Water Distribution
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Jun Liu ◽  
Yinyin Kang

Abstract The consideration of isolation valves and segments is essential for evaluating the water service and resilience of water distribution systems when shutdowns are required under pipe failure. However, little work has been done on assessing the resilience response and intervention based on segments. This study investigates the impact of intervention (valve density and protection of critical segment) and response (recovery time and recovery sequence) on system resilience taking valve layout into consideration. An algorithm to identify segments based on the graph theory is proposed. Resilience is quantified using the satisfactory rate of the water supply demand. Critical segments are ranked based on resilience analysis. The resilience evaluation method is applied to a case study network. It is found that valve optimization can significantly reduce the number of valves without considerably decreasing the resilience performance. Valve density and the protection of critical segment can reduce the severity of pipe failure, while efficient recovery response can reduce the severity and shorten the duration of pipe failure simultaneously. The criticality of segments depends on the segment location and hydraulic interdependency among segments.

2021 ◽  
Luo Xu ◽  
cong li ◽  
Guozijian Wei ◽  
Jie Ji ◽  
Eric Lichtfouse ◽  

Abstract Sulfamethoxazole (SMX) is a veterinary drugs and feed additives, which has been frequently detected in surface waters in recent years. This paper investigated the kinetics, evolution of toxicity and antibiotic resistance genes (ARGs) of SMX in reactions with free chlorine (FC) to evaluate the fate of SMX in batch reactors and water distribution systems (WDS). In the range of investigated pH (6.3 – 9.0), the SMX degradation had the fastest rate at close to neutral pH. The chlorination of SMX could be described by the first-order kinetics, with specific second-order rate constants in batch reactors of (2.23 ± 0.07) × 102 M− s and (5.04 ± 0.30) × 101 M− s− for HClO and ClO−, respectively. And in WDS of (1.76 ± 0.07) × 102 M− s− and (4.06 ± 0.62) × 101 M− s−, respectively. The SMX degradation rate was also affected by pipe material, and the rate followed the order: stainless-steel pipe (SS) > ductile iron pipe (DI) > polyethylene pipe (PE). The flow rate from 0.7 to 1.5 m/s led to an increase of SMX degradation rate in DI, but the increase was limited. In addition, SMX could increase the toxicity of water initially, yet the toxicity reduced to the level of tap water after 2 hours chlorination. The relative abundance of ARGs (sul1 and sul2) of tap water samples was significantly increased under different conditions including only use SMX, chlorination products of SMX, or pretreatment with SMX followed by chlorination.

2021 ◽  
Vol 13 (22) ◽  
pp. 12929
Gideon Johannes Bonthuys ◽  
Marco van Dijk ◽  
Giovanna Cavazzini

The drive for sustainable societies with more resilient infrastructure networks has catalyzed interest in leakage reduction as a subsequent benefit to energy recovery in water distribution systems. Several researchers have conducted studies and piloted successful energy recovery installations in water distribution systems globally. Challenges remain in the determination of the number, location, and optimal control setting of energy recovery devices. The PERRL 2.0 procedure was developed, employing a genetic algorithm through extended period simulations, to identify and optimize the location and size of hydro-turbine installations for energy recovery. This procedure was applied to the water supply system of the town of Stellenbosch, South Africa. Several suitable locations for pressure reduction, with energy recovery installations between 600 and 800 kWh/day were identified, with the potential to also reduce leakage in the system by 2 to 4%. Coupling the energy recovery installations with a pipe replacement model showed a further reduction in leakage up to a total of above 6% when replacing 10% of the aged pipes within the network. Several solutions were identified on the main supply line and the addition of a basic water balance, to the analysis, was found valuable in preliminarily evaluation and identification of the more sustainable solutions.

Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1278
Shahmir Janjua ◽  
Ishtiaq Hassan ◽  
Muhammad Umair Ali ◽  
Malik Muhammad Ibrahim ◽  
Amad Zafar ◽  

Inhabited by almost 20 million people, Karachi, also known as the “city of lights”, houses almost 60 percent of the industries in Pakistan and is considered as the financial and industrial center of the country. The city contributes almost 12–15 percent to the gross domestic product (GDP), showing its significance in Pakistan’s economy. Unfortunately, with the increase in population, the city is facing a serious shortage of water supply. The current allocation of water among the city's districts is not equitable, which has caused water scarcity and even riots in some areas. Surface water and ground water are the two primary sources of water supply in the city. The water supply provided by Karachi Water and Sewerage Board (KWSB) is approximately 650 million gallons per day (MGD) against a demand of 480–866 million gallons per day (MGD), resulting in a serious shortfall. Keeping a holistic view in mind, this paper focuses specifically on proposing measures to address the gap in proposing concrete solutions to manage Karachi’s increasing water woes. It also proposes a water allocation mechanism and uses Nash bargaining theory to address the inefficient and unequal water distribution. Results indicate that our suggested policies and water allocation mechanism have the potential to simultaneously resolve the supply–demand mismatch and water shortage problems of the city.

