Are Disposable Trays Biodegradable

Opt for FSC-certified recycled paper or bamboo plates; avoid polystyrene (500+ years to decompose). Check BPI compostable labels, skip PFAS-coated options to cut microplastic release and landfill waste.

Non-Biodegradable Materials

Polypropylene (PP) Trays

With its relatively low cost of about 8,000-10,000 RMB per ton (compared to other engineering plastics) and an annual consumption approaching 1.2 million tons (in China’s food container sector alone), Polypropylene completely dominates the takeaway and fast-food industry.

1. From Oil to Your Hand: How is a PP Tray Made?

The life of PP begins in a petrochemical plant. In huge cracking units, feedstocks like naphtha are broken down at temperatures exceeding 800°C, producing propylene monomer. Then, through polymerization, countless propylene molecules link into long chains with the help of catalysts, forming polypropylene powder or pellets. This process is extremely energy-intensive, with carbon emissions for producing 1 kg of PP raw material ranging from 1.5 to 3 kg CO₂ equivalent.

Next, these PP pellets are sent to processing plants, melted in injection or compression molding machines at 160-220°C, injected into molds, and cooled for a few seconds before a finished tray is born. A medium-sized injection molding machine can produce 300 to 500 meal boxes per hour. This high-efficiency, standardized production is the fundamental reason its cost can be as low as 0.3 to 0.8 RMB per unit (depending on size and thickness). Compared to an industrially compostable PLA tray typically starting at 1.2 RMB, PP’s cost advantage is overwhelming.

2. Why Does It Dominate Your Takeaway Bag?

PP’s success is no accident; it’s earned through several core performance metrics.

• Heat Resistance Champion: PP has a high melting point of 160-170°C, and its heat deflection temperature (under 0.45MPa load) can reach about 110°C. You can safely put a food-filled PP container in the microwave on high power for 3-5 minutes, and it will largely maintain its shape. In contrast, the popular compostable material PLA has a heat deflection temperature of only 50-60°C, becoming soft and floppy in the microwave.
• Durable and Tough: PP has excellent toughness, with an impact strength typically in the range of 3-5 kJ/m². Simply put, if you accidentally drop the container while cycling home with takeaway, it’s unlikely to break, effectively preventing spills. At the same time, its hardness (Rockwell R scale) is about 80-100, stiff enough to hold its shape without feeling flimsy.
• Good Chemical Resistance: PP has decent resistance to water, oil, salt, and acids. At room temperature, its 24-hour water absorption rate is below 0.01%, so it won’t get soggy like paperboard. It also has good barrier properties against common edible oils (like salad oil) for short periods without leakage. However, note that its resistance to strong oxidizers and certain organic solvents (like chlorinated hydrocarbons) is weak.

3. The Invisible Cost: A Long-Term Environmental Battle

In the natural environment, the degradation of a PP tray is measured not in years, but in centuries. Under ideal conditions with oxygen and ample sunlight, it first becomes brittle and fragments due to UV exposure (photodegradation), a process that can take decades. But to be completely mineralized by microbes into CO₂ and water, studies suggest it takes at least 400 to 500 years, or even longer.

One study estimates that under the continuous action of ocean waves and sunlight, a PP meal box can produce thousands to tens of thousands of microplastic particles smaller than 5 mm within a year. These particles can adsorb persistent organic pollutants from the seawater, reaching concentrations up to a million times higher than the surrounding water, and then enter the food chain.

4. Recycling: A Harsh Reality

In theory, PP (recycling code 5) is recyclable.

