Impact of industrial waste water treatment plants on Dutch surface waters and drinking water sources

Molecular docking and molecular dynamics simulation decoding molecular mechanism of EDCs binding to hERRγ

CONTEXT

Human estrogen-related receptor γ (hERRγ) is a key protein involved in various endocrines and metabolic signaling. Numerous environmental endocrine-disrupting chemicals (EDCs) can impact related physiological activities through receptor signaling pathways. Focused on hERRγ with 4-isopropylphenol, bisphenol-F (BPF), and BP(2,2)(Un) complexes, we executed molecular docking and multiple molecular dynamics (MD) simulations along with molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) and solvation interaction energy (SIE) calculation to study the detailed dynamical structural characteristics and interactions between them. Molecular docking showed that hydrogen bonds and hydrophobic interactions were the prime interactions to keep the stability of BPF-hERRγ and hERRγ-BP(2,2)(Un) complexes. Through MD simulations, we observed that all complexes reach equilibrium during the initial 50 ns of simulation, but these three EDCs lead to local structure changes in hERRγ. Energy results further identified key residues L268, V313, L345, and F435 around the binding pockets through CH-π, π-π, and hydrogen bonds interactions play an important stabilizing role in the recognition with EDCs. And most noticeable of all, hydrophobic methoxide groups in BP(2,2)(Un) is useful for decreasing the binding ability between EDCs and hERRγ. These results may contribute to evaluate latent diseases associated with EDCs exposure at the micro level and find potential substitutes.

METHOD

Autodock4.2 was used to conduct the molecular docking, sietraj program was performed to calculate the energy, and VMD software was used to visualize the structure. Amber18 was conducted to perform the MD simulation and other analyses.

Assessing the Persistence and Mobility of Organic Substances to Protect Freshwater Resources

Persistent and mobile organic substances are those with the highest propensity to be widely distributed in groundwater and thereby, when emitted at low-levels, to contaminate drinking water extraction points and freshwater environments. To prevent such contamination, the European Commission is in the process of introducing new hazard classes for persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances within its key chemical regulations CLP and REACH. The assessment of persistence in these regulations will likely be based on simulated half-life, t _1/2, thresholds; the assessment of mobility will likely be based on organic carbon-water distribution coefficient, K _OC, thresholds. This study reviews the use of t _1/2 and K _OC to describe persistence and mobility, considering the theory, history, suitability, data limitations, estimation methods, and alternative parameters. For this purpose, t _1/2, K _OC, and alternative parameters were compiled for substances registered under REACH, known transformation products, and substances detected in wastewater treatment plant effluent, surface water, bank filtrate, groundwater, raw water, and drinking water. Experimental t _1/2 values were rare and only available for 2.2% of the 14 203 unique chemicals identified. K _OC data were only available for a fifth of the substances. Therefore, the usage of alternative screening parameters was investigated to predict t _1/2 and K _OC values, to assist weight-of-evidence based PMT/vPvM hazard assessments. Even when considering screening parameters, for 41% of substances, PMT/vPvM assessments could not be made due to data gaps; for 23% of substances, PMT/vPvM assessments were ambiguous. Further effort is needed to close these substantial data gaps. However, when data is available, the use of t _1/2 and K _OC is considered fit-for-purpose for defining PMT/vPvM thresholds. Using currently discussed threshold values, between 1.9 and 2.6% of REACH registered substances were identified as PMT/vPvM. Among the REACH registered substances detected in drinking water sources, 24-30% were PMT/vPvM substances.

