The Difference Between Biodegradable and Compostable Waste

* This article was last updated in and is based on extensive research from reputable sources, including scientific studies, government reports, and environmental organizations. For further reading and verification, refer to the sources list.

Introduction

The escalating volume of waste generated worldwide poses a significant environmental challenge, driving the need for more sustainable waste management solutions^[1]. In response, terms like biodegradable and compostable have gained widespread use, often marketed as environmentally friendly alternatives to conventional waste disposal. However, these terms are frequently used interchangeably, causing confusion among consumers and even within industries^[2].

This article offers a comprehensive analysis of the key differences between biodegradable and compostable waste, examining their core characteristics, how they decompose, their environmental impacts, and the standards that govern their labeling. A clear understanding of these distinctions is essential to support effective waste management practices and reduce the long-term environmental impact of modern waste systems.

Not sure what counts as biodegradable trash? See the full list of items here.

Characteristics and the Biodegradation Process

Biodegradable waste encompasses any organic matter present in waste that can be decomposed by microorganisms and other living organisms into simpler substances^[1:1]. These simpler substances include carbon dioxide, water, methane, compost, humus, and simple organic molecules^[3]. The primary sources of biodegradable waste are typically plant and animal matter^[4]. Common examples include kitchen waste such as spoiled food, trimmings, and inedible parts of produce, as well as yard waste like grass clippings and leaves^[5].

Additionally, paper waste, certain types of biodegradable plastics, human waste, manure, sewage, and slaughterhouse waste fall under this category^[5:1]. Interestingly, the definition can sometimes extend to certain inorganic materials that can be decomposed by bacteria under specific conditions, such as gypsum and its products^[5:2]. This highlights the context-dependent nature of the term within waste management.

The process of biodegradation is a natural phenomenon driven by microorganisms like bacteria and fungi, along with abiotic factors such as temperature, ultraviolet (UV) radiation, and the presence or absence of oxygen^[4:1]. These agents work together to break down complex organic substances into simpler forms that can be reintegrated into the environment^[4:2]. Biodegradation typically occurs in three main stages^[6].

The first stage, biodeterioration, involves the physical weakening of the material's structure, often through exposure to abiotic factors and the initial action of organisms^[6:1]. This weakening prepares the material for the next stage, biofragmentation, where microorganisms secrete enzymes that cleave the bonds within the material, breaking it down into smaller pieces, such as oligomers and monomers^[6:2]. The final stage is assimilation, where these fragmented compounds are absorbed and incorporated into the cells of the microorganisms^[6:3].

The process can proceed in the presence of oxygen, known as aerobic digestion, or in the absence of oxygen, termed anaerobic digestion^[5:3]. Aerobic digestion generally occurs more rapidly, while anaerobic digestion is notable for producing methane as a byproduct, which can be captured and used as a renewable energy source^[5:4].

It is crucial to recognize that the timeframe for biodegradation can vary significantly, ranging from days for vegetable scraps to years for materials like wood and even millennia for certain plastics and glass^[6:4]. This variability underscores a key distinction between biodegradable and compostable waste: the former lacks specific conditions and a defined timeframe for complete breakdown. The broad nature of the term "biodegradable" can be problematic, particularly in marketing, as it does not guarantee rapid or complete decomposition in all environments^[7].

Wondering how long biodegradable trash takes to decompose? Get the full timeline here.

Specific Decomposition Requirements

Compostable waste refers to organic material that, under specific conditions within a composting system, will decompose into a nutrient-rich soil amendment known as compost or humus^[2:1]. This category represents a subset of biodegradable waste, distinguished by its requirement for a controlled environment and the beneficial nature of its end product^[2:2]. Effective composting necessitates a specific combination of several key factors^[8].

Firstly, oxygen is crucial, as composting is primarily an aerobic process that requires sufficient air circulation to support the microorganisms responsible for decomposition^[9]. Secondly, moisture levels must be carefully managed; an ideal range of 40–60% humidity is typically needed to facilitate microbial activity without creating anaerobic conditions^[9:1]. Thirdly, the presence of a diverse community of microorganisms, including bacteria, fungi, and other microbes, is essential for breaking down the organic matter^[9:2].

