Deutscher Verein des Gas und Wasserfaches

BACKGROUND: Some microorganisms can respire with extracellular electron acceptors using an extended electron transport chain to the cell surface. This process can be applied in bioelectrochemical systems in which the organisms produce an electrical current by respiring with an anode as electron acceptor. These organisms apply flavin molecules as cofactors to facilitate one-electron transfer catalyzed by the terminal reductases and in some cases as endogenous electron shuttles. RESULTS: In the model organism Shewanella oneidensis, riboflavin production and excretion trigger a specific biofilm formation response that is initiated at a specific threshold concentration, similar to canonical quorum-sensing molecules. Riboflavin-mediated messaging is based on the overexpression of the gene encoding the putrescine decarboxylase speC which leads to posttranscriptional overproduction of proteins involved in biofilm formation. Using a model of growth-dependent riboflavin production under batch and biofilm growth conditions, the number of cells necessary to produce the threshold concentration per time was deduced. Furthermore, our results indicate that specific retention of riboflavin in the biofilm matrix leads to localized concentrations, which by far exceed the necessary threshold value. CONCLUSION: This study describes a new quorum-sensing mechanism in S. oneidensis. Biofilm formation of S. oneidensis is induced by low concentrations of riboflavin resulting in an upregulation of the ornithine-decarboxylase speC. The results can be applied for the development of strains catalyzing increased current densities in bioelectrochemical systems.

Application of solar photocatalysis for water treatment is intensively studied. In this work, we investigated TiO2 modified with platinum (Pt/TiO2) and palladium (Pd/TiO2) using sulfamethoxazole (SMX) as the model contaminant. We considered the following parameters: (i) level of TiO2 modification with Pt/Pd, (ii) initial concentration of photocatalysts, (iii) geographic location where processes were conducted, and (iv) natural water matrix. The catalysts characterized by SEM, EDX, DRS, and XRD techniques showed successful deposition of Pd and Pt atoms on TiO2 surface that enabled light absorption in the visible (Vis) range, and therefore caused efficient SMX removal in all tested conditions. A comparison of the rate constants of SMX degradation in various conditions revealed that modification with Pd gave better results than modification with Pt, which was explained by the better optical properties of Pd/TiO2. The removal of SMX was higher with Pd/TiO2 than with Pt/TiO2, independent of the modification level. In the experiments with the same modification level, similar rate constants were achieved when four times the lower concentration of Pd/TiO2 was used as compared with Pt/TiO2. Formation of four SMX transformation products was confirmed, in which both amine groups are involved in photocatalytic oxidation. No toxic effect of post-reaction solutions towards Lepidium sativum was observed.

The third edition of the WHO Guidelines for Drinking-water Quality establishes a ‘Framework for Safe Drinking-water’ that promotes a risk assessment and risk management approach called Water Safety Plan (WSP). In Germany, the discussion on the WSP approach started with significant scepticism by various stakeholders questioning its added value in light of the high quality and service level of water supply. In response, the Federal Ministry of Health, the Federal Environment Agency and the DVGW Association for Gas and Water jointly took the leadership for initiating a sectoral dialogue process involving water suppliers and local public health offices, including a series of WSP pilot projects to evaluate WSP feasibility, benefits and expected challenges for scaling-up. As the regulatory system in Germany makes explicit reference to ‘generally acknowledged codes of good practice’ the paper also examines how far the suite of established DVGW technical and managerial standards already supports WSP implementation. The evaluation process confirmed an added value of the WSP approach under Germany's national conditions, clearly providing an impetus for safeguarding a high quality and service level of drinking-water supply. Various activities to support scale-up implementation of a WSP-type approach have been initiated, including the preparation of step-by-step guidance in German (i.e. DVGW Guidelines W 1001), information campaigns to broadly raise awareness amongst all stakeholders in water supply, and capacity building initiatives.

Abstract Carbonate rocks in the Mediterranean region form karst landscapes with a variety of morphological and hydrological features, and are of particular interest from a water management perspective as they represent major karst aquifers. The Mediterranean Karst Aquifer Map and Database (MEDKAM) provides a 1:5,000,000 scale map showing the distribution of carbonate and evaporite rocks that can host karst groundwater resources, with additional information on other hydrogeological settings, selected terrestrial and submarine karst springs, caves and karst groundwater-dependent ecosystems. A statistical evaluation shows that carbonate rocks cover ~39.5% of the Mediterranean region within a 250-km focus area from the coastline. North Africa has the largest continuous area of carbonate rocks, while smaller countries in the Middle East and the Dinarides have the largest proportion of carbonate rocks in relation to their total area. Carbonate rocks are also widespread in coastal areas, occurring along ~33.6% (14,000 km) of the total Mediterranean coastline, including large islands such as Crete and Mallorca, and ~25.9% (6,400 km) of the continental coastline. Two additional maps display (1) groundwater recharge, showing a climatic gradient from north to south, and (2) groundwater storage trends, indicating a mean annual karst groundwater loss from 2003 to 2020 of 436 million m 3 in the 250-km area. This study quantifies the carbonate rocks in the Mediterranean region and shows their importance for groundwater resources. MEDKAM will serve as a basis for further research and improved international cooperation in karst groundwater management.

