Investigation of the occurrence of microplastics from the waste water at five different textile production facilities in Sweden

Transcription

1 Investigation of the occurrence of microplastics from the waste water at five different textile production facilities in Sweden Swerea IVF-report 18004

2 REPORT Postal address Swerea IVF AB Box 104 SE MÖLNDAL Tfn +46 (0) Fax +46 (0) Client Visiting address Argongatan 30, SE MÖLNDAL Org. nr VAT no. SE Client s ref. no. Naturvårdsverket Samhällsavdelningen Contact person Our ref. no STOCKHOLM Yvonne Augustsson Object Investigation of the occurrence of microplastics from the waste water at five different textile production facilities in Sweden. Picture 1. Example of bundles with fibres This report may not be reproduced other than in full, except with prior written approval of the issuing laboratory. General terms and conditions for Swerea IVF apply and are available on or may be ordered from Swerea IVF. Page 1 of 23

3 Table of content page Summary... 3 Introduction... 4 Test procedure... 5 Results... 7 Conclusions and discussion... 9 Appendix 1 Pictures of fibres from microscopic particle counting Appendix 2 Pictures of organic particles from microscope and FTIR spectra Appendix 3 Tables with detected non-fibre shaped particles and fibre shaped particles presented in number per size Page 2 of 23

4 Summary Swerea IVF investigated the occurrence of microplastics in the waste water from five different textile production facilities in Sweden. The facilities were chosen by the Swedish Environmental Protection Agency and had agreed to the study and they were also assured anonymity. The waste water samples were collected at the outlet of the equalisation basin during one week of production. The method used in the investigation was an In-House method developed by Swerea IVF AB which includes filtration and a microscopic analysis. The particle counting was performed using a software programme that characterize and count the number of fibre shaped particles and non-fibre shaped particles. Depending on the number of particles in the samples, different filter sizes were used. The parameters used for fibre shaped particles detection was a minimum fibre length of 100µm and minimum fibre width of 50µm. On some of the samples additional FTIR (Fourier Transformed Infrared Spectroscopy) was used to identify the fibres and particles. The results conclude that all five production facilities have emissions of microplastics in the waste water, both fibre shaped and non-fibre shaped. The amount of fibre shaped particles as a percentage of the total detected particles varied between 27 %-46 %. The released number of fibre shaped particles varied between 1, millions per production week. Due to the fact that some fibres were tied up in bundles and therefore could not be counted and that the equipment do not detect transparent fibres - the real number of released microplastics is higher. The findings from the additional FTIR analysis support the hypothesis that the detected fibre-shaped particles mainly are microplastics, in this study mainly from both polyamide and polyester. Further research is needed to get better knowledge of how different sizes and shapes of microplastics affects the waste water treatment plants (WWTP), if there is any leakage of microplastics from the Swedish WWTPs, the magnitude of the leakage and how the leakage can be prevented. Page 3 of 23

5 Introduction Microplastics is a generic term for very small fragments of plastics from different synthetic origin with an approximately length from 1 nm to 5 mm. Microplastics are very much discussed, risks and impact on the environment as well as the magnitude. During 2016 the Swedish Environmental Protection Agency initiated a study conducted by IVL Swedish Environmental Institute 1. The results concluded that washing of synthetic fibres, roads and tires, synthetic turfs, bottom colour for boats, industrial production and handling of primary plastics and general littering are the most important sources of microplastics in Sweden. Another potential source could be production facilities of textiles from synthetic fibres. The Swedish Environmental Protection Agency therefore gave Swerea IVF the assignment to investigate the occurrence of microplastics from the waste water at five different production facilities in Sweden. These facilities handle processes for pretreatment and/or dying and/or printing and/or finishing of textiles. The production facilities collected waste water during one week of production and then sent the water samples to Swerea IVF for analysis. In a study within the programme Mistra Future Fashion during 2017, Swerea IVF developed an inhouse method 2 for counting shedded fibres and particles from textiles with a method of combined filtration and microscopy. The hypothesis is that if the microplastics are from textile origin - they are fibre shaped (with a distinct elongated oblong shape). The method proved to be very suitable as a screening method to get an overview of shedded particles and fibres. The idea was to use the same method when investigating particles from the waste water to get a first estimation of any presence of microplastics. After counting the particles on the filtrates Swerea IVF also conducted an additional identification of a selection of non-fibre shaped particles as well as some of the fibre shaped particles to conclude that they indeed were microplastics and not other substances. 1 Swedish sources and pathways for Microplastics to the marine environment. A review of existing data. IVL-report C183 march Revised in March Page 4 of 23

