Contamination Of Water Systems Research Articles

Decontamination of biological agents from drinking water infrastructure: A literature review and summary

This report summarizes the current state of knowledge on the persistence of biological agents on drinking water infrastructure (such as pipes) along with information on decontamination should persistence occur. Decontamination options for drinking water infrastructure have been explored for some biological agents, but data gaps remain. Data on bacterial spore persistence on common water infrastructure materials such as iron and cement-mortar lined iron show that spores can be persistent for weeks after contamination. Decontamination data show that common disinfectants such as free chlorine have limited effectiveness. Decontamination results with germinant and alternate disinfectants such as chlorine dioxide are more promising. Persistence and decontamination data were collected on vegetative bacteria, such as coliforms, Legionella and Salmonella. Vegetative bacteria are less persistent than spores and more susceptible to disinfection, but the surfaces and water quality conditions in many studies were only marginally related to drinking water systems. However, results of real-world case studies on accidental contamination of water systems with E. coli and Salmonella contamination show that flushing and chlorination can help return a water system to service. Some viral persistence data were found, but decontamination data were lacking. Future research suggestions focus on expanding the available biological persistence data to other common infrastructure materials. Further exploration of non-traditional drinking water disinfectants is recommended for future studies.

Biofilms: The Stronghold of Legionella pneumophila

Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.

Hierarchically Structured Manganese Oxide-Coated Magnetic Nanocomposites for the Efficient Removal of Heavy Metal Ions from Aqueous Systems

In this study, hierarchical MnO2-coated magnetic nanocomposite (Fe3O4/MnO2) was synthesized by a mild hydrothermal process, and its application for removing heavy metal ions from contaminated water systems was examined. Structural characterization showed that the Fe3O4 nanoparticle core was coated with amorphous MnO2 shell with flowerlike morphology. The as-prepared nanocomposite had a large surface area and high magnetic saturation value, which ensured its good sorption ability and convenience of separation. Fe3O4/MnO2 exhibited a greatly improved removal capacity toward four different heavy metals (Cd(II), Cu(II), Pb(II), and Zn(II)) compared to unmodified Fe3O4 nanoparticles. The adsorption property of Fe3O4/MnO2 was studied with Cd(II) in more detail. The sorption equilibrium data were well fitted to the Langmuir model, and the maximum adsorption capacity toward Cd(II) was 53.2 mg g(-1). Fe3O4/MnO2 retained over 80% of its adsorption capacity under various solution conditions that are typically encountered in natural waters. This nanocomposite was easily recovered and reused through consecutive adsorption-desorption experiments with the assistance of an external magnetic field. Overall, the findings propose that Fe3O4/MnO2 could be used as an effective recyclable adsorbent for heavy metal ions.

Water Network Protection from Intentional Contamination by Sectorization

Each single phase of a water supply network, from water adduction to distribution to end-users, is exposed to many diverse potential sources of intentional contamination (or malicious attacks). One of the most dangerous threats is a backflow attack that occurs when a pump system, easily available on the market, is utilized to overcome the pressure gradient of network pipes. In this work, a simple backflow attack with cyanide being introduced into a real-water system is modeled and the most dangerous introduction points for a contaminant incident are defined. Moreover, the network vulnerability has been analyzed by computing the lethal dose of cyanide ingested by users and the total length of the contaminated water system. Eventually the effects of network partitioning and district isolation to protect water supply systems have been investigated. The results show how district closing - by network sectorization techniques used to improve leakage search and reduction - can significantly decrease contaminant diffusion and protect part of the users from cyanide uptake. Network sectorization can also reduce the risk of simple malicious attacks because several introduction points are necessary to have a massive negative impact on the network. Simulation results also show that in some cases water network partitioning may worsen water network protection and further studies are necessary to design water districts for network security and safety.

Tracking Down an Epidemic’s Source

Researchers find the source of an epidemic using relatively little information. Their technique could also help authorities track down contamination in water systems or locate problems in electrical grids.

