Implementation of initial emission mitigation measures for 1,4-dioxane in Germany: Are they taking effect?

Biologically active filtration (BAF) for metabolic 1,4-dioxane removal from contaminated groundwater

1,4-Dioxane is a persistent contaminant that is not effectively removed by conventional water treatment processes. In this study, bench-scale granular activated carbon (GAC)-based biologically active filtration (BAF) systems were developed to metabolically degrade 1,4-dioxane at environmentally relevant levels (<1000 μg L-1). BAF was established using predeveloped biologically activated carbon particles by mixing a 1,4-dioxane-degrading microbial community with granular activated carbon. 1,4-Dioxane removal performance was examined at a range of 1,4-dioxane concentrations (100-1000 μg L-1), hydraulic loading rates (3.6-14 cm h-1), and with the presence of co-contaminants (natural organic matter (NOM) and 1,1-DCE). BAFs achieved 69 ± 7 % removal with an influent 1,4-dioxane concentration of 100 μg L-1 and hydraulic loading rates of 3.6-14 cm h-1, with the lowest effluent concentration of 21 μg L-1. The presence of NOM and 1,1-DCE negatively and irreversibly impacted 1,4-dioxane removal performance of BAF, and pretreatment processes to remove co-contaminants are crucial to maintain the 1,4-dioxane removal efficiency. Microbial analysis revealed the enrichment of 1,4-dioxane degrading species (CB1190-like bacteria) and functional genes responsible for 1,4-dioxane biodegradation (dxmB and aldh) at the top 12 cm of the columns, suggesting the effectiveness of biological 1,4-dioxane removal within short column lengths. This study demonstrated effective metabolic 1,4-dioxane removal at environmentally relevant concentrations by the BAFs, and can provide insights into designing better 1,4-dioxane remediation strategies.

France-Wide Monitoring of 1,4-Dioxane in Raw and Treated Water: Occurrence and Exposure Via Drinking Water Consumption

In recent years, 1,4-dioxane has emerged as a pollutant of increasing concern following widespread detection in the aquatic environment of several countries. This persistent contaminant with specific physical and chemical properties can be rapidly dispersed and transported to river banks, groundwater and drinking water. Given the limited data on its occurrence in France, it was considered necessary to assess the potential exposure of the French population to this compound in drinking water. An analytical method based on solid-phase extraction (SPE) combined with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed and validated during this study with a limit of quantification (LOQ) of 0.15 µg/L. Recoveries in natural water matrices ranged from 113 to 117% with a relative bias not exceeding 17%. This method was used for a nationwide campaign at almost 300 sites, evenly distributed over 101 French départements (administrative units), including some that were overseas. Of the 587 samples analysed, only 8% had a concentration that was greater than or equal to the LOQ. 1,4-Dioxane was detected mainly (63%) in raw and treated water from sites associated with historical industrial practices related to the use of chlorinated solvents. Concentrations of 1,4-dioxane ranging from 0.19 to 2.85 µg/L were observed in the raw water and from 0.18 to 2.46 µg/L in the treated water. Drinking water treatment plants using ozonation, granular activated carbon and chlorination have limited effectiveness in the removal of 1,4-dioxane. The results of this study are the first step towards bridging the knowledge gap in the occurrence of 1,4-dioxane in France.

Ubiquitous occurrence of 1,4-dioxane in drinking water of China and its ecological and human health risk

The occurrence and distribution of 1,4-dioxane was investigated in 280 source and finished drinking water samples from 31 Chinese cities, based on which its ecological and health risks were systematically evaluated. The findings demonstrated that 1,4-dioxane was detected in about 80.0 % samples with values ranging from n.d. to 7757 ng/L in source water and n.d. to 2918 ng/L in drinking water. 1,4-Dioxane showed limited removal efficiency using conventional coagulation-sedimentation-filtration processes (14 % ± 48 %), and a removal efficiency of 35 % ± 44 % using ozonation-biological activated carbon advanced treatment processes. Relatively higher concentrations, detection frequency and environmental risk were observed in Taihu Lake, Yellow River, Yangtze River, Zhujiang River, and Huaihe River mainly in the eastern and southern regions, where there are considerable industrial activities and comparatively high population densities. The widespread presence as by-products during manufacturing consumer products e.g., ethoxylated surfactants, suggested municipal wastewater discharges were the dominant source for the ubiquitous occurrence of 1,4-dioxane, while industrial activities, e.g. resin manufacturing, also contribute considerably to the elevated concentrations of 1,4-dioxane. The estimated risk quotients were in the range of <1.5 × 10-4 for ecological risk, <5.0 × 10-3 by oral exposure and < 5.0 × 10-2 by inhalation exposure for health risk, illustrating limited ecological harm to water environment or chronic toxicity to human health. For carcinogenic risk, 1,4-Dioxane presented a mean risk of 1.8 × 10-6 by oral exposure, which slightly surpassed the recommended acceptable levels of U.S. EPA (<10-6), and risk from inhalation exposure could be negligible. The pervasiveness in drinking water, low removal efficiencies during water treatment processes, and suspected health impacts, highlighted the necessity to set related water quality standards of 1,4-dioxane in order to improve water environment in China.

Occurrence, Distribution, and Environmental Behavior of Persistent, Mobile, and Toxic (PMT) and Very Persistent and Very Mobile (vPvM) Substances in the Sources of German Drinking Water

Persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances have been recognized as a threat to both the aquatic environment and to drinking water resources. These substances are currently prioritized for regulatory action by the European Commission, whereby a proposal for the inclusion of hazard classes for PMT and vPvM substances has been put forward. Comprehensive monitoring data for many PMT/vPvM substances in drinking water sources are scarce. Herein, we analyze 34 PMT/vPvM substances in 46 surface water, groundwater, bank filtrate, and raw water samples taken throughout Germany. Results of the sampling campaign demonstrated that known PMT/vPvM substances such as 1H-benzotriazole, melamine, cyanuric acid, and 1,4-dioxane are responsible for substantial contamination in the sources of German drinking water. In addition, the results revealed the widespread presence of the emerging substances 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and diphenylguanidine (DPG). A correlation analysis showed a pronounced co-occurrence of PMT/vPvM substances associated predominantly with consumer or professional uses and also demonstrated an inhomogeneous co-occurrence for substances associated mainly with industrial use. These data were used to test the hypothesis that most PMT/vPvM substances pass bank filtration without significant concentration reduction, which is one of the main reasons for introducing PMT/vPvM as a hazard class within Europe.