Microplastics from headwaters to tap water: occurrence and removal in a drinking water treatment plant in Barcelona Metropolitan area (Catalonia, NE Spain).

Nowadays, the presence of microplastics in drinking water is of concern worldwide due to potential impacts on human health. This paper has examined the presence of microplastics along the Llobregat river basin (Catalonia, Spain) and studied their behaviour and elimination along the drinking water treatment plant (DWTP). Due to different water composition, different sampling and sample preparation protocols were used to determine microplastics from river water and in the DWTP. Identification of microplastics of size range from 20 µm to 5 mm was performed by fourier-transform infrared spectroscopy (FTIR). Microplastics were detected in 5 out of 7 points along the Llobregat basin, with concentrations ranging between non-detected and 3.60 microplastics/L. In the intake of the DWTP, the mean concentration was 0.96 ± 0.46 microplastics/L (n=5), with a predominance of polyester (PES) and polypropylene (PP) and at the outlet the mean concentration was of 0.06 ± 0.04 microplastics/L with an overall removal efficiency of 93 ± 5%. Sand filtration was identified as the key stage in microplastic removal (78 ± 9%). Furthermore, the results showed that ultrafiltration/reverse osmosis (advanced treatment) is more effective for microplastic removal than ozonation/carbon filtration stage (upgraded conventional treatment). In addition, a preliminary migration test of the different materials used in the DWTP has been performed to identify potential sources of microplastics in each treatment step.

Formation of new disinfection by-products of priority substances (Directive 2013/39/UE and Watch List) in drinking water treatment.

The degradation of priority substances (Directive 2013/39/UE and Watch List) by chlorine dioxide (ClO2) and the formation of disinfection by-products (DBPs) in a drinking water treatment plant (DWTP) located near Barcelona (NE Spain) were investigated. For the first time, the reactivity with ClO2 of several compounds frequently found at the entrance of the DWTP such as erythromycin, clarithromycin, chlorpyrifos, and imidacloprid was evaluated in both simulated and real conditions. To identify potential DBPs, experiments were performed at laboratory scale by simulating the operational disinfection conditions in the DWTP. Liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) working in full scan and target-MS/HRMS modes was used for the identification of the generated DBPs. Several new DBPs were found, three from erythromycin, one from clarithromycin, two from chlorpyrifos, and one from imidacloprid. Then, the presence and behavior through DWTP treatment of priority substances and their DBPs were investigated in order to evaluate their generation in real working conditions. Two of the potential DBPs, anhydroerythromycin, and N-desmethyl clarithromycin were already identified in the raw water of DWTP, but N-desmethyl clarithromycin was also generated after the chlorine dioxide treatment step. Both compounds were eliminated by the treatments applied in the DWTP; anhydroerythromycin was eliminated after ozonation in the upgraded conventional treatment and after reverse osmosis in the advanced treatment while N-desmethyl clarithromycin is recalcitrant in the upgraded conventional treatment, but it was eliminated by reverse osmosis.

Simultaneous analysis of 11 haloacetic acids by direct injection-liquid chromatography-electrospray ionization-triple quadrupole tandem mass spectrometry and high resolution mass spectrometry: occurrence and evolution in chlorine-treated water.

A fast, simple, selective, and sensitive method for the analysis of 11 haloacetic acids (HAAs) in chlorine-treated water has been developed. The method is based on liquid chromatography-electrospray ionization-triple quadrupole tandem mass spectrometry (LC/ESI-QqQ-MS/MS) with direct injection of the aqueous sample. The main novelty of this method over the previously published procedures based on different techniques of mass spectrometry with direct injection is the combination of the simultaneous analysis of three types of HAAs (chlorinated, brominated, and iodinated) with its simplicity and low LODs (0.01-0.6 µg/L), avoiding the use of ion-pairing reagents for LC as well as the complexity and high cost of other techniques such as ion chromatography and capillary electrophoresis coupled to tandem mass spectrometry (IC-MS/MS and CE-MS/MS). The developed method was compared with another procedure carried out in our laboratory based on direct injection-liquid chromatography-electrospray ionization-high-resolution mass spectrometry with an Orbitrap analyzer (LC/ESI-Orbitrap-HRMS). The application of this technique to HAA analysis had not been previously described. LODs achieved by LC-HRMS (0.01-2 µg/L) were higher than the ones obtained by LC-MS/MS. Therefore, the LC/ESI-QqQ-MS/MS method was applied to the analysis of real samples. Quality parameters were calculated with satisfactory results and real samples related to three drinking water treatment plants (DWTPs), tap water, and the drinking water distribution system of Barcelona area (Catalonia, NE Spain) were analyzed. Furthermore, the evolution of HAA concentration along time in a DWTP-treated water sample was studied.

Multiresidue analysis of 24 Water Framework Directive priority substances by on-line solid phase extraction-liquid chromatography tandem mass spectrometry in environmental waters.

This paper reports the development of a fully multiresidue and automated on-line solid phase extraction (SPE) - liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of 24 priority substances (PS) belonging to different classes (pesticides, hormones or pharmaceuticals) included in the Directive 2013/39/UE and the recent Watch List (Decision 2015/495) in water samples (drinking water, surface water, and effluent wastewaters). LC-MS/MS conditions and on-line SPE parameters such as sorbent type, sample and wash volumes were optimized. The developed method is highly sensitive (limits of detection between 0.1 and 1.4ngL-1) and precise (relative standard deviations lower than 8%). As part of the method validation studies, linearity, accuracy and matrix effects were assessed. The main advantage of this method over traditional off-line procedures is the minimization of tedious sample preparation increasing productivity and sample throughput. The optimized method was applied to the analysis of water samples and the results revealed the presence of 16 PS in river water and effluent water of wastewater treatment plants.

Simultaneous determination of the potential carcinogen 1,4-dioxane and malodorous alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes in environmental waters by solid-phase extraction and gas chromatography tandem mass spectrometry.

1,4-dioxane is a synthetic industrial solvent used in various industrial processes, and it is a probable human carcinogen whose presence in the aquatic environment is frequently reported. Alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes are compounds that have been identified as causing several odor episodes in waters over the last years, with the result of downtime of drinking water treatment plants. According to published studies, some of these episodes may be caused either by resins synthesis processes, or by industrial residues added to dehydrated sludge in wastewater treatment plants (WWTPs) in order to increase biogas production efficiency. Analytical methods based on closed loop stripping analysis (CLSA) are routinely used when taste and odor events appear, but this technique has demonstrated to be unsuitable to determine 1,4-dioxane at trace levels. In this context, drinking water companies tend to focus on determining odorous compounds, but not on those compounds that are potentially harmful. The suitability of a SPE method and further analysis by GC/MS-MS to simultaneously determine 1,4-dioxane and alkyl-1,3-dioxanes and dioxolanes has been demonstrated. Recoveries in surface waters spiked at 25ng/L ranged from 76% to 105%, whereas method quantification limits (MQLs) varied from 0.7 to 26ng/L for dioxanes, and dioxolanes and 50ng/L for 1,4-dioxane. Uncertainties were evaluated at two different concentrations, 0.02µg/L and 0.4µg/L, with values of 25% for 1,4-dioxane, and of 16-28% for alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes for the later. The methodology has been successfully applied to samples from the aquifer of the Llobregat River (NE. Spain).