditions in a real distribution system. The results showed that among pipe characteristics, the period of installation impacts significantly kw and kt. Results of kw for three different materials confirmed that residual chlorine degradation at the pipe walls for grey-cast iron, which is older and metallic, is much higher than that for ductile cast iron and PVC pipes. In older pipes, up to 97% of residual chlorine can be degraded at the pipe walls, while the role of bulk reactions can reach about 35% in newer pipes. The obtained information can be integrated to identify pipes for rehabilitation/renewal and locations for booster rechlorination.

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Modelling chlorine wall decay in a full-scale water supply system

Cited by 28 publications

References 25 publications

Integrated EPANET‐MSX process models of chlorine and its by‐products in drinking water distribution systems

Integrated EPANET‐MSX process models of chlorine and its by‐products in drinking water distribution systems

Calculating Chlorine Concentration Bounds in Water Distribution Networks: A Backtracking Uncertainty Bounding Approach

Full-scale determination of pipe wall and bulk chlorine degradation coefficients for different pipe categories

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