scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Stochastic approach for performance evaluation regarding water distribution systems

2007 ◽  
Vol 56 (9) ◽  
pp. 29-36 ◽  
Author(s):  
M. Möderl ◽  
T. Fetz ◽  
W. Rauch
Keyword(s):  
Performance Evaluation ◽  
Case Studies ◽  
Distribution Systems ◽  
Water Distribution ◽  
Performance Indicator ◽  
Water Distribution Systems ◽  
Stochastic Approach ◽  
Cumulative Distribution ◽  
Design System ◽  
The Impact

A traditional procedure for performance evaluation of systems is to test approaches on one or more case studies. However, it is well known that the investigation of real case studies is a tedious task. Moreover, due to the limited amount of case studies available it is not certain that all aspects of a problem can be covered in such procedure. With increasing computer power an alternative methodology has emerged, that is the investigation of a multitude of virtual case studies by means of a stochastic consideration of the overall performance. Within the frame of this approach we develop here a modular design system (MDS) for water distribution systems (WDSs). With the algorithmic application of such a MDS it is possible to create a variety of different WDSs. As an example of stochastic performance evaluation the impact of pipe breakages on WDSs is estimated applying a pressure driven performance indicator. This performance indicator is evaluated stochastically. Likewise the performance evaluation of a variety of WDSs is also performed stochastically. Cumulative distribution function, histogram and other statistical properties of 2,280×1,000 performance results of the different WDSs are calculated to highlight the applicability of the introduced stochastic approach.

scholarly journals Development and identification of a multi-species water quality model for reclaimed water distribution systems

2015 ◽  
Vol 5 (3) ◽  
pp. 360-371
Author(s):  
Shun Li ◽  
Fu Sun ◽  
Siyu Zeng ◽  
Xin Dong ◽  
Pengfei Du
Keyword(s):  
Water Quality ◽  
Distribution Systems ◽  
Water Distribution ◽  
Reclaimed Water ◽  
Water Distribution Systems ◽  
Water Quality Model ◽  
Bulk Liquid ◽  
Model Parameters ◽  
Quality Model ◽  
Long Distance

With the rapid development of a centralized wastewater reuse scheme in China, water quality concerns arise considering the long-distance transport of reclaimed water in distribution systems from wastewater treatment plants to points of use. To this end, a multi-species water quality model for reclaimed water distribution systems (RWDSs) was developed and validated against the data from part of a full-scale RWDS in Beijing. The model could simulate organics, ammonia nitrogen, residual chlorine, inert particles, and six microbial species, i.e. fecal coliforms, Enterococcus spp., Salmonella spp., Mycobacterium spp., and other heterotrophic and autotrophic bacteria, in both the bulk liquid and the biofilm. Altogether, 56 reaction processes were involved, and 37 model parameters and seven initial values were identified. Despite the limited monitoring data and the associated gross uncertainty, the model could simulate the reclaimed water quality in the RWDS with acceptable accuracy. Regional sensitivity analysis suggested that the model had a balanced structure with a large proportion of sensitive parameters, and the sensitivity of model parameters could be reasonably interpreted by current knowledge or observation. Furthermore, the most sensitive model parameters could generally be well identified with uncertainties significantly reduced, which also favored the trustworthiness of the model. Finally, future plans to improve and apply the model were also discussed.

Regulation response of pilot operated diaphragm pressure reducing valves: laboratory testing and impact on the performance of pressure control modes in water distribution systems

2021 ◽  
Author(s):  
Mouna Doghri ◽  
Sophie Duchesne ◽  
Annie Poulin ◽  
J.-P. Villeneuve
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Pressure Control ◽  
Quebec City ◽  
Real Time Control ◽  
Hydraulic Simulation ◽  
Pressure Setting ◽  
Time Control ◽  
The Impact

Pressure control is recognized as an efficient measure to reduce leaks from water distribution systems. The effectiveness of various pressure control modes, by means of pilot operated diaphragm pressure reducing valves (PRVs), is evaluated in this paper taking into account the sensitivity of the valve to various settings. First, the response of a PRV to consecutive pressure settings variations was experimentally evaluated in the hydraulic simulation laboratory of National Institute for Scientific Research (INRS). These experiments revealed that the studied valve reacts only when the pressure setting variation corresponds to at least 1/6 turn of the pilot valve. Second, a real case study from Quebec City, Canada, was simulated in order to evaluate the impact of the PRV response on three pressure control modes: fixed control, time based control, and real time control (RTC). The results show that RTC of pressure leads to leakage rate reduction on the studied network but that the PRV operational constraints limit the expected performance of RTC.

