scholarly journals Interactions of Cryptosporidium parvum, Giardia lamblia, Vaccinal Poliovirus Type 1, and Bacteriophages φX174 and MS2 with a Drinking Water Biofilm and a Wastewater Biofilm

2008 ◽  
Vol 74 (7) ◽  
pp. 2079-2088 ◽  
Author(s):  
Karim Helmi ◽  
Sylvain Skraber ◽  
Christophe Gantzer ◽  
Raphaël Willame ◽  
Lucien Hoffmann ◽  
...  
Keyword(s):  
Drinking Water ◽  
Cryptosporidium Parvum ◽  
Giardia Lamblia ◽  
Viral Genome ◽  
Water Distribution ◽  
Distribution Networks ◽  
Protozoan Parasites ◽  
Poliovirus Type ◽  
Wide Range

ABSTRACT Biofilms colonizing surfaces inside drinking water distribution networks may provide a habitat and shelter to pathogenic viruses and parasites. If released from biofilms, these pathogens may disseminate in the water distribution system and cause waterborne diseases. Our study aimed to investigate the interactions of protozoan parasites (Cryptosporidium parvum and Giardia lamblia [oo]cysts) and viruses (vaccinal poliovirus type 1, φX174, and MS2) with two contrasting biofilms. First, attachment, persistence, and detachment of the protozoan parasites and the viruses were assessed with a drinking water biofilm. This biofilm was allowed to develop inside a rotating annular reactor fed with tap water for 7 months prior to the inoculation. Our results show that viable parasites and infectious viruses attached to the drinking water biofilm within 1 h and persisted within the biofilm. Indeed, infectious viruses were detected in the drinking water biofilm up to 6 days after the inoculation, while viral genome and viable parasites were still detected at day 34, corresponding to the last day of the monitoring period. Since viral genome was detected much longer than infectious particles, our results raise the question of the significance of detecting viral genomes in biofilms. A transfer of viable parasites and viruses from the biofilm to the water phase was observed after the flow velocity was increased but also with a constant laminar flow rate. Similar results regarding parasite and virus attachment and detachment were obtained using a treated wastewater biofilm, suggesting that our observations might be extrapolated to a wide range of environmental biofilms and confirming that biofilms can be considered a potential secondary source of contamination.

Improving water age estimation in a drinking water distribution network by field study and digital modeling

2021 ◽  
Author(s):  
Jon Kristian Rakstang ◽  
Michael B. Waak ◽  
Marius M. Rokstad ◽  
Cynthia Hallé
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Network Model ◽  
Age Estimation ◽  
Water Distribution ◽  
Distribution Network ◽  
Distribution Networks ◽  
Plate Count ◽  
Water Age ◽  
Drinking Water Distribution

<p>Municipal drinking water distribution networks are complex and dynamic systems often spanning many hundreds of kilometers and serving thousands of consumers. Degradation of water quality within a distribution network can be associated to water age (i.e., time elapsed after treatment). Norwegian distribution networks often consist of an intricate combination of pressure zones, in which the transport path(s) between source and consumer is not easily ascertained. Water age is therefore poorly understood in many Norwegian distribution networks. In this study, simulations obtained from a water network model were used to estimate water age in a Norwegian municipal distribution network. A full-scale tracer study using sodium chloride salt was conducted to assess simulation accuracy. Water conductivity provided empirical estimates of salt arrival time at five monitoring stations. These estimates were consistently higher than simulated peak arrival times. Nevertheless, empirical and simulated water age correlated well, indicating that additional network model calibration will improve accuracy. Subsequently, simulated mean water age also correlated strongly with heterotrophic plate count (HPC) monitoring data from the distribution network (Pearson’s R= 0.78, P= 0.00046), indicating biomass accumulation during distribution—perhaps due to bacterial growth or biofilm interactions—and illustrating the importance of water age for water quality. This study demonstrates that Norwegian network models can be calibrated with simple and cost-effective salt tracer studies to improve water age estimates. Improved water age estimation will increase our understanding of water quality dynamics in distribution networks. This can, through digital tools, be used to monitor and control water age, and its impact on biogrowth in the network.</p>

scholarly journals Technical note: Problem specific variators in a genetic algorithm for the optimization of drinking water networks

