Chula’s Potassium Liquid Soap from Used Cooking Oil for a Greener Environment and Circular Economy

A researcher from Chulalongkorn University’s Institute for Environmental Research has made it possible to transform used vegetable oil into potassium liquid soap that cleanses effectively, is water soluble, 100% biodegradable, and safe for the wastewater treatment system. The product can be a viable option to add value and increase community potential to handle used cooking oil.  The researcher hopes that soon the product can also extend to insect control agents in organic farm plots.

Used cooking oil should not be used repeatedly since it contains carcinogens that are harmful to our health.  Moreover, incorrect disposal methods can also bring about adverse public health and environmental effects.  Instead, with good management, used cooking oil can become a valuable resource as is the case of vegetable oil from the industrial food sector that has been turned into biodiesel fuels.

There remain, however, large quantities of cooking oils from households and commercial establishments that require proper management.  This problem is what led Dr. Nattapong Tuntiwiwattanapun, a researcher from the Environmental Research Institute to find a possible solution leading to his research work on the transformation of used vegetable oil into potassium liquid soap that each community could manufacture on their own.

The problem of what to do with used cooking oil

Used cooking oil or UCO is a form of organic waste generated in the cooking process that involves all of us either directly or indirectly.  The oil may come from the food industry, restaurants, hotels, and our households which, as the sector, we should be most concerned about since no legal control or enforcement is yet available.

Statistics provided by the Energy Policy and Planning Office of the Ministry of Energy indicate that in 2017, used cooking oil in Thailand amounted to around 74 million liters which means that currently, the numbers should already have increased to around 115 million liters per year in 2022. How is this staggering amount of used oil being managed and what are their impacts?    

According to Dr. Nattapong, the industrial sector already follows the legal guidelines of the Department of Industrial Works both in terms of wastewater treatment and biodiesel production.  There are altogether 15 biodiesel plants in Thailand most of which are scattered around the central, eastern, and southern regions.   

“Used cooking oil fetches a high price if they are sourced from areas close to the biodiesel factories.  In remote places such as provinces in the north and northeast, the oil fetches a lower price since there are also transportation costs involved.  This usually results in the oil being thrown out.”  Dr. Nattapong enumerated on the problem which worsens in the case of households that are not motivated to sell their used oil for biodiesel production.  The oil gets thrown into the sewer or mixed with other forms of garbage which causes great damage to the environment.    

“If used oil gets mixed with recycled waste it would lead to contamination whereby that waste cannot be used.  Used oil comes in liquid form that does not dissolve in water and when mixed with plastics is extremely hard to remove.”   

Moreover, when the contaminated oil gets to a landfill, it can lead to anaerobic digestion that generates methane, a greenhouse gas that affects global warming 23 times worse than carbon dioxide!

How the idea of transforming used cooking oil into potassium liquid soap was conceived

When it comes to the sorting of waste, Chula’s canteens follow the Chula Zero waste guidelines with systematic forms of waste management on campus.  The remaining challenge concerns the used cooking oil and fat residue. 

“Chula’s Office of Physical Resources Management came to us with the task of what to do with fat residue from the canteens on campus.  There have been several research projects that mix fat residue for composting purposes. Our experiments with fat residue and used cooking oil which is water-insoluble to compost with fertilizer did not yield very good results.  The next step was to make the fat residue water-soluble by turning them into potassium liquid soap that was then composted with the Chamchuree (rain tree) leaves.  We were thus able to get rid of the fat residue with the added benefit of enriching the Chamchuree fertilizer with potassium.”  

Potassium soap and its outstanding qualities

With its surface-active agents, Potassium or K–Soap is as effective as other cleansers on the market in removing stains on surfaces.  What makes K-Soap special is its low toxin for microbes making it 100% biodegradable compared to other sulfate-based cleansers commonly used in households.  Potassium soap also has disinfesting abilities at the levels permitted by organic farming standards.   

Pioneering the production of K–Soap in local communities

With funding from the National Higher Education, Science, Research and Innovation Policy Council, the research team started its K-Soap production with a community enterprise at Baan Phai Lueang in Nan Province as part of a project to promote environmentally friendly tourism in Nan.   

“The idea was to create potassium soap that was safe and easy for members of the community to manufacture.  Our main focus was to increase their potential in waste management and to be able to benefit from income-generating projects.”

The process helped create a circular economy with community enterprises purchasing the raw materials from within Nan province and manufacturing them as potassium soap.  The soap was tested as a product used to clean garbage trucks belonging to Meaung Nan municipality as well as to clean road surfaces, wash rags, and cleaning temple restrooms, for example.   The reception was good since not only was the product effective and easy to manufacture but the production cost was much lower than the cleaning products that were in use.  Aside from Nan, the project has also been implemented in the Pak Lad Community of Samut Prakan Province based on the Zero-Waste concept supported by Dow Thailand Group.

Adding value to K-Soap through organic farming

Aside from its cleansing qualities, Dr. Nattapong also realizes there is a chance of a value-added K-Soap in the agricultural sector as well.  Working in collaboration with Chula’s School of Agricultural Resources, the project has developed the soap so that it has surfactant qualities to boost the biopharmaceutical ingredients that control plant diseases and pests in safe and organic agriculture farming 

In the future, the project hopes to experiment with using potassium liquid soaps for cleaning purposes as well as to wash off pesticide residues in fruits and vegetables from the time they are in the orchards to ensure better safety.  K-soap was also given to the PGS (Participatory Guarantee System) group of organic farmers as an alternative to experiment in organic farming and found that it can effectively repel mealybugs, ants, and some worms.

“K-Soap has very low toxic levels and takes only 5 days to biodegrade after which it releases potassium to the plants.”   

Chula’s potassium soap production is now based in Nan Province.  The soap is ready for production for cleaning purposes and aphid control.  To apply the product for agricultural use Dr. Nattapong says they need to wait for the test results from the demonstration farms.  The product is expected to be ready for the agricultural sector in 2023 or 2024.   

The community and waste management and the circular economy

Today, most of the garbage we generate is still scattered and collection remains a problem.   Dr. Nattapong still sees waste management as an area-based matter that should draw people together to take part in solving the problem, sort their garbage and recycle or upcycle as a way to increase its benefits and generate income for the community.   For a large city with a very low level of food security, we need to expand the green areas such as by planting vegetables on rooftops or in urban areas.  Waste management measures that take leftover food for composts to make fertilizer or used cooking oil turned into cleaning substances helps not only to reduce garbage but also reduces environmental impact while increasing agricultural urban areas as well.”

Dr.  Nattapong’s ideas also include adding value to the waste generated in various types of food production such as fat residue that isn’t so widely known, coffee grounds or plastics with oil stains, etc.

“We can eliminate all garbage if there is proper and efficient sorting so that they can be turned into raw materials to be turned into products to benefit the communities based on the circular economy concepts,” he concluded.

For those who are interested in trying out the potassium liquid soap and its use for pest control, contact Dr. Nattapong to obtain product samples by emailing Nattapong.T@chula.ac.th .

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