The "degradable plastic" defined by the national standard is not a good way to solve the problem of plastic grunge. Although the environmental impact of biodegradable plastics is less than non-degradable plastic, it still leads to many environmental issues, so it can only see it as a substitute for alleviating plastic problems, rather than a solution of plastic problems. Although we can have expectations for technology development, in accordance with the current level of science and technology, only reduce consumption can minimize the impact of plastic products on the environment. To completely compare biological degradation plastics and traditional plastics, we may wish to disassemble the lifecycle of plastics.
1. Plastik terdegradasi umum
Saat ini dibahas bahwa plastik biodegradable, yang menggunakan sumber daya hayati terbarukan, seperti tanaman, mikroorganisme, dll, dan beberapa menggunakan sumber daya fosil. Plastik biodegradable komersial yang paling umum digunakan adalah PHA (polyhydroxy fatty acid ester) dan PLA (polylactic acid), yang masing-masing dikenai mikroorganisme (feeding by crop) dan jagung sebagai bahan baku utama.
2, produksi plastik yang dapat terdegradasi
2.. Since the current source of biodegradable plastic raw materials is crops (corn, sugar cane, etc.), rather than fossil fuels, so from raw materials, biodegradable plastics can save approximately half of fossil fuel than traditional plastics. If the world's traditional plastics are replaced by biodegradable plastics, it can save approximately 3.49 million barrel fuels per day, accounting for about 4 percent fossil fuel consumption in the world.
2.2. Plastik tradisional yang mengkonsumsi lebih sedikit energi daripada karakteristik selama proses produksi plastik biodegradable. Dalam proses produksi plastik biodegradable, umumnya 2500-45 juta energi kokas, dan PLA yang paling umum membutuhkan 44,7 juta energi volute. Plastik tradisional perlu mengkonsumsi 7300-86 juta energi kokas per kilogram, yang jauh lebih tinggi daripada plastik biodegradable. Jika plastik global non-degradable diganti dengan plastik biodegradable, maka dapat menghemat 1-2,2 1019 joule energi setiap tahun sesuai dengan produksi plastik global 2019. Ini menyumbang 1,7-3,8 persen dari konsumsi energi global sebesar 5,8 1020 Joule pada tahun 2019.
2.3. Dari segi biaya produksi, harga plastik biodegradable saat ini sedikit lebih tinggi dari plastik tradisional (antara 1-2 kali lipat), tetapi sesuai dengan kecepatan perkembangan industri, harga akan terus menurun dalam waktu dekat.
2.4. Produksi 1 kg plastik PLA biodegradable membutuhkan sekitar 2,65 kilogram jagung, memproduksi 1 kg plastik PHA biodegradable membutuhkan sekitar 3,7 kg jagung. Menurut data 2019, jika semua plastik tradisional diganti menjadi PLA, sekitar 975 juta ton jagung dikonsumsi setiap tahun; jika semua plastik tradisional diganti menjadi PHA, sekitar 1,36 miliar ton jagung dikonsumsi setiap tahun. Pada saat yang sama, produksi jagung global 2018/2019 adalah 1,09 miliar ton, mendekati biaya penggantian plastik. Apalagi dengan semakin banyaknya jagung, atau lahan pertanian yang digunakan untuk menanam bahan baku seperti plastik biodegradable, harga jagung dan tanaman lainnya secara alami akan naik, sehingga terus mengancam ketahanan pangan di daerah rendah pangan. Dapat dilihat bahwa plastik yang dapat terurai secara hayati merupakan ancaman utama bagi pasokan pangan global, dan sulit untuk sepenuhnya menggantikan plastik tradisional sebelum teknologi tersebut tercapai.
2.5. Selama proses penanaman bahan baku plastik biodegradable, banyak digunakan pupuk dan insektisida, di mana zat beracun akan menembus ke dalam air, dan keamanan air minum, keamanan satwa liar, dan keamanan tanah.
