지방자치단체의 생물폐기물 처리장은 지속 가능성이 더 높은 것으로 추정되는 생분해성 플라스틱 잔류물로 환경을 오염시키는 데 일조하고 있습니다.

Dec 23, 2023

Scientific Reports 12권, 기사 번호: 9021(2022) 이 기사 인용

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생분해성 플라스틱(BDP)은 특히 기술적인 퇴비화 조건에서 쉽게 광물화될 것으로 예상됩니다. 그러나 샘플 매트릭스의 복잡성으로 인해 현실적인 조건에서 성능 저하 연구가 크게 방해되었습니다. 여기에서는 최첨단 도시 혐기성/호기성 바이오폐기물 처리 공장에서 나온 퇴비와 비료에 BDP 잔류물이 있는지 조사했습니다. 우리는 농업 및 원예용 비료로 사용되는 최종 퇴비에서 1mm보다 큰 BDP 조각을 상당수 발견했습니다. 깨끗한 퇴비화 봉투와 비교했을 때, 회수된 BDP 조각은 재료 특성에 차이가 있어 잠재적으로 추가 생분해 가능성이 낮아졌습니다. 1mm 미만의 BDP 단편이 대량으로 추출되었으며 퇴비 건조 중량의 0.43wt%에 이르렀습니다. 마지막으로, 혐기성 처리 중에 생산된 액체 비료에는 리터당 500μm 미만의 수천 개의 BDP 조각이 포함되어 있습니다. 따라서 우리의 연구 질문은 현재 사용 가능한 BDP가 비료 생산과 같은 환경 관련 분야의 응용 프로그램과 호환 가능하다면입니다.

생분해성 플라스틱(BDP)은 호일, 포장재, 가방용 일반 플라스틱에 대한 환경 친화적인 대안으로 점점 더 제안되고 있습니다. BDP 활용이 상당한 이점을 얻을 수 있는 분야 중 하나는 유기 생활 폐기물 수집입니다. 현재 수집된 대부분의 가정용 바이오폐기물은 기존 비닐봉지에 의해 오염되어 있는데, 이는 아마도 인구의 상당 부분이 바이오폐기물을 비닐봉지에 수집하는 것을 선호하기 때문일 것입니다. 그러나 기존 플라스틱은 분해되지 않으므로 생물폐기물 처리장에 들어가서는 안 됩니다. 결과적으로 정교한 분류 절차를 통해 들어오는 바이오 폐기물에서 가능한 한 완전히 제거되어야 하며, 이는 또한 분해 가능한 유기 물질의 상당한 손실을 초래합니다. 해당 물질로 생산된 바이오가스(전기, 열) 및 비료가 수익을 창출하는 반면, 쓰레기는 상당한 비용을 들여 처리해야 하기 때문에 그러한 손실은 발전소 운영자에게 이익이 되지 않습니다. 정교한 준비에도 불구하고 바이오폐기물 처리장에 플라스틱이 유입되는 것을 완전히 방지할 수는 없으며, 특히 < 0.1wt와 같은 고품질 인증 퇴비에서 허용되는 최대 플라스틱 양과 관련하여 엄격한 규제가 도입되었습니다. §3, 4b, DüMV 및 §3, 4c, DüMV에 따른 %. 실행 가능성 때문에 오염 정량화에는 2mm가 넘는 플라스틱 조각만 포함되며, 가까운 시일 내에 이 제한이 1mm를 넘는 조각으로 낮아질 것으로 예상됩니다. 이러한 상황에서 퇴비화 가능한 비닐봉지는 매력적인 옵션으로 간주됩니다. 특히 퇴비화를 통한 기술적 바이오폐기물 처리 조건은 분해에 이상적이어야 하며 가정용 바이오폐기물 수집을 위한 전용 봉투가 슈퍼마켓에 등장했기 때문입니다. 물론, 생물폐기물 처리장에서 호일과 봉지로 인한 모든 부작용이 생분해성 봉지 도입을 통해 자동으로 해결되는 것은 아닙니다. 작업자는 특히 생분해성 물질이 상당한 수준으로 분해되지 않을 것으로 예상되는 혐기성 소화 중에 기계에 대한 두려움을 느끼는 것으로 알려져 있습니다. 그러나 이와 관련된 많은 부분은 실제 작동 조건에 따라 달라집니다. 활발하게 혼합하는 식물은 상자식물보다 더 많은 어려움에 직면할 수 있습니다.