• Cleaning Cost is a Hurdle: Recycling plants receiving PP containers soiled with grease must clean them thoroughly. The cost of water, electricity, and labor to clean one ton of waste PP containers can be as high as 200-400 RMB, while the market price for clean, recycled PP material might only fluctuate around 5,000-7,000 RMB per ton. This narrow profit margin discourages many recyclers, who prefer to recycle cleaner, higher-value PET bottles (recycling code 1).
• Downcycling is the Norm: Even when recycled, after one thermal processing cycle, PP’s molecular chains break down, and its properties (especially impact strength) decrease by 15%-30%. Therefore, recycled PP can almost never be used again for food-grade containers requiring high hygiene and strength standards; the vast majority is “downcycled” into lower-grade products like car bumpers, trash cans, or garden edging. At the end of its life cycle, it still faces incineration or landfill.
• Abysmal Recycling Rates: Overall, although PP is theoretically recyclable, the actual recycling rate for single-use food containers is pitifully low. In regions with better waste sorting, this figure might barely reach 10%-15%; in most areas, over 85% of PP meal boxes ultimately end up in incinerators or landfills.

Expanded Polystyrene (EPS) Foam Trays

This white foam, composed mostly of air, has a density typically between 15-30 kg/m³. A tray weighing only 10-15 grams can occupy significant space in a trash bin. Globally, over 6 million tons of EPS are produced annually, with about 30% used for food packaging and disposable tableware.

Its extremely low cost (raw material cost per tray may be less than 0.1 RMB) and excellent insulation properties make it difficult to completely replace in the fresh food transport and cheap takeaway sectors. However, the ensuing environmental cost is far heavier than its price tag.

1. Over 90% of Its “Weight” is Air

Expanded Polystyrene foam, scientifically known as foamed polystyrene, is most remarkable for its physical structure. Its precursor is small PS resin beads containing about 5-8% of a blowing agent like pentane or butane. When heated by steam, the beads soften, the blowing agent vaporizes, causing the beads to expand like popcorn by 40-80 times, turning into pre-expanded beads filled with closed cells.

Subsequently, these pre-expanded beads are filled into a mold and steamed again, causing the beads to fuse together, forming the final shaped product. Therefore, the foam tray in your hand consists of over 95% air by volume, with solid plastic accounting for less than 5%. This achieves extreme lightweightness but also destined its “bulky” nature, occupying enormous space in waste collection and transport, resulting in very low transport efficiency.

2. Too Cheap to Refuse, But Too Expensive for Society to Bear

The cost advantage of foam trays is overwhelming. Its main raw material is styrene. Although the monomer price fluctuates, after foaming, the material cost per unit volume becomes extremely low. The production cost of a standard fish or meat tray can easily be controlled below 0.1 RMB. This is an irresistible choice for fresh food supermarkets, market vendors, and low-cost fast-food restaurants with slim profit margins. In comparison, a PP tray of the same size may be 3 to 5 times more expensive, and a molded pulp tray might be 5 to 8 times more expensive.

Collecting and transporting foam waste is highly uneconomical because it occupies a huge volume but is very light, leading to extremely low efficiency for collection vehicles. The collection and transportation cost per ton of foam waste may be more than twice that of ordinary mixed waste. When landfilled, it occupies a large amount of land space and will not decompose for hundreds of years.

3. In Nature, It’s Almost “Immortal”

EPS is chemically very stable. Its closed-cell structure makes it water-resistant, insoluble in water, and almost non-biodegradable by microorganisms. Nature lacks enzymes that can effectively break down the long chains of polystyrene polymers. In the environment, its degradation relies mainly on physical fragmentation.

• Photodegradation: UV radiation can break PS molecular chains, making the material brittle and faded. But this process only occurs on the surface and is extremely slow. A foam tray may take decades in sunlight to become significantly brittle.
• Physical Fragmentation: Under external forces like wind, water, and mechanical friction, the brittle foam breaks into smaller and smaller pieces. One tray can fragment into thousands of microplastic pieces within a year.
• Biodegradation: Under ideal laboratory conditions, some studies report specific bacterial strains can degrade PS very slowly, but the degradation rate is negligible and has no practical significance in the natural environment. It is widely believed that the complete degradation of EPS under natural conditions takes over 500 years, possibly even thousands of years.