Fourthly, temperature plays a significant role; thermophilic composting, which occurs at temperatures between 131–160°F (55–70°C), is often preferred as it accelerates decomposition and helps to destroy pathogens and weed seeds^[2:3]. Fifthly, the carbon-to-nitrogen ratio of the composting materials must be balanced, ideally around 30:1, to provide the necessary nutrients for the microorganisms; carbon-rich "browns" (like dry leaves) provide energy, while nitrogen-rich "greens" (like food scraps) support microbial growth^[8:1]. Lastly, particle size influences the rate of decomposition, with smaller particles offering a greater surface area for microbial action^[10].

The necessity of these controlled conditions underscores why compostable waste may not break down effectively in environments lacking these parameters, such as typical landfills^[11]. Landfills, being largely anaerobic, do not provide the oxygen required for proper composting, leading to slow, anaerobic decomposition and the production of methane, a potent greenhouse gas^[11:1].

Therefore, the intended environmental benefits of compostable materials are best realized when they are processed in dedicated composting facilities or managed through home composting systems where these conditions can be met^[2:4].

Learn how biodegradable trash supports a healthier environment. Read the environmental benefits.

Biodegradation Timeframes for Various Materials

The time it takes for biodegradable materials to decompose varies dramatically depending on the type of material and the environment in which it is placed^[6:5]. The following table provides a comparative overview of the approximate decomposition times for common biodegradable materials in natural environments, landfills, and ideal composting conditions.

Material	Natural Environment (Approx.)	Landfill (Approx.)	Compost (Ideal Conditions)
Vegetables	5 days – 1 month	Years	Weeks
Paper	2 – 5 months	Months – Years	Weeks – Months
Cotton T-shirt	6 months	Years	Months
Orange Peels	6 months	Years	Months
Wool Socks	1 – 5 years	Years	Months
Plastic-coated Milk Cartons	5 years	Decades	-
Leather Shoes	25 – 40 years	Decades	Years
Nylon Fabric	30 – 40 years	Decades	-
Tin Cans	50 – 100 years	Decades	-
Aluminum Cans	80 – 100 years	Centuries	-
Glass Bottles	1 million years	Indefinite	-
Cigarette Butts	18 months – 10 years	Years	-
Plastic Bags	500 years – Forever	Centuries	-
Biodegradable Plastics	3 – 6 months (specific)	Years	Weeks – Months

This data illustrates the wide spectrum of decomposition rates. While some organic materials like vegetables and paper break down relatively quickly, others, such as plastic bags and glass bottles, can persist in the environment for centuries or even longer^[12].

Notably, the conditions within a landfill often hinder rapid biodegradation due to the lack of light, water, oxygen, and sufficient microbial activity^[13]. Even materials like paper, which decompose relatively quickly in open environments, can remain largely intact in landfills for extended periods^[14].

Biodegradable plastics, while designed to break down faster than conventional plastics, often require specific conditions, such as those found in industrial composting facilities, to achieve their intended degradation within a reasonable timeframe^[12:1].

In the oxygen-deprived environment of a landfill, their decomposition can be significantly delayed, potentially leading to methane emissions^[15]. The stark contrast in these timeframes underscores the importance of proper waste management strategies beyond simply relying on a material being labeled "biodegradable."

See how biodegradable trash breaks down versus regular waste. Read the full breakdown here.

The Specific Conditions Required for Composting

Achieving effective composting requires meticulous management of the environmental conditions that support microbial activity^[8:2]. Aeration, or the presence of oxygen, is paramount for the aerobic microbes that efficiently break down organic matter; without it, anaerobic conditions can lead to slow decomposition and unpleasant odors^[16]. Maintaining adequate moisture is also critical, as microorganisms need water to thrive and facilitate the transport of nutrients within the compost pile; the ideal moisture content is often described as feeling like a wrung-out sponge^[10:1].