2021 ◽  
Y.C. Huang ◽  
W.L. Yang

Abstract This letter presents a novel approach for efficient deployment of top pressure sensors in water distribution network. Flow-Tracking analysis using head loss coverage ratio explores a least number of top sensors in network topologies. The following sequence of top sensor plans can be effortlessly determined by simple greedy algorithm. A regular hydraulic model with 33 sensor nodes is to validate the fast and effective feature of flow-tracking method. A top set of 5 sensor nodes selected by head loss coverage ratio Hcr in flow-tracking analysis agree exactly with top set of 5 sensitive nodes selected by objective function f(Xk) by means of Sensitivity Analysis. A linear relationship between objective function f(Xk) and heads loss coverage ratio Hcr of top sensor nodes reveals high accuracy mapping from flow-tracking method to Sensitivity Analysis. Time complexity of searching top sensors node set by flow-tracking analysis is O(m⋅n). Average pressure error can be expected as low as 0.08 m with top-two sensors in sensors layout. As top sensors in deployment plan are all used, minimum error of 0.04 m is achieved. Flow-Tracking analysis has the advantages of little time complexity and accurate top sensors strategy as a new efficient solution for pressure sensors deployment in associated flow network.

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3268
Stephen Little ◽  
Andrew Woodward ◽  
Glenn Browning ◽  
Helen Billman-Jacobe

Drinking water distribution systems (WDSs) within buildings on pig farms have critical elements of their design and management that impact water provision to pigs, water quality, the efficacy of in-water antimicrobial dosing, and, thus, pig health and performance. We used a mixed-methods approach to survey managers of 25 medium to large single-site and multi-site pig farming enterprises across eastern and southern Australia. We found wide variation in the configuration (looped or branched) and total length of WDSs within buildings across farms and in pipe materials and diameters. Within many conventional buildings and some eco-shelters, WDSs were ‘over-sized’, comprising large-diameter main pipelines with high holding volumes, resulting in slow velocity water flows through sections of a WDS’s main pipeline. In over half of the weaner buildings and one-third of grower/finisher buildings, the number of pigs per drinker exceeded the recommended maximum. Few farms measured flow rates from drinkers quantitatively. WDS sanitization was not practiced on many farms, and few managers were aware of the risks to water quality and pig health. We identified important aspects of water provision to pigs for which valuable recommendations could be added to industry guidelines available to pig farm managers.

2021 ◽  
Vol 9 ◽  
Yao Li ◽  
Yuxing Li ◽  
Xi Liu ◽  
Yonghong He ◽  
Tian Guan

Purpose: The aims of the study were to investigate cellular mechanisms of cold cataract in young lenses of wild-type C57BL/6J (B6WT) mice treated at different temperatures and to test a hypothesis that cold cataract formation is associated with the changes in lens protein and water distribution at different regions across lens fiber cells by Raman spectroscopy (RS).Methods: RS was utilized to scan the mouse lens at different regions with/without cold cataract. Three regions with various opacification along the equatorial axis in the anterior–posterior lens section were scanned. The intensity ratio of Raman bands at 2,935 and 3,390 cm−1 (Ip/Iw) were used to evaluate lens protein and water distribution. We further determined water molecular changes through Gaussian profiles of water Raman spectra.Results: Three specific regions 1, 2, and 3, located at 790–809, 515–534, and 415–434 μm away from the lens center, of postnatal day 14 B6WT lenses, were subjected to RS analysis. At 37°C, all three regions were transparent. At 25°C, only region 3 became opaque, while at 4°C, both regions 2 and 3 showed opacity. The sum of the difference between Ip/Iw and the value of linear fitting line from scattered-line at each scanning point was considered as fluctuation degree (FD) in each region. Among different temperatures, opaque regions showed relatively higher FD values (0.63 and 0.79 for regions 2 and 3, respectively, at 4°C, and 0.53 for region 3 at 25°C), while transparent regions provided lower FD values (less than 0.27). In addition, the decrease in Gaussian peak II and the rising of Gaussian peak III and IV from water Raman spectra indicated the instability of water molecule structure in the regions with cold cataract.Conclusion: Fluctuation degrees of RS data reveal new mechanistic information about cold cataract formation, which is associated with uneven distribution of lens proteins and water across lens fiber cells. It is possible that RS data partly reveals cold temperature-induced redistribution of lens proteins such as intermediate filaments in inner fiber cells. This lens protein redistribution might be related to unstable structure of water molecules according to Gaussian profiles of water RS.

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