4. A “Seeder” of Microplastics, Ubiquitous

The most dangerous stage of an EPS tray is not during its use, but after it is discarded. Once in the environment, it begins to continuously “produce” microplastics. Due to its brittle texture and low density, it is easily carried by wind and rain into sewers, eventually entering rivers and oceans.

Under the action of wave action and UV exposure, a larger piece of foam plastic will rapidly break apart, producing a large number of microplastic particles smaller than 5 mm, even further breaking down into nano-sized particles. Due to their hydrophobic nature, these particles act like magnets, adsorbing persistent organic pollutants from seawater, with surface pollutant concentrations up to a million times higher than the surrounding water.

5. Recycling? The Ideal is Plump, the Reality is Lean

In theory, EPS is recyclable, but the obstacles in practice are almost insurmountable.

• Volume is a Fatal Flaw: Collecting and transporting air-filled foam trays is extremely inefficient. The solution is to use specialized “hot melters” or “compactors” to melt them into high-density plastic blocks at temperatures of 90-120°C, reducing the volume to 1/50 to 1/90 of the original. But this requires additional equipment investment and operating costs, limiting the deployment of collection points.
• Contamination is a Problem: Foam trays contaminated with food, grease, or blood are difficult and costly to clean, further reducing their recycling value.
• Abysmal Recycling Rates: Considering these factors, the global recycling rate for EPS packaging remains extremely low. Even in regions with better recycling systems, the rate is difficult to exceed 10%. In most places, this figure is below 5%, even close to zero. Over 90% of discarded foam trays ultimately end up in landfills, incinerators, or directly leak into the natural environment.

Biodegradable/Compostable Materials

Current global bioplastics production capacity is about 2.41 million tons, but less than one-third of that can decompose rapidly in the natural environment. Over 60% of “eco-friendly” meal boxes on the market are primarily composed of Polylactic Acid (PLA), a material derived from corn starch that requires industrial composting conditions at 58 to 70 degrees Celsius for 6 to 12 weeks to decompose into carbon dioxide and water.

Biodegradable vs. Compostable

According to industry analysis, China’s market consumes over 2 million tons of so-called “degradable” food service packaging annually, but the capacity gap for supporting industrial composting treatment exceeds 85%.

In the oxygen-deficient, low-temperature (typically below 30°C) environment of a landfill, a PLA meal box may decompose not much faster than traditional plastic, taking decades to fully mineralize.

Biodegradable: A Slow Process Without Promises

• Vast Time Spans: An ordinary paper towel might decompose in damp soil within a few weeks. In contrast, a cup made from Polylactic Acid (PLA), labeled “biodegradable,” will have its molecular structure remain almost stable for the first 12 months in 25°C ambient seawater or soil, with a mass loss rate typically still below 10% after 24 months. Achieving over 90% complete degradation in a natural environment could take several years to decades.
• Highly Condition-Dependent: The degradation rate is highly dependent on environmental factors like the microbial population, temperature, humidity, and oxygen content. In dry, cold landfill bottoms, the decomposition process of any biodegradable material almost grinds to a halt. At temperatures below 10°C, the activity of most degrading enzymes drops to very low levels, making the decomposition process negligibly slow.

Compostable: A “Technical Contract” with Strict Standards

• Industrial Composting: An “Accelerated” Reactor. Industrial composting facilities create optimal conditions for degradation by controlling parameters. Conditions include:
  • Temperature: Must be maintained in the high range of 58-70°C. This temperature not only accelerates microbial metabolism but also kills pathogens and weed seeds. It is usually maintained by turning or forced aeration.
  • Humidity: Kept in the optimal range of 50%-60%. Too low humidity inhibits microbial activity; too high creates anaerobic conditions, producing methane and odors.
  • Carbon-to-Nitrogen Ratio (C/N): Maintained between 20:1 and 30:1.
  • Oxygen Content: Must be an aerobic process, with oxygen concentration greater than 5%.