6 Test procedure Sampling Five production facilities were chosen by the Swedish Environmental Protection Agency to be investigated with respect to the occurrence of microplastics in the waste water. The facilities were assigned to collect the waste water directly after the equalisation basin or alternatively after waste water treatment during one production week those days they had any production, see table 1. The water was collected between During these days, each facility collected a water sample in individual glass bottles supplied from Swerea IVF. The water samples were then returned to Swerea IVF by a courier service. Before filtration one flow proportional sample from each facility was mixed in a new bottle that was shaken before filtration to avoid any sedimentation, see table 3 and 4. Table 1. Sampling at the production facility Production facility A B C D E Sampling of water At the outlet of the equalisation basin At the outlet of the equalisation basin At the outlet of the equalisation basin After waste water treatment In the equalisation basin Table 2. Waste water in m 3 per day at each facility Date Outflow,[m 3 ] Production facility A B C D E In total Table 3. Flow proportional water sample mixed and filtrated at Swerea IVF Date Water sample,[ml] Production facility A B C D E Page 5 of 23

7 Analysis An earlier developed in-house method at Swerea IVF 2 was used to analyse the number of fibre shaped particles. The method includes filtration and a microscopic analysis. In other studies 2 regarding shedding from textiles, sizes of 1 mm (1 000 µm) or less has been investigated. The particle counting was performed using a software programme that characterize and count the number of fibre shaped particles and non-fibre shaped particles. Depending on the number of particles in the samples, different filter sizes were used. Microscopic Particle Counting Equipment: Leica DM4000M microscope and software Leica Cleanliness Expert V. 4.9 After drying the filters, the particles were counted automatically in a light microscope. The normal procedure for particle counting is to use a filter with smaller pore size than the smallest particle size counted. That was not possible in this investigation, because of the high contamination level and the viscosity of the fluid samples. Therefore particles from 100µm were counted on nylon net filters with a pore size of 100 µm. This may have caused that some particles and fibres with a length of >100µm went through the filter during the filtration depending on the orientation of the particles and fibres when they reached the filter. For example, if a straight fibre with a length of 100 µm but smaller width reached the filter in vertical direction. The microscope analysis identified the quantity of fibre shaped and non-fibre shaped particles in different size classes including longest non-fibre shaped particles as well as the longest fibre shaped particles according to the parameters applied, see Annex 3. The parameters used for fibre shaped particles detection was a minimum fibre length of 100µm and minimum fibre width of 50µm. Some manual changes were made to the largest detected non-fibre shaped particles and fibre shaped particles after the automatic detection due to several half-detected fibre shaped particles and some transparent non-fibre shaped particles that had been counted as a fibre shaped particle. FTIR analysis Equipment: Bruker Lumos FTIR microscope in ATR mode. Fourier Transform An additional analysis identified the content of the particles from the filtrate from each facility. The particles (regardless of shape) have been analyzed. Infrared Spectroscopy (FTIR) is an analytical method for identifying organic (and sometimes inorganic) materials. Organic materials means compounds made of carbon. Examples of different types of organic compounds are plastics, rubber, oil, grease, glue, textile fibers, etc. FTIR is based on infrared light, which is transmitted along different wavelengths. The light meet the material and then reflect / transmit to a receiver that records the amount of absorbed light. The amount of absorbed light is specific for each material. A spectrum is generated with absorption bands for the chemical bonds in the material. Page 6 of 23

8 Results Table 4.Counted particles (regardless of shape) larger than 100 µm Number of particles (regardless of shape) Production facility A B C D E Number of particles per liter Number of particles during one production week [in millions] The number of particles during one production week was calculated by taking the total amount of waste water (table 3, last row ) times the number of particles per liter (table 4, row 1). Example from production facility A: m 3 x = liter liter x 470 particles/liter = 737 millions of particles during one production week Table 5. Counted fibre shaped particles larger than 100 µm Number of fibre shaped particles Number of fibre shaped particles per liter Number of fibre shaped particles during one production week [in millions] Percentage of fibre shaped particles of the total number of detected particles [%] Production facility A B C D E The parameters used for fibre detection was a minimum fibre length of 100µm and maximum fibre width of 50µm. The number of fibre shaped particles during one production week was calculated by taking the total amount of waste water (table 3, last row) times the number of fibre shaped particles (table 5, row1) Example from production facility A: m 3 x = liter liter x 130 particles/liter = 204 millions of particles during one production week The percentage of fibre shaped particles was calculated by dividing the fibre shaped particles per litre (table 5, row 1) with the total number of particles per litre (table 4, row 1) Example production facility A 130/ 470 = 28 % Page 7 of 23

9 Table 6a. Detected content of some of the non-fibre shaped particles using FTIR microscope Production facility A B C D E Content of some non-fibre shaped particles A lot of unknown spherical very hard matter covered by yeast Polyester and polyamide in bundles of fibres, aromatic ethylene polyester compound Fibre mix of natural and synthetic fibres in bundles Bundles of acetate fibres A lot of inorganic particles, ceramic pigment, ester compound Table 6b. Detected content of some of the fibre shaped particles using FTIR microscope Production facility Content of some fibre shaped particles A B C D E Polyamide Polyamide, polyester Cotton Cotton/viscose Polyamide Table 6a and 6b shows that microplastics were detected from all five production facilities, as separate fibres or in bundles or both. There is a relatively good correspondence between the origin of detected particles (regardless of shape) and the fibres that, according to the production facilities, were produced the week of sampling. There are also specific fibres produced the same week that have not been found among the detected particles (regardless of shape). Possible reasons for this could be where and how the sampling was conducted, eventual sedimentation, they could be hidden in clods or that these fibres were not among the particles that were chosen for further identification since the identification only was performed on a selection of particles as a first screening. For pictures and FTIR spectra, see Appendix 1-2. Page 8 of 23

