scholarly journals The potential for health risks from intrusion of contaminants into the distribution system from pressure transients

2003 ◽  
Vol 1 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Mark W. LeChevallier ◽  
Richard W. Gullick ◽  
Mohammad R. Karim ◽  
Melinda Friedman ◽  
James E. Funk
Keyword(s):  
Health Risks ◽  
Negative Pressure ◽  
Distribution System ◽  
High Speed ◽  
Distribution Systems ◽  
Transient Pressure ◽  
Pressure Transients ◽  
Data Loggers ◽  
Human Viruses ◽  
Treated Drinking Water

The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.

scholarly journals Managing risks from virus intrusion into water distribution systems due to pressure transients

2011 ◽  
Vol 9 (2) ◽  
pp. 291-305 ◽  
Author(s):  
Jian Yang ◽  
Mark W. LeChevallier ◽  
Peter F. M. Teunis ◽  
Minhua Xu
Keyword(s):  
Viral Infection ◽  
Negative Pressure ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Quantitative Microbial Risk Assessment ◽  
Pressure Transients ◽  
Negative Pressure Transients ◽  
Negative Pressures

Low or negative pressure transients in water distribution systems, caused by unexpected events (e.g. power outages) or routine operation/maintenance activities, are usually brief and thus are rarely monitored or alarmed. Previous studies have shown connections between negative pressure events in water distribution systems and potential public health consequences. Using a quantitative microbial risk assessment (QMRA) model previously developed, various factors driving the risk of viral infection from intrusion were evaluated, including virus concentrations external to the distribution system, maintenance of a disinfectant residual, leak orifice sizes, the duration and the number of nodes drawing negative pressures. The most sensitive factors were the duration and the number of nodes drawing negative pressures, indicating that mitigation practices should be targeted to alleviate the severity of low/negative pressure transients. Maintaining a free chlorine residual of 0.2 mg/L or above is the last defense against the risk of viral infection due to negative pressure transients. Maintaining a chloramine residual did not appear to significantly reduce the risk. The effectiveness of ensuring separation distances from sewer mains to reduce the risk of infection may be system-specific. Leak detection/repair and cross-connection control should be prioritized in areas vulnerable to negative pressure transients.

Chlorine sensitivity of environmental, distribution system and biofilm coliforms

1997 ◽  
Vol 35 (11-12) ◽  
pp. 289-292 ◽  
Author(s):  
D. P. Sartory ◽  
P. Holmes
Keyword(s):  
Drinking Water ◽  
River Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Bulk Water ◽  
Coliform Bacteria ◽  
Environmental Distribution ◽  
River Waters ◽  
E Coli ◽  
Treated Drinking Water

Coliform bacteria, isolated from treated drinking water supplies, can be derived from a range of sources (e.g. infiltration, breakthrough at the treatment works or from the biofilm established within the pipework). The sensitivity of these bacteria to chlorine may be related to their source and metabolic status. Strains of coliforms were isolated from sewage works effluents, river and reservoir waters as well as from the bulk water and biofilms from distribution systems. These were assayed for sensitivity to free and total chlorine using two assay procedures. For E. coli, the isolates from the distribution system bulk water showed greater resistance to free chlorine than those from sewage effluents and equivalence to those from river waters. For non-E. coli coliforms (mainly strains of Klebsiella, Enterobacter and Citrobacter), those from distribution system biofilms showed the greatest sensitivity to free and total chlorine whilst those from river water had the greatest resistance.

Organic characterisation tools for distribution system management

2009 ◽  
Vol 9 (1) ◽  
pp. 1-8 ◽  
Author(s):  
C. W. K. Chow ◽  
Philipp Kuntke ◽  
Rolando Fabris ◽  
Mary Drikas
Keyword(s):  
Water Quality ◽  
Organic Carbon ◽  
Distribution System ◽  
High Performance ◽  
Distribution Systems ◽  
Management Strategies ◽  
Molecular Size ◽  
Quality Parameters ◽  
Size Exclusion ◽  
Treated Drinking Water