생분해성에 대한 일반적인 정의는 유럽 표준 EN 13432(퇴비화 및 생분해를 통해 복구 가능한 포장재에 대한 요구 사항 - 포장의 최종 승인을 위한 테스트 계획 및 평가 기준1)에 나와 있으며, 이는 재료가 전환되면('광물화') 생분해성이 있음을 명시하고 있습니다. ') 산소가 있을 때 미생물 활동에 의해 CO2, 물, 무기염 및 바이오매스가 되거나 산소가 없을 때 메탄, CO2, 물, 무기염 및 바이오매스가 생성됩니다. 정의는 분명하지만, 실제 생분해는 일반적으로 테스트 물질이 있는 호기성 표준 배양에서 생성된 CO2를 유사한 양의 시험 물질이 포함되지 않은 배양과 시험 물질이 없는 배양에서 비교함으로써 비특이적인 방식으로 추정됩니다. 셀룰로오스와 같은 천연 생분해성 물질. 이러한 상황에서는 생분해성 물질의 분해 메커니즘에 대해 아무것도 알 수 없습니다. 특히 물질의 상당 부분이 환경과 인간 건강에 상당한 영향을 미치는 것으로 간주되는 미세 플라스틱 및 나노 플라스틱, 즉 입자로 남아 있는 경우에는 더욱 그렇습니다. 더욱이, 현재의 생분해성/퇴비화 가능 물질은 혐기성 조건에서 분해되는 것이 인증되지 않았습니다. 또한 퇴비화라는 용어는 생분해성 플라스틱과 관련하여 사용됩니다. EN 13432는 물질의 90wt%가 2mm 미만의 입자로 단편화(붕해)되는 경우, 즉 12주간의 표준화된 퇴비화 후 90wt%가 완전히 광물화된 물질을 퇴비화 가능한 물질로 정의합니다. 6개월 이내. 나머지 10wt%는 바이오매스로 변환되거나 단순히 미세플라스틱으로 조각화될 수 있습니다. 또한, 퇴비화 가능한 물질은 최종 퇴비에 중금속을 가져오거나 환경독성 효과를 유발하지 않을 수 있습니다.

