City Water Distribution System Research Articles

Seasonal variations of microbial community and antibiotic resistome in a suburb drinking water distribution system in a northern Chinese city

Antibiotic resistance genes (ARGs) are an emerging issue for drinking water safety. However, the seasonal variation of ARGs in drinking water distribution systems (DWDS) is still unclear. This work revealed the tempo-spatial changes of microbial community, ARGs, mobile genetic elements (MGEs) co-occurring with ARGs, ARG hosts in DWDS bulk water by means of metagenome assembly. The microbial community and antibiotic resistome varied with sampling season and site. Temperature, ammonia, chlorite and total plate count (TPC) drove the variations of microbial community structure. Moreover, environmental parameters (total organic carbon (TOC), chlorite, TPC and hardness) shifted antibiotic resistome. ARGs and MGEs co-occurring with ARGs showed higher relative abundance in summer and autumn, which might be attributed to detached pipe biofilm. In particular, ARG-bacitracin and plasmid were the predominant ARG and MGE, respectively. ARG hosts changed with season and site and were more diverse in summer and autumn. In winter and spring, Limnohabitans and Mycobacterium were the major ARG hosts as well as the dominant genera in microbial community. In addition, in summer and autumn, high relative abundance of Achromobacter and Stenotrophomonas were the hosts harboring many kinds of ARGs and MGEs at site in a residential zone (0.4 km from the water treatment plant). Compared with MGEs, microbial community had a greater contribution to the variation of antibiotic resistome. This work gives new insights into the dynamics of ARGs in full-scale DWDS and the underlying factors.

Prediction of Fault Occurrences in Smart City Water Distribution System Using Time-Series Forecasting Algorithm

The proposed research work is focused on forecasting the future requirements of water supply based on the current requirement of water and also identifying the possibility of occurrences of cracks and leaks using the ARIMA (autoregressive integrated moving average) model. The experiments were conducted using real-time experimental hardware. The pressure data obtained and their p -value is less than 0.05, which represents the stability of the data in the ARIMA model. The forecasted pressure data range between 0.451379 N/m2 and 2.022273 N/m2. The frequency of the forecasted pressure ranges between 1.706869 N/m2 and 3.065836 N/m2 (maximum peak) and −0.81046 N/m2 and 1.042164 N/m2 (minimum peak). Forecasted data of pressure at damaged condition lie between 2.880788 N/m2 and 3.29797 N/m2 and frequency ranges between 4.866227 N/m2 and 5.664348 N/m2. Similarly, future forecasted data of water requirement for the next 1 year range between 614.6292 (liters/week) and 620.0099 (liters/week), the frequency of the forecast value with maximum ranging from 617.0086 (liters/week) to 628.5465 (liters/week), and the minimum peaks ranging from 611.0967 (liters/week) to 612.2914 (liters/week). The above data are for a single water distribution pipeline.

Legionella monitoring in the New York City water distribution system 2017 to 2019

AbstractThis study investigated prevalence of Legionella in the New York City (NYC) water distribution system using International Organization for Standardization 11731:2017 and Legiolert (IDEXX, USA) culture‐based methods and polymerase chain reaction. All water samples met applicable Environmental Protection Agency and New York State water quality guidelines. Eighty‐five percent (448/528) of water samples were positive for Legionella DNA. Despite this, Legionella bacteria were detected in only 2.8% (15/544) of water samples using culture methods. All Legionella pneumophila culture‐positive samples were recovered from a single distribution site, which was undergoing a street reconstruction project. The site had conditions indicative of stagnation, and an adjacent building's service line was periodically backflowing. These factors indicate that L. pneumophila may have been introduced from an external source. The lack of culturable Legionella in samples with detectable Legionella DNA suggests that NYC practices are sufficient to protect against culturable Legionella in NYC's water distribution system.

Corrosion Characterization at Surface and Subsurface of Iron-Based Buried Water Pipelines.