2018 ◽  
Author(s):  
Karel van Laarhoven ◽  
Ina Vertommen ◽  
Peter van Thienen
Keyword(s):  
Drinking Water ◽  
Real World ◽  
Water Distribution ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Technical Note ◽  
Practical Implementation ◽  
Utility Level ◽  
Water Utility ◽  
Drinking Water Distribution

Abstract. Genetic algorithms can be a powerful tool for the automated design of optimal drinking water distribution networks. Fast convergence of such algorithms is a crucial factor for successful practical implementation at the drinking water utility level. In this technical note, we therefore investigate the performance of a suite of genetic variators that was tailored to the optimisation of a least-cost network design. Different combinations of the variators are tested in terms of convergence rate and the robustness of the results during optimisation of the real world drinking water distribution network of Sittard, the Netherlands. The variator configurations that reproducibly reach the furthest convergence after 105 function evaluations are reported. In the future these may aid in dealing with the computational challenges of optimizing real world networks.

An Outbreak of Giardiasis and Amoebiasis at a Ski Resort in Sweden

1989 ◽  
Vol 21 (3) ◽  
pp. 143-146 ◽  
Author(s):  
Y. Andersson ◽  
B. de Jong
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Giardia Lamblia ◽  
Water Distribution ◽  
Water Reservoir ◽  
Polluted Water ◽  
Double Infection ◽  
Ski Resort ◽  
The North ◽  
Drinking Water Reservoir

A large number of tourists contracted gastroenteritis at the end of December 1986 at a ski resort in the north of Sweden. The outbreak was due to the intrusion of sewage in the drinking water reservoir through a spillway overflow connected to the sewer. Sewage polluted the drinking water. One to three days after drinking the polluted water, at least 3,600 persons of 4,000 at risk contracted gastroenteritis. The attack rate was 90%. Giardia lamblia was isolated from 1,480 persons and Entamoeba histolytica from 106. At least 50 persons contracted a double infection with G. lamblia and E. histolytica. G. lamblia cysts were isolated from two points in the water distribution system.

scholarly journals Hydraulic Model Calibration and Performance Assessment of Pressure Managed Areas with Multiple Inlets

2020 ◽  
Author(s):  
Attila Bibok ◽  
Roland Fülöp
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Model Calibration ◽  
Water Distribution ◽  
Real Life ◽  
Distribution Networks ◽  
General Purpose ◽  
Pressure Management ◽  
Pressure Setting ◽  
Drinking Water Distribution

Pressure management is a widely adopted technique in the toolset of drinking water distribution system operators. It has multiple benefits, like reducing physical losses in pipe networks with excessive leakage, prolong the expected lifetime of the pipes and protecting home appliances from unacceptably high pressure. In some cases, even legislation compliance can be the motivation behind pressure management: It is mandatory to supply water at the customer’s connection between 1.5 and 6.0 bar in Hungary since 2011. Diaphragm pressure reducing valves are widespread in the drinking water distribution networks. Although, their sensitivity for gas pocket accumulation in the valve house makes hydraulic calibration of these pressure managed areas a challenging task for hydraulic modelers and network operators. This is especially true when more than one inlet is used to supply the same area in order to increase resilience and flow capacity.This paper investigates the hydraulic properties of pressure reduced areas with multiple inlet points. Model calibration using a single valve and minor loss was found insufficient because the additional pressure loss referenced to the pressure setting has a non-quadratic relationship with flow-rate on the discharge side under real-life circumstances. This phenomenon can be handled by using a PRV (pressure reducing valve) + GPV (general purpose valve) in series.

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