Long-term monitoring programme of polychlorinated dioxins and polychlorinated furans in ambient air of Catalonia, Spain (1994-2015).

Reductions in concentrations of persistent organic pollutants were observed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a comparison of two consecutive decades ending in December 31, 2015 (n = 413) and compiled from a 48-station long-term air-monitoring network in Catalonia, Spain. Reductions were observed in geometric mean concentration of total PCDD/Fs, decreasing at a rate of 11% yr-1. Results reflect the relative success of improved pollution control measures at industry and traffic locations. At traffic and industrial locations, PCDD/Fs were reduced by around 68% (from 70 to 22 fg I-TEQ/m3) and 66% (from 57 to 19 fg I-TEQ/m3), respectively. The highest concentration of 1196 fg I-TEQ/m3 was observed during the first decade at an industrial location. The highest concentration over the second decade was at a background location during winter (674 fg I-TEQ/m3). Winter observations are generally higher than those recorded in summer, as evident in an 8-year period of moderate PCDD/F levels (<250 fg I-TEQ/m3, n = 143). PCDD/F congener profiles were identified has having less chlorinated PCDD/F, indicating the presence of nearby combustion sources at selected locations. More long-term sampling campaigns, combined with network optimization and integration into a meteorological model, can offer a tool for future PCDD/Fs control measures in not only Catalonia - but also applicable to other areas.

Analytical approach and occurrence for the determination of mass concentration of PCDD/PCDF and dl-PCB in flue gas emissions using long-term sampling devices.

In this work, a reliable methodology for the simultaneous analysis of PCDD/PCDF and dioxin-like PCB (dl-PCB) in flue gas emissions collected using continuous sampling devices is proposed. The analytical scheme followed the minimum requirements described in the EU standard EN-1948:1,2,3,4 according to samples containing large amounts of dioxins and dl-PCBs or samples collected over a long period of time of about 4 weeks. Parameters, such as reproducibility, precision, limits of detection (LOD), limits of quantification (LOQ), extract aliquot size, analytical blanks, extraction efficiency, as well as the amount of internal standards required for an accurate determination, were assessed. The findings demonstrate the suitability of the proposed analytical scheme for the analysis of PCDD/PCDF and PCB in samples collected using long-term sampling devices. The analysis of five different 5% v/v sample aliquots reported %RSD values lower than 10% for all of the 29 congeners at both low and high levels. Similarly, %RSD values were 3.2 and 2.0 for the low level samples and 0.9 and 1.1%RSD for the high level extracts for PCDD/PCDF and dl-PCB, respectively expressed in total TEQ units. Re-extraction provided values less than 3%, expressed in TEQ. Based on blank analyses, LOD values of 100 pg I-TEQ for PCDD/PCDF and 10 pg WHO-TEQ for dl-PCB were achieved when 5% v/v aliquots were analyzed. Finally, the proposed analytical approach was tested with samples from a wide range of combustion processes such as hazardous and municipal waste incinerators, as well as cement kilns (with and without waste co-incineration).

Assessment of polychlorinated dibenzo-p-dioxin and dibenzofuran emissions from a hazardous waste incineration plant using long-term sampling equipment.

The aim of this work is to evaluate the performance of a continuous monitoring system for the analysis of the mass concentration of PCDD/Fs from stationary sources. Data was acquired from a modern, state of the art, hazardous waste thermal treatment plant for a period of more than 2 years using a commercial available continuous monitoring system. The study consisted of a total of 16 samples, collected in periods from 1 week to 2 months resulting in an average of 360 m³ sampled flue gas per sample. The study showed the system was able to confirm that for a period of more than 2 years the plant was complying with the limit of 0.1 ng I-TEQ/Nm(3). In addition, the data showed the typical fingerprint of such installations which is useful for example in impact studies. Long-term samples were compared to five short-term samples (6 h) collected every 6 months during the study period. Principal component analysis was applied to PCDD/Fs obtained data as useful statistical tool to find out trends and similarities between different samples. Improvement in terms of representativeness of data was achieved through continuous assessment since the starts of the project. The obtained data was further used to determine the emission factor for this activity and the total annual PCDD/Fs release to the atmosphere.

