•Microplastics (sized 20 – 5000 µm) numbers in Dutch tap water are low (< 2MP/L).•Drinking water treatment removes the vast majority of microplastics from intake surface water.•Samples taken in ...groundwater treatment facility contain hardly any microplastics compared to surface water.•Compared to other sources, such as air, food and beverages, the exposure contribution of tap water is minimal.•Microplastics accumulate in the environment during natural water treatment steps, such as sedimentation and soil passage.
Microplastics are ubiquitous and consequently enter drinking water treatment plants. Knowledge of the microplastic fate in drinking water production is still very limited, although explorative studies have shown tap water contains low contents of microplastics. In this study, we measure microplastic concentrations in drinking water sources and assess the effectiveness of various drinking water treatment facilities to reduce the microplastic concentrations in water to gain insight into the fate of microplastics. Two analytical techniques, laser direct infrared spectroscopy (LDIR) and optical microscopy, have been applied to cover the particle size range from 20 µm to 5 mm. In total five different drinking water sites were investigated using four different types of raw water (groundwater, surface water, dune filtrate and riverbank filtrate) for drinking water production.
This research shows that drinking water treatment removes the majority of microplastics and that concentration of microplastics larger than 20 µm in tap water is less than 2 microplastics particles per litre. Between the different raw water sources it is found that groundwater had by far the lowest microplastics concentrations (< 1.000 microplastics per m3) and the highest concentration was found in riverine water, up to 460.000 particles per m3, specifically in the Lek Canal () (a canal connected to the river Rhine). On average the most abundant plastics found are polyamide (PA, 33%), polyethylene terephthalate (PET, 15%), rubbers (10%), polyethylene (PE, 10%) and chlorinated polyethylene (CPE, 7%). This study also showed that natural treatment steps, such as dune infiltration and sedimentation, remove microplastics effectively. However, this may introduce an adverse effect where microplastics potentially accumulate in the sediment and environment.
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A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These ...charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H2O2, activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca2+ solutions compared to similar concentrations of Na+, while that of anionic compounds is three fold weaker in SO42- solutions compared to equal concentrations of Cl−.
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► We show the influence of different inorganic ions on the sorption of organic ions. ► Column experiments are used to evaluate in the influence of the different salts. ► Ion-exchange materials can be a useful material in water treatment in combination with AC.
UV/H2O2 processes in drinking water treatment may generate byproducts which cause an increased response in Ames fluctuation assays. As this probably involves a mixture of substances in very low ...concentrations, it is challenging to identify the individual byproducts. Therefore it was studied under which conditions mutagenic byproducts are formed and how this can be prevented. It was found that positive Ames fluctuation test responses only are obtained when Medium Pressure UV lamps are used, and not with Low Pressure lamps. This probably is explained by the photolysis of nitrate, which plays an important role in the formation of mutagenic byproducts. The most important parameters involved in the formation of such byproducts were demonstrated to be the nitrate concentration, the natural organic matter, the UV spectrum of the lamps, and the UV dose applied. These factors explain up to 74–87% of the Ames fluctuation test responses after UV/H2O2 drinking water treatment. By taking this into account, drinking water utilities can estimate whether UV processes applied in their case may cause the formation of mutagenic byproducts, and how to take measures to prevent it.
•UV disinfection of drinking water at low UV dose does not seem to give mutagenic byproducts.•LP UV lamps do not cause the formation of mutagenic byproducts.•Formation of mutagenic byproducts by MP UV lamps largely depends on dose, nitrate and NOM concentration.•Formation of mutagenic byproducts is caused by photolysis of nitrate and reaction with NOM.
At first it seemed that UV processes for disinfection and advanced oxidation were "harmless", as they didn't involve the addition of "dangerous" chemicals nor seemed to result in the formation of ...toxic byproducts. However, recently it has become clear that also during UV processes mutagentic/genotoxic byproducts may be formed. It was found that these are nitrogen containing aromatic compounds, which are formed by the reaction of photolysis products of nitrate with (photolysis products of) natural organic matter. Now more has become clear on the formation process of these compounds, it is possible to limit or even prevent their formation during e.g. UV/H
O
processes. Besides, it appears to be possible to remove such byproducts by means of filtration processes. Thus, UV based processes can safely be applied in water treatment.
