Assimilable Organic Carbon Concentrations and Bacterial Numbers in a Water Distribution System

1993 ◽  
Vol 27 (3-4) ◽  
pp. 159-166 ◽  
Author(s):  
R. A. Gibbs ◽  
J. E. Scutt ◽  
B. T. Croll
Keyword(s):  
Seasonal Variation ◽  
Organic Carbon ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Seasonal Pattern ◽  
Agar Plate ◽  
Plate Count ◽  
Spatial And Seasonal Variation ◽  
Plate Counts

A three year study was conducted to investigate bacterial growth in a drinking water distribution system in the UK. Bacterial numbers were estimated using Yeast Extract Agar plate counts. Plate counts in the distribution system showed patterns of spatial and seasonal variation. The spatial pattern was that plate counts increased through the distribution system until approximately 30 to 40 hours retention time and remained constant further through the distribution system. The seasonal pattern was that plate counts were low in the winter and had large peaks in the summer and autumn. Assimi able organic carbon (AOC) concentrations were measured in the second and third years of the study using an adenosine triphosphate (ATP) assay. There appeared to be no relationship tietween AOC concentrations and the spatial and seasonal variation in plate counts. The lack of correlation may have been caused by a lack of sensitivity in the AOC technique. Another explanation is that the increase in plate counts through the distribution system was due to an increase in the culturability of bacteria on plate count media, rather than an increase in bacterial numbers. Bacteria may not have grown through the distribution system and therefore not utilised the AOC.

Real-time ArcGIS and heterotrophic plate count based chloramine disinfectant control in water distribution system

2015 ◽  
Vol 68 ◽  
pp. 812-820 ◽  
Author(s):  
Xiaohui Bai ◽  
Xinghua Zhi ◽  
Huifeng Zhu ◽  
Mingqun Meng ◽  
Mingde Zhang
Keyword(s):  
Real Time ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Plate Count ◽  
Heterotrophic Plate Count

Characterization of Non-Enteric Bacterial Regrowth in the Water Supply Distribution Network from a Eutrophic Reservoir

1989 ◽  
Vol 21 (3) ◽  
pp. 49-53 ◽  
Author(s):  
R. A. Gibbs ◽  
C. R. Hayes
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Pathogenic Bacteria ◽  
Seasonal Pattern ◽  
Distribution Network ◽  
Water Distribution Network ◽  
Bacterial Regrowth ◽  
Organic Carbon Concentration ◽  
Plate Counts ◽  
Heterotrophic Plate Counts

An area of a distribution network receiving organically rich treated water was studied for a period of one year to gain further understanding of the regrowth of bacteria in a water distribution network. These bacteria are considered to be harmless to man. Surveys additional to this study confirmed that enteroviruses and pathogenic bacteria (as defined by EC directives) were absent, consistent with the general absence of coliforms. Fixed points were sampled regularly for bacteriological analysis and for relevant physical and chemical parameters. Heterotrophic plate counts were carried out using standard methods and a study was conducted to test alternative techniques. It was found that bacterial regrowth occurred close to the treatment works and longer retention resulted in little increase in plate counts. Monochloramine residuals of 0.26mg/l or less did not prevent regrowth. The assimilable organic carbon concentration decreased through the distribution system and increased following booster chlorination. Plate counts showed a seasonal pattern peaking in the spring and autumn and decreasing in the summer and winter. The predominant genera of bacteria were Pseudomonas, Alcaligenes and Aeromonas with maximum counts of 17,000, 23,000 and 1,700 CFU/ml respectively. Heterotrophic plate counts using the R2A medium, spread plate method and 7 day incubation period were on average 190 times greater than counts using the UK standard method. The increase in count gained by using the alternative method was greatest at the sampling points furthest from the treatment works.

scholarly journals Influence of seasonal variation on water quality in tropical water distribution system: is the disease burden significant?

2014 ◽  
Vol 49 ◽  
pp. 186-196 ◽  
Author(s):  
Ayotunde T. Etchie ◽  
Tunde O. Etchie ◽  
Gregory O. Adewuyi ◽  
Krishnamurthi Kannan ◽  
Satish R. Wate ◽  
...  
Keyword(s):  
Water Quality ◽  
Seasonal Variation ◽  
Distribution System ◽  
Disease Burden ◽  
Water Distribution ◽  
Water Distribution System ◽  
Tropical Water

Investigation into biofilms in a local drinking water distribution system

Biofilms ◽  
2005 ◽  
Vol 2 (1) ◽  
pp. 19-25 ◽  
Author(s):  
J. Y. Hu ◽  
B. Yu ◽  
Y. Y. Feng ◽  
X. L. Tan ◽  
S. L. Ong ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Plate Count ◽  
Residual Chlorine ◽  
Biofilm Growth ◽  
Water Plant ◽  
Biofilm Development

Biofilm growth within a water distribution system could lead to operational problems such as pipe corrosion, water quality deterioration and other undesirable impacts in water distribution systems. With the high ambient temperatures experienced in Singapore, the operating environment in water distribution systems is expected to be more conducive to biofilm development. We have recently conducted a survey on biofilms potentially present in a local water distribution system.The survey results indicated that residual chlorine (±standard deviation) decreased from 1.49±0.61 mg/l (water plant outlets) to 0.82±0.21 mg/l (block pipes) or 0.18±0.06 mg/l (unit pipes), respectively. Consumed chlorine, instead of residual chlorine, was found to be correlated with biofilm bacterial population. Assimilable organic carbon (AOC) level was 160±66 μg acetate C/l, and AOC:PO4-P:NO3-N was about 8:13:1. Carbon source seemed to be the limiting nutrient for bacterial growth. The concentration of iron increased from <0.04 mg/l (water plant outlets) to 0.22±0.10 mg/l (all sites). All samples showed negative results in a coliform test. The average heterotrophic plate count (HPC) for the suspended bacteria was 20 colony-forming units (c.f.u.)/ml (2 days, 35 °C) or 290 c.f.u./ml (8 days, 35 °C). The average HPC for the biofilm bacteria was 6500 c.f.u./cm2 (2 days, 35 °C) or 29000 c.f.u./cm2 (8 days, 35 °C). High HPC values in samples B2a, B2b and B3a (representing biofilm samples at site 2 from block/unit pipes and biofilm samples at site 3 from block pipes, respectively) illustrated that the relevant sample sites had a higher probaboility of biofilm growth.

