Modelling of Escherichia coli removal by a low-cost combined drinking water treatment system

Water Science & Technology Water Supply ◽

10.2166/ws.2020.084 ◽

2020 ◽

Author(s):

Stephen Siwila ◽

Isobel C Brink

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Granular Media ◽

Colloidal Particles ◽

Water System ◽

Drinking Water Treatment ◽

Theoretical Modelling ◽

Critical Parameters ◽

Future Research ◽

Bacterial Inactivation

Abstract This work presents mathematical modelling of Escherichia coli (E.coli) removal by a multi-barrier point-of-use drinking water system. The modelled system is a combination of three treatment stages: filtration by geotextile fabric followed by filtration and disinfection by silver-coated ceramic granular media (SCCGM) then granular activated carbon (GAC) filtration. The presented models accounted for removal mechanisms by each treatment stage. E.coli was modelled as a microbial particle. E.coli inactivation by SCCGM was modelled using the Chick's, Chick-Watson, Collins-Selleck and complete mix system bacterial inactivation kinetic models, which were considered adequately representative for describing the removal. Geotextile removal was modelled using colloidal filtration theory (CFT) for hydrosol deposition in fibrous media. The filtration removal contributions by the SCCGM and GAC were modelled using CFT for removal of colloidal particles by granular media. The model results showed that inactivation by silver in the SCCGM was the main bacterial removal mechanism. Geotextile and GAC also depicted appreciable removals. The theoretical modelling approach used is important for design and optimization of the multi-barrier system and can support future research in terms of material combinations, system costs, etc. Collector diameter, particle size, filtration velocity and contact time were identified as critical parameters for E.coli removal efficiency.

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A novel low-cost multi-barrier system for drinking water treatment in rural and suburban areas

Water Practice & Technology ◽

10.2166/wpt.2019.083 ◽

2019 ◽

Vol 15 (1) ◽

pp. 48-65 ◽

Cited By ~ 1

Author(s):

Stephen Siwila ◽

Isobel C. Brink

Keyword(s):

Drinking Water ◽

Water Treatment ◽

Granular Media ◽

Low Cost ◽

Water System ◽

Drinking Water Treatment ◽

Fecal Coliforms ◽

E Coli ◽

Suburban Areas ◽

Novel Concept

Abstract A low-cost multi-barrier drinking water system incorporating geotextile fabric for pre-filtration, silver-coated ceramic granular media (SCCGM) for filtration and disinfection, granular activated carbon (GAC) as an adsorption media and a safe storage compartment for treated water has been developed and tested. The developed system offers a novel concept of point-of-use drinking water treatment in rural and suburban areas of developing countries. The system is primarily aimed at bacterial and aesthetic improvement and has been optimised to produce >99.99% E. coli and fecal coliforms removal. Although particular emphasis was placed on the elimination of bacteria, improvement of the acceptability aspects of water was also given high priority so that users are not motivated to use more appealing but potentially unsafe sources. This paper discusses key system features and contaminant removal performance. A system using SCCGM only was also tested alongside the multi-barrier system. Strengths and weaknesses of the system are also presented. Both the developed and SCCGM-only systems consistently provided >99.99% E. coli and fecal coliforms removal at an optimum flow of 2 L/h. The developed system significantly recorded improvements of aesthetic aspects (turbidity, color, taste and odor). Average turbidity removals were 99.2% and 90.2% by the multi-barrier and SCCGM-only systems respectively.

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Research progress on the injury mechanism and detection method of disinfectant-injured Escherichia coli in the drinking water system

Journal of Water Supply Research and Technology—AQUA ◽

10.2166/aqua.2021.017 ◽

2021 ◽

Author(s):

Cui-min Feng ◽

Na Zhu ◽

Ji-yue Jin ◽

Ying Li ◽

Zhen Xu ◽

...

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Water System ◽

Damage Mechanism ◽

Water Disinfection ◽

Detection Methods ◽

Research Progress ◽

Future Research ◽

Drinking Water System ◽

Sublethal Injury

Abstract Sublethally injured bacteria can still develop into normal bacteria under favorable growth conditions, and their pathogenicity poses a great threat to human health. In the drinking water system, some bacteria cause sublethal injury under the action of disinfectants, that is, disinfectant-injured bacteria. Hence, the detection of disinfectant-injured bacteria and the elucidation of injury mechanisms are of great significance for ensuring the microbial safety of drinking water systems. This article takes the indicator bacteria Escherichia coli as the research object, reviews and summarizes the sublethal injury conditions, damage mechanism, and detection methods of disinfectant-injured bacteria in drinking water, and puts forward a prospect for the future research directions of drinking water disinfection and disinfectant-injured bacteria.

