Tests have shown that biochar, produced from plant biomass, livestock and agroindustrial by-products, improves soil conditions and paves the way for the development of sustainable, value-added fertilizers for the agricultural sector.
Almost a year after its launching, the program “Thermochemical transformation of agricultural waste into materials and energy: a circular economy model for the sustainability of the agricultural sector”, led by the Technological Development Unit (UDT) of the Universidad de Concepción, shows promising advances in the production trials of biochar, the central element of its proposal.
Biochar – the result of pyrolysis, a process of thermochemical decomposition of biomass – has gained recognition for its multiple benefits: soil improvement, water retention and carbon dioxide storage capacity, among others.
Tests carried out by the research team of Biochar Chile, the abbreviated name of the UDT’s technological proposal, have shown that this material not only acts as an NPK fertilizer (nitrogen, phosphorus and potassium), but also stimulates plant growth, retains water and has zero toxicity for plants.
The five-year initiative, approved by Corfo in its call for ‘Technological Programs for Productive Transformation in the Face of Climate Change’, addresses the environmental and sustainability challenges posed by agricultural waste, through its thermochemical transformation to produce biochar.
A relevant milestone of this first year is the pyrolysis tests with the Kon Tiki reactor, an artisanal technology that has made it possible to validate the operating conditions and obtain quality biochar. “This equipment will soon be used in pilot tests with farmers in the commune of Casablanca (Valparaíso Region), in collaboration with the Prodesal team, thus strengthening the articulation with territorial actors and technology transfer,” said the project director, Dr. Cristina Segura Castillo.
Diversity of residues
Inputs for the production of biochar include plant biomass residues, such as wheat straw, nut shells, fruit pruning residues – tests have also been carried out with alperujo, a residue from olive oil production – and animal residues, such as pig and poultry manure.
Additionally, in a complementary manner and in a small proportion, the co-processing of agricultural plastics is incorporated together with biomass in the pyrolysis process.
The specialist explains that the controlled addition of these plastics makes it possible to increase the generation of pyrolysis gases and vapors, providing additional energy, especially when it is required to facilitate the drying of waste with high moisture content.
“What we do is to valorize this plastic without the need for other recycling facilities, and we prevent it from contaminating the soil or water because we do not have a collection and treatment system,” the researcher said.
Another aspect of the program is the use of by-products from the production of biochar, called pyrolysis liquids, which have properties of interest for the formulation of exterior paints.
There are several areas of work, but the central objective of the program is the production of biochar, insists Cristina Segura, who sees projections for the development of an industry of this type in the country.
Sustainable technology with national projection
The main objective of Biochar Chile is the valorization of plant and animal biomass waste from the sector for its reuse in a circular economy perspective, said the researcher.
In this way, the waste converted into biochar is re-integrated into the soil, as an agricultural amendment, improving its properties and productivity; “but with the additional benefit that we are capturing carbon”, adds the director of Biochar Chile.
The doctor in Engineering Sciences affirms that it is a technological solution that allows the integral and efficient transformation, from the energetic point of view, of the wastes. “The idea is that several plants can be materialized as a business model, in the different regions of the country, to take advantage of the waste of each area”, said the specialist in thermochemical processes.
Validation tests
Dr. Segura evaluates positively this first year of the program which, in her opinion, has made significant progress towards the objectives of valorizing agroforestry residues through the production of biochar as a strategy for sustainable development and circular economy in the silvo-agricultural sector.
In the area of agricultural applications, favorable results have been observed in the projects for the development of a NPK (nitrogen, phosphorus, potassium) biochar fertilizer and another for water retention.
To date, biochars obtained from wheat and pea straws, quinoa husks, rice and nuts (such as European hazelnut and walnut shells), as well as other livestock and agro-industrial by-products, have been processed and characterized.
“These materials have been evaluated agronomically in collaboration with Professor Marco Sandoval Estrada and his team from the Faculty of Agronomy UdeC, Chillán campus. The results indicate that the biochars do not present toxicity for plants, that they act as NPK fertilizers and stimulate plant growth,” he explained.
Environmental potential
On the other hand, the project “Sustainability Study of Biochar Chile”, led by Dr. Yannay Casas-Ledón, has advanced in the evaluation of the environmental potential of biochar, focusing on residues such as wheat, bird guano and European hazelnut shells.
“Through a Life Cycle Assessment (LCA) approach, the systems have been delimited and detailed environmental inventories have been prepared, identifying critical stages in different impact categories. Preliminary results are already guiding process improvements and methodologies are being integrated for the generation of carbon credits under international standards, reinforcing the role of biochar as an effective tool for climate mitigation,” he explained.
Finally, more sophisticated pyrolysis equipment is in the process of being imported, which will allow continuous and controlled production of biochar, facilitating the technological scaling-up of the program, a key tool for strengthening the project’s technical capabilities and moving towards pre-industrial production of the resource.
“All these advances consolidate Biochar Chile as a technological platform with high potential to provide concrete solutions to environmental, agricultural and territorial challenges, under principles of sustainability and circular economy”, said the professional.
Source: Jeannette Valenzuela Mella, Noticias UdeC