• Home Composting: A More Stringent Challenge. An even higher standard than industrial composting is the “Home Compostable” certification (e.g., the OK compost HOME mark in Europe). It requires the material to decompose within 12 months under ambient temperatures (20-30°C) and the fluctuating conditions of a typical home compost bin.

Differences: Time Standards, Residues, and Certification Barriers

The most fundamental differences lie in three aspects:

First, a world of difference in time scale. Compostable promises to “solve the problem within 180 days.”

Second, different requirements for degradation products. Compostable standards strictly stipulate that the residues after degradation must be non-toxic and harmless to plants, and must not contain plastic residues larger than a certain size (e.g., larger than 2 mm).

Third, the certification system is the only true test. Because “compostable” is a controlled standard, third-party certification is crucial. Globally recognized certification marks include the US’s BPI, Europe’s OK compost INDUSTRIAL and OK compost HOME. If the product packaging lacks these specific certification logos and only has the seller’s “compostable” or “biodegradable” claims, their authenticity should be highly doubted. In China, a spot check of 50 online-sold meal boxes labeled “degradable” found that less than 15% had clear, verifiable international or domestic compost certification marks on their packaging.

Mainstream Compostable Materials

Performance and Cost Comparison

A standard 650ml takeaway meal box made from traditional Polypropylene (PP) plastic has a factory price of about 0.25 RMB, while a similar-sized Polylactic Acid (PLA) box costs 0.55-0.7 RMB, and a bagasse box about 0.45-0.6 RMB.

This price premium of over 100% buys compromised performance: PLA boxes have a maximum heat resistance typically only 60°C, risking deformation if microwaved (800W) for over 1 minute; bagasse boxes, when holding 95°C hot soup or oily food, have an effective waterproof layer lasting about 2 hours, with leakage probability increasing with time and temperature.

From a merchant’s perspective, the packaging cost per takeaway order increases directly by 0.3-0.45 RMB. For a store with a thousand daily orders, the annual packaging cost increases by over 100,000 RMB net, but the user experience may decline due to packaging failure.

Physical Properties

Heat Resistance Temperature: A Difficult Chasm to Cross

Heat resistance is one of the biggest shortcomings of alternative materials. Below is a comparison of the heat resistance properties of common materials:

PLA’s molecular structure dictates that it softens rapidly when its glass transition temperature (Tg) is exceeded. Holding freshly cooked stir-fries (often over 75°C) or dishes with sauce, the container may show significant warping or shrinkage within 30 minutes of delivery. Although modified PLA improves heat resistance, its raw material cost is 15%-25% higher than regular PLA, and production capacity is limited.

Mechanical Strength and Sealability: The Paradox of Weight and Cost

• Drop Performance: A PP plastic meal box filled with 500 grams of content, when dropped from a height of 1 meter, typically has a breakage rate below 5%. A bagasse box of the same specification, under the same test, may have a breakage rate of 10%-15%. To achieve similar strength, the wall thickness of the bagasse box needs to be increased, making it 20%-30% heavier than a PP box, directly increasing the raw material cost per piece and transportation logistics costs.
• Sealability: Plastic boxes can achieve high sealing through ultrasonic welding or precision clasps, preventing soup leakage. PLA boxes can also use similar processes, but the strength of the seal decreases rapidly when heated. Bagasse boxes basically cannot achieve reliable physical sealing, mainly relying on simple lid closure, with weak leak-proof ability.

Cost Structure Breakdown: Where is the Expense?

The table below compares the approximate cost structure per 10,000 units for boxes of different materials (unit: RMB):

The high cost of compostable materials mainly comes from two aspects: first, upstream raw materials (like PLA resin) currently have a small market scale and high technical barriers, keeping unit prices high; second, during processing, material characteristics (like PLA’s slow crystallization speed, bagasse pulp’s high drying energy consumption) lead to lower production efficiency and greater difficulty in controlling the defect rate.

End-of-Life Treatment Cost: The Overlooked “Second Half of Life”

Evaluating whether a material “replaces” plastic must consider the disposal cost after the product is discarded.