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Tangential-Flow Ultrafiltration with Integrated Inhibition Detection for Recovery of Surrogates and Human Pathogens from Large-Volume Source Water and Finished Drinking Water

Applied and Environmental Microbiology ◽

10.1128/aem.01164-10 ◽

2010 ◽

Vol 77 (1) ◽

pp. 385-391 ◽

Cited By ~ 48

Author(s):

Kristen E. Gibson ◽

Kellogg J. Schwab

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Drinking Water Treatment ◽

Source Water ◽

Murine Norovirus ◽

Human Pathogens ◽

Volume Source ◽

Tangential Flow ◽

Water Treatment Plants ◽

Human Enteric Viruses

ABSTRACTTangential-flow ultrafiltration was optimized for the recovery ofEscherichia coli,Enterococcus faecalis,Clostridium perfringensspores, bacteriophages MS2 and PRD1, murine norovirus, and poliovirus seeded into 100-liter surface water (SW) and drinking water (DW) samples. SW and DW collected from two drinking water treatment plants were then evaluated for human enteric viruses.

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Opportunistic pathogens and faecal indicators in drinking water associated biofilms in Cluj, Romania

Journal of Water and Health ◽

10.2166/wh.2012.148 ◽

2012 ◽

Vol 10 (3) ◽

pp. 471-483 ◽

Cited By ~ 15

Author(s):

A. Farkas ◽

M. Drăgan-Bularda ◽

D. Ciatarâş ◽

B. Bocoş ◽

Ş. Ţigan

Keyword(s):

Drinking Water ◽

Human Health ◽

Treatment Plant ◽

Water System ◽

Drinking Water Treatment ◽

Microbial Consortia ◽

Opportunistic Pathogens ◽

Water Safety ◽

Potential Threat ◽

Faecal Indicators

Biofouling occurs without exception in all water systems, with undesirable effects such as biocorrosion and deterioration of water quality. Drinking water associated biofilms represent a potential risk to human health by harbouring pathogenic or toxin-releasing microorganisms. This is the first study investigating the attached microbiota, with potential threat to human health, in a public water system in Romania. The presence and the seasonal variation of viable faecal indicators and opportunistic pathogens were investigated within naturally developed biofilms in a drinking water treatment plant. Bacterial frequencies were correlated with microbial loads in biofilms as well as with physical and chemical characteristics of biofilms and raw water. The biofilms assessed in the current study proved to be extremely active microbial consortia. High bacterial numbers were recovered by cultivation, including Pseudomonas aeruginosa, Escherichia coli, Aeromonas hydrophila, intestinal enterococci and Clostridium perfringens. There were no Legionella spp. detected in any biofilm sample. Emergence of opportunistic pathogens in biofilms was not significantly affected by the surface material, but by the treatment process. Implementation of a water safety plan encompassing measures to prevent microbial contamination and to control biofouling would be appropriate.

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Utilization of citrus microcarpa peels and papaya seeds as a natural coagulant for turbidity removal

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/920/1/012001 ◽

2021 ◽

Vol 920 (1) ◽

pp. 012001

Author(s):

Z Dollah ◽

N H Masbol ◽

A A Musir ◽

N A Karim ◽

D Hasan ◽

...

Keyword(s):

Drinking Water ◽

Colloidal Particles ◽

Mixing Time ◽

Drinking Water Treatment ◽

Optimal Dosage ◽

Turbidity Removal ◽

Natural Coagulant ◽

Fruit Waste ◽

Papaya Seeds ◽

Negative Impacts

Abstract Coagulation and flocculation are an essential component of both the treatment of drinking water and the treatment of wastewater. The coagulant is one of the materials or substances that is added to the water to remove, stabilizes and causes colloidal particles to settle. Chemical coagulants such as aluminum sulphate (alum), ferric chloride, and synthetic polymers are the most commonly used coagulants in the industry due to their efficacy in turbidity removal. However, the use of chemical-based coagulants has had some negative impacts on human health and the environment, such as Alzheimer’s disease, and has produced a high volume of toxic sludge. In order to reduce negative impacts, this led to the discovery of an alternative to the natural coagulant (plant-based) for drinking water treatment. The coagulant used in this study is a combination of fruit waste containing citrus microcarpa peels and papaya seed with a ratio of 80:20 and 40:60. In addition to determining the potential of the composite natural coagulant, the optimal dosage and the effect of the mixing duration are also studied in order to determine the best mixing duration for each stage of the coagulation-flocculation process. Laboratory-scale studies using jar test experiments were conducted on surface water to determine the percentage of turbidity removal. Fruit waste was collected from the UiTM Pulau Pinang cafeteria, dried in the oven for 24 hours at a temperature of 105°C. The optimum dosage of composite natural coagulant is 90 mg/L using an 80:20 ratio of citrus microcarpa peels and papaya seeds with 97% of turbidity removal. The optimum mixing time is determined where the fast mixing time is 180 rpm for 3 minutes, the slow mixing time is 20 minutes with 10 rpm and the settling time is 30 minutes. The study shows that citrus microcarpa peels and papaya seeds have the potential to become effective natural coagulants in the future.