In this investigation, high-performance size exclusion chromatography (HPSEC) was used to characterise organic matter in treated drinking water at key sampling locations along two selected distribution systems (chlorinated and chloraminated). Other water quality parameters such as colour, UV254, dissolved organic carbon (DOC) and assimilable organic carbon (AOC) as measured by bacterial regrowth potential (BRP), were also determined. One of the aims of this work was to develop new tools to monitor organic character change along the distribution system in order to identify impacting factors and develop management strategies based on water quality change. This study used samples from two contrasting distribution systems with different disinfection regimes and organic characteristics together with samples generated from laboratory simulations. System 1 is a chlorinated distribution system and generally requires elevated chlorine dosage to meet the demand due to the high DOC level. System 2 is a chloraminated system with stable water quality, low DOC and low chloramine dose (mild oxidation). Molecular size distribution determination using HPSEC is a very informative technique in assessing treatment processes and in this study the appearance of a molecular peak at 1,700 Da that can be used as an indicator of biological activity in distribution systems was confirmed. The use of BRP values, for upstream and downstream samples in the distribution system, was found to be a good approach to assess biological impacts on water stability. The observed biological impact from the biofilms between the studied systems were particularly useful in confirming the organic characterisation results.

scholarly journals Research on Coordinated Development of a Railway Freight Collection and Distribution System Based on an “Entropy-TOPSIS Coupling Development Degree Model” Integrated with Machine Learning

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Yun Jing ◽  
Si-Ye Guo ◽  
Xuan Wang ◽  
Fang-Qiu Chen
Keyword(s):  
Machine Learning ◽  
Distribution System ◽  
Information Acquisition ◽  
High Speed ◽  
Distribution Systems ◽  
Target System ◽  
Railway Transportation ◽  
Railway Freight ◽  
Transportation Capacity ◽  
Heavy Haul

In recent years, with the gradual networking of high-speed railways in China, the existing railway transportation capacity has been released. In order to improve transportation capacity, railway freight transportation enterprises companies have gradually shifted the transportation of goods from dedicated freight lines to passenger-cargo lines. In terms of the organization form of collection and distribution, China has a complete research system for heavy-haul railway collection and distribution, but the research on the integration of collection and distribution of the ordinary-speed railway freight has not been completed. This paper combines the theories of the integration of collection and distribution theory, coordination theory, and coupling theory and incorporates the machine learning fuzzy mathematics to construct an “Entropy-TOPSIS Coupling Development Degree Model” for dynamic intelligent quantitative analysis of the synergy of railway freight collection and distribution systems. Finally, we take the Tongchuan Depot of “China Railway Xi’an Group Co., Ltd.” as a research object to construct a target system and use the intelligent information acquisition system to collect basic data. The analysis results show that through the coordinated control of the freight collection and distribution system, the coordination between the subsystems of the integrated freight collection and distribution system is increased by 5.94%, which verifies the feasibility of the model in the quantitative improvement of the integration of collection and distribution system. It provides a new method for the research of integrated development of railway freight collection and distribution.

scholarly journals Effects of leakage points on intrusion volume in a simulated water distribution system

2019 ◽  
Vol 20 (1) ◽  
pp. 251-258
Author(s):  
Yu Shao ◽  
Shipeng Chu ◽  
Chenkai Dang ◽  
Tingchao Yu
Keyword(s):  
Health Risks ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Discharge Coefficient ◽  
Water Distribution System ◽  
Pilot Scale ◽  
Orifice Diameter ◽  
Urban Water ◽  
Public Health Risks

Abstract Contamination can intrude into urban water distribution systems through pipe leakage orifices or other deficiencies, which can create public health risks. Intrusion volume is a significant indicator of health risks when a pollution incident occurs. A pilot-scale platform was constructed to simulate the contamination intrusion through leakage holes caused by low or negative pressure events. The intrusion device was improved from the author's previous study by substituting the replaceable pipes in the main pipe for the side connecting pipe. Comparison between the two intrusion devices demonstrated that the intrusion device with the side connecting pipe may underestimate the intrusion volume. The orifice diameter range is extended to be 3–19.0 mm to analyze the effects of leakage sizes on the intrusion volume. The results show that the intrusion volume first increased and then decreased with increase of the orifice diameter. The calculated intrusion volume by the orifice discharge equation using the measured discharge coefficient is slightly different from the measured intrusion volume.

