Is Soap Biodegradable?

In this brief writeup we will be discussing the topic “Is soap biodegradable?”. We will be highlighting the aspects that make soap biodegradable, factors that influence the rate of biodegradability of soap and know if soap is a healthy option for a cleaner environment. 

Is soap biodegradable? 

The biodegradability of soap mainly depends on its chemical composition. Soap has a unique property of being soluble in water and at the same time it dissolves oily substances and dirt from our body. Though these two functions are literally opposite, soap can accomplish this because of its chemical nature. 

Soap has both hydrophilic (water loving) and hydrophobic (water hating) parts and thus it can mix both water and oil. Such nature of the material is called amphipathic. The solubility of soap is due to the presence of a hydrophilic part that attracts water. Being water soluble is also what makes soap biodegradable. 

Chemically, soaps are made of salts of fatty acids which can be acted upon by different types of bacteria. Though many factors such as temperature, pH, and condition of soil affects the biodegradation of soap, most of the available soaps are to some extent biodegradable by the microorganisms present in the soil. 

Soaps are an essential part of our everyday life to keep us clean and healthy. They are the most effective way to keep us away from germs. With the onset of new diseases and infections of the 21st century, its consumption has increased tremendously. A simple process of handwashing can keep the germs, bacteria, and even viruses away. 

Since the use of soap is unavoidable, it is important to maintain the balance between the environment and wastes generated by soaps. 

What factors are involved in biodegradation of soap? 

There are several factors that determine the extent to which soaps can be degraded. Soaps are usually biodegradable compared to detergents due to the difference in their chemical composition. Soaps are made from naturally available materials whereas detergents use synthetic materials such as ammonium hence these tends to be unaffected by bacteria or other microorganisms. 

Some of the factors that determine the biodegradability of soap can be summarized in the following points. 

  • Chemical composition 
  • Aerobic or anaerobic condition 
  • Where it is disposed 

Chemical Composition 

The chemical composition determines the material property of the soap. For any material to be biodegradable it must be broken down by naturally occurring microorganisms such as bacteria or fungi in a few months. 

However, the conventional soap that is made today contains chemicals like triclosan and triclocarban which are non-biodegradable and hence remain in soil for a longer time. Triclosan is a harmful chemical, and it is absorbed by our skin in small amounts. In some countries the FDA has banned the use of triclosan. 

Similarly, phosphates found in regular soaps also cannot be broken down by natural means. Biodegradable soaps on the other hand contain materials like sodium lauryl sulfate and lauryl alcohol which are completely biodegradable in both aerobic and anaerobic conditions

Which means they are also biodegradable in landfill and do not persist in the environment. 

Hence, any soaps that contain this biodegradable material are the most eco-friendly option for our healthy environment. 

Aerobic and anaerobic soil environment 

Certain species of Syntrophomonas bacteria are very helpful in degrading soap under aerobic conditions. Any surfactants in aerobic soil can undergo degradation without affecting the soil biota. However, some species of bacteria can also degrade specific elements of soap such as sodium stearate that can degrade in anaerobic condition and at specific temperature. 

Whereas some elements such as sodium laurate remain intact in these ambient conditions. 

Disposal of soap waste 

Soap waste disposal is an important aspect when considering the health of our environment. Most of the washed soaps are degraded by the bacterial system found in soil, but if these soap wastes are disposed of in water bodies, they prove hazardous to the ecosystem. 

Soap waste tends to form insoluble film on the surface of water which prevents oxygen diffusion thereby affecting water animals. The soap waste disposed of in your backyard is much safer than in any water bodies because water bodies do not contain the necessary microorganisms that can degrade soap elements. Hence, even if you are using the soap for cleaning purposes it is better to do it 200 ft away from any water bodies.

Is soap a healthier option for our environment? 

Soap is the only efficient method of cleaning us which is widely available. The worldwide consumption of soap is very high with China being the highest followed by the US and India. With more education on hygiene and healthy practices, the consumption of soap is increasing exponentially. 

The process of soap making creates no by-products, utilizes very less energy, and is not harmful to our environment. Moreover, it utilizes the naturally available renewable raw materials such as vegetable oil. Even more, the process of making soap from waste frying oil is another attribute for a healthy environment. 

All these aspects of soap make it a healthier choice for maintaining a clean and disease-free environment. However, there is a flip side to the use of any type of soap. When soap waste is directly dumped in water bodies, they tend to enhance the growth of water plants or algae to an extent that it creates an imbalance to the aquatic ecosystem. 

There is another source of waste from the use of soap and that is soap itself. Many hotels provide soaps to their customers for their overnight stay. Many don’t use it or even if used there is a lot left over. This is the case of over thousands of hotels worldwide and a waste of around five million bars of unused soap every day. 

This lucrative number of soaps end up in landfill and affect our valuable environment. With an aim to save our planet, people and companies are developing strategies to deal with soap wastage. Soap aid is one such company that collects hotel soap and reprocess by sorting and cleaning to form a hygienic bar soap. 


In this brief note we have discussed the topic “Is soap biodegradable?” and elaborated some factors that decide the biodegradability of soap. On a final note, it is highlighted with proper choice of raw materials and packaging, soap is a healthy biodegradable option for a cleaner environment.

Frequently asked question (FAQs): “Is soap biodegradable?” 

Which is biodegradable soap or detergent? 

Soap tends to be more biodegradable than detergents as it uses raw materials such as sodium lauryl sulfate and lauryl alcohol that are easily degraded by bacteria. However, detergents are synthetic products and contain raw materials such as triclosan and triclocarban which are not only toxic but are not degraded by natural means. 

Is soap bad for the environment? 

The answer to this question depends on how effectively we are using soap. Biodegradable soaps that use natural raw materials are a better choice for our environment. Disposing soap waste in soil or treating sewage water before spilling in water bodies helps to maintain the natural balance of our ecosystem. 

What makes soap non-biodegradable? 

Certain chemicals present in soap such as triclosan and triclocarban makes the soap non-biodegradable. Several factors such as chemical composition of soap, its breakdown in aerobic and anaerobic condition, and its disposal in soil or water is what decides the biodegradability of soap. 

Why is soap more environmentally friendly? 

Soaps are more eco-friendly than any other cleansing products. Compared to detergent, soap making is an energy efficient process and is biodegradable. Soaps do not use harmful chemicals but utilize renewable sources such as vegetable oil thus protecting our planet from the overuse of fossil reserves. 

Does soap contain plastic? 

Though many cleansing products such as toothpaste and facial scrubs contain plastic microbeads, soap as it is does not contain any plastic material. However, plastic is an integral part of the soap industry as they are needed for its packaging and storage. 

Is soap better than shower gel for the environment? 

Shower gels are the most convenient way to clean up for some. However, if you are looking for a most eco-friendly option then bar soap is the best. Shower gel contains microbeads, and its use is controversial. In some places the use of microbeads is banned. Moreover, the bar soaps use less plastic material for packaging compared to shower gels. 

Does Soap pollute water? 

Soap wastes that are directly disposed of in water bodies cause harmful effect to aquatic systems. They tend to form insoluble film which prevent diffusion of oxygen and hence affects the water animals. The presence of soap in water also enhances the growth of water plants which further creates an imbalance in oxygen levels. 


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Antonić, B.; Dordević, D.; Jančíková, S.; Tremlova, B.; Kushkevych, I. Physicochemical Characterization of Home-Made Soap from Waste-Used Frying Oils. Processes 2020, 8, 1219.

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