Organic wastes are naturally biodegradable, but they contribute to environmental pollution and management issues. Composting and pyrolysis are widely used technologies for recycling these wastes into valuable organic products for soil health and crop production. In the current study, fruits vegetables waste (FVW) was converted to biochar, compost, and co-composted biochar. The microcrystal structure, functional groups, surface morphology, and nutrient contents of organic materials were investigated by XRD, FTIR, SEM-EDS, AAS, multi C-N analyzer, and ICP-OES techniques. Heavy metals contamination was not detected in the biomass used for pyrolysis and compost preparation. FVW had an acidic pH (5.92), while biochar, compost, and co-composted biochar had an alkaline pH. Total macronutrient (K, Na, S) and micronutrient (Cu, Fe) concentrations were higher in compost and co-composted biochar, with the exception of K, which was higher in biochar. Biochar had the highest surface area (4.99 m²g), followed by FVW, compost, and co-composted biochar. Co-composted biochar had a porous structure. Si, Ca, and Al contents were common in all organic materials, while P, K, Mg, and S were found with lower concentrations in both biochar and compost. Iron was only found in compost and co-composted biochar. Quartz, sylvite, and calcite were common minerals found in all organic treatments. Biochar contained more aromatic carbon ring structure C=C/C=O and aromatic C-H bending as compared to FVW and compost, thus, making biochar a stable carbon rich material suitable for soil carbon sequestration.

Waste management is necessary for environmental and economic sustainability, but it depends upon socioeconomic, political, and environmental factors. More countries are shifting toward recycling as compared to landfilling; thus, different researchers have presented the zero waste concept, considering the importance of sustainability. This review was conducted to provide information about different well established and new/emerging technologies which could be used to recover nutrients from wastes and bring zero waste concepts in practical life. Technologies can be broadly divided into the triangle of nutrient accumulation, extraction, and release. Physicochemical mechanisms, plants, and microorganisms (algae and prokaryotic) could be used to accumulate nutrients. Extraction of nutrient is possible through electrodialysis and crystallization while nutrient release can occur via thermochemical and biochemical treatments. Primary nutrients, i.e., nitrogen, phosphorus, and potassium, are used globally and are non-renewable. Augmented upsurges in prices of inorganic fertilizers and required discharge restrictions on nutrients have stimulated technological developments. Thus, well-proven technologies, such as biochar, composting, vermicomposting, composting with biochar, pyrolysis, and new emerging technologies (forward osmosis and electro-dialysis) have potential to recover nutrients from wastes. Therefore, reviewing the present and imminent potential of these technologies for adaptation of nutrient recycling from wastes is of great importance. Since waste management is a significant concern all over the globe and technologies, e.g., landfill, combustion, incineration, pyrolysis, and gasification, are available to manage generated wastes, they have adverse impacts on society and on the environment. Thus, climate-friendly technologies, such as composting, biodegradation, and anaerobic decomposition, with the generation of non-biodegradable wastes need to be adopted to ensure a sustainable future environment. Furthermore, environmental impacts of technology could be quantified by life cycle assessment (LCA). Therefore, LCA could be used to evaluate the performance of different environmentally-friendly technologies in waste management and in the designing of future policies. LCA, in combination with other approaches, may prove helpful in the development of strategies and policies for the selection of dynamic products and processes.