Conversion of agricultural wastes into magnetic biochars: Towards sustainable applications in agricultural and environmental sectors (AGRI-BIOCHAR)

Agricultural biowastes (AGBW) have been increasingly generated in Oman and Qatar due to heavy investments in agricultural activities in recent years. They include mainly animal manure and lignocellulosic biomasses (crop residues, grass clippings, and livestock wastes). Due to the absence of systematic and sustainable management options in these countries, these products can be a serious threat to human health and environment. At the same time, these AGBW are rich in organic matter and valuable nutrients, which are useful for both soil quality improvement and crop production enhancement in a context of circular economy. AGBW cannot be used directly as amendments for agricultural soils due to their non-stability and relatively high inorganic elements content, which could negatively affect crops growth and contaminate the scarce groundwater resources. Various technologies have been tested in order to transform these raw products into more stable materials that can be used in various domains including energy, environment, and agriculture. Pyrolysis process, which consists in the thermochemical conversion of biomasses at moderate temperatures in absence of oxygen, has been pointed out this last decade as an attractive, promising and sustainable management option of AGBW. This process has the main advantage of ensuring a complete conversion of AGBW into: i) biofuels that can be purified and then used as a renewable energy source, and ii) a solid residue called biochar that is a stable carbonaceous material that can be reused in various domains including agriculture and environment. In this project, named AGRI-BIOCHAR, the biochars derived from the co-pyrolysis of various local Omani and Qatari AGBW will be firstly deeply characterized by using sophisticated analytical devices available in Sultan Qaboos University (SQU) and Qatar University (QU). Then, some selected biochars will be modified through iron salts in order to produce magnetic biochars with enhanced physico-chemical properties. Afterwards, the generated magnetic biochars will be used for nutrients (nitrogen and phosphorus) recovery from urban and specific industrial wastewaters (fertilizer companies). The release of nutrients from these nutrients-loaded magnetic biochars will be investigated under controlled conditions at laboratory scale (batch + column). On the basis of these studies, the slow release of nutrients form local agricultural soils amended with different doses of magnetic biochars will be investigated in pot mode. These pots will be cultivated with local high-value crops (i.e. tomatoes) and the effect of the magnetic biochars dose onto their growth as well as the microbial activity will be investigated versus time for complete growth cycle. Given the fact that magnetic biochars could act, under specific conditions, as catalysts for the oxidation of emerging organic pollutants (such as pesticides and pharmaceuticals), this effect will be also investigated under laboratory batch and column experiments. This degradation efficiency will be studied under different experimental conditions including the initial concentrations of these pollutants, the magnetic biochar type and dosages, the contact time and pH of reaction. On the other hand, AGRI-BIOCHAR will enable researchers, and concerned national stakeholders to co-develop the required knowledge and co-implement the adapted methods and sustainable practices for tackling the challenging issues of agricultural wastes management, wastewater treatment and reuse, and crop production improvement. In addition, one direct impact of the project is capacity building and technology transfer as graduate students from SQU and QU will be actively involved in the execution of the planned tasks. We intend that AGRI-BIOCHAR will be considered as a technology demonstrator to showcase the role played by magnetic biochars in the tertiary wastewaters treatment and in the improvement of vegetable production yields in hot environments. We aim that the developed approach in this project will be transferred to other countries in the region having similar challenges (climate harshness, solid wastes abundance, wastewater quality, poor agricultural soils). Finally, AGRI-BIOCHAR is in line with the 2030 United Nations Sustainable Development Goals (UN-SDGs) strategy, the 2040 Oman vision addressing several of its thirteen fixed priorities, especially those related to ?Education, Learning, Scientific Research and National Capabilities?, ?Development of Governorates and Sustainable Cities?, and ?Environment and Natural Resources?. In addition, the fourth pillar of Qatar National Vision 2030 (QNV2030) gives high priority to the Environmental Development that seeks a balance between development needs, food security and protecting the environment. Ultimately, the project will try to contribute to the increase of the agricultural soils carbon stocks as recommended by the ?4? United Nations COP21 initiative? and satisfies the intergovernmental panel on climate change (IPCC) requirements proposed measures in order to overcome the negative effects of climate changes.