scholarly journals Pressure-driven modelling of water distribution systems

2003 ◽  
Vol 3 (1-2) ◽  
pp. 255-261 ◽  
Author(s):  
T. Tanyimboh ◽  
B. Tahar ◽  
A. Templeman
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Line Search ◽  
Water Distribution Systems ◽  
Operating Conditions ◽  
Governing Equations ◽  
Novel Method ◽  
Newton Raphson ◽  
Abnormal Operating Conditions ◽  
Demand Driven Analysis

This paper presents a novel method to model water distribution systems (WDS) with insufficient pressure. Methods for the prediction of the performance of a WDS with pressure deficiencies are reviewed. The influence of imposed relationships between nodal heads and outflows is assessed and numerical results are given. A Newton-Raphson technique plus line search is employed for solving the governing equations. It is demonstrated that the approach offers superior results for the hydraulic performance of networks under abnormal operating conditions compared to demand-driven analysis-based models.

scholarly journals Risk-based sensor placement methods for burst/leak detection in water distribution systems

2017 ◽  
Vol 17 (6) ◽  
pp. 1663-1672 ◽  
Author(s):  
E. Forconi ◽  
Z. Kapelan ◽  
M. Ferrante ◽  
H. Mahmoud ◽  
C. Capponi
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Social Economic ◽  
Water Distribution Systems ◽  
Water System ◽  
Water Distribution Network ◽  
Leak Detection ◽  
Optimal Placement ◽  
Water Volume ◽  
The Impact

Abstract The optimal placement of sensors for burst/leak detection in water distribution systems is usually formulated as an optimisation problem. In this study three different risk-based functions are used to drive optimal location of a given number of sensors in a water distribution network. A simple function based on likelihood of leak non-detection is compared with two other risk-based functions, where impact and exposure are combined with the leak detection likelihood. The impact is considered proportional to the demand water volume while the exposure is related to the importance of the connections and it is evaluated in social, economic or safety terms. The methods are applied to a district metered area of the Harrogate network by means of a modified EPANET model, to take into account the pressure-driven functioning conditions of the system. The results show that the exposure can lead to a different sensor location ranking with respect to other criteria used and hence the proposed methodology can represent a useful tool for water system managers to distribute the sensors in the network, complying with hydraulic, social and economical requirements.

A New Energy Optimization Strategy for Pumping Operation in Water Distribution Systems

2012 ◽  
Author(s):  
Dhafar Al-Ani ◽  
Saeid Habibi
Keyword(s):  
Distribution System ◽  
Energy Cost ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Energy Optimization ◽  
Operating Conditions ◽  
Optimization Strategy ◽  
Multi Objective

As time goes on, more and more operating-modes based on changing demand profiles will be compiled to enrich the range of feasible solutions for a water distribution system. This implies the conservation of energy consumed by a water pumping station and improves the ability for energy optimization. Another important goal was improving safety, reliability, and maintenance cost. In this paper, three important goals were addressed: cost-effectives, safety, and self-sustainability operations of water distribution systems. In this work, the objective functions to optimize were total electrical energy cost, maintenance costs, and reservoir water level variation while preserving the service provided to water clients. To accomplish these goals, an effective Energy Optimization Strategy (EOS) that manages trade-off among operational cost, system safety, and reliability was proposed. Moreover, the EOS aims at improving the operating conditions (i.e., pumping schedule) of an existing network system (i.e., with given capacities of tanks) and without physical changes in the infrastructure of the distribution systems. The new strategy consisted of a new Parallel Multi-objective Particle Swarm optimization with Adaptive Search-space Boundaries (P-MOPSO-ASB) and a modified EPANET. This has several advantages: obtaining a Pareto-front with solutions that are quantitatively equally good and providing the decision maker with the opportunity to qualitatively compare the solutions before their implementation into practice. The multi-objective optimization approach developed in this paper follows modern applications that combine an optimization algorithm with a network simulation model by using full hydraulic simulations and distributed demand models. The proposed EOS was successfully applied to a rural water distribution system, namely Saskatoon West. The results showed that a potential for considerable cost reductions in total energy cost was achieved (approximately % 7.5). Furthermore, the safety and the reliability of the system are preserved by using the new optimal pump schedules.

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