Effects of Coffee Marc and Illite on Decomposition and Ammonia Emissions During Black Soldier Fly ( Hermetia illucens ) Larval Treatment of Fermented Laying Hen Manure

Black soldier fly ( Hermetia illucens , BSF) larvae are increasingly promoted as a sustainable solution for organic waste management, offering the benefits of mitigating environmental impacts and establishing effective waste degradation methodologies. However, no previous studies have explored the potential of using coffee marc and illite in combination with fermented laying hen manure. This study focused on enhancing the decomposition process and minimizing the environmental footprint of fermented laying hen manure by supplementing it with coffee marc or a combination of coffee marc and illite, and using BSF larvae. In comparison with TRT 1 (fermented laying hen manure + coffee marc), the 2nd and 3rd instar BSF larvae for TRT 2 (fermented laying hen manure + a combination of coffee marc and illite) groups demonstrated the highest biodegradation efficacy and suppressed NH 3 formation. Notably, TRT 2 presented the favorable nutritional conditions for the larvae, as reflected by optimal pH values (7.09 for 2nd instar and 6.69 for 3rd instar) and total nitrogen levels (5.21% for 2nd instar and 6.21% for 3rd instar), both of which surpassed ideal benchmarks. Furthermore, fermented manure mixtures in TRT 2 exhibited significantly improved ADF, NDF, and hemicellulose contents, which are key regulators of larval development and crucial for improving the quality of organic fertilizer. Based on these results, we recommend using 3rd instar BSF larvae for laying hen farming. This method offers two key advantages: the production of premium organic fertilizer during composting, which reduces environmental impact, and the efficient bioremediation of organic waste.