Unit Template Based Control of PV-DSTATCOM

2020 ◽  
Vol 13 (1) ◽  
pp. 36-42
Author(s):  
Gunjan Varshney ◽  
Durg S. Chauhan ◽  
Madhukar P. Dave ◽  
Nitin
Keyword(s):  
Power Quality ◽  
Power Factor ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Phase Distribution ◽  
Voltage Regulation ◽  
Photovoltaic Array ◽  
Quality Issues ◽  
Static Compensator

Background: In modern electrical power distribution systems, Power Quality has become an important concern due to the escalating use of automatic, microprocessor and microcontroller based end user applications. Methods: In this paper, power quality improvement has done using Photovoltaic based Distribution Static Compensator (PV-DSTATCOM). Complete simulation modelling and control of Photovoltaic based Distribution Static Compensator have been provided in the presented paper. In this configuration, DSTATCOM is fed by solar photovoltaic array and PV module is also helpful to maintain the DC link voltage. The switching of PV-STATCOM is controlled by Unit template based control theory. Results: The performance of PV-DSTATCOM has been evaluated for Unity Power Factor (UPF) and AC Voltage Control (ACVC) modes. Here, for studying the power quality issues three-phase distribution system is considered and results have been verified through simulation based on MATLAB software. Conclusion: Different power quality issues and their improvement are studied and presented here for harmonic reduction, DC voltage regulation and power factor correction.

scholarly journals A Game-Theoretic Loss Allocation Approach in Power Distribution Systems with High Penetration of Distributed Generations

Mathematics ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 158
Author(s):  
Farzaneh Pourahmadi ◽  
Payman Dehghanian
Keyword(s):  
Power Systems ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Power Distribution Systems ◽  
Loss Allocation ◽  
Distributed Generators ◽  
High Penetration ◽  
Game Theoretic ◽  
Allocation Approach

Allocation of the power losses to distributed generators and consumers has been a challenging concern for decades in restructured power systems. This paper proposes a promising approach for loss allocation in power distribution systems based on a cooperative concept of game-theory, named Shapley Value allocation. The proposed solution is a generic approach, applicable to both radial and meshed distribution systems as well as those with high penetration of renewables and DG units. With several different methods for distribution system loss allocation, the suggested method has been shown to be a straight-forward and efficient criterion for performance comparisons. The suggested loss allocation approach is numerically investigated, the results of which are presented for two distribution systems and its performance is compared with those obtained by other methodologies.

scholarly journals Application of genetic programming to modeling pipe failures in water distribution systems

2010 ◽  
Vol 13 (3) ◽  
pp. 419-428 ◽  
Author(s):  
Qiang Xu ◽  
Qiuwen Chen ◽  
Weifeng Li
Keyword(s):  
Genetic Programming ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Pipe Failure ◽  
Beijing City ◽  
Failure Data ◽  
Processing Strategies ◽  
Gis Data ◽  
Failure Models

The water loss from a water distribution system is a serious problem for many cities, which incurs enormous economic and social loss. However, the economic and human resource costs to exactly locate the leakage are extraordinarily high. Thus, reliable and robust pipe failure models are demanded to assess a pipe's propensity to fail. Beijing City was selected as the case study area and the pipe failure data for 19 years (1987–2005) were analyzed. Three different kinds of methods were applied to build pipe failure models. First, a statistical model was built, which discovered that the ages of leakage pipes followed the Weibull distribution. Then, two other models were developed using genetic programming (GP) with different data pre-processing strategies. The three models were compared thereafter and the best model was applied to assess the criticality of all the pipe segments of the entire water supply network in Beijing City based on GIS data.

scholarly journals Protection of Sensitive Loads in Distribution Systems Using a BSFCL-DVR System

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1615
Author(s):  
Mehdi Firouzi ◽  
Saleh Mobayen ◽  
Hossein Shahbabaei Kartijkolaie ◽  
Mojtaba Nasiri ◽  
Chih-Chiang Chen
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Fault Current ◽  
Dynamic Voltage Restorer ◽  
Voltage Quality ◽  
Voltage Restorer ◽  
Point Of Common Coupling ◽  
Dynamic Voltage ◽  
Bridge Type ◽  
In The Beginning

In this paper, an incorporated bridge-type superconducting fault current limiter (BSFCL) and Dynamic Voltage Restorer (DVR) is presented to improve the voltage quality and limiting fault current problems in distribution systems. In order to achieve these capabilities, the BSFCL and DVR are integrated through a common DC link as a BSFCL-DVR system. The FCL and DVR ports of the BSFCL-DVR system are located in the beginning and end of the sensitive loads’ feeder integrated to the point of common coupling (PCC) in the distribution system. At first, the principle operation of the BSFCL-DVR is discussed. Then, a control system for the BSFCL-DVR system is designed to enhance the voltage quality and limit the fault current. Eventually, the efficiency of the BSFCL-DVR system is verified through the PSCAD/EMTDC simulation.

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