A novel PES-C/(GO-COOH/Ce) blended membrane for treating heavy-metal-ion wastewater

A GO-COOH/Ce complex was introduced into a phenolphthalide polythersulfone (PES-C) matrix to prepare a PES-C/(GO-COOH/Ce) blended membrane by nonsolvent-induced phase transformation (NIPS). FT-IR and EDS analysis confirmed that the GO-COOH/Ce complex was successfully incorporated into the PES-C matrix. SEM showed that the blended membrane possessed an asymmetric structure with finger-like pores. The best comprehensive performance was obtained for a PES-C/(GO-COOH/Ce) blended membrane prepared using 0.1 wt.% of the GO-COOH/Ce complex in the casting liquid. The specific results for the blended membrane were as follows: the fluxes of pure water and 0.1 g/L lead nitrate solution were 272 L/m2·h and 214 L/m2·h, respectively; the rejection of bovine serum albumin (BSA) was 99.4%; the rejection of lead ions was 96.2%; the moisture content was 10.9%; the contact angle was 67.1°; the Young's modulus was 35.7 MPa; and the flux recovery ratio was 1.5 times higher than that of the pure PES-C membrane. The antibacterial-zone diameters of the PES-C/(GO-COOH/Ce) blended membrane used against Escherichia coli and Staphylococcus aureus were 2.50 cm and 2.88 cm, respectively. A catalytic cleaning test showed a flux recovery ratio of 63% after washing the PES-C/(GO-COOH/Ce) blended membrane with a 0.2 g/L acetic acid solution for 0.5 h.

Treatability of hazardous substances in industrial wastewater: case studies for textile manufacturing and leather production sectors

Hazardous substances used and produced by different industrial activities pose a potential risk to the environment and to human health. Different physicochemical and/or biological processes are used in industrial wastewater treatment; these methods, however, may not be effective in removing these substances. This study was carried out to comparatively evaluate the removal of hazardous substances through conventional wastewater treatment processes that are used by major industries in Turkey. A four-season monitoring study was carried out in textile manufacturing and leather production sectors, representing industrial activities in Turkey. Samples were analyzed for 45 priority substances defined by the European Union and 250 specific pollutants listed in the Turkish Regulation on Surface Water Quality. For both wastewaters, where biological treatment was performed after pretreatment, their characteristics showed that organics were almost completely removed. except for dichloromethane (44-51% removals) and dioxin and dioxin-like compounds (64-69% removals). Additionally, different removal ratios (16-97%) were obtained for metals; the poorer removal was observed for B, Ba, Ag, Sb, and Si. The remaining metals (Cu, Pb, Sb, V, Si for textile; Cr, Cu, Sb, Si for leather effluents) in the treated wastewaters were still higher than environmental quality standards (EQS) of receiving water bodies. The study revealed that existing treatment processes were not adequate for efficient hazardous substance removal and there is an urgent need to improve them. Finally, advanced treatment technologies were suggested for specific pollutants together with their unit treatment costs.

Removal and environmental risk assessment of contaminants of emerging concern from irrigation waters in a semi-closed microalgae photobioreactor

The present study evaluated the efficiency of a semi-closed, tubular, horizontal photobioreactor (PBR) to treat a mixture of irrigation and rural drainage water, focusing in the removal of different contaminants of emerging concern (CECs), and evaluating the environmental impact of the resulting effluent. Target CECs included pharmaceuticals, personal care products and flame retardants. Of the 13 compounds evaluated, 11 were detected in the feed water entering the PBR, and diclofenac (DCF) (1107 ng L^-1) and N,N-diethyl-toluamide (DEET) (699 ng L^-1) were those present at the greatest concentrations. The best removal efficiencies were achieved for the pharmaceuticals diazepam (94%), lorazepam (LZP) (83%) and oxazepam (OXA) (71%), and also for ibuprofen (IBU) (70%). For the rest of the CECs evaluated, attenuation was similar to that obtained after conventional wastewater treatment, ranging from basically no elimination (carbamazepine (CBZ) and tris-(2-chloroethyl) phosphate (TCEP)) to medium efficiencies (DCF and tributyl phosphate (TBP) (50%)). Environmental risk assessment based on hazard quotients (HQs) resulted in HQ values < 0.1 (no risk associated) for most of the compounds and most of the trophic levels considered. Values between 1 and 10 (moderate risk) were obtained for tonalide (AHTN) (fish) and CBZ (invertebrates). The most sensitive trophic level was green algae, whereas fish and aquatic plants were the most resilient. Our results suggest that microalgae-based treatments could become a green, cost-effective alternative to conventional wastewater treatment regarding the efficient elimination of these contaminants.

