Compositing of food waste and its product performance on ipomoea aquatica

Abstract

Food waste (FW) is a global issue and their disposal at landfills created another environmental problems. Since FW is biodegradable, they can be treated through composting. The importance of fungi in degrading recalcitrant materials during FW decomposition process has yet to be extensively characterized. While most of the previous studies focused on one type of composting method, the comparison with other methods are scarce. Hence, this study aimed to compare the physicochemical parameters and to identify the fungi associated with FW in conventional and spinning barrel composting method. Physicochemical parameters including temperature, pH, moisture content (MC) and C/N ratio and fungal isolation on potato dextrose agar (PDA) were done in triplicate every three days interval throughout 30 composting days. Physicochemical parameters were analyzed using GraphPad Prism. Different fungal colonies were isolated, subcultured and identified using 18S rRNA gene sequencing. Based on the results, MC in spinning barrel reached the optimum range of 54.61 % on day 30. A total of 7 fungal isolates were found associated with FW. The fungi identified between these two methods are almost similar based on morphological observation and molecular analysis due to source of the FW which comprised identical components such as rice, eggs, chicken and chicken bones, and vegetables remain. The effectiveness of FW compost produced from both methods was combined in appropriate proportions to be tested. FW compost, NPK fertilizer and combination of both were applied on Ipomoea aquatica to determine the best fertilization treatment by observing at plant height, leaves number, leaf width, soil pH and nutrient contents in the soil. After five weeks of planting, the combination of NPK fertilizer and FW compost recorded an optimum soil pH and highest nutrients content in the soil which resulted in significant growth on plant; tallest height, highest leaves number and largest leaf width. In short, spinning barrel was found to be superior to conventional composting method in maintaining final optimum MC. Fungal isolates from this study could be further characterized for their functional abilities such as degradation of cellulolytic biomass, proteolytic activity and degradation of chitin. The combined use of NPK fertilizer and FW compost was found to be the best fertilization treatment and could be used to promote the planting of I. aquatica.