Water pipe surface deterioration is the result of continuous electrochemical reactions attacking the surface due to the interaction of the pipe surface with environments through the time function. The study presents corrosion characterization at the surface and sub-surface of damaged ductile iron pipe (DIP) and galvanized steel (GS) pipes which served for more than 40 and 20 years, respectively. The samples were obtained from Addis Ababa city water distribution system for the analysis of corrosion morphology patterns at different surface layers. Mountains 8.2 surface analysis software was utilized based on the ISO 25178-2 watershed segmentation method to investigate corrosion features of damaged pipe surface and to evaluate maximum pit depth, area, and volume in-situ condition. Based on the analysis maximum values of pit depth, area and volume were 380 m, 4000 m2, and 200,000 m3, respectively, after 25% loss of the original 8 mm thickness of DIP. Similarly, the pit depth of the GS pipe was 390 whereas the maximum pit area and volume are 4000 m2 and 16,000 m3, respectively. In addition, characterizations of new pipes were evaluated to study microstructures by using an optical microscope (OM), and a scanning electron microscope (SEM) was used to analyze corrosion morphologies. Based on the SEM analysis, cracks were observed at the sub-surface layer of the pipes. The results show that uniform corrosion attacked the external pipe surface whereas pitting corrosion damaged the subsurface of pipes. The output of this study will be utilized by water suppliers and industries to investigate corrosion phenomena at any damage stage.

Persistent Pockets of Low Chlorine Residual in New York City's Drinking Water Distribution System: A Case Study

Key TakeawaysPockets of low chlorine residual have been found in New York City's water distribution system, with fluctuating water demand resulting from the seasonal operation of local institutions.Variations of the chlorine residual profiles in one such pocket were found through both field and laboratory investigations.Once the cast‐iron pipe was replaced with ductile‐iron pipe in the study area, an acceptable chlorine residual was usually maintained; when low chlorine residuals were observed, low‐velocity flushing remediated the situation.

Assessment of probable causes of chlorine decay in water distribution systems of Gaborone city, Botswana

Assessment of probable causes of chlorine decay in water distribution systems of Gaborone city, Botswana Gaborone city water distribution system (GCWDS) is rapidly expanding and has been faced with the major problems of high water losses due to leakage, water shortages due to drought and inadequate chlorine residuals at remote areas of the network. This study investigated the probable causes of chlorine decay, due to pipe wall conditions and distribution system water quality in the GCWDS. An experimental approach, which applied a pipe-loop network model to estimate biofilm growth and chlorine reaction rate constants, was used to analyse pipe wall chlorine decay. Also, effects of key water quality parameters on chlorine decay were analysed. The water quality parameters considered were: natural organic matter (measured by total organic carbon, TOC; dissolved organic carbon, DOC; and ultraviolet absorbance at wavelength 254, UVA-254, as surrogates), inorganic compounds (iron and manganese) and heterotrophic plate count (HPC). Samples were collected from selected locations in the GCWDS for analysis of water quality parameters. The results of biofilm growth and chlorine reaction rate constants revealed that chlorine decay was higher in pipe walls than in the bulk of water in the GCWDS. The analysis of key water quality parameters revealed the presence of TOC, DOC and significant levels of organics (measured by UVA-254), which suggests that organic compounds contributed to chlorine decay in the GCWDS. However, low amounts of iron and manganese (< 0.3 mg/L) indicated that inorganic compounds may have had insignificant contributions to chlorine decay. The knowledge gained on chlorine decay would be useful for improving water treatment and network operating conditions so that appropriate chlorine residuals are maintained to protect the network from the risks of poor water quality that may occur due to the aforementioned problems.

Cholera Epidemic - Lusaka, Zambia, October 2017-May 2018.