Abstract Collaboration between academics and practitioners promotes knowledge transfer between research and industry, with both sides benefiting greatly. However, academic approaches are often not feasible given real‐world limits on time, cost and data availability, especially for risk and uncertainty analyses. Although the need for uncertainty quantification and risk assessment are clear, there are few published studies examining how scientific methods can be used in practice. In this work, we introduce possible strategies for transferring and communicating academic approaches to real‐world applications, countering the current disconnect between increasingly sophisticated academic methods and methods that work and are accepted in practice. We analyze a collaboration between academics and water suppliers in Germany who wanted to design optimal groundwater monitoring networks for drinking‐water well catchments. Our key conclusions are: to prefer multiobjective over single‐objective optimization; to replace Monte‐Carlo analyses by scenario methods; and to replace data‐hungry quantitative risk assessment by easy‐to‐communicate qualitative methods. For improved communication, it is critical to set up common glossaries of terms to avoid misunderstandings, use striking visualization to communicate key concepts, and jointly and continually revisit the project objectives. Ultimately, these approaches and recommendations are simple and utilitarian enough to be transferred directly to other practical water resource related problems.

Abstract Antibiotics are extensively used in human medicine, aquaculture, and animal husbandry, leading to the release of antimicrobial resistance into the environment. This contributes to the rapid spread of antibiotic-resistant genes (ARGs), posing a significant threat to human health and aquatic ecosystems. Conventional wastewater treatment methods often fail to eliminate ARGs, prompting the adoption of advanced oxidation processes (AOPs) to address this growing risk. The study investigates the efficacy of visible light-driven photocatalytic systems utilizing two catalyst types (TiO 2 -Pd/Cu and g-C 3 N 4 -Pd/Cu), with a particular emphasis on their effectiveness in eliminating bla TEM , ermB , qnrS , tetM . intl1 , 16 S rDNA and 23 S rDNA through photocatalytic ozonation and peroxone processes. Incorporating O 3 into photocatalytic processes significantly enhances target removal efficiency, with the photocatalyst-assisted peroxone process emerging as the most effective AOP. The reemergence of targeted contaminants following treatment highlights the pivotal importance of AOPs and the meticulous selection of catalysts in ensuring sustained treatment efficacy. Furthermore, Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis reveals challenges in eradicating GC-rich bacteria with TiO 2 and g-C 3 N 4 processes, while slight differences in Cu/Pd loadings suggest g-C 3 N 4 -based ozonation improved antibacterial effectiveness. Terminal Restriction Fragment Length Polymorphism analysis highlights the efficacy of the photocatalyst-assisted peroxone process in treating diverse samples.

The current European legislation requires that combined effects of the active substances and any substance of concern contained in biocidal products are taken into account in environmental risk assessment. The hypothesis whether the consideration of active substances together with all formulation additives that are labeled as presenting an environmental hazard is sufficient for a reliable environmental risk assessment was tested in the present study by investigating 3 wood preservative products. Relevant single substances in the products, some of their generic mixtures, the biocidal products themselves, and aqueous eluates prepared from the products (representing potential environmental mixtures) were tested for effects on algal growth and Daphnia acute immobilization as well as reproduction. Predictions for the products and the eluates were based on the concept of concentration addition and were mostly found to provide reliable or at least protective estimates for the observed acute and chronic toxicity of the mixtures. The mixture toxicity considerations also indicated that the toxicity of each product was dominated by just 1 of the components, and that assessments based only on the dominating substance would be similarly protective as a full-mixture risk assessment. Yet, there remained uncertainty in some cases that could be related to the toxicity of transformation products, the impact of unidentified formulation additives, or synergistic interaction between active substances and formulation additives.

