Physico-Chemical Characterization of Food Wastes for Potential Soil Application

Abstract

Food waste is a matter of deep concern as it is creating multidimensional threats to the environment. Though these are potential sources of plant nutrients, a detailed investigation has not yet been conducted. Hence, a physico-chemical characterization of non-edible food waste such as brinjal waste, potato peels, banana peels, orange peels, eggshells, cow bones, chicken bones, fish bones, and their combined waste was accomplished using FTIR, TGA, XGT-5000, CHN corder, etc. The present study revealed that plant waste samples had lower ash contents (1.36–7.79%) but higher volatile matter (72.33–80.04%), and the reverse was true in animal waste. In addition, animal waste, except eggshells (22.48%), had lower fixed carbon (1.01–2.83%). On the other hand, fruit waste was documented with higher fixed carbon (11.33–14.27%). Results also indicated that animal waste and their combined samples, except eggshells, contained more nitrogen (3.82–5.06%). The concentration of P was statistically significant in the combined fruit sample (28.21% ± 8.451), followed by banana peels (24.96% ± 11.644). Vegetable waste contained a significantly higher amount of K (24.90% ± 28.311–37.92% ± 24.833) than other waste. Maximum Ca (68.82% ± 10.778) and Mg (15.37% ± 29.88) were recorded in eggshell and fish bone waste, respectively. Except for Zn and Mn in eggshells, the waste studied contained a significant amount of micronutrients. FTIR demonstrated the presence of different functional groups such as alcoholic group (OH), aliphatic chain (C–H), aromatic chain (C–H), alkyl aryl ether (C–O), carbonyl group (C=O), alkene (C=C), thiocyanate (S–CN), isothiocyanate (N=C=S), allene (C=C=C), sulphate (S=O), amine (N–H), and NO stretching band, which varied with the waste used. Thermogravimetric analysis revealed that plant waste degraded more quickly than animal waste. Eggshells were found to be less degradable by increased temperature, followed by cow bones > fish bones > chicken bones. The waste material used in the study was slightly acidic (6.67–6.82) in nature. Correlation analysis of the nutrients showed mainly positive relations in all samples for macro and micronutrients. Therefore, non-edible food waste can be a possible source of plant nutrients.