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. Cov khoom siv yooj yim degradable
Tam sim no tau tham txog tias biodegradable plastics, uas siv cov khoom siv hluav taws xob txuas ntxiv dua tshiab, xws li cov qoob loo, cov kab mob, thiab lwm yam, thiab qee qhov siv cov khoom siv fossil. Kev lag luam feem ntau siv cov yas biodegradable yog PHA (polyhydroxy fatty acid ester) thiab PLA (polylactic acid), uas feem ntau raug rau cov kab mob (noj los ntawm cov qoob loo) thiab pob kws ua cov khoom siv tseem ceeb.
2, degradable yas ntau lawm
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. Cov khoom siv niaj hnub siv hluav taws xob tsawg dua li cov yam ntxwv thaum lub sij hawm tsim cov yas biodegradable. Hauv cov txheej txheem tsim cov yas biodegradable, nws feem ntau yog 2500-45 lab coke zog, thiab feem ntau PLA xav tau 44.7 lab lub zog. Cov tsoos plastics yuav tsum haus 7300-86 lab coke zog ib kilogram, uas yog ntau dua li biodegradable plastics. Yog hais tias lub ntiaj teb no tsis-degradable yas yog hloov nrog ib tug biodegradable yas, nws yuav txuag tau 1-2.2 1019 joule zog txhua txhua xyoo raws li 2019 ntiaj teb no yas ntau lawm. Nws suav txog 1.7-3.8 feem pua ntawm kev siv hluav taws xob thoob ntiaj teb ntawm 5.8 1020 Joules hauv 2019.
2.3. Hais txog cov nqi tsim khoom, tus nqi ntawm biodegradable plastics tam sim no me ntsis siab dua li cov yas yas (nruab nrab ntawm 1-2 zaug), tab sis raws li kev loj hlob ceev ntawm kev lag luam, tus nqi yuav pheej yig dua nyob rau yav tom ntej.
2.4. Kev tsim tawm ntawm 1 kg ntawm biodegradable PLA plastics yuav tsum muaj kwv yees li 2.65 kilograms ntawm pob kws, ua 1 kg ntawm biodegradable PHA yas yuav siv li ntawm 3.7 kg ntawm pob kws. Raws li 2019 cov ntaub ntawv, yog tias tag nrho cov khoom siv yas raug hloov mus rau hauv PLA, kwv yees li 975 lab tons ntawm pob kws tau noj txhua xyoo; Yog tias tag nrho cov khoom siv yas raug hloov mus rau hauv PHA, kwv yees li 1.36 billion tons ntawm pob kws tau noj txhua xyoo. Nyob rau tib lub sijhawm, 2018/2019 thoob ntiaj teb cov pob kws ntau lawm yog 1.09 billion tons, ze rau tus nqi hloov cov yas. Ntxiv mus, nrog ntau pob kws, lossis cov av cog qoob loo yog siv los cog cov khoom siv raw xws li biodegradable plastics, cov nqi ntawm pob kws thiab lwm yam qoob loo yuav nce siab, yog li txuas ntxiv hem cov zaub mov lav hauv cheeb tsam zaub mov tsawg. Nws tuaj yeem pom tau tias biodegradable plastics yog ib qho kev hem thawj loj rau cov khoom noj khoom haus thoob ntiaj teb, thiab nws yog qhov nyuaj rau tag nrho lwm cov khoom siv plastics ua ntej cov thev naus laus zis tau ua tiav.
2.5. Thaum lub sijhawm cog cov khoom siv raw ntawm cov yas biodegradable, ntau cov chiv thiab tshuaj tua kab yog siv, qhov twg cov tshuaj lom yuav nkag mus rau hauv dej, thiab kev nyab xeeb ntawm cov dej haus muaj kev nyab xeeb, kev nyab xeeb ntawm cov tsiaj qus, thiab kev nyab xeeb ntawm av.
3, degradable yas recycling
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. Thaum muaj tswv yim degradation plastics tsis zoo zoo, lawv yuav decompose ib tug loj npaum li cas ntawm greenhouse gases-methane nyob rau hauv ib tug aerobic ib puag ncig.
3.3. Thaum muaj tswv yim degradation plastics tsis zoo zoo, tom qab nkag mus rau hauv ib puag ncig marine, nws raug txo kom tsawg los ntawm cov kab mob txaus thiab oxygen, thiab biodegradation efficiency. Vim tias nws tsis tuaj yeem degrade nyob rau lub sijhawm, cov yas degradable no tseem muaj qhov tshwm sim zoo rau cov kab mob hauv hiav txwv ua ntej qhov degradation tiav.
4 pivtus tub ntawm tag nrho cov pa roj carbon emissions
Vim yog cov khoom sib txawv, cov yas biodegradable tsawg dua li cov yas yas hauv tag nrho lub neej. Vim tias cov khoom siv raw ntawm biodegradable yas yog cov nroj tsuag, lawv cov degradation tsawg dua cov pa roj carbon dioxide hauv cov nroj tsuag, yog li cov pa roj carbon dioxide emissions ntawm biodegradable plastics feem ntau yog los ntawm cov khoom siv hluav taws xob thaum lub sij hawm tsim khoom thiab kev thauj mus los. Cov khoom siv yas ib kilogram ntawm cov yas yas yuav tso tawm 2.5-3.4 kilograms ntawm carbon dioxide nyob rau hauv nws lub neej voj voog, thiab biodegradable yas yuav tso tawm 1.8 kg ntawm carbon dioxide ib kilogram ntawm biodegradable plastics. Yog tias cov yas ib txwm hloov nrog biodegradable plastics, nyob ntawm hom, lub ntiaj teb yuav tso tawm 0-830 lab tons ntawm carbon dioxide txhua xyoo (xav txog lub neej voj voog ntawm tag nrho cov khoom). Qhov kev txiav txim no yog kwv yees li 2.3 feem pua piv rau kwv yees li 36 billion tons ntawm carbon emissions ib xyoos twg 17.
5 muaj peev xwm hem
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.