The aim of the study was the strong reduction of facultative pathogenic bacteria (FPB), and clinically relevant antibiotic resistance genes (ARGs) from secondary effluent. To evaluate the ARGs removal efficiency comparative study of individual unit processes and combined AOPs has been performed. The present work investigated: i) removal of selected ARGs, namely blaTEM, ermB, qnrS, tetM, five FPB as well as 16S rDNA and the integrase gene intl1 involved in horizontal gene transfer; ii) bacterial regrowth potential after treatment; (iii) the removal of the total genomic DNA content, by mono- and bimetallic TiO2-CuPd rutile photocatalysts under visible light radiation in real secondary effluent. The nanoparticles were characterized by UV–vis, XRD, HRTEM, Raman and XPS. TiO2-CuPd/VIS inactivation gives the highest (more than 2 log units removal) efficiency for almost all targets (blaTEM, ermB, tetM, intl 1, and 16S rRNA) compared to monometallic catalysts. The highest efficiency toward blaTEM was achieved after ozonation and TiO2-CuPd/O3/VIS (3.22 and 3.23 LRV, respectively). It was found that despite similar FPB inactivation, lower DNA destruction was found after O3 compared to TiO2-CuPd/O3/VIS treatment. The blaTEM and enterococci were completely removed during TiO2-CuPd/O3/Vis and TiO2-Cu/O3/Vis. While, catalytic ozonation leads to only slightly blaTEM removal (0.64 and 0.44 LRV for TiO2-CuPd/O3 and TiO2-Cu/O3, respectively). Photocatalytic ozonation with the application of TiO2-CuPd leads to significant removal of FPB and ARGs due to synergistic effect between Pd and Cu, which leads to acceleration of ozone – catalysts reaction. Photocatalytic ozonation has the greatest potential giving promising possibilities for eliminating AMR.

Abstract Metallic materials, predominantly steels, are the most common structural materials in the various components along the hydrogen supply chain. Ensuring their sustainable and safe use in hydrogen technologies is a key factor in the ramp-up of the hydrogen economy. This requires extensive materials qualification, however, most of the accepted; and standardized test methods for determining the influence of gaseous hydrogen on metallic materials describe complex and costly procedures that are only available to a very limited extent worldwide. The hollow specimen technique is a simple, rapid, and economical method designed to overcome the limitations of the current methods for the qualification of metallic materials under high-pressure hydrogen gas. However, this technique is not yet standardized. The TransHyDE-H2Hohlzug project is presented in this article, along with the main steps required to optimize the hollow specimen technique. This includes closing knowledge gaps related to the specimen geometry, surface quality, and gas purity in dedicated working packages, thus contributing to a comprehensive standardization of the technique for tests in high-pressure hydrogen gas. Impact statement The hydrogen economy is considered a key solution for achieving climate neutrality in Europe, as it plays a crucial role in the decarbonization of sectors such as transport, industry, power, etc. Ensuring the safety and reliability of infrastructure is crucial for the ramp-up of the hydrogen economy. Therefore, it is necessary to meticulously study the materials and components used for infrastructure under conditions that closely resemble in-service conditions. The currently standardized methods are limited as they do not precisely replicate in-service conditions, and when they do, they are often complex, costly, and not easily accessible. This article presents the hollow specimen technique, a simple, and economical method developed to address the limitations of current standardized methods. The results from this work will contribute to the standardization of this technique for tests in high-pressure hydrogen gas. This will enable a faster evaluation of materials for hydrogen applications by industry and academia, thereby contributing to the growth of the hydrogen economy. Graphical abstract

The toxicity of 17 active pharmaceutical ingredients (APIs) was investigated using standardized acute and chronic tests with Daphnia magna and 2 algae species. Chronic toxicity was generally greater for Daphnia than for algae. Compilation of additional data resulted in 100 APIs for which the acute-to-chronic ratio (ACR) was determined for Daphnia. The frequency of high ACRs (~20% with ACRs > 100) indicates that specific receptor-mediated toxicity toward D. magna is rather common among APIs. The 11 APIs with ACRs > 1000 included lipid-modifying agents, immunosuppressants, antibiotics, antineoplastics, antiobesics, antivirals, and antihistamines. There was no consistent association between ACR and chronic toxicity, ionization status, or lipophilicity. High ACRs were not exclusively associated with the presence of orthologs of the pharmacological target in Daphnia. Statins, acetylcholinesterase inhibitors, and antihistamines are discussed in more detail regarding the link between targets and toxic mode of action. For acetylcholinesterase inhibitors, receptor-mediated toxicity was already apparent after acute exposure, whereas the high ACR and chronic toxicity of some antihistamines probably related to interaction with a secondary rather than the primary pharmacological target. Acute or modeled chronic toxicity estimates have often been used for prioritizing pharmaceuticals. This may be seriously misleading because chronic effects are currently not predictable for APIs with specific receptor-mediated toxicity. However, it is exactly these APIs that are the most relevant in terms of environmental risks. Environ Toxicol Chem 2022;41:601-613. © 2021 SETAC.

