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A biofilm is a biologically active matrix attached to the surface of cells and their extracellular products. As they are a mixture of many microorganisms, the microbiological activity of biofilms varies according to their position in the aggregate. With particular emphasis on drinking water distribution systems, this review focuses on the process of biofilm formation, associated bacteria, chlorine resistance of bacteria, and the predominant surface materials. We have compiled studies on the bacteria in drinking water distribution systems and their interactions with biofilm formation on different materials, and we also analysed the chlorine-resistant bacteria and their problems in the water networks. The materials used in the drinking water network are significantly affected by the disinfection method used to produce the biofilm that adheres to them. Some studies propose that the material is inconsequential, with the disinfection process being the most significant factor. Studies suggest that materials based on plastics (such as PVC and HDPE) tend to be more effective in controlling biofilm formation or removal than those based on metals (such as stainless steel), which have been found to be less effective in some instances. Chlorine-resistant strains are becoming more and more common in drinking water networks, resulting in the occurrence of diseases such as typhus and cholera. [ABSTRACT FROM AUTHOR]

This paper provides a summary of the knowledge of drinking-water temperature increases and present daily, seasonal, and yearly temperature data of drinking-water distribution systems (DWDS). The increasing water temperatures lead to challenges in DWDS management, and we must assume a promotion of invertebrates as pipe inhabitants. Macro-, meio-, and microinvertebrates were found in nearly all DWDS. Data in relation to diversity and abundance clearly point out a high probability of mass development, and invertebrate monitoring must be the focus of any DWDS management. The water temperature of DWDS is increasing due to climate change effects, and as a consequence, the growth and reproduction of invertebrates is increasing. The seasonal development of a chironomid (Paratanytarus grimmii) and longtime development of water lice (Asellus aquaticus) are given. Due to increased water temperatures, a third generation of water lice per year has been observed, which is one reason for the observed mass development. This leads to an impact on drinking-water quality and an increased health risk, as invertebrates can serve as a host or vehicle for potential harmful microbes. More research is needed especially on (i) water temperature monitoring in drinking-water distribution systems, (ii) invertebrate development, and (iii) health risks. [ABSTRACT FROM AUTHOR]

This paper provides a summary of the knowledge of drinking-water temperature increases and present daily, seasonal, and yearly temperature data of drinking-water distribution systems (DWDS). The increasing water temperatures lead to challenges in DWDS management, and we must assume a promotion of invertebrates as pipe inhabitants. Macro-, meio-, and microinvertebrates were found in nearly all DWDS. Data in relation to diversity and abundance clearly point out a high probability of mass development, and invertebrate monitoring must be the focus of any DWDS management. The water temperature of DWDS is increasing due to climate change effects, and as a consequence, the growth and reproduction of invertebrates is increasing. The seasonal development of a chironomid (Paratanytarus grimmii) and longtime development of water lice (Asellus aquaticus) are given. Due to increased water temperatures, a third generation of water lice per year has been observed, which is one reason for the observed mass development. This leads to an impact on drinking-water quality and an increased health risk, as invertebrates can serve as a host or vehicle for potential harmful microbes. More research is needed especially on (i) water temperature monitoring in drinking-water distribution systems, (ii) invertebrate development, and (iii) health risks.

With the big demand on water supply during the last century due to population growth, the approbation of new technology to assure water quality at lower cost is essential. This paper presents a drinking water distribution system (DWDS) based on a nonlinear fuzzy modeling technique. The approach uses a multi-input multi-output (MIMO) Takagi–Sugeno (T–S) fuzzy model, which is relevant for constructing a large class of nonlinear processes. The proposed framework is validated on a real drinking water distribution system, the MIMO fuzzy T–S model was implemented, in the context of nonlinear predictive control to regulate the water quality (the chlorine concentration in drinking water). The objective is to keep the system outputs within upper and lower limits from the requirement of health regulations. [ABSTRACT FROM AUTHOR]