Environmental remediation from heavy metal pollution using polyacrylamide–grafted gum arabic, <em>Moringa oleifera</em>, and blended products of <em>Moringa oleifera</em> and polyacrylamide-grafted gum arabic

Graft copolymers of polyacrlamide-grafted gum arabic were synthesized, blended with Moringa oleifera and characterized by IR spectroscopy. The potentials of the products to remove heavy metals from aqueous solutions were studied at room temperature (30oC) and this was experimented on iron (III) ions (Fe3+). The extent of metal ions removal was determined from sorption capacity values of several sorbents. The results showed that all the polymeric products investigated displayed significant sorption capacities. The abilities of the grafted product polyacrylamide-grafted gum arabic (GA-g-PAAM) to clarify wastewater to a high degree and also remove heavy metals from contaminated water systems, are good indications of the importance of material transformation, especially gum arabic which is hitherto, an emulsifier, and other products of phytoorigin. The sorption capacities of the synthesized and natural products could lead to a blissful expansion of the spectrum of substances that can be used to detoxify our environment through well guided technologies.Keywords: Gum arabic, Moringa oleifera, sorption capacity, sorbent, phyto-products, detoxify, environment

Evaluation of an Automated Dental Unit Water System's Contamination Control Protocol

This study addresses the efficacy of an automated decontamination protocol using the germicide 'tetra acetyl ethylene diamine (TAED) perborate' (Farmec SpA, Italy). The germicide TAED perborate protocol is used in the Castellini Dental Units fitted with an Autosteril unit (an automated device that can cycle 0.26% TAED perborate solution and sterile water for cleaning the water system between patients and overnight). Prior to testing the Autosteril and the 0.26% TAED perborate protocol on the Logos Jr Dental Unit (Castellini SpA, Italy), TAED perborate was used on a dental unit water system simulation device. A dental unit water system simulation device equipped with four dental unit water systems and with naturally grown and mature biofilm contamination was used in this study (three treatment units and one control). One treatment group used a simulated 5 minutes contact with TAED perborate and sterile water for irrigation; the second used a simulated 5 minutes contact with TAED perborate and 2 ppm ClO2 for irrigation; the third used a simulated 5 minutes contact with TAED perborate and municipal water for irrigation. The control group used municipal water for irrigation with no cleaning/disinfection protocols. This protocol was repeated for 30 cycles. Laser scanning confocal microscopy (LSCM) was used to study the effects on natural and mature biofilms, and R2A agar used to quantify heterotrophic plate counts in the effluent irrigant. Antimicrobial efficacy was evaluated by challenging TAED perborate with microbes and spores (M. smegmatis and B. subtilis). Deleterious effects of the germicide were evaluated on metal and nonmetal parts of dental unit water systems. Heterotrophic plate counts using R2A agar and LSCM of the lines were conducted to assess biofilm and microbial control. Baseline water samples showed mean contamination >5.6 log10 cfu/ml. After initial cleaning, all three groups maintained mean contamination levels of less than 1.1 (SD <0.3) log10 cfu/ml. LSCM of baseline samples was positive for live biofilm in all groups. At the end of the study, viable biofilm was only present in the control. In the microbial challenge test, all vegetative organisms were killed within 30 seconds of contact, while spores were killed within 5 minutes. Corrosion was seen in metals used in US-manufactured dental unit materials, while not observed in those used in the Castellini Logos Jr dental unit. In this study, the TAED perborate protocol was effective in biofilm control and control of dental treatment water contamination. Use of sterile water or 2 ppm ClO2 along with TAED treatment also controlled planktonic contamination effectively. Environmental biofilms contaminate dental unit water systems over time and affect the quality of dental treatment water. Contaminants include environmental biofilms, microbes, including gram-negative rods and endotoxins in high doses that are not of acceptable quality for treating patients. There are many germicidal protocols for treating this contamination and one such is the prescribed use of TAED perborate used in conjunction with sterile water for irrigation in the autosteril device, an integral component of the Castellini dental units for between patient decontamination of dental unit water systems. This study was conducted on an automated simulation dental unit water system to test the TAED perborate protocol's efficacy on naturally grown, mature environmental biofilms, it's efficacy on microbes and spores and it's effects on materials used in dental unit water systems. This translational research addresses both microbial control and material effects of TAED perborate in studying efficacy and possible deleterious effects and simulated use in dentistry. Currently, this antimicrobial use protocol is followed worldwide in the Castellini dental units that are used in day-to-day dental patient care.

Assessing antibiotic resistance profiles in Escherichia coli and Salmonella species from groundwater in the Mafikeng area, South Africa

