再生PLA/PBAT:降解塑料回收造粒,与堆肥路线之争怎么看

塑料知识科普 发布时间: 2026-09-15 1415 阅读

I advise you not to use biodegradable materials unless your product truly needs to rot in the soil. This may sound contradictory, but anyone in this industry understands — the words 'biodegradable' sound fancy, but when it actually comes to the workshop, questions about how to recycle them, whether they can be re-pelletized, and whether composting is truly reliable all come up. Today’s article will clearly explain the 'twin stars' of biodegradable plastics, PLA and PBAT: how they are recycled and pelletized, what disputes have arisen along the composting route, and how factories producing biodegradable materials should calculate their costs. After reading this, you’ll have a complete understanding and won’t need to ask around anymore.

First, let's get familiar with this pair of twins. PLA is polylactic acid, made by fermenting starch from corn, sugarcane, and the like into lactic acid and then polymerizing it. It is transparent and firm, very good at making disposable food containers, cup lids, and utensils, and under industrial composting conditions, it can degrade into carbon dioxide and water within three to six months. PBAT is polybutylene adipate terephthalate, more petroleum-based, soft, tough, with high melt strength, particularly stable for film blowing, and is often blended with PLA to add toughness to the stiff PLA. Together, the two form the main formula for degradable shopping bags, mulch films, and food containers on the market. Ningbo Kolong New Materials Co., Ltd. supplies plastic raw materials, integrating both industry and trade, and commonly keeps stock of various recycled plastic types year-round. Degradable and recycled materials like PLA/PBAT fall into a category with high environmental requirements and more sophisticated processing techniques.

The sources of recycled PLA/PBAT are somewhat different from ordinary plastics. The bulk of degradable material comes from disposable products—like food containers, shopping bags, and mulch film—which are very dirty and mixed after use, making sorting difficult. The materials that are truly easy to recycle are industrial scraps from factories: the sprues and waste from film blowing, thermoforming, and injection molding, which are clean, uniform, and of the same formulation. According to industry data, composite PLA/PBAT waste film can go through a 'low-temperature crushing—melt filtration—pelletizing' closed loop, with the proportion of recycled material blended with new material controlled within just over ten percent, and the tensile strength can still maintain around 90% of the original value. Therefore, when doing degradable material recycling, securing the industrial scraps first is far more reliable than picking up old bags all over the world. Ningbo Kolon New Materials Co., Ltd. collects this type of material, prioritizing clean factory scraps and does not take miscellaneous post-consumer films from unknown sources.

Whether to recycle into pellets or send it for composting, the two options have been constantly debated.

In the biodegradable materials circle, there has been an ongoing debate for the past two years: should waste plastic be recycled into pellets, or sent for composting? One side says that burying it in the soil and letting it decompose is the truly environmentally friendly way; the other side argues that composting plants simply don’t have enough capacity, and not recycling the scraps into pellets is a waste. Both arguments seem reasonable, but when it comes down to the workshop, you need to know which side you stand on. Let's first explain the reality of the composting route, so you can understand why recycling into pellets has slowly become the preferred choice.

Figure 1 PLA lunch boxes, PBAT pellets, and granulation machine unit

Degradable materials aren't just done by burying them in the soil; composting isn't that magical.

Many people have a misunderstanding about biodegradable materials: anyway, they can degrade, so just bury them in the soil after use. This needs to be a reality check. Industrial composting of PLA requires temperatures of 50 to 60 degrees Celsius, sufficient humidity, and a composting facility with specific microorganisms; only then will it decompose in three to six months. If you just throw it into ordinary soil or a home flower pot, it can quietly sit there for years or even decades, and it barely degrades in seawater. PBAT decomposes relatively faster in soil; under normal temperature, it can lose a significant portion of its weight in about a year, but it still requires enough moisture and microbes.