On October 6, 2017, an outbreak of cholera was declared in Zambia after laboratory confirmation of Vibrio cholerae O1, biotype El Tor, serotype Ogawa, from stool specimens from two patients with acute watery diarrhea. The two patients had gone to a clinic in Lusaka, the capital city, on October 4. Cholera cases increased rapidly, from several hundred cases in early December 2017 to approximately 2,000 by early January 2018 (Figure). In collaboration with partners, the Zambia Ministry of Health (MoH) launched a multifaceted public health response that included increased chlorination of the Lusaka municipal water supply, provision of emergency water supplies, water quality monitoring and testing, enhanced surveillance, epidemiologic investigations, a cholera vaccination campaign, aggressive case management and health care worker training, and laboratory testing of clinical samples. In late December 2017, a number of water-related preventive actions were initiated, including increasing chlorine levels throughout the city's water distribution system and placing emergency tanks of chlorinated water in the most affected neighborhoods; cholera cases declined sharply in January 2018. During January 10-February 14, 2018, approximately 2 million doses of oral cholera vaccine were administered to Lusaka residents aged ≥1 year. However, in mid-March, heavy flooding and widespread water shortages occurred, leading to a resurgence of cholera. As of May 12, 2018, the outbreak had affected seven of the 10 provinces in Zambia, with 5,905 suspected cases and a case fatality rate (CFR) of 1.9%. Among the suspected cases, 5,414 (91.7%), including 98 deaths (CFR = 1.8%), occurred in Lusaka residents.

Hydraulic analysis of the water supply system of the Roman city of Perge

Fluid dynamics is a valuable tool to characterize and to interpret ancient hydraulic remains. In this study, the peculiar water channel situated in the middle of the main street of the ancient Roman city of Perge is investigated. More precisely, the water flow in the channel (and in diversions originating from this channel) is characterized and the results are analyzed in order to gain a better understanding of the city water distribution system. The peculiarity of the system lies in the unusual channel dimensions in Roman standard, as well as in the presence of blocks perpendicular to the flow, regularly placed every 7m on the whole channel length. Furthermore, upstream of some of the blocks, terracotta pipes are inserted in the walls of the channel. They were bringing water to the east and to the west of the city. The results show that the channel must have been the only north-south water transportation axis of the city and that the presence of the blocks was imperative, not only to ensure the aesthetic of the channel, but also its functionality.

Emergency Repair Scope Partition of City Water Distribution Network: a Novel Approach Considering the Node Importance

The timely repair of City Water Distribution System, a basic guarantee for the life of city residents, requires a reasonable supervision area partition of the City Water Distribution Network (CWDN). In this paper, a graph-theoretic and multi-objective approach for the partition of CWDN is presented. The proposed framework is mainly based on rescue distance and extreme workload of the same area. The rescue distance is expressed by effective distance, which is calculated by the adjustment of straight line distance and seeking smallest value. Extreme workload refers to the average importance of failure nodes belonging to a same crew and needing to be placed in balance. The node importance is coupled with node function importance and node structure importance, and they are calculated using knowledge of Graph Theory. This approach can finish the emergency repair scope partition quickly and easily since it does not rely on precise hydraulic simulation which requires complex calibration processes and computation, while remaining meaningful from a physical and topological point of view. The method is also applied to the analysis of a CWDN and successfully tested, with the result that there emerged a 7.83% decrease of the rescue distance. In addition, the balance of extreme workload was found to be three times higher than the previous.

Assessment of the biodegradation intensity of organic compounds in water using the squalene biomarker

An approach based on the quantitative determination of squalene biomarker by the chromato-mass-spectrometry method has been proposed for assessment of the intensity of biotransformation of organic compounds in water. The method sensitivity amounted to 5 × 10–5 mg/dm3. It is recommended to use squalene for the detection of stagnant zones in the city water distribution system and the biological activity in filtering layers of wells of infiltration water intakes and in filters for industrial and domestic water treatment. An enhanced intensity of biotransformation processes is related to the rise of squalene concentration in the tested water.