Escherichia coli and Salmonella species occur as normal flora in the gastrointestinal tract of animals and humans. However, pathogenic strains exist that cause disease in humans. Infections may result from the consumption of water and food contaminated with faeces of human and animal origin. In South Africa, residents of most rural communities rely on untreated ground water for survival. This practice results to the transfer of pathogenic micro-organism to humans and thus amplifies the need to identify contaminated water systems. Results obtained may adequately address water quality problems and hence protect public health. The study was conducted to isolate and determine the antibiotic resistance profiles of E. coli and Salmonella species from the groundwater obtained from two rural communities in the North-West province, S.A. Nineteen ground water samples were analyzed for characters of E. coli and Salmonella species. Only those isolates that satisfied all the primary (oxidase and the triple sugar iron) and secondary identification criteria (API 20E and rapid slide agglutination test) for E. coli and Salmonella species were used. A total of 63 E. coli and 64 Salmonella isolates were identified. The antibiotic susceptibilities of these isolates were evaluated against a panel of 10 antibiotics. A large proportion (56.7 to 57.6%) of the E. coli isolated from both Dibate and Verdwall were resistant to vancomycin. Similarly, large proportions (51.5 to 78.8%) of the E. coli isolated from Verdwall were resistant to ampicilin and erythromycin when compared to those isolated from Dibate. Furthermore, a higher percentage (90.0 to 100%) of Salmonellaisolated from both Dibate and Verdwall were resistant to ampicillin, erythromycin and vancomycin. AP-E-VA was the predominant phenotype for E. coli isolated from both Dibate and Verdwall in 40 and 20%, respectively, while the phenotypes AP-E-T-VA and AP-E-VA were dominant among the Salmonella species isolated in this study. The results indicated that E. coli and Salmonella could serve as indicator organisms necessary to assess the quality of ground water and their levels are critical parameters that could help to drive management strategies. This will limit the effect of these pathogens on consumers, as some water samples were visibly identified to be contaminated. Key words: Salmonella, E. coli, multiple antibiotic resistant (MAR), phenotype.

Isotopically Modified Nanoparticles for Enhanced Detection in Bioaccumulation Studies

This work presents results on synthesis of isotopically enriched (99% (65)Cu) copper oxide nanoparticles and its application in ecotoxicological studies. (65)CuO nanoparticles were synthesized as spheres (7 nm) and rods (7 × 40 nm). Significant differences were observed between the reactivity and dissolution of spherical and rod shaped nanoparticles. The extreme sensitivity of the stable isotope tracing technique developed in this study allowed determining Cu uptake at exposure concentrations equivalent to background Cu concentrations in freshwater systems (0.2-30 μg/L). Without a tracer, detection of newly accumulated Cu was impossible, even at exposure concentrations surpassing some of the most contaminated water systems (>1 mg/L).

As (V) Biosorption in an Aqueous Solution Using Chemically Treated Lemon (Citrus aurantifolia Swingle) Residues

The use of biosorbents to remove metals and metalloids from contaminated water systems has gained great usage in various parts of the world. The objective of the current study was to test lemon peels as biosorbents for As (V). Lemon peels were chemically characterized and arsenic contact experiments were performed to determine the adsorption capacity of the peels using different empirical models. The model that fit the experimental data was the Lagergren empirical model with a correlation coefficient of R= 0.8841. The results show that lemon peels were able to retain 474.8 μg of As (V)/g of biosorbent. Lemon agro-industrial waste can be useful in the removal of heavy metals, such as arsenic, from aqueous media.

Legionella pneumophila urinary antigen subtyping using monoclonal antibodies as a tool for epidemiological investigations

Legionnaires' disease is diagnosed predominantly by urinary antigen detection, and patient isolates are rarely available. The lipopolysaccharide (LPS) epitope pattern of isolates detected by monoclonal antibodies is an accepted marker for the phenotyping of L. pneumophila serogroup 1 strains into monoclonal subgroups. L. pneumophila LPS is the dominant antigen in patients' urinary specimens. By using commercially available microtiter wells coated with rabbit anti-Legionella serogroup 1 IgG as the catching antibody, LPS components in urine specimens were bound and detected separately by corresponding monoclonal antibodies of the Dresden Panel. The subtyping of LPS on urinary antigen molecules by using enzyme-linked immunosorbent assay (ELISA) allows deducing of first evidences for the identity/non-identity of environmental isolates and the legionellosis pathogen. Most importantly in our study, urinary antigen typing possesses high probability to distinguish (or does not distinguish) if the pathogen belongs to the MAb 3/1-negative L. pneumophila strains, which are widespread contaminants of water systems, but represent the minority of patient isolates.