The problem is that the domestic industrial composting infrastructure has not kept up at all. Industry data shows that by the end of 2025, there will be just over a hundred industrial composting facilities nationwide that truly have the capacity to process biodegradable plastics, mainly concentrated in pilot cities like Beijing, Shanghai, Guangzhou, and Shenzhen, with limited annual processing capacity. A large number of so-called 'compostable' degradable bags still end up in landfills or incineration plants, where, in the absence of oxygen, without microbes, and at insufficient temperatures, they cannot decompose at all, and instead end up mixing with traditional plastic recycling, causing more confusion. This highlights the awkward reality for degradable materials: they are designed for composting, but in reality, there is no way to compost them.

The trick here is that although both PLA and PBAT are called biodegradable materials, their processing characteristics are completely different. PLA is brittle and hard, with low melt strength, and can easily burst when film-blown on its own, so pure PLA can’t be made into film and PBAT must be added to toughen it; PBAT is soft and tough, with high melt strength, so the bubbles are very stable when film-blown. This determines that their recycling must also be considered separately: PLA is moisture-sensitive, and it undergoes hydrolytic chain scission when melted with any water, decreasing its strength, so it must be thoroughly dried before pelletizing; PBAT is relatively more robust, but for materials mixed with PLA, it’s necessary to make sure it’s a blend formula when recycling and not to forcefully separate them. In short, the first hurdle in recycling biodegradable materials is not the equipment, but to first distinguish between PLA, PBAT, and blends; collecting them mixed together is pointless.

So for manufacturers making degradable materials, you need to be clear in your mind: don’t put all your hopes on 'use it up and compost it.' No matter how well your product meets composting standards, downstream consumers and sanitation systems may not be able to handle it, and in the end, it will still end up in landfills. If you really want to make the environmental balance clear, it’s better to manage scrap materials at the production stage—reusing them within the factory loop, which neither pollutes traditional plastic recycling nor increases costs on the spot. This is currently the most practical form of recycling. As for composting, follow the certification route if conditions and order requirements allow; if not, don’t force it. Don’t spend on the composting premium only to have the material remain un-decomposed in the end, wasting money.

This led to the second path—recycling and pelletizing. Since composting is unreliable, the approach is the same as with ordinary plastics: collect clean factory scraps, re-pelletize them, and mix them back for use. The mechanical recycling of PLA is actually very similar to PET: crushing, washing, drying, and melt pelletizing, and it can also be chemically hydrolyzed back into lactic acid monomers. PBAT film edge scraps have high melt strength, and their closed-loop recyclability is also good. This path does not rely on composting facilities; the scraps can be monetized on-site, which is currently the main feasible route for recycling degradable materials.

However, the path of recycling and pelletizing isn't something you can just blindly follow. One taboo for degradable materials is mixing them with conventional PE or PP. Once mixed, the material won't break down in composting facilities—traditional plastics don't degrade, so mixing them in essentially contaminates a batch of good material, and the 'compostable' certification that customers want becomes invalid. Therefore, experienced recycling factories have a strict rule when regenerating degradable materials: collect and process degradable materials separately, and never mix them with conventional plastics during recycling. Another important point is not to be greedy with the mixing ratio. In closed-loop reuse, the proportion of recycled material is generally kept at around ten percent; too much mixing will reduce transparency, strength, and degradation performance. The old practice in this industry is to take small steps, make samples to test, and then increase the amount gradually. The grade table below is classified according to source and form.

LevelMain sourceKey indicatorsTypical uses
PLA injection molded recycled materialTransparent tableware, cup lid injection molding gateTransparent and slightly hard, compostableDisposable tableware, cup lids, stationery
PLA Sheet Material / Thermoformed RecycledHeat-formed edges of the lunch boxTransparent, thermoformableLunch boxes, blister packs, disposable products
PBAT blown film recycled materialShopping bags, mulch film blown film edgesFlexible, high melt strengthFilm, shopping bags, agricultural film
PLA/PBAT Blend RecyclingIn-plant scraps of blended modified materialsModerately soft and hard, with good toughnessDegradable bags, films, disposable products
Starch Blend Recycled MaterialStarch-based biodegradable material scrapsLow cost, slightly crispyLow-end disposable products, cushioning
Industrial Compostable Certified Recycled MaterialScraps with compostable certificationMeets composting standardsExport, Brand Degradable Products

Explanation: The recycling of PLA/PBAT currently mainly refers to GB/T 40006.1 "Plastics – Recycled Plastics – Part 1: General Rules" and the corporate standards of various manufacturers; degradation performance is related to composting conditions (industrial composting usually requires 55–60°C, sufficient moisture, and specific microorganisms). The indicators in the table are summarized from publicly available industry information and manufacturers' technical data. For more grades and physical property parameters, please refer to the manufacturers' official TDS.