The temperature of the compost pile is another crucial factor; temperatures in the range of 131 to 160 degrees Fahrenheit (55 to 71 degrees Celsius) promote rapid decomposition and can kill harmful pathogens and weed seeds^[10:2]. This heat is generated by the metabolic activity of the microorganisms themselves^[17].

The carbon-to-nitrogen (C:N) ratio is a fundamental chemical aspect of composting. Microorganisms use carbon for energy and nitrogen for building their cells; an optimal ratio of around 30:1 ensures a balanced food source for these decomposers^[10:3].

"Brown" materials, rich in carbon (e.g., dry leaves, wood chips), should be mixed with "green" materials, high in nitrogen (e.g., food scraps, grass clippings), in the appropriate proportions^[10:4]. Finally, the particle size of the materials being composted affects the surface area available for microbial attack; smaller pieces decompose more quickly^[10:5].

Composting facilities play a vital role in managing these conditions on a large scale^[2:5]. These facilities employ various methods, such as windrow composting (large piles turned regularly), in-vessel composting (enclosed systems with controlled environments), and static pile composting (aeration through pipes), to optimize the decomposition process^[18].

Community composting initiatives also contribute by providing localized sites for organic waste processing^[19]. Home composting, while on a smaller scale, can be effective if these principles of aeration, moisture, temperature, and nutrient balance are applied in compost piles or bins^[2:6].

The controlled nature of these environments in composting, particularly in industrial settings, is what distinguishes it from the more variable and often less efficient biodegradation that occurs in natural environments or landfills.

Get a complete overview of biodegradable trash. Explore its types, benefits, and challenges.

Comparing and Contrasting Biodegradable and Compostable Waste

The terms biodegradable and compostable are often used interchangeably, yet they represent distinct concepts in waste management^[2:7]. Biodegradable is the broader term, encompassing any material that can be broken down naturally by microorganisms over time^[2:8].

This process can occur in various environments, including landfills, soil, and water, and the timeframe for decomposition is highly variable, ranging from weeks to centuries^[2:9]. Furthermore, biodegradable materials may leave behind residues, and there is no specific requirement for the end product to be beneficial^[2:10].

In contrast, compostable refers to a specific type of biodegradable material that will break down into a nutrient-rich substance (compost) under a defined set of composting conditions^[2:11]. These conditions typically involve a specific timeframe (e.g., 90–180 days in industrial facilities), adequate oxygen, moisture, temperature, and microbial activity^[2:12].

A crucial point to remember is that all compostable materials are biodegradable, but not all biodegradable materials are compostable^[20]. The term "biodegradable" when used in marketing can often be misleading because of its lack of specificity regarding the timeframe and environmental conditions required for breakdown^[7:1]. In some regions, the use of "biodegradable" in the marketing of single-use products is even prohibited due to these ambiguities^[7:2].

The controlled environment and the production of beneficial compost are the key differentiators that make "compostable" a more precise and often environmentally preferable term.

Labeling and Certification Standards for Biodegradable and Compostable Products

To help consumers differentiate between truly compostable products and those that are merely marketed as such, various labeling and certification standards have been developed^[2:13]. These standards are typically managed by third-party certifiers who verify that products meet specific criteria for composting, such as those outlined in ASTM D6400 and D6868 in North America, and EN 13432 in Europe^[21].

Products that achieve these certifications often display specific logos, such as the Biodegradable Products Institute (BPI) mark in the US, or the TÜV AUSTRIA OK Compost HOME and INDUSTRIAL certifications in Europe and Australia^[2:14]. These certifications assure consumers that the product will break down properly in the intended composting environment (industrial or home) within a specified timeframe and will not leave harmful residues^[22].

In addition to certification logos, some regions have regulations regarding the labeling of compostable products, often requiring the use of green, beige, or brown colors to signal compostability and the inclusion of the word "compostable"^[23]. Conversely, to prevent confusion and greenwashing, terms like "biodegradable," "degradable," and "decomposable" are often prohibited on products that are not certified as compostable for industrial facilities^[23:1].