Use of Escherichia coli BOX-PCR fingerprints to identify sources of fecal contamination of water bodies in the State of São Paulo, Brazil

Repetitive element sequence-based polymerase chain reaction (rep-PCR) is one of the commonest methods used to identify sources of fecal contamination of water systems. In this work, BOX-A1R-based repetitive extragenic palindromic-PCR (BOX-PCR) was used to discriminate Escherichia coli strains originating from different animals and water sources, and the suitability of the technique for bacterial source tracking (BST) was evaluated. A total of 214 strains from humans, 150 strains from animals, 55 strains from sewage and 77 strains from water bodies were analyzed by the BOX-PCR technique. When maximum similarity between the fingerprints was used, a correct classification rate of 84% was achieved for strains from human and animal sources. Furthermore, 95% of the strains found in sewage were classified as being from human sources by at least one of the four classification tools used. Classification of the strains found in water bodies in the State of São Paulo was based on the fingerprints obtained for human and animal sources. Most of the sampling sites appeared to be affected by mixed sources of fecal contamination. The use of BOX-PCR for BST could be especially valuable in developing countries, where simplicity and cost are important considerations.

Environmental Scientists, Biologically Active Compounds, and Sustainability: The Vital Role for Small-Scale Science

Tracking the existence and degree of anthropogenic chemical contamination of water systems is a daunting task. The spatial extent of many jurisdictions is daunting to measure, let alone arranging for time-tracking data sets. Taking a cue from ornithological surveys, perhaps a network of academia/government experts and (“amateur”) citizen-scientists could create a data set that would at least provide a better handle on where to focus resources and attention. Kolok and Schoenfuss discuss the merits and possible organization of such an approach.

Fluorescent Probes for Pd2+ Detection by Allylidene–Hydrazone Ligands with Excellent Selectivity and Large Fluorescence Enhancement

Because palladium is widely used in various catalysts and converters, which results in a high level of contamination of water systems and the soil by residual palladium, there is an urgent need for Pd(2+)-sensitive and -selective probes. Based on the special affinity of Pd(2+) to conjugated double-bond ligands, two fluorescence probes (RPd2 and RPd3) that contain conjugated allylidene-hydrazone ligands that link to colorless rhodamine-spirolactam have been developed. The results show that conjugated allylidene-hydrazones have a much better affinity toward Pd(2+), and consequently provide the probes with more acute color change and fluorescence enhancement (≈170-fold), and better selectivity over other metal ions (especially platinum-group elements, or PGEs) than the unconjugated allyl-hydrazine. With richer electron density and a more suitable stereo effect in the allylidene-hydrazone group, RPd2 displays the best specificity toward Pd(2+) and affords convenient detection by the naked eye. Its potential application for Pd(2+)-contaminated water and soil-sample analysis is revealed by proof-of-concept experiments.

The fate of Cu, Zn, and Cd in the initial stage of water system contamination: The effect of phytoplankton activity

The fate of Cu, Zn and Cd after their entry into an unpolluted fresh water body was studied as a function of a condition of a natural phytoplankton community. In a field experiment, additives of metals entered into light and dark mesocosms twice to simulate effects of primary and repeated contamination. Over 31 days, the reproduction of new generation of a phytoplankton as renewable source of the suspended particles capable to metal biosorption was higher in a light mesocosm. As a result the residual concentration of metals in water decreased faster and their content in the settled deposits was higher in a light mesocosm, than in a dark mesocosm. Efficiency of planktonic channel in deducing of metals from water with settling deposits (in the order of Cu>Zn>Cd) depends on intensity of a phytoplankton reproduction in the initial stage of water ecosystem contamination.

High‐Performance, Superparamagnetic, Nanoparticle‐Based Heavy Metal Sorbents for Removal of Contaminants from Natural Waters

We describe the synthesis and characterization of high-performance, superparamagnetic, iron oxide nanoparticle-based, heavy metal sorbents, which demonstrate excellent affinity for the separation of heavy metals in contaminated water systems (i.e., spiked Columbia River water). The magnetic nanoparticle sorbents were prepared from an easy-to-synthesize iron oxide precursor, followed by a simple, one-step ligand exchange reaction to introduce an affinity ligand to the nanoparticle surface that is specific to a heavy metal or class of heavy metal contaminants. The engineered magnetic nanoparticle sorbents have inherently high active surface areas, allowing for increased binding capacities. To demonstrate the performance of the nanoparticle sorbents, river water was spiked with specific metals and exposed to low concentrations of the functionalized nanoparticles. In almost all cases, the nanoparticles were found to be superior to commercially available sorbent materials as well as the unfunctionalized iron oxide nanoparticles.