This guidance document provides a tiered framework for risk assessors and facilitates risk managers in making decisions concerning the approval of active substances (AS) that are chemicals in plant ...protection products (PPPs) and biocidal products, and authorisation of the products. Based on the approaches presented in this document, a conclusion can be drawn on the impact of water treatment processes on residues of the AS or its metabolites in surface water and/or groundwater ed for the production of drinking water, i.e. the formation of transformation products (TPs). This guidance enables the identification of actual public health concerns from exposure to harmful compounds generated during the processing of water for the production of drinking water, and it focuses on water treatment methods commonly used in the European Union (EU). The tiered framework determines whether residues from PPP use or residues from biocidal product use can be present in water at water ion locations. Approaches, including experimental methods, are described that can be used to assess whether harmful TPs may form during water treatment and, if so, how to assess the impact of exposure to these water treatment TPs (tTPs) and other residues including environmental TPs (eTPs) on human and domesticated animal health through the consumption of TPs via drinking water. The types of studies or information that would be required are described while avoiding vertebrate testing as much as possible. The framework integrates the use of weight‐of‐evidence and, when possible alternative (new approach) methods to avoid as far as possible the need for additional testing.
► Reaction kinetics and CFD-model to predict conversion in UV/H2O2 reactors. ► Tested for three different UV lamps. ► Tested for six different reactor geometries. ► Tested for various water matrices ...and qualities. ► Model gives good prediction of conversion for organic micropollutants.
The UV/H2O2 advanced oxidation process is increasingly applied as a barrier against organic micro pollutants in drinking water treatment. Adequate modeling of the purification process, resulting in a reliable prediction of the reactor performance, would make it possible to optimize the operating parameters as a function of seasonal or diurnal fluctuations in the influent composition, and thus save energy while still guaranteeing safe drinking water. We recently developed two design tools to predict full scale performance of UV/H2O2 reactors: the UVPerox I and II models. UVPerox I is based on a kinetic model, describing both photolysis and oxidation. By means of Computational Fluid Dynamics (CFD) calculations of the reactor the UV dose distribution inside the reactor can be calculated, while the kinetic model gives the conversion as a function of the UV dose. UVPerox I is shown to be applicable to reactors equipped with Low Pressure (LP) or Dielectric Barrier Discharge (DBD) UV lamps, using a broad range of organic compounds, resulting in a <5–10% deviation from experimental data for different water matrix compositions. The conversion of micro pollutants as a function of the UV dose can also be experimentally determined, using a collimated beam (CB) set-up. The dose response curves thus obtained can also be directly implemented in the CFD-model of the reactor (UVPerox II). Using several model compounds UVPerox II is shown to be applicable to reactors equipped with three kinds of UV lamps (LP-, MP- UV and DBD lamps), each with its own emission spectrum. The deviation from experimental data was found to be <5–10%, independent of the composition of the water matrix. Both models were applied to several reactor geometries. Good agreement was obtained between both models and the actual conversion data for three types of UV lamps in various pilot reactors and water types.
In the context of an increasing societal demand for transparency in parallel with rapidly increasing numbers and concentrations of substances found in drinking water, this paper investigates how ...different drinking water customers perceive their tap water quality, and possible risks involved. Empirically, the paper draws on results from a representative survey, a series of interviews and focus groups conducted in the Netherlands, applying both a traditional and modern segmentation approach based on four types of perspectives (“aware and committed”, “down to earth and confident”, “egalitarian and solidary”, and “quality and health concerned”). Although in general it was found that people’s trust in tap water is high, certain groups are more concerned about water quality and health effects than others. It was shown that transparency and the availability of more information about water treatment and quality would contribute to increasing customer trust. It was also observed that, at least in the Netherlands, people have a larger trust in drinking water companies than in other institutions. Therefore, instead of referring to standards made by other institutions, it is recommended that water companies themselves provide information on water quality and emphasize their treatment procedures.
Background
Safe and clean drinking water is essential for human life. Persistent, mobile and toxic (PMT) substances and/or very persistent and very mobile (vPvM) substances are an important group of ...substances for which additional measures to protect water resources may be needed to avoid negative environmental and human health effects. PMT/vPvM substances do not sufficiently biodegrade in the environment, they can travel long distances with water and are toxic (those that are PMT substances) to the environment and/or human health. PMT/vPvM substance research and regulation is arguably in its infancy and in order to get in control of these substances the following (non-exhaustive list of) knowledge gaps should to be addressed: environmental occurrence; the suitability of currently available analytical methods; the effectiveness and availability of treatment technologies; the ability of regional governance and industrial stewardship to contribute to safe drinking water while supporting innovation; the ways in which policies and regulations can be used most effectively to govern these substances; and, the identification of safe and sustainable alternatives.