scholarly journals Identification of Bacteria in Biofilm and Bulk Water Samples from a Nonchlorinated Model Drinking Water Distribution System: Detection of a Large Nitrite-Oxidizing Population Associated with Nitrospira spp

2005 ◽  
Vol 71 (12) ◽  
pp. 8611-8617 ◽  
Author(s):  
Adam C. Martiny ◽  
Hans-Jørgen Albrechtsen ◽  
Erik Arvin ◽  
Søren Molin
Keyword(s):  
Drinking Water ◽  
Organic Carbon ◽  
Water Samples ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Bulk Water ◽  
Drinking Water Distribution System ◽  
Assimilable Organic Carbon ◽  
Drinking Water Distribution

ABSTRACT In a model drinking water distribution system characterized by a low assimilable organic carbon content (<10 μg/liter) and no disinfection, the bacterial community was identified by a phylogenetic analysis of rRNA genes amplified from directly extracted DNA and colonies formed on R2A plates. Biofilms of defined periods of age (14 days to 3 years) and bulk water samples were investigated. Culturable bacteria were associated with Proteobacteria and Bacteriodetes, whereas independently of cultivation, bacteria from 12 phyla were detected in this system. These included Acidobacteria, Nitrospirae, Planctomycetes, and Verrucomicrobia, some of which have never been identified in drinking water previously. A cluster analysis of the population profiles from the individual samples divided biofilms and bulk water samples into separate clusters (P = 0.027). Bacteria associated with Nitrospira moscoviensis were found in all samples and encompassed 39% of the sequenced clones in the bulk water and 25% of the biofilm community. The close association with Nitrospira suggested that a large part of the population had an autotrophic metabolism using nitrite as an electron donor. To test this hypothesis, nitrite was added to biofilm and bulk water samples, and the utilization was monitored during 15 days. A first-order decrease in nitrite concentration was observed for all samples with a rate corresponding to 0.5 × 105 to 2 × 105 nitrifying cells/ml in the bulk water and 3 × 105 cells/cm2 on the pipe surface. The finding of an abundant nitrite-oxidizing microbial population suggests that nitrite is an important substrate in this system, potentially as a result of the low assimilable organic carbon concentration. This finding implies that microbial communities in water distribution systems may control against elevated nitrite concentrations but also contain large indigenous populations that are capable of assisting the depletion of disinfection agents like chloramines.

Affect of Assimilable Organic Carbon (AOC) and Phosphorus to Heterotrophic Microbial Growth in Drinking Water Distribution System

2011 ◽  
Vol 383-390 ◽  
pp. 4031-4037
Author(s):  
Deng Ling Jiang ◽  
Guo Wei Ni ◽  
Yan Hua Chen ◽  
Qing Jie Zhu
Keyword(s):  
Drinking Water ◽  
Organic Carbon ◽  
Distribution System ◽  
Water Distribution ◽  
Microbial Growth ◽  
Water Distribution System ◽  
Drinking Water Distribution System ◽  
Assimilable Organic Carbon ◽  
Drinking Water Distribution ◽  
Growth Of Bacteria

The content of assimilable organic carbon (AOC) has been proposed to control the growth of heterotrophic microbe in drinking water distribution systme. However, recent results have shown that there are regions where it is predominantly phosphorus which determines the extent of microbial growth in drinking water. The growth of bacteria was studied in a drinking water distribution system where the content of AOC was high (40.84- 551.35 μg acetate-C/L) and the content of Microbially Available Phosphorus (MAP) was also high (0.69-8.01 μg PO43--P/L). It was AOC other than phosphorus that controlled the growth of bacteria in the drinking water distribution system. Comparably obvious linear relationship was found between the maximum HPC and the maximum content of AOC of the distribution system. Removal of organic matters is ideal approach to control water quality of the drinking water distribution system.

Study on the Characteristics of Biodegradable Dissolved Organic Carbon and Bacteria Regrowth in Drinking Water Distribution-System of a Chinese City

2011 ◽  
Vol 243-249 ◽  
pp. 4839-4845
Author(s):  
Jian Wei Ma ◽  
Jun Liang Liu ◽  
Xin Li
Keyword(s):  
Drinking Water ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Front Part ◽  
Biodegradable Dissolved Organic Carbon ◽  
Total Bacteria ◽  
Back Part

Many researchers pay their attentions to the biostability of drinking water more and more. Biodegradable dissolved organic carbon can provide a good indicator for biostability of drinking water in distribution-system. The main objective of this study was to research the regulations of concentration changes of biodegradable dissolved organic carbon and the populations of the total bacteria in water distribution-system of a city in china. The field experiments showed that the values of biodegradable dissolved organic carbon decreased along the main pipes in the water distribution-system, and the rate of the decrease was lower in the front part of the two main pipes than in the back part. At the same time, the populations of the total bacteria increased in the front part of the NO.1 main pipe and decreased in the back part. Our research provided the theoretical foundation for limiting the bacteria regrowth and to ensure the biostability of drinking water.

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