Sustainable Liquid Fertilizers: A Review of Production from Food Waste and Fish Waste

The generation of food and fish waste globally poses significant environmental and economic challenges. With over 1 billion tonnes of food wasted annually and up to 50% of fish mass discarded during processing, transforming this organic waste into liquid fertilizers presents a promising solution aligned with circular economy principles. Transforming these wastes into sustainable liquid fertilizers offers a promising solution to reduce landfill burden and promote circular economy practices. This review consolidates knowledge on the nutrient composition of food and fish waste, the biological and chemical processes used to convert them into fertilizers, and the comparative advantages over synthetic fertilizers. It highlights the environmental benefits of reduced greenhouse gas emissions and improved soil health, along with economic incentives such as lower input costs and new market opportunities. The review also addresses existing barriers, such as contamination risks, regulatory hurdles, and logistical constraints and explores future directions for optimizing production technologies and standardizing quality. By integrating waste management with sustainable agriculture, food and fish waste-derived fertilizers contribute to global sustainability goals and resilient farming systems.