2 mm, which, according to these studies, were no longer in evidence after the composts had been conditioned by the customary sieving steps. In one case, foils certified as biodegradable were purposely introduced in controlled amounts into the digestion/composting process, and again no plastic fragments were visible in the finished—sieved—compost6. The size fraction < 2 mm was not considered in any of these studies./p> 5 mm fraction corresponding to the contamination by residual “macroplastic” (5 mm is a commonly used upper size limit for “microplastic”, anything larger is macroplastic) and a 1–5 mm fraction corresponding to the regulatory relevant residual contamination by microplastic. The lower limit of 1 mm rather than 2 mm was chosen in anticipation of the expected changes in regulation, where the replacement of the 2 mm limit by a 1 mm limit is imminent./p> 5 mm and/or the 1–5 mm sieving fractions using FTIR analysis3 (Fig. 1; Table 1). All recovered fragments appeared to stem from foils, bags or packaging, since they were thin compared to their length and width (see Suppl Figure S1 for typical examples). Fragments with overlapping signatures, most likely PBAT/PLA mixtures or blends, were also found (see Suppl Figure S2 for the interpretation of the spectra). In addition, the recorded BDP fragment spectra (Fig. 1A) showed high similarity to the FTIR spectra of commercial compostable bags sold in the vicinity of the biowaste treatment plants (Fig. 1B), which together with the geometry of the recovered fragments led us to assuming that the majority of the BDP entered the biowaste in the form of such bags./p> 5 mm or 1–5 mm) in which the fragment was found, and finally, the fragment number. Fragment F#1_5mm_4 therefore represents the 4th fragment collected in the > 5 mm size fraction from the finished compost of plant number 1. Bags were arbitrarily numbered 1–10, see Suppl Table S1 for supplier information. The spectra (in grey) of the reference materials for PLA and PBAT are given as basis for the interpretation. Spectra in red refer to test samples consisting only of PBAT, while those in blue indicate samples composed of PBAT/PLA mixtures./p> 5 mm size fraction (Table 1) and for that reason has become state-of-the-art in preparing quality composts (contamination by plastic fragments > 2 mm of less than 0.1 wt%). Given that the size of the fragments is a crucial factor regarding ecological risk, we analyzed the sizes (length Î width) of the BDP fragments in comparison to that of the plastic fragments with signatures of commodity plastics such as PE (Fig. 2). BDP fragments found in a given compost sample tended to be smaller than the fragments stemming from non-BDP materials, which may indicate that BDPs degrade faster or tend to disintegrate into tinier particles than commodity plastics. This may also explain why in the compost from plant #2, no BDP fragments were found in the particle fraction retained by the 5 mm sieve (> 5 mm fraction), while 19 such particles were found in the fraction then retained by the 1 mm sieve (1–5 mm fraction). Interestingly, plant #2 is the only one included in our study that uses no mechanical breakdown of the incoming biowaste. This reduces the mechanical stress on the incoming material. Mechanical stress can alter the properties of plastic foils such as the crystallinity whereby crystallinity has been shown to influence the biological degradation of BDP such as PLA7./p> 1 mm. (A) Fragments found in the finished compost from plant #1, (B) in the finished compost from plant #2, and (C) in the pre-compost from plant #3. For reasons of statistical relevance, only samples containing more than 20 BDP fragments per kg of compost were included in the analysis./p> 5 mm or 1–5 mm) in which the fragment was found, and finally, the fragment number. Bags were arbitrarily numbered 1–10, see Suppl Table S1 for supplier information. The spectra (in grey) of the reference materials for PLA and PBAT are given as basis for the interpretation. Spectra in red refer to test samples consisting only of PBAT, while those in blue indicate samples composed of PBAT/PLA mixtures. (C) Chemical structures of PLA and PBAT, chemical shifts of the protons are assigned as indicated in the reference spectra in (B)./p> 5 mm or 1–5 mm) in which the fragment was found, and finally, the fragment number./p> 5 mm or 1–5 mm) in which the fragment was found, and finally, the fragment number./p> 1 mm were found in the collected LF samples. This is hardly surprising, given that the LF is produced by press filtration of the digestate after the anaerobic stage. Such a filtration step can be expected to retain fragments > 1 mm in the produced filter cake, which goes into the composting step, leaving the filtrate, i.e. the LF, essentially free of such particles. Anaerobic digestion is currently not assumed to contribute significantly to the degradation of BDP17,22, but the process conditions (mixing, pumping) may promote breakdown of larger fragments, particularly when additives such as plasticizers23 leach out of the material./p> 20,000 BDP microparticles of a size ranging from 10 µm to 500 µm enter each m2 of agricultural soil whenever LF is applied on agricultural surfaces./p> 1 mm. Six compost samples representing the more contaminated ones based on the content of fragments > 1 mm, namely, f#1, f#2, p#3, f#3, p#4 and f#4 (nomenclature: f or p for finished or pre-compost, followed by plant number), were extracted with a 90/10 vol% chloroform/methanol mixture. The amounts of PBAT and PLA in the obtained extracts were then quantified via 1H-NMR (Table 4). Briefly, the intensity of characteristic signals in the extract spectra of the compost samples (see Suppl Figure S4) were compared to peak intensities produced by calibration standards of the pure polymer dissolved at a known concentration in the chloroform/methanol. All samples and standards were