Feasibility of Black Soldier Fly Larvae and Biochar as Novel Approaches for Treating Swine Waste in North Carolina

North Carolina, the third-largest swine producer in the United States, generates over 10 billion gallons of waste annually. Current management practices, such as open-air waste lagoons and digesters, have proven ineffective, leading to severe environmental and public health concerns. This study explores a novel dual treatment approach to address these challenges: black soldier fly larvae (BSFL) for solid-phase waste processing and engineered biochar for liquid-phase wastewater treatment. BSFL efficiently decompose organic waste in an aerobic, emission-free process, converting waste into protein-rich biomass for potential reuse. Key factors in BSFL performance are moisture content, larval density, and feeding rate, which influence larval growth and waste removal efficiency. While no studies have examined their effects on larval digestion physiology. This study evaluated the impact of varying moisture levels (low 65%, medium 75%, and high 85%), larval density (high: 5, low: 2; unit: larvae/cm²) and feeding rate (high: 200, medium: 100, and low: 50; unit: mg/larva/day) on BSFL metabolic efficiency, digestive enzyme activity, and contaminant reduction. For liquid-phase treatment, engineered biochar presents a promising solution for removing organics, nutrients, pathogens, and antibiotics from swine wastewater. Unlike prior studies on controlled solutions, this research tests biochar’s effectiveness in treating raw swine wastewater, bridging real-world knowledge gaps. This study is the first to explore the enzymatic physiology of BSFL under varying moisture and feeding conditions, as well as the field applicability of biochar for antibiotic removal in raw swine wastewater. BSFL reared on swine waste with 65% moisture content exhibited the highest contaminant removal efficiency, along with the greatest larval mass increase and high protein content, making it optimal for swine waste treatment. A high larval density (>5 larvae/cm²) and optimized feeding rates (<200 mg/larvae/day) is crucial effective BSFL-based swine manure management to enhance larval growth, enzymatic activity, and waste removal while addressing density-related challenges. Additionally, biochar activated with zinc chloride/iron(III) chloride significantly improved the removal of COD (72.90%) and E. coli (80.47%) from swine wastewater, while all biochar types showed comparable effectiveness in removing TP, TN, TSS, and sulfathiazole. These findings contribute to the development of sustainable, climate-resilient waste treatment technologies, offering a cleaner and more efficient alternative for managing swine waste while mitigating environmental risks.