10 Conclusion and discussion The results conclude that all five production facilities have emissions of microplastics in the waste water, both fibre shaped and non-fibre shaped. However, the majority of the detected particles were not fibre shaped. The amount of fibre shaped particles as a percentage of the total detected particles varied between 27 %-46 %, see table 4. Approximately 100 to fibre shaped particles per liter of water were detected. The results show the detected number of particles that were flushed out with the waste water. The real number of particles (regardless of shape) is higher. This is due to the fact that we found clogged bundles of fibre shaped particles which were not dissolvable. The particles also need to have a certain contrast compared to the filter in order to be detected, i.e. transparent particles will not be counted. An additional identification analysis was performed to investigate the content of the detected fibre shaped and non-fibre shaped particles. The findings support the hypothesis that the detected fibreshaped particles mainly are microplastics. For facility C and D the microplastics were tied up in bundles and the identified separate fibres were more of natural origin, i.e. cotton/viscose. When analysing the content of a few selected non-fibre shaped particles, both polyester and polyamide were detected among other matter. At facility B some acetate particles was detected and at facility C we also found additional cotton particles. On one of the filtrates we found a lot of inorganic particles and in another filter many hardened clods. Note that some of the smaller particles were too small to be analyzed, as they were submerged in the filter itself. There is a need for more research to unravel whether these even smaller particles comes from deteriorated fibre shaped microplastics or from some other source. It is also important to take into account that a facility with low emissions of particles (regardless of shape) still can be the largest polluter due to larger amounts of waste water. During the analysis various challenges occurred due to a large amount of particles in the samples besides the fibre shaped particles. For some of the analyzed samples this caused minor problems during filtration and the following counting of fibre shaped particles. In the filtration the large number of particles sometimes caused the filter to get clogged up and for that reason it was necessary to increase the filter size. In the analysis and counting phase the software occasionally mistook unknown particles for fibre shaped particles although it was obvious not to be a fibre shaped particle after a visual examination. In the opposite direction, some fibre shaped particles were not detected by the software programme if they were too bright or the contrast between the particles and the filter were too low. We also detected bundles of fibre shaped particles clogged together with a hardened substance, the programme then counted the whole bundle as one fibre shaped particle. When comparing results, it is important to take into account the relatively high uncertainty in the particle counting. It is recommended to use the results primarily as a tool to get a better understanding and as a screening of microplastics in the waste water from production facilities. Further research is also needed to get better knowledge of how different sizes of microplastics affects the waste water treatment plants (WWTP), if there is any leakage of microplastics from the Swedish WWTPs, the magnitude of the leakage and how the leakage can be prevented. Page 9 of 23

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12 Appendix 1. Pictures of fibres from microscopic particle counting. Facility A t Page 11 of 23

13 Facility B Page 12 of 23

14 Facility C Page 13 of 23

15 Facility D Page 14 of 23

16 Facility E Page 15 of 23

17 Appendix 2. Pictures of organic particles from microscope and FTIR spectra. Fig.2 Facility A- Several of the particles contain yeast. Here are two types (red and blue curve). Page 16 of 23

18 Fig.3 Facility B- The particles consist likely of fibres. Blue curve correspond to polyester and red curve is a mix of polyester and nylon. Page 17 of 23

19 Fig.4 Facility B- The spectrum shows a mixed compound containing ethylene, esters and aromatics. Page 18 of 23

20 Fig. 5 Facility C- The spectrum shows a mixed compound containing esters and ceramics pigment. Page 19 of 23

21 Fig. 6 Facility D- The particles contain acetate fibres. Page 20 of 23

22 Fig. 7 Facility E- The particles contain a mix of fibres. The brown curve shows a nylon mix and pink curve a cotton/polyester mix. Page 21 of 23

23 Fig. 8 In facility A, B and E were nylon fibres found (pink curve) and in facility C and D were cotton found (blue curve). Page 22 of 23

24 Annex 3. Tables with detected particles and fibre shaped micro plastics presented in number per size Table 7a. Total number of particles (regardless of shape) and fibre shaped particles during one production week larger than 100 µm Total number of particles and fibre shaped particles in one production week [in millions] Particle size [µm] Production facility A B C D E Total Fibres* Total Fibres* Total Fibres* Total Fibres* Total Fibres* *fibre shaped particles Table 7b. Total number of counted particles (regardless of shape) whereof fibre shaped particles, sorted in particle size Particle size [µm] Total number of particles whereof fibre shaped particles [number per liter] Production facility A B C D E Total Fibres* Total Fibres* Total Fibres* Total Fibres* Total Fibres* *fibre shaped particles Table 7c. Percentage of fibre shaped particles of the total number detected particles. Percentage of fibre shaped particles[%]. Particle size [µm] Production facility A B C D E Page 23 of 23