Uncertainty assessment of polychlorinated dibenzo-p-dioxins and dibenzofuran and dioxin-like polychlorinated biphenyl analysis in stationary source sample emissions in accordance with the impending European standard EN-1948 using fly ashes.

The analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) present in stack gas emissions and solid residues from incinerators will be mandatory in the foreseeable future. European standard EN-1948 is in the process of being updated through the addition of a new Part 4 related to the analysis of the 12 dl-PCBs. Therefore, either a comprehensive and reliable method capable of analyzing all of these 29 compounds (12 dl-PCBs and 17 2,3,7,8-PCDD/Fs) needs to be developed, or the existing PCDD/F analytical procedure must be adapted to include the dl-PCBs. This study has taken the latter approach of modifying PCDD/F methodology and in particular the fractionation step, by isolating dioxins and dl-PCBs into separate fractions ready for high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC/HRMS) analysis. Results obtained from the analysis of Certified Reference Materials (CRM-490 and CRM-615) and fly ashes from the European Committee for Standardization (CEN) intercalibration study demonstrated that the proposed methodology is appropriate to determine the dl-PCBs in accordance with the impending European standard EN-1948. Uncertainty values obtained during the validation of the analytical methodology were 13% total I-TEQ (International Toxic Equivalent) for PCDD/Fs and 31% total WHO-TEQ (World Health Organization Toxic Equivalent) in the case of dl-PCBs. In addition, 'real' samples such as emissions and fly ashes were successfully analyzed following the proposed analytical method.

Dioxin abatement strategies and mass balance at a municipal waste management plant.

Since the thermal management of municipal solid waste (MSW) is considered to be one of the major sources of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), the purpose of this study was to show the results of a dioxin abatement program performed in the municipal waste incineration (MWI) plant of Tarragona (NE Spain). Previously, stack gas emission levels of PCDDs/PCDFs around 3.26 ng I-TEQ/Nm3 were determined when the gas-cleaning system consisted only of an electrostatic precipitator (ESP). Decreased levels, below 0.1 ng I-TEQ/ Nm3, were observed when a new air pollution control system was installed. This new system was improved by the injection of activated carbon, which helped to lower the levels of PCDDs/PCDFs to around 0.01 ng I-TEQ/Nm3. Considering the absence of a particular impact on herbages, soils, and ambient air around the plant, as reported in previous works, and the hypothesis that a modern installation could become a sink for dioxins instead of a source, a dioxin mass balance was evaluated. The study compared in a large-scale MWI plant the levels of PCDDs/PCDFs of all input and output contributors (MSW, ambient air, stack gas emission, fly ash, and slag) forming part of the inventory collected in various monitoring campaigns. The findings revealed a remarkable homogeneity in output values (between 1.19 and 2.62 ng I-TEQ/yr) in contrast to the large variability observed in input values. In the first sampling campaign, the dioxin content in MSW was around 64.15 ng I-TEQ/kg, and a negative balance of 7.68 g I-TEQ/yr was calculated. However, in the latest campaign, levels were about 2.36 ng I-TEQ/kg MSW, resulting in a positive balance of 2.28 g I-TEQ/yr.

Dioxin mass balance in a municipal waste incinerator.

A dioxin mass balance in an Spanish municipal waste incinerator (MWI) is presented. Input and output inventories from two sampling collection episodes including the analysis of PCDD/PCDF in urban solid waste (USW), stack gas emissions, fly ash and slag are reported. In one collection the levels of USW were around 8 pg I-TEQ/g and non-thermal destruction was observed overall. In the other collection the levels of USW were higher (around 64 pg I-TEQ/g) and the dioxin balance revealed a thermal destruction. Analysis of the different waste materials (textile, organic, plastic, wood and paper) was performed separately and the textile samples presented the highest levels.