normalized using the 1,2-dichloroethan signal at 3.73 ppm as internal standard. See also Suppl Figure S5 for an exemplification of the quantification of the PBAT/PLA ratios. Based on the amounts of PBAT and PLA extracted from a known amount of compost, the total mass concentration (wt% dry weight) of these polymers in the composts was calculated./p> 2 mm. Moreover, residues of PBAT and PLA were found in all investigated compost samples, including the finished compost from plant #4, which had shown no contamination by larger BPD fragments (Table 1). The pre-compost from that plant had shown a few contaminating BDP fragments in the > 5 mm fraction. However, in regard to the fragments < 1 mm, the composts from plant #4 showed a similar incidence, at least for PLA, as the finished compost samples from the other plants (Table 4)./p> 1.100 U mL−1), Pektinase L-40 (activity: > 900 U mL−1, Exo PGA, > 300 U mL−1 Endo PGA, > 300 U mL−1 Pektinesterase), and Cellulase TXL (activity: > 30 U mL−1) were from ASA Spezialenzyme GmbH (Wolfenbüttel, Germany), Viscozyme L (activity: > 100 FBG U g−1) was from Novozymes A/S (Bagsværd, Denmark)./p> 1 mm, approximately 3 L of the compost sample was weighed and evenly distributed into 6 glass vessels (capacity 3 L each). The material was suspended in 2.5 L of water and first sieved with a mesh size of 5 mm (yielding fraction > 5 mm). All particles retained by the sieve were collected with tweezers and transferred to the system for ATR-FTIR analysis, see below, while the material passing the sieve was sieved again at 1 mm, followed again by collection of the retained particles (yielding fraction 1–5 mm), which were subsequently also analyzed by ATR-FTIR. Sieves were from Retsch GmbH (Haan, Germany; test sieve, IS 3310-1; body/mesh, S-Steel; body, 200 mm × 50 mm. For the analysis of the chemical nature of the collected particles Attenuated total reflection—Fourier transform infrared (ATR-FTIR) spectrometry (spectrometer: Alpha ATR unit, Bruker 27; equipped with a diamond crystal for measurements) was used. Spectra were taken from 4000 to 400 cm−1 (resolution 8 cm−1, 16 accumulated scans, Software OPUS 7.5) and compared with entries from an in-house database described previously24 or the database provided by the manufacturer of the instrument (Bruker Optik GmbH, Leipzig, Germany). This comparison of the IR-spectra allowed to distinguish biodegradable from conventional plastic fragments, but also from residues of other materials including unknowns. An incident light microscope (microscope, Nikon SMZ 754T; digital camera, DS-Fi2; camera control unit, DS-U3; software, NIS Elements D) was used for visual documentation of all particles identified by ATR-FTIR as synthetic plastics (biodegradable or otherwise)./p> 1 mm. For the preparation of the plastic fragments < 1 mm (down to 10 µm) an adjusted enzymatic-oxidative digestion method based on a method suggested by Löder et al. 2017 was adapted25. For this, the liquid fertilizer sample was mixed well with a metal rod and 50 mL were quickly poured into a 300 mL glass beaker (Schott-Duran). The metal rod and the glass beakers were washed in advance with Millipore water. Then 50 mL of a 10 wt% sodium dodecyl sulfate (SDS) solution (≥ 95 % SDS; Karl Roth) was added and the mixture incubated at 50 °C for 72 h under gentle agitation (Universal Shaker SM 30 B, Edmund Bühler GmbH, Bodelshausen, Germany). Subsequently, 2 × 25 mL of 30% hydrogen peroxide was slowly added under a fume hood. Since the reaction of hydrogen peroxide with organic matter is highly exothermic, an ice bath was used to keep the reaction temperature below 40 °C. Once the reaction had subsided and the mixture had again reached room temperature, the solution was filtered over a 10 µm stainless-steel-mesh filter (47 mm diameter, Rolf Körner GmbH, Niederzier, Germany) with a vacuum filtration unit (3-branch stainless-steel vacuum manifold with 500 mL funnels and lids, Sartorius AG, Göttingen, Germany). All filtrations were conducted under a laminar flow hood to minimize contamination with microplastics from the surrounding air. All matter retained by the filter was rinsed with filtered (0.2 µm) deionized water to remove residual chemicals. Afterwards, the retained matter was rinsed into a fresh 300 mL glass beaker with approximately 50 mL of 0.1 M Tris-HCl buffer (pH 9.0). As particles tended to adhere to the stainless-steel filter, the filter was also placed into the beaker. Ten milliliters of Protease A-01 solution were added and the beaker was incubated at 50 °C for 12 h with gentle agitation. Afterwards, the filter was thoroughly rinsed off into the beaker with filtered deionized water to recover any adhering particles and then used to filter the incubated solution. The retained matter was rinsed into a fresh glass beaker with 25 mL of 0.1 M NaAc buffer (pH 5). The filter was again placed in the jar as well, 5 mL of the Pektinase L-40 solution was added, and the beaker was incubated for 72 h at 50 °C. The filter was rinsed and used to filter the sample as before. Any matter retained by this filtration step was again rinsed into a fresh glass beaker with 25 mL of 0.1 M NaAc buffer (pH 5). The filter was again placed in the beaker, 1 mL of a Viscozyme L solution was added, and the jar was incubated at 50 °C for 48 h. The sample was filtered and the retained matter was transferred into 25 mL of a 0.1 M NaAc buffer (pH 5). Five mL of Cellulase TXL solution was added and the jar was incubated at 40 °C for 24 h./p>

3.0.CO;2-3" data-track-action="article reference" href="https://doi.org/10.1002%2F%28SICI%291099-1581%28199704%298%3A4%3C203%3A%3AAID-PAT627%3E3.0.CO%3B2-3" aria-label="Article reference 8" data-doi="10.1002/(SICI)1099-1581(199704)8:43.0.CO;2-3"Article CAS Google Scholar /p>

이전의: 실제를 통한 아테미아 부화 과정에 선택된 비생물적 요인이 미치는 영향 다음: 끈적끈적한 상황은 고분자 과학에 도움이 됩니다

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