scholarly journals Trihalomethanes formation in Iranian water supply systems: predicting and modeling

2015 ◽  
Vol 13 (3) ◽  
pp. 859-869 ◽  
Author(s):  
Ali Akbar Babaei ◽  
Leila Atari ◽  
Mehdi Ahmadi ◽  
Kambiz Ahmadiangali ◽  
Mirzaman Zamanzadeh ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Temperature ◽  
Distribution Systems ◽  
Water Distribution ◽  
Pearson Correlation ◽  
Multiple Linear Regression Model ◽  
Residual Chlorine ◽  
Water Supply Systems ◽  
Drinking Water Distribution Systems ◽  
Bromide Ion

Trihalomethanes (THMs) were the first disinfection by-products discovered in drinking water and are classified as probable carcinogens. This study measures and models THMs formation at two drinking water distribution systems (WDS1 and WDS2) in Ahvaz City, Iran. The investigation was based on field-scale investigations and an intensive 36-week sampling program, from January to September 2011. The results showed total THM concentrations in the range 17.4–174.8 μg/L and 18.9–99.5 μg/L in WDS1 and WDS2, respectively. Except in a few cases, the THM concentrations in WDS1 and WDS2 were lower than the maximum contaminant level values. Using two-tailed Pearson correlation test, the water temperature, dissolved organic carbon, UV254, bromide ion (Br−), free residual chlorine, and chlorine dose were identified as the significant parameters for THMs formation in WDS2. Water temperature was the only significant parameter for THMs formation in WDS1. Based on the correlation results, a predictive model for THMs formation was developed using a multiple regression approach. A multiple linear regression model showed the best fit according to the coefficients of determination (R2) obtained for WDS1 (R2 = 0.47) and WDS2 (R2 = 0.54). Further correlation studies and analysis focusing on THMs formation are necessary to assess THMs concentration using the predictive models.

scholarly journals Dynamics of Biofilm Regrowth in Drinking Water Distribution Systems

2016 ◽  
Vol 82 (14) ◽  
pp. 4155-4168 ◽  
Author(s):  
I. Douterelo ◽  
S. Husband ◽  
V. Loza ◽  
J. Boxall
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Influential Factors ◽  
Residual Chlorine ◽  
Water Supply Systems ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Biofilm Development

ABSTRACTThe majority of biomass within water distribution systems is in the form of attached biofilm. This is known to be central to drinking water quality degradation following treatment, yet little understanding of the dynamics of these highly heterogeneous communities exists. This paper presents original information on such dynamics, with findings demonstrating patterns of material accumulation, seasonality, and influential factors. Rigorous flushing operations repeated over a 1-year period on an operational chlorinated system in the United Kingdom are presented here. Intensive monitoring and sampling were undertaken, including time-series turbidity and detailed microbial analysis using 16S rRNA Illumina MiSeq sequencing. The results show that bacterial dynamics were influenced by differences in the supplied water and by the material remaining attached to the pipe wall following flushing. Turbidity, metals, and phosphate were the main factors correlated with the distribution of bacteria in the samples. Coupled with the lack of inhibition of biofilm development due to residual chlorine, this suggests that limiting inorganic nutrients, rather than organic carbon, might be a viable component in treatment strategies to manage biofilms. The research also showed that repeat flushing exerted beneficial selective pressure, giving another reason for flushing being a viable advantageous biofilm management option. This work advances our understanding of microbiological processes in drinking water distribution systems and helps inform strategies to optimize asset performance.IMPORTANCEThis research provides novel information regarding the dynamics of biofilm formation in real drinking water distribution systems made of different materials. This new knowledge on microbiological process in water supply systems can be used to optimize the performance of the distribution network and to guarantee safe and good-quality drinking water to consumers.

The Laboratory Study of Drinking Water Biofilms

2014 ◽  
Vol 535 ◽  
pp. 455-459
Author(s):  
Jing Guo Zhao ◽  
Yu Long Yang ◽  
Cong Li
Keyword(s):  
Drinking Water ◽  
Water Temperature ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Future Research ◽  
Pipe Material ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Key Aspects

Due to the existence of some kinds of minim organic matters in drinking water distribution systems, biofilms are commonly found on the inner walls of pipe networks, and it can contribute to the deterioration to water quality and influence water supply security. The current situations of the study of the biofilm are summarized. Two typical kinds of reactors often used in laboratories are stated. And numerous environmental factors influencing biofilm formation, including hydraulic condition, water temperature, pipe material, water temperature, disinfectant residuals and nutrient element, are reviewed. Furthermore, some key aspects for future research to control the development of biofilms are proposed. Keywords: drinking water distribution system; biofilm; simulation system; disinfectant residual

scholarly journals Spatial diversity of chlorine residual in a drinking water distribution system: application of an integrated fuzzy logic technique