Der Beitrag widmet sich einer diachronen Korpusuntersuchung zur Kasusrektion von Sekundärpräpositionen im Deutschen Textarchiv (DTA) und im DWDS-Kernkorpus über den Zeitraum von 1497 bis 1999. Untersucht werden exemplarisch die denominalen Präpositionen dank und laut sowie die deverbalen Präpositionen während und entsprechend. Dabei zeigt sich, dass die bisherigen Erklärungsansätze für die beobachteten Entwicklungstendenzen zu kurz greifen: Ein einheitliches Bild ergibt sich bei der Entwicklung der hier untersuchten Präpositionen nicht. Für die Hypothese, der Wechsel der Kasusrektion werde zur Differenzierung vom Spenderlexem genutzt (Di Meola 2006), sprechen zwar die Entwicklung von laut zur Dativrektion und der Übergang von dank zur Genitivrektion, dagegen spricht allerdings, dass die ursprüngliche Genitivpräposition während ihre Rektion recht lange und stabil beibehält. [ABSTRACT FROM AUTHOR]

Abstract Drinking water distribution systems (DWDS) may be a "Trojan Horse" for some waterborne diseases caused by opportunistic pathogens (OPs). In this study, two simulated DWDS inoculated with groundwater were treated with chlorine (Cl 2) and ultraviolet/chlorine (UV/Cl 2) respectively to compare their effects on the OPs distributed in four different phases (bulk water, biofilms, corrosion products, and loose deposits) of DWDS. 16S rRNA genes sequencing and qPCR were used to profile microbial community and quantify target genes of OPs, respectively. Results showed that UV/Cl 2 was more effective than single Cl 2 to control the regrowth of OPs in the water with the same residual chlorine concentration. However, the OPs inhabiting the biofilms, corrosion products, and loose deposits seemed to be tolerant to UV/Cl 2 and Cl 2 , demonstrating that OPs residing in these phases were resistant to the disinfection processes. Some significant microbial correlations between OPs and Acanthamoeba were found by Spearman correlative analysis (p < 0.05), demonstrating that the ecological interactions may exist in the DWDS. 16S rRNA genes sequencing of water samples revealed a significant different microbial community structure between UV/Cl 2 and Cl 2. This study may give some implications for controlling the OPs in the DWDS disinfected with UV/Cl 2. Graphical abstract Image 1 Highlights • Opportunistic pathogens in the water, biofilms, corrosion products, and loose deposits of DWDS were quantified respectively. • UV/free chlorine controlled the opportunistic pathogens in water more efficiently than single chlorine. • Opportunistic pathogens in the biofilms, corrosion products and loose deposits were tolerant to UV/free chlorine. • Potential microbial correlations existed between the target opportunistic pathogens. • Apparent shift of bacterial community was captured in both ARs disinfected with UV/free chlorine and chlorine. [ABSTRACT FROM AUTHOR]

Abstract Simulated drinking water distribution system (DWDS) treated with O 3 -BAC-Cl 2 (ozone-biological activated carbon-chlorine) was constructed to study its effects on the regrowth of five typical opportunistic pathogens (OPs). It was found that O 3 -BAC-Cl 2 could significantly reduce the regrowth of target OPs in the effluents of DWDS compared with Cl 2 and O 3 -Cl 2 with the same residual chlorine levels. However, the effect of O 3 -BAC-Cl 2 on the average numbers of target OPs gene markers in the biofilms of DWDS was not apparent, suggesting that OPs in the biofilms of DWDS were tolerant to the upstream disinfection process. The quantification of target OPs in the BAC-filter column demonstrated that OPs decreased with the increase of depth, which was likely due to the organic nutrient gradient and microbial competition inside the BAC-filter. Increase in the ozone dose could further reduce the OPs at the bottom of the BAC-filter. Spearman correlation analysis demonstrated that some significant correlations existed between target microorganisms, suggesting potential microbial ecological relationships. Overall, our results demonstrated that the BAC-filter may act as a "battlefield" suppressing the OPs through microbial competition. O 3 -BAC-Cl 2 could be an effective multi-barrier process to suppress the proliferation of OPs in the bulk water of DWDS. However, OPs protected by the biofilms of DWDS should receive further attention because OPs may be detached and released from the biofilms. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

