Resource Utilization of Residual Organic Sludge Generated from Bioenergy Facilities Using Hermetia illucens Larvae

Abstract

Residual organic sludge generated from bioenergy facilities (BF-rOS) is often disposed instead of recycled, thus contributing to further environmental pollution. This study explored the resource utilization of BF-rOS using Hermetia illucens larvae (BSFL). When BF-rOS was fed to BSFL for two weeks, the dry weight per individual BSFL was approximately 15% of that of BSFL that were fed food waste (FW). However, the dry weight increased by approximately two-fold in BSFL that were fed effective microorganism (EM)-supplemented BF-rOS containing 60% moisture. However, under both conditions, the BSFL did not mature into pupae. In contrast, the highest dry weight per BSFL was observed with the BF-rOS/FW (50%:50%) mixture, regardless of EM supplementation. Furthermore, the highest bioconversion rate was observed when the BSFL were fed the BF-rOS/FW (50%:50%) mixture, and the frass produced by the BSFL contained fertilizer-appropriate components. In addition, the nutritional components of the BSFL exhibited a nutrient profile suitable for animal feed, except for those fed BF-rOS only. In conclusion, this investigation demonstrates that BF-rOS should be recycled for fertilizer production by mixing it with FW as a BSFL feed, which generates the valuable insect biomass as potential nutrition for animal feeding.