Efficiencies of unconventional bulking agents in composting food waste in Korea

Deogratius Luyima,Chang-Hoon Lee,Taek-Keun Oh,Seong-Jin Park,Jae-Han Lee

doi:10.1186/s13765-020-00554-6

Abstract

Sawdust is the main bulking agent used to compost food waste in Korea but it is not an economically desirable choice because its availability entirely depends on imports. Since food waste composting provides agricultural, environmental and economic benefits, it is vital that we search for suitable replacements to sawdust from the locally available materials. In this study, we assessed the composting characteristics of food waste amended with various bulking agents including sawdust, ginkgo leaves, insect feces, and mushroom waste. Each of the bulking agents was mixed with the food waste in ratios of 3:7, respectively. Even though the initial temperatures were highest in the mixture of the food waste and insect feces whose temperature stood at 65 °C against 39, 58 and 51 °C in the sawdust, ginkgo leaves and mushroom waste mixtures, respectively on the third day of the experiment (DAT 3), it was terminated on the 21st day (DAT 21) because of excessively high water content (70.92%). The water content of the composted food waste supplemented with sawdust, mushroom waste, and ginkgo leaves stood at 51.28, 39.81, and 44.92%, respectively at the end of the experiment and therefore, the fully mature composts satisfied the water content requirement of less than 55% established by the Rural Development Agency of the ministry of Agriculture of Korea. The results of the CoMMe-101, Solvita and seed germination index indicated that the composted food waste amended with the mushroom waste and ginkgo leaves matured relatively quicker than that of the sawdust amendment. Based on the above observations, it is clear that the mushroom waste and ginkgo leaves are actually more effective bulking agents than the sawdust and as such, are recommended as suitable replacements for sawdust in food waste composting.

Highlights

Food waste constitutes a copious proportion of the municipal solid waste and is expected to incessantly increase against the backdrop of rapidly growing human population, urbanisation and blossoming global economy [1]
Adhikari et al [6] assessed the suitability of different materials for use as bulking agents in composting food waste and they indicated that a good bulking agent must have an excellent water absorbing capacity, a neutral pH, a relatively high C/N ratio and ability to maintain a free air space of above 30%
In the initial stages of composting, mesophilic microorganisms degrade relatively low-molecular substances which raises the temperature of the compost pile giving way to the thermophilic phase

Summary

Introduction

Food waste constitutes a copious proportion of the municipal solid waste and is expected to incessantly increase against the backdrop of rapidly growing human population, urbanisation and blossoming global economy [1]. Food waste generation in South Korea stands at 14,389-ton d ay−1 according to the data from the Ministry of Environment and accounting for Possibilities of improving on the above mentioned inadequate properties of food waste have been widely studied with a sole goal of optimising the composting process in order to abate negative environmental impacts and produce quality soil amendments. In this regard, Lee et al Appl Biol Chem (2020) 63:68. The purpose of this study was to assess and select the various locally available potential bulking agents basing on temperature changes of the compost pile, physicochemical characteristics and speed of maturity of the composted materials

Objectives

Methods

Results