Degradable material recycling and granulation saves the scraps and maintains the degradable identity.

Degradable material is not cheap when new, and collecting industrial scraps for granulation can indeed save a bit. But the recycling of degradable materials has an extra hurdle compared to ordinary plastics—you can't sacrifice the 'compostable' identity just to save money. The calculations have to be done this way.

Cost itemnew materialRegenerationDifference Explanation
Price per ton of materialHighera bit lowerIndustrial clean scraps are cheap, but after use, the miscellaneous films are even more messy.
Degradation performanceMeets composting standardsClosed-loop regeneration remains relatively goodIf mixed with traditional plastic, it is no longer considered biodegradable material.
Transparency/AppearanceThe new material is cleanThe fresh water outlet is acceptableThe miscellaneous material is yellowed and contains impurities
Processing stabilityWindow stableNeeds to be dried and conditioned againPLA is afraid of moisture; it easily hydrolyzes when containing water.
Composting outletComposting is allowed with certificationThere are few domestic composting plantsNo access to composting, recycling into granules is more realistic
Comprehensive costBenchmarkOnly the right materials save money.Mixing in traditional plastics will damage the biodegradability reputation

Based on this account, the boundary list below helps you determine how to collect and use the degraded scraps in your hands.

Suitable for recycling: Factory-clean PLA/PBAT scraps can be closed-loop granulated and a small proportion can be mixed back into new material to make the same type of products; gate runner reuse in mulch film and shopping bag factories.

Don't mix traditional PE/PP into degradable materials: once mixed in, the material is no longer degradable, and the composting certification becomes invalid.

PLA is afraid of moisture: recycled material must be thoroughly dried before granulation, otherwise the water will hydrolyze during melting, breaking the molecular chains and causing strength collapse.

For export and brand orders that require compostable certification: make sure to use certified recycled materials, and do not pass off ordinary mixed materials as certified.

Relying on 'just burying it in the ground will do': In reality, composting facilities are rare, and recycling into pellets is more reliable than composting.

The scraps from the lunchbox factory flowed back into the production line.

Let me give a typical scenario example. Ningbo Cologne New Materials Co., Ltd. has dealt with some factories in the field of degradable materials. Below, we will reconstruct common situations in the industry.

In East China, there is a factory that produces disposable PLA meal boxes, and the thermoforming workshop piles up a lot of trimmed waste every day. Previously, the boss took the easy route and disposed of it at a low price as waste plastic, but seeing that new PLA material was getting more expensive year by year made him nervous. He also considered recycling it himself, but after several attempts, the meal boxes made from recycled material either turned yellow or became brittle, and simply couldn't pass customer standards, so he ended up throwing them away.

Through a peer introduction, this factory brought in Cologne New Materials. Cologne New Materials didn’t ask about the price first; they asked for clarity: whether the waste material was clean, whether scraps of ordinary PP lunch boxes were mixed in, and how high the thermoforming process temperature was. After understanding these points, the advice given was: separately collect the PLA after cleaning and trimming, never mix it with other materials; thoroughly dry the moisture before pelletizing, melt at low temperature and filter, then mix a small proportion back with new material to make the same type of lunch boxes; don’t be greedy with the mixing ratio, start with just over ten percent and see if the transparency and sheet punching stability are okay before increasing. The key is to stick to the line of 'not mixing with traditional plastics' to preserve the degradable nature of this material.