• Plastic (PP/PS): In the existing system, if mixed into other waste, its primary disposal methods are incineration or landfill. Incineration can recover some thermal energy; landfilling costs about 50-100 RMB per ton.
• Compostable Materials: The ideal path is entry into industrial composting facilities. However, the industrial composting fee in major Chinese cities is currently about 200-400 RMB per ton, higher than waste incineration (about 150-280 RMB/ton). More importantly, if the contamination rate of compostable waste exceeds 3%-5% (e.g., mixed with ordinary plastic), the quality of the entire batch of compost will be substandard and can only be diverted to incineration, increasing sorting costs and risks.

Proper Disposal

Identification Pitfalls

Don’t Trust the Ads, Trust the Code: Recognize These “Hard Currency” Labels

The “OK compost” Family: The Difference Between Industrial and Home Grade

China’s “Dual J” Label: The Benchmark of the New National Standard

Unmasking “Pseudo-Degradable” Claims: Analyzing the Most Common Misleading Buzzwords

1. “Corn Starch-Based” or “Contains Bio-based Materials”
   Many plates advertise containing 30%-40% corn starch, with the remaining 60% or more being traditional plastic (like PP, PE). These products are completely non-compostable. They may disintegrate in the natural environment, but the remaining plastic fragments become microplastics that are harder to clean up, with a pollution cycle potentially exceeding 500 years.
2. “Photodegradable” or “Oxo-degradable”
   These technologies typically involve adding additives to plastic, causing it to break down into powder under sunlight or air. But over 50 international environmental organizations have jointly opposed such technologies because their final product is microplastics, not true “degradation.” The EU has introduced regulations restricting the use of such products. Fragmentation is not degradation; it is more insidious pollution.
3. Only a #7 Recycling Triangle Symbol, with “PLA” Written Inside
   This is merely a material identifier, not an environmental promise. It only tells you “I am made of PLA,” but does not state under what conditions I can decompose.

Hands-On Verification: A Quick Check Method Taking Minutes

• Touch and Knead: Firmly rub the edge or corner of the plate. Pure pulp or bagasse products will fray and shed fibers; paper plates coated with PE plastic will show the coating separating from the paper base when rubbed, revealing a smooth plastic film.
• Water Drop Test: Place a drop of water on an inconspicuous area of the plate. A compostable bagasse plate will absorb water quickly within 5-10 seconds, with the drop spreading rapidly. A water droplet on a plastic or coated plate will maintain a hemispherical shape and not be absorbed for over 30 seconds or even longer.
• Tearing and Burning (Use Caution): Tear off a small corner and light it. Pure paper products burn to ash; PLA products have a smell similar to burning straw, with a blue flame at the base; ordinary plastic (PP/PS) burns with black smoke and a pungent odor, and drips molten material.

Divide and Conquer

China’s annual domestic waste collection volume exceeds 240 million tons, but even in first-tier cities, the accuracy of household waste sorting is often below 40%. One wrong disposal action has costs far beyond imagination: if a PLA compostable plate mixes into the plastic recycling stream, it can contaminate up to 1.5 tons of PET recyclate, causing its value to plummet by 30% or more;

If a plastic plate mistakenly enters food waste, it can ruin the quality of an entire batch of about 10 tons of compost, causing the output to exceed impurity standards. To correct these errors, sorting centers need to add 6-8 sorters per hour, increasing labor costs equivalent to a rise of 80-120 RMB per ton in waste treatment fees.