Methods
The work is the outcome of the third PMT workshop, held in March 2021, that brought together diverse scientists, regulators, NGOs, and representatives from the water sector and the chemical sector, all concerned with protecting the quality of our water resources. The online workshop was attended by over 700 people. The knowledge gaps above were discussed in the presentations given and the attendees were invited to provide their opinions about knowledge gaps related to PMT/vPvM substance research and regulation.
Results
Strategies to closing the knowledge, technical and practical gaps to get in control of PMT/vPvM substances can be rooted in the Chemicals Strategy for Sustainability Towards a Toxic Free Environment from the European Commission, as well as recent advances in the research and industrial stewardship. Key to closing these gaps are: (i) advancing remediation and removal strategies for PMT/vPvM substances that are already in the environment, however this is not an effective long-term strategy; (ii) clear and harmonized definitions of PMT/vPvM substances across diverse European and international legislations; (iii) ensuring wider availability of analytical methods and reference standards; (iv) addressing data gaps related to persistence, mobility and toxicity of chemical substances, particularly transformation products and those within complex substance mixtures; and (v) advancing monitoring and risk assessment tools for stewardship and regulatory compliance. The two most effective ways to get in control were identified to be source control through risk governance efforts, and enhancing market incentives for alternatives to PMT/vPvM substances by using safe and sustainable by design strategies.
An increasing number of people want to reduce their environmental footprint by using harvested rainwater as a source for drinking water. Moreover, implementing rainwater harvesting (RWH) enables ...protection against damage caused by increasing precipitation frequency and intensity, which is predicted for Western Europe. In this study, literature data on rainwater quality were reviewed, and based on Dutch climatological data the usable quantity of rainwater in the Netherlands was calculated. For two specific cases, (1) a densely populated city district and (2) a single house in a rural area, the total costs of ownership (TCO) for decentralized drinking water supply from harvested rainwater was calculated, and a life cycle assessment (LCA) was made. For the single house it was found that costs were very high (€60–€110/m3), and the environmental impact would not decrease. For the city district, costs would be comparable to the present costs of centralized drinking water production and supply, but the environmental benefit is negligible (≤1‰). Furthermore, it was found that the amount of rainwater that can be harvested in the city district only covers about 50% of the demand. It was concluded that the application of rainwater harvesting for drinking water production in the Netherlands is not economically feasible.
Activated carbon is employed for the adsorption of organic micropollutants (OMPs) from water, typically present in concentrations ranging from ng L−1 to μg L−1. However, the efficacy of OMP removal ...is considerably deteriorated due to competitive adsorption from background dissolved organic matter (DOM), present at substantially higher concentrations in mg L−1. Interpreting the characteristics of competitive DOM is crucial in predicting OMP adsorption efficiencies across diverse natural waters. Molecular weight (MW), aromaticity, and polarity influence DOM competitiveness. Although the aromaticity-related metrics, such as UV254, of low MW DOM were proposed to correlate with DOM competitiveness, the method suffers from limitations in understanding the interplay of polarity and aromaticity in determining DOM competitiveness. Here, we elucidate the intricate influence of aromaticity and polarity in low MW DOM competition, spanning from a fraction level to a compound level, by employing direct sample injection liquid chromatography coupled with ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry. Anion exchange resin pre-treatment eliminated 93% of UV254-active DOM, predominantly aromatic and polar DOM, and only minimally alleviated DOM competition. Molecular characterization revealed that nonpolar molecular formulas (constituting 26% PAC-adsorbable DOM) with medium aromaticity contributed more to the DOM competitiveness. Isomer-level analysis indicated that the competitiveness of highly aromatic LMW DOM compounds was strongly counterbalanced by increased polarity. Strong aromaticity-derived π-π interaction cannot facilitate the competitive adsorption of hydrophilic DOM compounds. Our results underscore the constraints of depending solely on aromaticity-based approaches as the exclusive interpretive measure for DOM competitiveness. In a broader context, this study demonstrates an effect-oriented DOM analysis, elucidating counterbalancing interactions of DOM molecular properties from fraction to compound level.
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•Cutting-edge RPLC-FT-ICR-MS revealed DOM competition at a fraction-to-compound level.•Resin removed 93% of UV254-active DOM, yet with minimal alleviation of DOM competition.•26% molecular formulas of PAC-adsorbable DOM dominated the overall competitiveness.•Polarity robustly counterbalanced the competitiveness of aromatic DOM.•Aromaticity enhanced nonpolar DOM adsorption but exerts no impact on polar DOM.
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