Environmental applications of pistachio waste: A review

A tremendous quantity of pistachio waste is produced worldwide annually, offering both environmental challenges and opportunities. This agricultural by-product can be repurposed in various forms, including sieved pistachio shells, pistachio-derived biochar, or in combination with other materials for diverse environmental applications. Notably, pistachio waste can be converted into materials with a high surface area and porous structure, primarily used as adsorbents for removing various pollutants such as dyes, pharmaceutical agents, heavy metals, and greenhouse gases. The adsorption process involves utilizing pistachio waste in different forms such as powder, biochar, or activated carbon, and in conjunction with nanomaterials like TiO₂ nanoparticles. Research indicates that pistachio waste enhances compost quality by reducing the C/N ratio, improving plant germination, and enhancing phosphorus accessibility for plants in arid regions. Moreover, studies evaluating the partial substitution of animal feed with pistachio waste show promising results in terms of digestibility, immune response enhancement, and growth rate in animals. With its high potassium and calcium content, the conversion of pistachio waste into high surface area materials serves as a catalyst for photocatalytic pollutant degradation and as a promoter for catalytic efficiency in various processes. Furthermore, the pyrolysis products of pistachio waste exhibit significant potential for biodiesel production, with studies showcasing its viability as a sustainable fuel source through parameters like a higher heating value, low activation energy, and reduced gas emissions. This review comprehensively discusses recent advancements in utilizing pistachio waste for environmental applications, emphasizing its versatility and promising benefits in waste management and resource utilization.