Making Paint from Calcium Carbonate recycled from shells in foodwaste

PrizesSchoolProject TitleParticipants
1st Prize S$6,000Woodlands Secondary SchoolMaking Paint from Calcium Carbonate recycled from shells in foodwasteSaarvieenrash Ragubalar, Gurpreet Kaur Dhaliwal, Ang Ee Jin, Kat Wan Yee
Project Summary

Calcium carbonate is a raw material used in huge quantities in various industries such as in the construction industry, as ingredients for building material, coatings and cement and in the manufacturing of common products including paint, glass, plastics, paper and antacids. A total of 1.2 million tons of calcium carbonate was used in paint production annually in America, Western Europe and China. Commercially, calcium carbonate is obtained via mining and quarrying which often lead to adverse impact to the environment and the ecosystem resulting in the loss of habitat, loss of biodiversity, soil erosion, deforestation, noise air and water pollution. Thus, it is important to explore alternative sources of calcium carbonate which are more environmentally friendly.

In our project, we explore the feasibility of using calcium carbonate that is recycled from food waste including the shells of hen eggs and a few types of shellfish such as the ark clam, bamboo clam (Lala) and mussels in one of the main application for calcium carbonate, paint production.

These various types of shells were tested for their calcium carbonate content with the result of a high calcium carbonate content of 92.5% for Venus clams, 92.3% for Bamboo clams (Lala), 88.8% for hen eggshells and a relatively lower content of 77.3% for mussels. Based on these data, we selected the Venus clams, Bamboo clams (Lala) and hen eggshells to proceed with our investigation as they contain a lower concentration of impurities.

We collected the hen eggshells and the shells of Venus clams and bamboo clams (Lala) and processed them by crushing and grinding to obtained fine particles which were then sieved. Manual grinding for the shellfish was tedious as they were too hard and we were unable to obtain the required amount of calcium carbonate powder for our investigation. Egg shells were softer and the calcium carbonate particles from the eggshells which were obtained from manual grinding were sent to TUV SUD PBS, a product-testing company for filtering to obtain calcium carbonate powder which was finer than 44 mm in particle size.

With assistance from Nippon Paint, our recycled source of calcium carbonate was made into paint and was tested against a standard paint using testing methods that adheres to the Singapore Standard (SS) and American Society of Testing and Material (ASTM).

Based on the detailed test results, our paint product was comparable to the standard paint. This shows that it is possible to use recycled source of calcium carbonate from waste products such as eggshells in paint-making. Improvements can be made to our recycle source of calcium carbonate by filtering it through a finer sieve of 500 mesh size to improve the fineness of the paint and further treatments can be performed to remove impurities so as to whiten the paint manufactured.

We think that with the appropriate equipment and facilities, recycled calcium carbonate which are derived from shellfish can also be obtained and applied in paint-making. Further investigation can also be carried out to test for the applications of the recycled calcium carbonate in other products.