Looking at this account in terms of the market makes it clearer. In the past two years, with the push of the plastic restriction orders, the quantity of biodegradable shopping bags and compostable meal boxes has increased rapidly, and the industrial scraps in factories have also increased. But PLA and PBAT new materials themselves are not cheap, and making disposable products yields thin profits. Whoever can catch the factory scraps while they are still clean can significantly lower their costs. The problem is that this business looks low-threshold but is actually high: you have to recognize PLA and PBAT, distinguish between blended and pure materials, and adhere to the rule of not mixing with traditional plastics. Just collecting a room full of miscellaneous bags out of enthusiasm won't fetch good prices and might damage your reputation. So in the business of collecting biodegradable materials, the insiders have always quietly been collecting factory scraps, while those who are not knowledgeable are still worried about the miscellaneous materials they collect.

After trying this out, the transparency and molding of the food containers stabilized, the scraps were no longer sold cheaply as waste, and costs dropped significantly. The boss later said that he used to think that recycling biodegradable materials was troublesome, but actually the problem wasn’t with recycling itself, it was that the rule 'don’t mix anything in' hadn’t been firmly established. Those who have worked with biodegradable materials for a long time have reached a consensus: their value is not in being buried in the soil, but in retrieving clean scraps while they are still 'clean.' This is also why Ningbo Cologne New Materials Co., Ltd. insists on sorting PLA/PBAT recyclables by source and not mixing them with conventional plastics — because the reputation of biodegradable materials can’t be repaired once it’s ruined.

The factory later incorporated recycling into the workshop process: the trimmed PLA from thermoforming goes directly into a dedicated hopper, never mixed with materials from other workshops; before granulation, the drying temperature and time are fixed, and only materials with excessive moisture content are put into the machine; the recycling ratio starts at 10%, and every batch is checked for transparency and sheet quality, gradually increasing once stable. After more than half a year, the external sales of trim waste decreased, more was recycled back into the production line, and the workshop corners became cleaner. The boss calculated that in just one year, the savings from trim materials alone were enough to give the workshop a substantial bonus.

Choose recycled material for degradation, first ask whether it is for composting or re-pelletizing

Finally, list the application scenarios and recommended levels in a comparison chart, and just follow it. Regarding degradable materials, don't just look at whether they 'can degrade'; you need to consider whether your product actually needs to degrade, or if you just want to have an eco-friendly label. These two are very different, so don't be blinded by the word 'degradable' and think it will turn to mud wherever you bury it. Think it through before placing an order; the real savings are actual money, not just a superficial environmental concept, and certainly not just for show to customers or something to put on the packaging.

Application scenarioRecommendation LevelPrecautionsWhen not to use
Disposable tableware/cup lidPLA injection molded recycled materialCheck the transparencyRequires high transparency, no impurities, using new material
Degradable shopping bags/ground filmPBAT or blended recyclingControl admixture content ≤ 15%Don't mix in traditional PE
Meal Box / Thermoformed BlisterPLA Material RecyclingBake through before granulationDo not use with aqueous hydrolysis
Export/Brand Degradable ProductsCompost Certified Recycled MaterialRetain certificationDon't pretend ordinary miscellaneous stuff is something else
Low-grade disposable cushioningStarch blending regenerationLow costHigh appearance requirements, do not use
Durable long-term use partCautiousDegradable materials are not durableDon't use degradable materials to do durable work.

The place for degradable materials is not in the soil; it is to return to the production line where it is still clean.

Recycled PLA/PBAT, cost reduction accounting for degradable materials

Ningbo Cologne New Materials Co., Ltd. has long been supplying degradable recyclable plastics such as PLA and PBAT, covering sources like injection molding grade, blown film grade, and blending grade. These materials are used in scenarios such as disposable tableware, degradable shopping bags, mulch films, and modified raw materials. How is recycled degradable material granulated? How do you choose between this and the composting route?

Statement: The brands and trademarks mentioned in this article are owned by their respective manufacturers. This article is a third-party material knowledge sharing. The specific grades, parameters, prices, certifications, and other information involved in the text are subject to the latest official data from each manufacturer; degradation performance is based on the results of the corresponding standard tests. This article does not constitute any purchasing or investment advice.

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