Plastic or Plastic-Coated Plates: The Dry Waste Bin is Their Only Destination

• How to Identify:
  • Feel: The surface feels waxy, smooth, and completely non-absorbent. Rub the edge firmly; you can feel a distinct plastic film (PE coating), and may even peel off a thin plastic skin.
  • Sound: When bent, a pure PP/PS plastic plate makes a crisp, tough “snap,” while a plastic-coated paper plate makes a dull “thud.”
  • Label: Check the recycling triangle symbol on the bottom. If it’s #5 PP or #6 PS, resolutely put it in dry waste. If unlabeled, treat it as plastic by default.
• Why It Must Go to Dry Waste:
  • Damage to the Recycling System: Plastic recycling involves melting and re-pelletizing. Taking PET bottle flakes (#1 plastic) as an example, their recycling temperature window is 260-280°C. If a PP plate (melting temperature ~160-170°C) mixes in, it forms difficult-to-disperse “fish eyes” in the PET, causing the strength of the recycled plastic strands to drop by over 50%, potentially rendering a whole batch of recyclate worth 8,000 RMB/ton worthless.
  • Damage to the Composting System: In the industrial composting environment of about 60°C, they do not decompose at all, ultimately becoming impurities mechanically screened out and then sent for incineration as waste. This process not only fails to achieve resource recovery but also consumes additional energy for screening.
• Subsequent Path: Entering a dry waste incinerator, its calorific value is about 35-40 MJ/kg, which can be used for power generation, but the dioxins and other gases produced require treatment in temperatures above 850°C combined with advanced flue gas purification systems (costly).

Truly Compostable Plates (Bagasse/Pure Pulp): The Food Waste Bin is the Optimal Solution

Home Composting Practical Parameters:

• • Conditions: Requires a compost bin with a volume of at least 0.3 cubic meters, maintaining a carbon-to-nitrogen ratio (C/N) between 25:1 and 30:1 (can mix plate fragments with fruit/vegetable scraps). The pile temperature is best maintained at 40-50°C, and turned 1-2 times per week to provide oxygen.
  • Cycle: Under ideal conditions, a bagasse plate completely decomposes into humus in 3-6 months. If simply torn and buried in soil, decomposition time may extend to 8-12 months.

The Power of Industrial Composting:

In professional equipment, through forced aeration, spraying, and turning, the temperature can quickly rise to 55-65°C and be maintained for 2-3 weeks (high temperature kills pathogens and weed seeds). At this intensity, the plate can completely degrade within 45-60 days. The output is organic fertilizer meeting national standards, with organic matter content potentially exceeding 30%.

Cost of Incorrect Disposal:

If disposed of as dry waste and incinerated, its calorific value is only 16-18 MJ/kg, much lower than plastic, reducing overall power generation efficiency. If landfilled, decomposing in an anaerobic environment produces methane (CH₄), a greenhouse gas with 28-34 times the global warming potential of CO₂ over a century.

PLA Bioplastic: The Most Finicky, Most Afraid of Misplacement

Industrial Composting is the “Only Lifeline”:

PLA decomposition is a two-step process: hydrolysis and microbial digestion. It first requires a humid, hot environment of 50-60°C for its polymer chains to break within 3-6 weeks (hydrolysis); only then can microorganisms intervene, completely decomposing it over the next 4-8 weeks.

“What if there is no industrial composting plant in my city?”

If local government clearly requires PLA to be placed in food waste, follow that rule (assuming backend processing exists). If uncertain, the safest, lowest social cost choice is to treat it as “Residual/Dry Waste”. Because:

1. If it mixes with food waste and the backend lacks industrial composting capacity, it becomes an impurity like ordinary plastic, adding sorting cost for nothing.
2. If it contaminates the plastic recycling stream, its destructiveness is as described earlier, devastating. Faced with uncertainty, classifying it as dry waste is the rational choice of “choosing the lesser of two evils.”

Mixed Material Plates (e.g., Airline Aluminum Foil Meal Boxes): Definitely Dry Waste

• Why They Can’t Be Recycled: A common aluminum foil laminated meal box has foil thickness of only 0.05-0.08 mm, tightly bonded to the plastic or paper base. Existing recycling technologies, whether hydropulping or thermal melting, struggle to economically separate them thoroughly. The cost of separating one ton of such waste is often 2-3 times the value of the recovered aluminum and plastic, resulting in recycling rates persistently below 5%.
• Disposal Method: Without hesitation, put it in dry waste.