A technique for producing an ecological fertilizer based on eggshells, developed by researcher Roger Borges at the Federal University of Paraná (UFPR), may contribute to reducing imports of fertilizers and chemical fertilizers by Brazil, which last year totaled US$ $15.2 billion, a 90% increase compared to 2020.
According to data from the Brazilian trade balance, from the Foreign Trade Secretariat (Secex), fertilizers were the most imported products by the country, in the transformation industry. In terms of quantity, Brazil imported 41.5 million tons of fertilizers, an expansion of 22%.
Currently a researcher at Embrapa Instrumentação, Roger Borges told Brazil Agency that the technique was developed from the use of asbestos tile to produce ecological fertilizer. “We use waste that is not used, such as eggshells, which are rich in calcium, or asbestos, which is a toxic waste.” Knowing the chemical components of the eggshell, the UFPR researchers thought of producing a fertilizer that would not harm the environment and that, at the same time, would be beneficial for agriculture.
The project was developed at the Laboratory of Chemistry of Advanced Materials (Laqma) at UFPR. The technique uses a mechanochemical milling process, in which materials react to form new products through the thermal energy and friction of the milling itself. The eggshell is placed in a high-energy ball mill, along with potassium phosphates, which react to form new compounds capable of providing phosphorus, calcium and potassium, three essential components for crop development, the university said.
Mixture
The industrial way proposed by the researchers to produce ecological fertilizer is to use more than one component. “The main composition of both asbestos and eggshells is calcium carbonate (CaCO3)”, explained Borges. Industrial production plans to mix eggshells with asbestos and other elements, such as potassium phosphate. “In the end, we have a fertilizer that can be used and does not represent any danger, like the one made with asbestos, for example”. According to the researcher, to be used alone, asbestos needs to undergo grinding treatment.
The researchers filed two patent applications at the National Institute of Industrial Property (Inpi) involving the treatment of asbestos and eggshells for the production of ecological fertilizers. “We are developing the product with the aim of selling it on the market”.
In the opinion of Roger Borges, the main savings in the use of these fertilizers is that the use is better, since a smaller amount of the product will be used and guarantee the same agricultural production, compared with the traditional fertilizer found in the market. There are also environmental advantages, which include the reuse of non-disposable materials, such as asbestos, which, due to its toxicity, requires its own landfills for its storage or is thrown into dumps, which requires money to operate these places. By removing these materials from the trash, Borges stated that it is possible to convert them into positive values.
There are two basic classifications: tailings and residue. In the case of asbestos, which is toxic waste, researchers are able to turn it into a by-product after it is treated. The eggshell, in turn, is considered waste. Although it does not represent any danger, it is also possible to direct the material to have a by-product. In addition, calcium carbonate is an important source of calcium that can be used as a limestone replacement for both asbestos and eggshells. Borges reiterated that fertilizers produced from residues or tailings have greater agronomic efficiency when compared to conventional fertilizers.
Process
The advantage of being a dry process, without the use of water, avoids the need for expensive drying steps, unlike other processes that use water as a solvent. In the final product, all the chemical elements present present high added value in agriculture, which eliminates the need for purification. Borges added that another advantage is the economy of products such as limestone, used in the production of mineral fertilizers because it is rich in calcium, because the reserves of these materials are finite, and it is essential to use them in a sustainable way. In 2020, Brazilian crops used more than 45,000 tons of agricultural limestone, much of which resulted from the exploitation of the country’s reserves.
Professor Fernando Wypych, from the Department of Chemistry at UFPR, who supervised the project, informed that, as it is less soluble in water, the new fertilizer is more sustainable, because its release is controlled. Unlike conventional fertilizers, which release nutrients at once, controlled-release fertilizers respond to plant stimuli (responsible stimulants) and maintain constant levels throughout the agricultural production cycle.
Wypych said that the lower solubility of the new fertilizer made from asbestos or eggshells combats the problem of eutrophication generated by conventional products, which make waters murky, consuming oxygen from rivers and lakes and causing the death of fish and others. aquatic animals. The decomposition of all this organic material produces a bad smell, in addition to carbon dioxide and methane, the main greenhouse gases (GHGs).
The technique also creates a by-product that can be used for the production of hydroxyapatite, which is a material based on phosphorus and calcium, used for the production of bone and dental prostheses. With greater added value, the substance makes the application more commercially attractive. The estimate is that, annually, almost 6 million tons of eggshells are produced in the world, according to the university.