3, daur ulang plastik yang dapat terdegradasi
3.1. Because the production of biodegradable plastics is too small, there is still lack of systematic, large-scale recovery methods. To give a simple example, when the garbage classification is proposed in Shanghai, many people need to shake the kitchen waste garbage when they are throwing garbage, and it is easy to stain your hands. So creating a creative wetting garbage bag, people want to throw the biodegradable garbage bag and wet garbage into wet trash. However, the garbage treatment department quickly sounded, indicating that although "degradable garbage bag" will most degrade, but it still has indiscriminated, even toxic and harmful ingredients, will affect the treatment of wet rubbish. Also, such garbage bag degradation speed is much slower than the kitchen waste, and cannot be treated synchronously. It can only be treated as dry waste incineration. Although biodegradable plastics can be degraded by biodegradation, it does not mean that they will ultimately break the recovery treatment, which is degraded.
3.2. Ketika plastik degradasi kreatif tidak dipulihkan secara efektif, mereka akan menguraikan sejumlah besar gas rumah kaca-metana dalam lingkungan aerobik.
3.3. Ketika plastik degradasi kreatif tidak pulih secara efektif, setelah memasuki lingkungan laut, itu sangat berkurang oleh mikroorganisme dan oksigen yang cukup, dan efisiensi biodegradasi. Karena tidak mungkin terdegradasi dalam waktu, plastik degradable ini masih memiliki kemungkinan besar untuk membahayakan organisme laut sebelum degradasi selesai.
4 perbandingananak dari emisi karbon keseluruhan
Karena bahan baku yang berbeda, plastik biodegradable kurang dari plastik tradisional di seluruh siklus hidup. Karena bahan baku plastik biodegradable sebagian besar adalah tanaman, degradasinya kurang dari karbon dioksida dalam pertumbuhan tanaman, sehingga emisi karbon dioksida dari plastik biodegradable terutama berasal dari emisi mekanis selama produksi dan transportasi. Plastik tradisional per kilogram plastik tradisional akan melepaskan 2,5-3,4 kilogram karbon dioksida dalam siklus hidupnya yang lengkap, dan plastik biodegradable akan melepaskan 1,8 kg karbon dioksida per kilogram plastik biodegradable. Jika plastik tradisional diganti dengan plastik biodegradable, tergantung pada spesiesnya, dunia akan melepaskan 0-830 juta ton karbon dioksida setiap tahun (pertimbangkan siklus hidup seluruh produk). Urutan ini sekitar 2,3 persen dibandingkan dengan sekitar 36 miliar ton emisi karbon per tahun 17.
5 potensi ancaman
When the environmental impact of degradable plastic (oil consumption, carbon emissions, energy consumption, agricultural pollution, etc.) still exists, and that degradable plastics will still cause environmental issues. If we are in this time, due to mistakes, it is harmless, and a large amount of "degradable" plastic product is used, the overall environmental impact (the impact of unit plastic products plastic products) may It will be greater than the era of traditional plastics. Not to mention the definition of degradation of plastics, it is still blurred. When it is "degradable plastic", "only needs a long time to degrade in the ideal environment", the environmental hazard Only increasing.
In summary, if you use a biodegradable plastic to replace the traditional plastic, 4 percent fossil fuel can be saved, reducing 2.3 percent carbon emissions worldwide, saving 2 percent of the world's energy consumption. Even if we use biodegradable plastics to replace all disposable plastics (approximately half of global plastics production), it can reach half of the results. At the same time, at the same time, replacement of disposable plastic products to degrade plastics can consume more than half of corn production, and cause risk from methane, pesticides, fertilizers, can't degrade in time. Therefore, it is necessary to emphasize that "degradable" does not explain that this plastic product can be simply harmless, which will still trigger a series of energy consumption, carbon emissions, food shortages, and so on. According to the current level of technology, "degradable plastic" is a way to slow the problem, it is not a way to solve the problem, and it is impossible to use degradable plastic products due to the word "degradable". If we all completely abandon the use of disposable products, it will not cause pollution and consumption of those fuel, energy, carbon emissions, etc., etc. Therefore, under the existing technological conditions, the use of conventional plastics is replaced with degradable / stacui plastics, and the use of a disposable plastic article is better.