Behavior of metals (Cu, Zn and Cd) in the initial stage of water system contamination: Effect of pH and suspended particles

The fate of potentially harmful metals (PHM) after their entry into an unpolluted fresh water body depends on the physicochemical and biological parameters of the aquatic ecosystem. This paper considers the effect of pH and suspended particles (SP) on the behavior of Cu, Zn and Cd when they enter a fresh water reservoir. In a field experiment, four mesocosms were constructed in the Novosibirskoye Reservoir to allow systematic variation of SP concentration (15 or 250 mg/L) and pH (8.5 or 6.5). The initial concentrations of Cu, Zn and Cd in the mesocosms were 1000, 1000 and 200 μg/L, respectively. Natural bottom sediments were used to provide additional mineral SP, and water hyacinth was used as a floating plant species. Over 11 days, measurements were made of several indicators: residual metal concentration in solution ([PHM] w ); metal concentration in SP ([PHM] s ); primary productivity of the phytoplankton community; mass of settled SP; PHM concentration in settled SP; and PHM bioaccumulation by water hyacinth. The ratio [PHM] w /[PHM] s in the water varied in the order Cu < Zn < Cd and was higher at pH 6.5 than at pH 8.5. This observation reflects different PHM sorption (Cu > Zn > Cd) onto mineral SP and PHM biosorption by planktonic organisms. Phytoplankton acts as a renewable source of organic SP and plays an important role in metal removal from the water in the mesocosms. After 11 days the residual concentrations of Cu, Zn and Cd in the mesocosm without SP addition (initial SP concentration was 15 mg/L) were 272, 355 and 84 μg/L, respectively. The residual concentrations of Cu, Zn and Cd in mesocosms with SP addition were 57, 100 and 14 μg/L at pH 8.5 and 80, 172 and 20 μg/L at pH 6.5, respectively. Therefore, addition of SP resulted in faster and more complete removal of metals into the bottom sediments. Floating plants (water hyacinth) accumulated PHM (Cu > Zn > Cd) more effectively at pH 8.5 than at pH 6.5, and PHM concentrations in the roots were higher than in settling SP. The general trends of PHM removal from contaminated water via sedimentation and bioaccumulation are compared with changes of metal speciation in solution.

Patterns in Potential Impacts Associated with Contamination Events in Water Distribution Systems

Properly designing contamination warning systems requires an understanding of potential public health impacts for a range of contaminated water systems and a wide range of contaminants. To address this need, we determined potential impacts for 12 actual systems serving populations ranging from ∼ 104 to over 106 persons by simulating contamination events for the systems. We found several consistent patterns in the estimated impacts (defined as the size of the population receiving an ingestion dose above a given level). Significant impacts, those similar to worst-case impacts, result from injections of contaminants at only a minority of nodes. For contaminants with high thresholds for adverse effects, significant exposures are concentrated near the injection location, and impacts are not sensitive to population served. However, for contaminants with low thresholds, significant exposures are present over a significant fraction of the system, and impacts are sensitive to population. When exposures are concent...

Analytical method of Cr stable isotope and its application to water pollution survey

High Cr (VI) concentration is a potential serious risk to environment and ecologic system. Thus, it is essential to effectively monitor Cr contamination in water systems and scientifically evaluate its evolution trend. A new method of in-situ tracer technique by Cr isotopic analysis for quantitatively estimating Cr-contamination and its regional evolution in natural waters as well as a case application are reported in this paper. Based on documented literatures, an experimental procedure for chemical separation and purification of Cr in water samples and its analytical method for Cr isotopic measurement by thermal ionization mass spectrometry (TIMS) are established. Eleven samples collected around a chemical factory in Hubei Province were analyzed by this technique. These samples show δ53Cr values ranging from −1.7‰ to 7.3‰ and an elevating trend with an increasing in distance from the sampling site to pollution source. A functional correlation following Rayleigh fractionation law was established between sample’s δ53Cr value and its extent of Cr contamination. This study suggests that Cr isotopic analysis is an effective method to reveal the spatial distribution and its evolution trend of Cr contamination in the regional water system. It is thus helpful to assessing the self-purifying ability of local water system according to Cr isotopic fractionation.

Research about prevent contamination of water system in department of stomatology by replace holding tank of water and distilled water for each person

Objective To know a kind of method to prevent contamination of water system in department of stomatology. Methods Divided 120 patients with dental diseases into the control group and the observation group randomly, there were 60 cases in each group. Replace the holding tank of wa-ter and distilled water per 24 hours was used in the control group, while the method of replace the hold-ing tank of water and distilled water for each person was used in the observation group, and then com-pared the contamination condition of water system between the two groups. Results The percent of pass of water system in the observaiton group was 100%, which significant higher than the 68.33% in the control group. Conclusions Replace the holding tank of water and distilled water for each person is a kind of method to avoid contamination of water system in department of stomatology. Key words: Holding tank of water, Distilled water, Department of stomatology; Contamination of water system