• Iron particle formation under different chlorine concentrations were studied. • High initial chlorine would prevent particle formation under a long hydraulic retention time. • EPS provided better protection for pipe corrosion under higher initial residual chlorine. • High initial chlorine may unexpectly increase the risk of microorganisms. Unlined iron pipe (UIP) is still widely in use in drinking water distribution systems (DWDS), discoloration easily happens after a long-time retention due to iron release, but the influence of initial chlorine on water quality under this condition is not clear. Here, we studied the water quality changes in UIP section reactors under different initial chlorine dosages. Results showed that chlorine could disappeared rapidly within 0.5 h in the UIP. The water with higher initial chlorine (5 mg/L) had higher turbidity in a short time (within 1.5 h), but for a longer retention time (2∼12 h), the highest turbidity was in the iron pipe without initial chlorine. Interestingly, a clear increase in adenosine triphosphate in the UIPs was observed with the increase of initial chlorine, which was in accordance with the results of heterotrophic plate count. Polysaccharide and protein increased with the increase of initial chlorine, which would benefit the formation of a protective layer to inhibit corrosion. This study reflects that during the overnight retention in UIP, raising chlorine would be effective to control discoloration, but chemical and microbiological risks may increase. [Display omitted] [ABSTRACT FROM AUTHOR]

The final quality of the drinking water in the consumers’ tap depends on the purification treatment applied, but also on its route through the drinking water distribution system (DWDS). This study assesses the quality of water treated by ultrafiltration membranes in a DWDS at a pilot scale in order to determine how possible network fouling affects drinking water quality, with special interest in natural organic matter, trihalomethanes (THM) and biofilm. Two different configurations were tested: an initial stage with an ultrafiltration (UF) system and a subsequent stage with coagulation-hydraulic flocculation (CF) pretreatment coupled to the UF. Although CF pretreatment helped reduce the dissolved organic matter (DOM) of the effluent that passed through the UF system, the high concentration of DOM promoted the fouling of the DWDS by organic matter deposits. This, together with the increase in water temperature in DWDS, allowed the adhesion of bacteria on the inner pipeline surface, encouraging the formation of a biofilm. Finally, despite the high concentration of DOM, THM generation was negligible throughout the study. [ABSTRACT FROM PUBLISHER]

Optimization of drinking water distribution systems has received considerable attention in the past decades, with an increasing use of supporting numerical methods. These have either remained in the academic domain, or found applications in practice for a limited number of specific optimization objectives. With the aim of supporting the Dutch drinking water companies in optimizing their network design, management and operation, we have developed the generic software platform Gondwana for the optimization of drinking water distribution networks. It targets a broad spectrum of single and multiobjective problems in the topics of design, network blueprints, water quality, (virtual) DMA design and location of water quality sensors, among several others. The platform aims to bring optimization techniques within reach of non-specialists with knowledge of the practical problem at hand and also provide expert users with flexibility and freedom. In this contribution, we present Gondwana and demonstrate its performance on well-known benchmark problems. [ABSTRACT FROM AUTHOR]

The German dictionary market has been confronted with a dramatic change in the past years. Traditional dictionary publishers shrank dramatically or even disappeared completely, and the largest academic dictionary, the Grimmsches Worterbuch, will definitely stop its work in 2016. This paper discusses how large documentary reference dictionaries can be planned and produced in this new context for the German market. The focus of this paper is put on the technological conditions and their impact on planning the lexicographical process, including the corpus base, automatization of information extraction, aggregation of existing information, workflow management, online-publication as well as user contributions. Several examples of existing German and English dictionary projects are discussed with respect to these aspects. A particular focus is placed on the Digitales Worterbuch der deutschen Sprache (DWDS). It is shown how the new technological possibilities help to balance richness and up-to-dateness of information with consistency and a minimum amount of redundancy, and more generally how a flexible project workflow can be established where time and budget constraints can be adapted to the project goals. [ABSTRACT FROM AUTHOR]