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Potential Repair of Escherichia coli DNA following Exposure to UV Radiation from Both Medium- and Low-Pressure UV Sources Used in Drinking Water Treatment

Applied and Environmental Microbiology ◽

10.1128/aem.68.7.3293-3299.2002 ◽

2002 ◽

Vol 68 (7) ◽

pp. 3293-3299 ◽

Cited By ~ 138

Author(s):

J. L. Zimmer ◽

R. M. Slawson

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Water Treatment ◽

Uv Radiation ◽

Drinking Water Treatment ◽

Low Pressure ◽

Plate Count ◽

Treatment Technology ◽

Medium Pressure ◽

Uv Lamp

ABSTRACT The increased use of UV radiation as a drinking water treatment technology has instigated studies of the repair potential of microorganisms following treatment. This study challenged the repair potential of an optimally grown nonpathogenic laboratory strain of Escherichia coli after UV radiation from low- and medium-pressure lamps. Samples were irradiated with doses of 5, 8, and 10 mJ/cm2 from a low-pressure lamp and 3, 5, 8, and 10 mJ/cm2 from a medium-pressure UV lamp housed in a bench-scale collimated beam apparatus. Following irradiation, samples were incubated at 37°C under photoreactivating light or in the dark. Sample aliquots were analyzed for up to 4 h following incubation using a standard plate count. Results of this study showed that E. coli underwent photorepair following exposure to the low-pressure UV source, but no repair was detectable following exposure to the medium-pressure UV source at the initial doses examined. Minimal repair was eventually observed upon medium-pressure UV lamp exposure when doses were lowered to 3 mJ/cm2. This study clearly indicates differences in repair potential under laboratory conditions between irradiation from low-pressure and medium-pressure UV sources of the type used in water treatment.

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Microspot With Integrated Wells (MSIW) for the Detection of E.coli

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73037 ◽

2013 ◽

Author(s):

Naga Siva Kumar Gunda ◽

Selvaraj Naicker ◽

Maryam S. Ghoraishi ◽

Subir Bhattacharjee ◽

Thomas G. Thundat ◽

...

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Water System ◽

Subsequent Treatment ◽

Contaminated Water ◽

Proper Treatment ◽

Red Color ◽

Enzyme Substrates ◽

Quality Water ◽

Gusa Gene

There is an increasing problem in getting quality water for developing countries. Water system is contaminated and without proper treatment, it has been consumed as drinking water. It is a big problem for health. Escherichia coli (E.coli) is the main cause for the contamination of water and illness in people. Early detection of E.coli presence in the drinking water followed by subsequent treatment for elimination of E.coli can solve this problem. The present work developed a new method for detecting E.coli in contaminated water using microspot with integrated wells (MSIW). The method involves the fabrication of MSIW, coating the MSIW with enzyme substrates such as 4-MUG substrate (4-Methylumbelliferyl-β-D-glucuronide, trihydrate) and Red-Gal substrate (6-Chloro-3-indolyl-β-D-galactoside) in proper medium and dispensing the contaminated water into MSIW. GlucuronidaseA (gusA) gene in E.coli encodes the beta-D-Glucuronidase (GUS) to hydrolyze the substrate 4-MUG enzymatically which leads to the generation of the fluorigenic compound 4-MU. β-galactosidase enzyme in E.coli produces red color when it reacts with Red-Gal substrate. Using portable optical readers, average color/fluorescence intensity emitting by MSIW is measured and quantified. Comparing obtained intensity values with calibrated intensity values, the level of contamination can be predicted for early warnings.

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Persistence of Nontuberculous Mycobacteria in a Drinking Water System after Addition of Filtration Treatment

Applied and Environmental Microbiology ◽

10.1128/aem.00759-06 ◽

2006 ◽

Vol 72 (9) ◽

pp. 5864-5869 ◽

Cited By ~ 51

Author(s):

Elizabeth D. Hilborn ◽

Terry C. Covert ◽

Mitchell A. Yakrus ◽

Stephanie I. Harris ◽

Sandra F. Donnelly ◽

...

Keyword(s):

Drinking Water ◽

Distribution System ◽

Distribution Systems ◽

Water Distribution ◽

Cold Water ◽

Nontuberculous Mycobacteria ◽

Treatment Plant ◽

Water System ◽

Drinking Water Treatment ◽

Drinking Water System

ABSTRACT There is evidence that drinking water may be a source of infections with pathogenic nontuberculous mycobacteria (NTM) in humans. One method by which NTM are believed to enter drinking water distribution systems is by their intracellular colonization of protozoa. Our goal was to determine whether we could detect a reduction in the prevalence of NTM recovered from an unfiltered surface drinking water system after the addition of ozonation and filtration treatment and to characterize NTM isolates by using molecular methods. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration and ozonation after 6 months of sampling. Sample sites included those at treatment plant effluents, distributed water, and cold water taps (point-of-use [POU] sites) in public or commercial buildings located within each distribution system. NTM were recovered from 27% of the sites. POU sites yielded the majority of NTM, with >50% recovery despite the addition of ozonation and filtration. Closely related electrophoretic groups of Mycobacterium avium were found to persist at POU sites for up to 26 months. Water collected from POU cold water outlets was persistently colonized with NTM despite the addition of ozonation and filtration to a drinking water system. This suggests that cold water POU outlets need to be considered as a potential source of chronic human exposure to NTM.

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