Potential Sludge Consumption by Black Soldier Fly Larvae (Hermetia illucens) After Fresh Waste Pretreatment

Black soldier flies (Diptera: Stratiomyidae) can reduce organic waste, including landfill waste, thereby mitigating health risks and enabling their use in circular economy applications. This study utilizes dewatered landfill sludges to determine if larvae can reduce waste and what the larval effects are. In our preliminary study, we found that sludge is difficult for larvae to consume; therefore, larvae were first fed fresh waste for four, seven, and ten days before placement onto sludge. This study aims to determine: (1) what sole sludge consumption is occurring, if any, and (2) if the number of days the larvae feeds on fresh waste affects larval growth, survival, and waste reduction on sludge. Additional insight into the nutritional and heavy metal content of the sludge, fresh waste, and larvae were also analyzed, with nutritional content of the larvae after sludge consumption varying little. Significant differences were found between seven- and ten-days pretreatments on growth rate (though substrate reduction was minor), while four-days fresh waste pretreatment had almost no survival. Waste management needs to evolve as the world population increases, leading to increased waste disposal. Black soldier flies (Diptera: Stratiomyidae) have been used before to reduce different types of organic wastes such as kitchen and food waste, recycling the waste rather than it ending up in landfills. However, little research has gone into using waste directly from landfills nor has much research investigated the effects of feeding those larvae two types of landfill waste within the same life cycle. Sludge is another substrate that ends up in landfills, adding to the amount of space needed for waste disposal. Our research aimed to test if black soldier flies could reduce landfill sludge by first feeding the larvae fresh waste.