Monochloramine (MCA) is a widely used secondary disinfectant to suppress microbial growth in drinking water distribution systems. In monochloraminated drinking water, a significant amount of extracellular DNA (eDNA) has been reported, which has many implications ranging from obscuring DNA-based drinking water microbiome analyses to posing potential health concerns. To address this, it is imperative for us to know the origin of the eDNA in drinking water. Using Pseudomonas aeruginosa as a model organism, we report for the first time that MCA induces the release of nucleic acids from both biofilms and planktonic cells. Upon exposure to 2 mg/L MCA, massive release of DNA from suspended cells in both MilliQ water and 0.9% NaCl was directly visualized using live cell imaging in a CellASIC ONIX2 microfluidic system. Exposing established biofilms to MCA also resulted in DNA release from the biofilms, which was confirmed by increased detection of eDNA in the effluent. Intriguingly, massive release of RNA was also observed, and the extracellular RNA (eRNA) was also found to persist in water for days. Sequencing analyses of the eDNA revealed that it could be used to assemble the whole genome of the model organism, while in the water, certain fragments of the genome were more persistent than others. RNA sequencing showed that the eRNA contains non-coding RNA and mRNA, implying its role as a possible signaling molecule in environmental systems and a snapshot of the past metabolic state of the bacterial cells.

• Scaling of CaCO 3 in undersaturated drinking water can be initiated by microbial activity. • CaCO 3 formation is overlooked in biofilm formation processes. • Bacteria can use different mechanisms to mediate CaCO 3 precipitation. • Bacteria can play an active role in the microbial CaCO 3 precipitation process. • Different CaCO 3 polymorphs can result from the microbial processes. Drinking water plumbing systems appear to be a unique environment for microorganisms as they contain few nutrients but a high mineral concentration. Interactions between mineral content and bacteria, such as microbial calcium carbonate precipitation (MCP) however, has not yet attracted too much attention in drinking water sector. This study aims to carefully examine MCP behavior of two drinking water bacteria species, which may potentially link scaling and biofouling processes in drinking water distribution systems. Evidence from cell density evolution, chemical parameters, and microscopy suggest that drinking water isolates can mediate CaCO 3 precipitation through previously overlooked MCP mechanisms like ammonification or biosorption. The results also illustrate the active control of bacteria on the MCP process, as the calcium starts to concentrate onto cell surfaces only after reaching a certain cell density, even though the cell surfaces are shown to be the ideal location for the CaCO 3 nucleation. [Display omitted] [ABSTRACT FROM AUTHOR]

The biofilms and water samples from a model installation built of PVC-U, PE-HD and cast iron pipes were investigated using standard heterotrophic plate count and 16S rRNA Next Generation Sequencing. The results of the high throughput identification imply that the construction material strongly influences the microbiome composition. PVC-U and PE-HD pipes were dominated with Proteobacteria (54–60%) while the cast pipe was overgrown by Nitrospirae (64%). It was deduced that the plastic pipes create a more convenient environment for the potentially pathogenic taxa than the cast iron. The 7-year old biofilms were described as complex habitats with sharp oxidation-reduction gradients, where co-existence of methanogenic and methanotrophic microbiota takes place. Furthermore, it was found that the drinking water distribution systems (DWDS) are a useful tool for studying the ecology of rare bacterial phyla. New ecophysiological aspects were described for Aquihabitans, Thermogutta and Vampirovibrio. The discrepancy between identity of HPC-derived bacteria and NGS-revealed composition of biofilm and water microbiomes point to the need of introducing new diagnostical protocols to enable proper assessment of the drinking water safety, especially in DWDSs operating without disinfection. • Plastic DWDS construction materials promote adhesion of potential pathogens. • Cultivation-based methods overlook the presence potentially pathogenic bacteria. • Pipeline biofilm create a complex habitat with sharp oxidation-reduction gradients. • Novel aspects of Aquihabitans and Thermogutta ecophysiology are described. • Non-pathogenic Vampirovibrio lifestyle is being inferred. [ABSTRACT FROM AUTHOR]