Vermicomposting of food waste using Perionyx excavatus

• Main Author: Kam, Jolene Qian Yu
• Other Authors: Wang Jing-Yuan
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Environmental engineering::Waste management
• Online Access: http://hdl.handle.net/10356/15830
• Institution: Nanyang Technological University

Vermicomposting, a novel municipal biosolids and solid waste treatment process that uses earthworms for the biodegradation of these organic wastes, is noted for its success in producing valuable soil amendment. Relative to other composting alternatives, vermicomposting proves to be an accelerated method for the degradation of food waste. The study presented in this final year project was an attempt to refine composting processes by evaluating vermicomposting process against traditional windrow composting process. This research also explored the potential of earthworm species Perionyx excavatus in rapid and effective degradation of food waste to produce valuable and nutrient-rich vermicompost. This study set out to determine three major aspects. The first part dealt with the potential impacts of horticultural compost addition into feedstock on the chemical composition of the end product of both composting and vermicomposting. The second part of the research attempted to evaluate the efficiency of utilizing Perionyx excavatus in vermicomposting process. Third portion of study comprised of the comparison of various parameters between the three different systems: traditional windrow composting, earthworm and mealworm vermicomposting. Windrow composting is a very slow process and hence techniques to speed up the process are warranted. In this study, vermicomposting was found to have possessed this attribute and the quality of product formed as a result of earthworm activity was more superior to ordinary composting as indicated by 7.71% improvement on volatile solids reduction and 3.02% on carbon content reduction. Vermicomposting was a better process, as compared to traditional windrow composting, in achieving high mass reduction of 83.68% and nutrient-richer end products. Improvements of percentages of 26.60 of phosphorous and 17.20 of potassium resulted from vermicomposting. Horticultural compost included in the process help the production of far more stable end products with stability index of 2.36. Mealworm-vermicomposting, though lacking in areas such as volatile solid and carbon content reduction, made it up in aspects of 15.54% improvement in total mass reduction and also nutrient enriching of end products. Earthworm-vermicomposting had bigger reduction in volatile solid of up to 5.11% and in carbon content of 21.9%. Perionyx excavatus was found to be able to achieve a maximum daily consumption rate of 0.52 g/g-worm/d, which was almost two times its own body weight, and they played a crucial role in 23.7% additional mass reduction of food waste. The 100% survivability and 37.5% biomass gain of Perionyx excavatus has proven itself as a valuable and important species with a high vermicomposting potential.