Microbe-driven valorisation of bio-waste for biofertilizer production: A comprehensive review

The rapid growth of the global population has significantly increased the production of bio-wastes, which are rich in essential plant nutrients such as phosphorus (P), nitrogen (N), and potassium (K). These nutrients can help mitigate the negative effects associated with synthetic fertilizers in agriculture. By repurposing bio-waste from sources like agricultural residues, animal manure, and sewage sludge, it is possible to recover valuable nutrients and create products that support a circular economy. This process of waste valorisation transforms waste into valuable products that improve soil health and promote plant growth. For example, vermicomposting of municipal solid waste using microbial consortia such as Nitrosomonas, Azotobacter, and Nitrobacter has been shown to significantly increase nutrient recovery, with reported improvements in nutrients to as high as 2.1–2.6% N, 1.5–1.7% P, and 1.4–1.6% K in vermicompost—considerably higher than those found in traditional animal manures. Using bio-based fertilizers derived from these wastes can boost agricultural productivity while reducing the environmental impact of non-organic fertilizers. Further investigation is required to evaluate the practical applications of bio-based fertilizers in the field. This need is underscored by insights from previous studies referenced in this review, which aim to uphold agricultural sustainability and productivity. This review highlights the potential of cutting-edge technology and microbial activity in developing bio-based fertilizers, advancing waste minimization, and optimizing resource use within a circular economy. Microbial and biological systems offer sustainable and efficient strategies for converting various bio-wastes into bio-based fertilizers, thereby supporting a circular economy in agriculture.