Environmental Engineering
F.A. Febria; A. Syafrita; A. Putra; H. Hidayat; C. Febrion
Abstract
BACKGROUND AND OBJECTIVES: Low-density polyethylene is one of the dominant recalcitrant plastic pollutants in the ocean, thus causing complicated problems. Biodegradation is an efficient, environmentally friendly, and sustainable option to overcome these problems. This study aims to quantitatively and ...
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BACKGROUND AND OBJECTIVES: Low-density polyethylene is one of the dominant recalcitrant plastic pollutants in the ocean, thus causing complicated problems. Biodegradation is an efficient, environmentally friendly, and sustainable option to overcome these problems. This study aims to quantitatively and qualitatively analyze the ability of marine bacterial isolates to degrade low-density polyethylene plastic.METHODS: Bacteria were isolated from plastic samples using serial dilution technique and inoculated on media containing low-density polyethylene powder. Bacterial degradation ability was analyzed quantitatively based on weight loss percentage and energy-dispersive X-ray spectroscopy values, as well as qualitatively based on changes in physical and chemical structures using Scanning Electron Microscopy and Fourier transform infrared spectroscopy. Meanwhile, bacterial isolates were identified based on gene sequence and phylogenetic analyses.FINDINGS: Four bacterial isolates were isolated from low-density polyethylene plastic samples. Quantitative analysis found that the low-density polyethylene film experienced weight loss up to 10-15 percent during 35 days of incubation, with a maximum daily weight loss rate of 0.004 milligrams per day, meaning that the four bacterial isolates have the potential to degrade plastic. Meanwhile, qualitative analysis based on Scanning Electron Microscope observations revealed changes in the physical structure of the film surface in the form of a rough surface, formation of holes, and breakdown into clumps across the film surface. Variations in these changes were tested. In the control, no changes occurred and the film surface remained flat and smooth. Conversely, the results of the energy dispersive X-ray spectroscopy spectrum analysis showed that the low-density polyethylene film broke down into smaller fragments, characterized by a decrease in mass from 98.51 percent to 98.23 percent. Fourier transform infrared observations showed variations in transmittance and wavenumbers, indicating changes in chemical bonds or functional groups in the low-density polyethylene film which caused it to become brittle and break down into smaller fragments with a lower molecular weight, making it easier for bacteria to digest. The results of the gene sequence analysis identified four bacterial isolates, namely Lysinibacillus sp. IBP-1, Bacillus sp. IBP-2, Bacillus paramycoides IBP-3, and Bacillus cereus IBP-4. Based on the quantitative and qualitative analyses, the ability of the bacterial isolates to degrade low-density polyethylene film was shown in the following order: Bacillus paramycoides IBP-3 > Bacillus cereus IBP-4 > Lysinibacillus sp. IBP-1 > Bacillus sp. IBP-2.CONCLUSION: All four marine bacterial isolates can use low-density polyethylene as the sole carbon source. Based on quantitative and qualitative analyses, Bacillus paramycoides IBP-3 has the best potential for degrading low-density polyethylene film. This study provides information on potential bacterial isolates that can be developed to control low-density polyethylene plastic waste.
Environmental Management
D.A. Syamsu; D. Deswati; S. Syafrizayanti; A. Putra; Y. Suteja
Abstract
BACKGROUND AND OBJECTIVES: Microplastics are plastic fragments measuring less than 5 millimeters which are formed from degraded plastic materials and have the potential to pollute the environment. Due to their widespread presence in the marine environment, microplastics have become a significant global ...
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BACKGROUND AND OBJECTIVES: Microplastics are plastic fragments measuring less than 5 millimeters which are formed from degraded plastic materials and have the potential to pollute the environment. Due to their widespread presence in the marine environment, microplastics have become a significant global threat. The presence of microplastics is often considered as causing pollution in various environments, especially aquatic ecosystems such as rivers and oceans. Microplastics contamination can even be found in consumed salt, thus raising concerns about its impact on human health. However, information on the presence of microplastics in salt is still very limited. This study aims to determine the abundance and characteristics of microplastics as contaminants in salt and assess the human exposure to microplastics in Indonesia.METHODS: A total of 21 samples of salt products were taken from various brands available in Padang City and Jambi City, Indonesia for analysis. Microplastics extraction was carried out by removing the organic materials contained in the salt samples using 30 percent hydrogen peroxide and then filtering them with a 0.45 micrometer pore filter. A stereomicroscope was used to detect the abundance, shape, size, and color of microplastics, while the Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy was utilized to identify the polymer type of the microplastics. Furthermore, human exposure to microplastics can be predicted by calculating the estimated dietary intake and taking into account the daily salt intake.FINDINGS: Microplastics were detected in significant amounts (p<0.05) in all salt samples, ranging from 33 to 313 particles/kilogram. The types of microplastics most commonly found in the samples were fragments (67.49 percent), fibers (23.82 percent), films (6.08 percent), and pellets (2.61 percent). The types of polymer identified include polyethylene, polypropylene, polyethylene terephthalate, and polyester. The dominant microplastics were 100-300 micrometers in size (47.3 percent) and black in color (52.88 percent). It is estimated that adults in Indonesia will be exposed to 60.225-571.225 microplastics/year if they consume 5 grams of salt/day or 120.45-1142.45 microplastics/year if they consume 10 grams of salt/day.CONCLUSION: Of the 21 salt samples analyzed, all were detected to contain microplastics. Inadequate and unhygienic salt production and contaminated seawater used as raw material contribute to microplastics contamination of salt, thus posing a risk to human health. By calculating of daily salt intake of the Indonesian population, it is possible to estimate their daily and annual exposure to microplastics. The results of this study contain useful information for the efforts to prevent microplastics contamination by relevant stakeholders and the provision of education and socialization about the proper salt production process in accordance with food safety standards as to reduce or even eliminate microplastics in salt. In addition, this study can provide valuable data on human exposure to microplastics in salt products that can assist policymakers in making standard references for microplastics.