This regulatory trend highlights the importance of clear and specific terminology for guiding consumers and reducing contamination in composting streams. For general "biodegradable" products, there is a significant lack of universal labeling and certification standards^[22:1].

This absence of standardized criteria contributes to the ambiguity of the term and makes it challenging for consumers to discern the true environmental impact of products labeled as merely biodegradable. The presence of robust certification programs for compostable products offers a much higher degree of reliability and transparency compared to the often vague claims associated with biodegradability.

Environmental Benefits and Drawbacks: Biodegradable vs. Compostable Materials

The use of both biodegradable and compostable materials presents potential environmental advantages and disadvantages compared to conventional, non-biodegradable materials. Biodegradable materials offer the benefit of reducing the accumulation of waste in landfills^[24]. They can have a lower overall environmental impact than traditional plastics, particularly if made from plant-based resources, potentially leading to more sustainable practices and reduced reliance on finite fossil fuels^[6:6]. In some instances, the manufacturing of biodegradable materials can result in lower carbon emissions^[6:7].

However, it is important to note that some biodegradable materials may not fully decompose, potentially leaving behind microplastics^[25]. Certain types can also release harmful substances like methane or heavy metals during their degradation^[6:8]. Furthermore, the concept of biodegradability can sometimes reinforce a single-use mentality, and proper disposal pathways may not always be readily available for all types of biodegradable materials^[6:9]. "Oxo-degradable" plastics, often marketed as biodegradable, are particularly concerning as they are known to fragment into microplastics, posing a significant environmental threat^[22:2].

Compostable materials offer several key environmental benefits. Primarily, they facilitate the diversion of organic waste from landfills, which significantly reduces the emission of methane, a potent greenhouse gas produced during the anaerobic decomposition of organic matter in landfill environments^[2:15].

The breakdown of compostable materials results in the creation of nutrient-rich compost, which can improve soil health, reduce the need for synthetic fertilizers, and enhance water retention in soils^[2:16]. When derived from bio-based sources, compostable materials also reduce our dependence on fossil fuels^[20:1]. The application of compost to soil can also contribute to carbon sequestration, helping to mitigate climate change^[26].

However, compostable materials also have potential drawbacks. If they end up in landfills, the lack of oxygen can lead to anaerobic decomposition and methane production, negating some of their intended benefits^[11:2]. The effectiveness of composting relies on proper collection and processing infrastructure, which is not yet universally available^[27]. Contamination of compost streams with non-compostable items can also reduce the quality of the final compost product^[28].

Furthermore, lifecycle assessments have indicated that in some cases, the production of compostable materials might have a higher greenhouse gas footprint compared to traditional plastics, depending on the specific materials and processes involved^[27:1]. Concerns have also been raised about the presence of PFAS in some compostable products, which could contaminate the resulting compost^[29]. Therefore, while both categories offer advantages, their environmental performance is contingent on proper management and disposal.

Conclusion

In summary, the key distinction between biodegradable and compostable waste lies in the specificity of the breakdown process and the nature of the end product. While all compostable materials are biodegradable, the reverse is not true. Biodegradability is a broad term indicating that a material can decompose naturally, but it lacks specific timeframes and environmental requirements, and the resulting substances may not be beneficial. Compostability, on the other hand, refers to the ability of a material to break down into nutrient-rich compost under controlled conditions within a defined period.

For effective waste management and to minimize environmental impact, a clear understanding of these differences is essential. Consumers should prioritize products with certified compostable labels, as these have undergone rigorous testing to ensure they will decompose appropriately in composting facilities without leaving harmful residues.

The development and expansion of adequate composting infrastructure are crucial to maximize the environmental benefits of compostable materials by diverting organic waste from landfills and producing valuable compost. Ultimately, informed consumption choices and responsible waste disposal practices are necessary to leverage the potential of both biodegradable and compostable materials in creating a more sustainable future.

Consumers should be wary of vague "biodegradable" claims and seek out certified "compostable" products when the goal is to contribute to a circular economy through composting.