Hydrogen is similar to natural gas in terms of its physical and chemical properties but does not release carbon dioxide when burnt. This makes hydrogen an energy carrier of great importance in climate policy, especially as an enabler of increasing integration of volatile renewable energy, progressive electrification, and effective emission reductions in the hard-to-decarbonize sectors. Leaving aside the problems of transporting hydrogen as a liquid, technological challenges along the entire supply chain can be considered as solved in principle, as shown in the experimental findings of the Hydrogen Innovation Program of the German Technical and Scientific Association for Gas and Water. By scaling up production and end-use capacities and, most importantly, producing hydrogen in regions with abundant renewable energy, hydrogen and its applications can displace natural gas at affordable prices in the medium term. However, this substitution will take place at different rates in different regions and with different levels of added value, all of which must be understood for hydrogen uptake to be successful.

Bivalent cations are known to affect the structural and mechanical properties of biofilms. In order to reveal the impact of Fe2+ ions within the cultivation medium on biofilm development, structure and stability, Bacillus subtilis biofilms were cultivated in mini-fluidic flow cells. Two different Fe2+ inflow concentrations (0.25 and 2.5 mg/L, respectively) and wall shear stress levels (0.05 and 0.27 Pa, respectively) were tested. Mesoscopic biofilm structure was determined daily in situ and non-invasively by means of optical coherence tomography. A set of ten structural parameters was used to quantify biofilm structure, its development and change. The study focused on characterizing biofilm structure and development at the mesoscale (mm-range). Therefore, biofilm replicates (n = 10) were cultivated and analyzed. Three hypotheses were defined in order to estimate the effect of Fe2+ inflow concentration and/or wall shear stress on biofilm development and structure, respectively. It was not the intention to investigate and describe the underlying mechanisms of iron incorporation as this would require a different set of tools applied at microscopic levels as well as the use of, i.e., omic approaches. Fe2+ addition influenced biofilm development (e.g., biofilm accumulation) and structure markedly. Experiments revealed the accumulation of FeO(OH) within the biofilm matrix and a positive correlation of Fe2+ inflow concentration and biofilm accumulation. In more detail, independent of the wall shear stress applied during cultivation, biofilms grew approximately four times thicker at 2.5 mg Fe2+/L (44.8 µmol/L; high inflow concentration) compared to the low Fe2+ inflow concentration of 0.25 mg Fe2+/L (4.48 µmol/L). This finding was statistically verified (Scheirer–Ray–Hare test, ANOVA) and hints at a higher stability of Bacillus subtilis biofilms (e.g., elevated cohesive and adhesive strength) when grown at elevated Fe2+ inflow concentrations.

A fully automatic torsion pendulum of the Collette type was built to test continuously‐annealed steels in the thickness range between 0.15 and 0.4 mm for their contents of dissolved nitrogen and carbon. The influence of composition and production conditions on unalloyed steels which had been annealed commercially and in the laboratory were investigated. It was found that, with an increase in the total carbon and aluminium contents, the percentages of the dissolved nitrogen and carbon decrease, whereas higher nitrogen contents resulted in an increase of the percentages dissolved. A higher coiling temperature of the hot band leads to a decrease in the nitrogen dissolved due to the formation of AIN, but to an increase of the carbon dissolved. As these effects almost compensate each other, the coiling temperature is not a suitable means to influence the aging potential. During the continuous annealing process, temperatures of more than 750°C result in a decrease of the nitrogen dissolved, which is completely precipitated as AIN leaving the carbon content nearly unaffected. No major differences were observed, when the material was annealed either with or without a subsequent overaging treatment. However, rapid cooling to low temperatures definitely increased the percentages of elements dissolved.

En el presente artículo se expone una visión personal, adquirida en buena medida desde la responsabilidad de dirigir la DVGW (la asociación alemana de compañías de distribución de agua y gas, que agrupa a varios miles de socios) sobre el futuro de la industria del agua en el mundo en general y en Europa en particular, a la luz de la Directiva Marco del Agua. La idea que preside el artículo es que cada país debe establecer los mecanismos necesarios para, a partir de sus peculiaridades y del conocimiento de la problemática de la industria del agua, garantizar en el tiempo la sostenibilidad de tan trascendental actividad.