Determination of corrosion and scaling levels of drinking water in distribution system: A study in Sarableh city (Ilam), western of Iran

Introduction: Corrosion and scaling of water in distribution systems in spite of imposing economic and aesthetic problems can lead to adverse effects on consumers' health. The present study was conducted to evaluate the corrosion and scaling of water distribution system of Sarableh city (Ilam, Iran) during summer and winter seasons in 2014. Materials and methods: Totally, 60 samples of water (30 samples in each season) in 30 points of the distribution system were analyzed in terms of temperature, calcium hardness, alkalinity, TDS (total dissolved solids), pH, and DO (dissolved oxygen). Then, the corrosion and scaling of water were determined by various indices. Results: The results of the indices showed that the quality of drinking water in Sarableh city water distribution system had a medium corrosion rate. Conclusion: According to the results, it is needed to take some measures for stabilizing water before entering drinking water into the distribution system in order to prevent various health problems for consumers.

English

The quality of drinking water at the point of delivery to the consumer is crucial in safeguarding consumer’s health. The current study was undertaken to assess the changes in residual chlorine content with distance in water distribution system in Gwalior city of Madhya Pradesh and assess its relation with the occurrence of total and faecal coliforms. Water samples were collected from the exit point of the treatment plant and taps at consumer households at an interval of 1 to 2 km. A total of 56 water samples were tested to determine residual chlorine content and presence of total and fecal coliforms using standard methods. Average concentrations of residual chlorine from all sampling location were between 0.08 to 0.98 mg/L. Total coliform was found at most of the sampling locations in the range of 0.82 to 7.15 MPN/100 ml. The fecal coliform at all sampling locations was found in the range of 0 to 4.10 MPN/100 ml. With time, the residual chlorine in the transported water dechlorinates. After covering some distance, the residual chlorine of the water was completely diminished thereby supporting massive microbial growth. The study proposed the likely causes of the transit dechlorination of water and recommended carrying out compulsory chlorination at water sources while maintaining reasonable residuals at the consumers’ end to eliminate the bacteriological contamination. Key words: Residual chlorine, total and fecal coliforms, drinking water chlorination, water contamination.

Risk Analysis Model for Water Pipeline Leakage Based on FAHP and BPNN

Scientific analysis of the leakage of the water distribution system in city is very helpful to water supply network’s maintenance and renovation, and hence reduces negative social effect and economic loss. A leakage risk nalysis model for water distribution system was established based on fuzzy analytical hierarchy process (FAHP) and BP neural network (BPNN). This model introduces FAHP to reasonably ensure initial state of BP neural network, and uses weighted superposition to mend learning sample set of BP neural network. The water distribution system of a city in Zhejiang province P. R. China was selected to test the proposed risk analysis model, which verifise its feasibility and effectivity.

Risk Assessment Modeling for Water Distribution Systems in Mega Cities

In study of a series of damages to water distribution systems caused by urban land subsidence, risk assessment modeling is necessary for risk management especially in Mega-cities. First of all, the Catastrophe Theory was employed to analyze the Catastrophe mechanism, and a function catastrophe simulation model was established accordingly to get the vulnerability index of water distribution system. Secondly, risk entropy model was used to analyze the risk of pipe network suffering the land subsidence with the disorder and uncertainty features according to risk theory. Finally, to get the risk index the water distribution system of Guangzhou city was taken to the risk assessment model utilizing the level of land subsidence identified by the dimensional analytical method. The results showed that the risk of land subsidence under the city water distribution system security upgrade is feasible to provide a risk assessment of the strategic decision-making model.

The Analysis and Improvement Measure of Chemical Stability of Water Quality in Jinan City Water Distribution System

The water quality chemical stability of Jinan's three waterworks (Quehua, Yuqing and Nanjiao waterworks) was analyzed through determination of several parameters affecting the chemical stability of water quality, including temperature, pH, Ca content, alkalinity, total hardness, total dissolved solids, chlorides, sulfates. For comprehensive and objective evaluation of the chemical stability of water, four water stability indexes LSI, RSI, AI, LR were used in this paper. The resulted index values indicated the corrosion in Jinan water distribution system may occur, and different source waters have different chemical characteristics. Yellow river water (Yuqing and Quehua) is high in chlorides and sulfates, while Nanjiao water is low in chlorides and sulfates. The improvement measure to chemical stability of water quality in Jinan City water distribution system included adding alkalinity, and blending water from different waters to reduce LR. The research proposed a way to control red water problem, which is meaningful to protect pipe works and improve tap water quality.