2014 ◽  
Vol 17 (2) ◽  
pp. 293-306 ◽  
Author(s):  
Donatella Termini ◽  
Gaspare Viviani
Keyword(s):  
Water Quality ◽  
Fuzzy Logic ◽  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Residual Chlorine ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Fuzzy Logic Technique

A reduction in the concentration of chlorine, which is used as a chemical disinfectant for water in drinking water distribution systems, can be considered to be an index of the progressive deterioration of water quality. In this work, attention is given to the spatial distribution of the residual chlorine in drinking water distribution systems. The criterion for grouping the water-quality parameters normally used is highly subjective and often based on data that are not correctly identified. In this paper, a cluster analysis based on fuzzy logic is applied. The advantage of the proposed procedure is that it allows a user to identify (in an automatic way and without any specific assumption) the zonation of the network and easily calibrate the unknown parameters. An analysis of the correlation between the sampling sites for the residual chlorine has been used to assess the applicability of the procedure.

scholarly journals Unchartered waters: the unintended impacts of residual chlorine on water quality and biofilms

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Katherine E. Fish ◽  
Nik Reeves-McLaren ◽  
Stewart Husband ◽  
Joby Boxall
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Internal Surface ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Water Safety ◽  
Internal Surface Area ◽  
Drinking Water Distribution Systems

Abstract Disinfection residuals in drinking water protect water quality and public heath by limiting planktonic microbial regrowth during distribution. However, we do not consider the consequences and selective pressures of such residuals on the ubiquitous biofilms that persist on the vast internal surface area of drinking water distribution systems. Using a full scale experimental facility, integrated analyses were applied to determine the physical, chemical and biological impacts of different free chlorine regimes on biofilm characteristics (composition, structure and microbiome) and water quality. Unexpectedly, higher free chlorine concentrations resulted in greater water quality degredation, observable as elevated inorganic loading and greater discolouration (a major cause of water quality complaints and a mask for other failures). High-chlorine concentrations also reduced biofilm cell concentrations but selected for a distinct biofilm bacterial community and inorganic composition, presenting unique risks. The results challenge the assumption that a measurable free chlorine residual necessarily assures drinking water safety.

scholarly journals Non-invasive Biofouling Monitoring to Assess Drinking Water Distribution System Performance

2021 ◽  
Vol 12 ◽  
Author(s):  
Frances C. Pick ◽  
Katherine E. Fish ◽  
Stewart Husband ◽  
Joby B. Boxall
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Bulk Water ◽  
Water Supply Systems ◽  
Customer Contact ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Contact Data

Biofilms are endemic in drinking water distribution systems (DWDS), forming on all water and infrastructure interfaces. They can pose risks to water quality and hence consumers. Our understanding of these biofilms is limited, in a large part due to difficulties in sampling them without unacceptable disruption. A novel, non-destructive and non-disruptive biofilm monitoring device (BMD), which includes use of flow cytometry analysis, was developed to assess biofouling rates. Laboratory based experiments established optimal configurations and verified reliable cell enumeration. Deployment at three operational field sites validated assessment of different biofouling rates. These differences in fouling rates were not obvious from bulk water sampling and analysis, but did have a strong correlation with long-term performance data of the associated networks. The device offers the potential to assess DWDS performance in a few months, compared to the number of years required to infer findings from historical customer contact data. Such information is vital to improve the management of our vast, complex and uncertain drinking water supply systems; for example rapidly quantifying the benefits of improvements in water treatment works or changes to maintenance of the network.

scholarly journals Effect of sodium hypochlorite on typical biofilms formed in drinking water distribution systems

2017 ◽  
Vol 15 (2) ◽  
pp. 218-227 ◽  
Author(s):  
Huirong Lin ◽  
Xuan Zhu ◽  
Yuxin Wang ◽  
Xin Yu
Keyword(s):  
Drinking Water ◽  
Sodium Hypochlorite ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Drinking Water Treatment ◽  
Cellular Damage ◽  
Residual Chlorine ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution

Human health and biological safety problems resulting from urban drinking water pipe network biofilms pollution have attracted wide concern. Despite the inclusion of residual chlorine in drinking water distribution systems supplies, the bacterium is a recalcitrant human pathogen capable of forming biofilms on pipe walls and causing health risks. Typical drinking water bacterial biofilms and their response to different concentrations of chlorination was monitored. The results showed that the four bacteria all formed single biofilms susceptible to sodium hypochlorite. After 30 min disinfection, biomass and cultivability decreased with increasing concentration of disinfectant but then increased in high disinfectant doses. PMA-qPCR results indicated that it resulted in little cellular damage. Flow cytometry analysis showed that with increasing doses of disinfectant, the numbers of clusters increased and the sizes of clusters decreased. Under high disinfectant treatment, EPS was depleted by disinfectant and about 0.5–1 mg/L of residual chlorine seemed to be appropriate for drinking water treatment. This research provides an insight into the EPS protection to biofilms. Resistance of biofilms against high levels of chlorine has implications for the delivery of drinking water.

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