Against the background of price controls for drinking water supply utilities in Germany, the comparability of utilities with regard to their specific structural conditions comes into focus. Relevant structural conditions were identified for the two main technical processes, namely water production (WP) and treatment, storage and distribution (TSD). A defined clustering process for comparable utilities has been developed. At the end of the process, groups of comparable utilities are obtained including information to what extent and in which structural condition these utilities are similar. These sets of relevant structural conditions and the clustering process were verified in a data assessment study with 45 German utilities. Applying the clustering process to the sample, WP and TSD peer groups of a certain utility are obtained, where structural similarities are above a certain threshold value. Performance and cost indicators of comparable utilities have been evaluated, providing interesting data on general performance levels and spread among individual utilities. The survey underlines the high standard of German water supply in terms of reliability, quality, customer service, sustainability and economic efficiency.

In this paper, the results of the application of an integrated power and gas distribution grid planning are presented. The paper is based on the problem definition and the solution approaches, which have already been developed and published by the authors. Therefore, the focus is on the considered scenarios and the real energy distribution grids, as well as on the results and conclusions. These include, that the potential for injecting hydrogen to natural gas grids is very limited and, consequently, the conversion to hydrogen grids should be prioritized.

Abstract Das Leitprojekt TransHyDE, mit einer Laufzeit von April 2021 bis März 2025, bewertet und testet Wasserstoff‐Transportlösungen in insgesamt elf Demonstrationsprojekten. Die praktische Erprobung wird durch eine wissenschaftliche Begleitforschung ergänzt, zu der auch das Teilprojekt TransHyDE‐Norm zählt. Zur Umsetzung der in TransHyDE behandelten Transportoptionen bedarf es einheitlicher Vorgaben in Form von Normen, Standards und Zertifizierungsprogrammen. Ziel des Vorhabens ist es daher, die Normung, Zertifizierung und Standardisierung von Transport‐, Verteil‐ und Speicheroptionen für Wasserstoff bzw. andere chemische Energieträger ganzheitlich zu untersuchen. So sollen Regelungslücken aufgezeigt und Lösungsansätze entwickelt werden.

This file contains an assesment of the quantitative structure of the existing gas infrastructure focussing on asset elements that are known to be sensitive over hydrogen additions and that in case of modifications or renewal introduce significant cost.<br>

The mandate issued by the European Commission in 2007 invited CEN (the European standardization organization) to draw up standards for gas quality parameters for H-gas that were the broadest possible within reasonable costs. The result was the publication of the standard EN16726 "Gas infrastructure - Quality of gas - Group H" in 2015. Natural gas group L was left out due to the smaller trade volume in Europe. However, this standard neither includes the Wobbe Index nor the Gross Calorific Value, both key combustion parameters of natural gas. The reason for this is that during the drafting of the standard, the different stakeholders involved were not able to reach an agreement on the range of these parameters. No consensus was found due to regional differences (gas composition, installation, service practices) and lack of knowledge about the impact of gas quality variations for a few applications. To solve this lack in the standard, CEN is currently working for an agreement on the Wobbe Index range and on the Wobbe variation rate between all interested stakeholders (a so-called CEN SFGas WG "Pre-normative Study of H-Gas Quality Parameters"). To help this process and with the aim to bring a technical view on issues and remedies, MARCOGAZ (Technical Association of the European Natural Gas Industry) has launched an initiative among its members to identify, collect, and analyze results of current and past investigations related to the influence of natural gas quality on gas applications. This initiative includes the identification of research projects and solutions/technologies on how to deal with the variation in gas quality and its possible impact on the safety, efficiency, and emissions of the applications.

Loss of Field (LOF) is a common fault in synchronous machine operation, often resulting from short circuits in the field winding or inadvertent tripping of the field breaker. Effective protection of synchronous generators against LOF is crucial due to its potential to cause generator and grid instability, reduced operational efficiency, and significant machine damage. This paper presents an advanced method for initiating a trip signal to the Loss of Excitation (LOE) relay in synchronous generators, utilizing real-time data monitoring and adaptive techniques for reliable detection. The proposed method leverages variations in rotor angle, generator voltage, and reactive power to promptly identify LOF conditions, enabling rapid implementation of protective actions. A Genetic Algorithm (GA) is employed to optimize the fitness function, while MATLAB/Simulink is used to model both the generator and its excitation system (ST1A exciter). Simulation results demonstrate that this method significantly outperforms existing approaches in terms of detection speed, accuracy, and reliability. This advancement enhances the protection of synchronous generators against power swing phenomena and other system disturbances, thereby contributing to the robustness and stability of power networks.