Assessment of apparent losses in urban water systems

AbstractApparent losses relate to water that is consumed but not paid for. Most research carried out in the last decade particularly in the United Kingdom focused mainly on leakage. Until now, there are no set procedures and guidelines for assessment of apparent losses. Much work remains to bring it to par with the available tools and methodologies for leakage management. In the absence of adequate data and proper methodology, most developed countries use default values, which tend to be lowest values for well‐managed water systems, for computation of apparent losses. These may not be appropriate for developing countries. This paper presents a methodology for the assessment of different components of apparent losses based on field audit and operational data for Kampala city's water distribution system in Uganda. Metering inaccuracies and illegal use have been found to be significant components of apparent losses. Appropriate intervention strategies have been developed based on the assessment.

Determination of water supply sources in the Barcelona distribution system by UV spectrophotometry and PLS

A new method for the water source apportionment of the Barcelona (Spain) water distribution system is proposed. The method is based on the combined use of UV spectrophotometric measurements in the wavelength from 190–230 nm, and multivariate data analysis using the Partial Least Squares (PLS) chemometric method. From the differences in the organic matter content of the different water sources and of their corresponding UV spectral features, PLS was able to determine the relative amounts of the two main river water sources in samples of tap water from the different locations of the Barcelona city water distribution system. The extension of the method to determine the relative amounts in water blends, prepared from samples from five water treatment plant sources of the same city’s distribution system, required the combined use of some other parameters. In particular, the distinction and apportion of the water coming from a desalinisation plant could be successfully achieved once concentrations of Boron were included in the analysis.

Water Distribution System Modeling and Simulation

This paper describes a project to integrate EPANET, Giris and SCADA to assist water engineers in assessing the water distribution system in city S. The integrated system simulates the flow and concentration of chemical contaminants in municipality's water distribution system. The integrated model is a powerful tool for routine planning and emergency response. The capabilities of the model can greatly assist in the decision making processes for network asset inventory, rehabilitation requirements, and financial planning. The system was tested using the S City database composed of approximately 13219 junctions and 14832 pipes whose diameter not less than 300 mm.

Use of Hydraulic Network Model for Evaluating Fire Flow Capacity of a Water Distribution Network

A WaterCAD hydraulic network model of the existing Ikpoba Hill Benin City water distribution system was constructed and calibrated for steady state simulation studies using the network’s physical, operational and calibration data. The model was then used for available fire flow analysis and system improvement design. Our study reveals that the existing network has available fire flow of O l/s and hence cannot provide needed flow for fire suppression. However, the proposed improved network with increased diameters of existing pipes and which also takes into account expected future growth has available fire flow of between 29.6l/s and 40l/s at the nodes in the network.On the basis of available fire flow at the nodes in the system, hydrant tagging, numbering and colour coding which can effectively increase the fire fighting ability of the fire department can be undertaken.

Bacterial species and variation in the biofilm of water distribution system in Harbin city

A model pipeline which dynamically simulates the drinking water distribution system was designed and kept running for twelve months with the tap water from Harbin. Biofilm was taken from its inner surface to isolate and identify the bacteria. Some biofilm was also taken from a real pipeline in Harbin. The results of microbiological analysis showed that there were similar dominant species both in the model and real pipeline, implying that those dominant species could grow well and form the biofilm easily under the same water quality and the same operating situation. The species vary with the length of the test period and reach a balance stage after a long test period. Some biofilm was analyzed by a scanning electron microscope for the further study of the bacterial growth. The SEM results confirmed that most of the bacterial growth on the inner surface of the pipeline were cocci and bacilli. In addition, the polymerase chain reaction (PCR) and agarose gel eletrophoresis were used to detect Pseudomonas aeruginosa . Biofilm samples from the model pipeline and the real distribution pipeline were analyzed by PCR. The PCR result showed that there was no Pseudomonas aeruginosa in both of the pipelines.