Towards 'one substance - one assessment': An analysis of EU chemical registration and aquatic risk assessment frameworks

With the Green Deal the EU aims to achieve a circular economy, restore biodiversity and reduce environmental pollution. As a part of the Green Deal a 'one-substance one-assessment' (OS-OA) approach for chemicals has been proposed. The registration and risk assessment of chemicals on the European market is currently fragmented across different legal frameworks, dependent on the chemical's use. In this review, we analysed the five main European chemical registration frameworks and their risk assessment procedures for the freshwater environment, covering 1) medicines for human use, 2) veterinary medicines, 3) pesticides, 4) biocides and 5) industrial chemicals. Overall, the function of the current frameworks is similar, but important differences exist between the frameworks' environmental protection goals and risk assessment strategies. These differences result in inconsistent assessment outcomes for similar chemicals. Chemicals are also registered under multiple frameworks due to their multiple uses, and chemicals which are not approved under one framework are in some instances allowed on the market under other frameworks. In contrast, an OS-OA will require a uniform hazard assessment between all different frameworks. In addition, we show that across frameworks the industrial chemicals are the least hazardous for the freshwater environment (median PNEC of 2.60E-2 mg/L), whilst biocides are the most toxic following current regulatory assessment schemes (median PNEC of 1.82E-4 mg/L). Finally, in order to facilitate a successful move towards a OS-OA approach we recommend a) harmonisation of environmental protection goals and risk assessment strategies, b) that emission, use and production data should be made publicly available and that data sharing becomes a priority, and c) an alignment of the criteria used to classify problematic substances.

Shifting the imbalance: Intentional reuse of Dutch sewage effluent in sub-surface irrigation

Worldwide, agricultural irrigation currently accounts for 69% of freshwater withdrawal. Countries with a temperate climate, such as the Netherlands, experience periodic freshwater shortages in agriculture. The pressure on available freshwater will increase due to climate change and a growing demand for freshwater by e.g. industrial activities. Possible alternative water resources are considered in order to meet the current and future water demand. In this study we explore where, and how much, sewage treatment plant (STP) effluent can directly be reused in agricultural sub-surface irrigation (SSI) during an average and a dry season scenario, for all active (335) Dutch STPs. SSI systems may have a higher water demand as part of the STP effluent is transported with groundwater flow, although aboveground irrigation has a loss of water due to interception. Furthermore, such aboveground irrigation systems provide direct contact of crops with irrigation water. SSI systems provide a soil barrier which may function as a filter and buffer zone. In the Dutch situation, direct intentional reuse of STP effluent can fulfill up to 25% of croplands SSI water demand present within a five-kilometer transport buffer from the STPs during an average season and 17% during a dry season. Hereto, respectively, 78% and 84% of the total available Dutch STP effluent would be used. Thus, the intentional direct STP effluent reuse in agricultural SSI has the potential to satisfy a significant amount of the agricultural water demand at a national scale, presuming responsible reuse: safe applications for humans and environment and no limiting effects on water availability for other actors.

Following the Water: Characterising de facto Wastewater Reuse in Agriculture in the Netherlands

De facto (or indirect) wastewater reuse is the practice of extracting from surface water bodies which are impacted by treated wastewater (TWW) for anthropogenic use. The extent to which surface water bodies in the Netherlands are impacted by TWW is poorly understood, and the distribution of de facto reuse even more so. This study addresses these knowledge gaps, with a focus on reuse for agricultural irrigation. This is achieved via a novel application of the Water Framework Directive (WFD) Explorer water quality model, allowing for the distribution of different flow components—namely TWW and flow from transboundary rivers—to be discerned for the national surface water network. When paired with data on surface water extractions for irrigation, this identifies notable areas of de facto reuse. Results show that during dry conditions, TWW is a significant flow component in many surface water bodies, particularly in smaller streams located close to WWTPs. De facto reuse is indicated as widespread, with several key areas identified in which extractions are from impacted surface water bodies. This study represents a first attempt to directly link TWW emissions to agricultural irrigation, highlighting a mechanism by which wastewater-associated contaminants can propagate through the hydrological system.