Black Soldier Fly Digesters – Converting food wastes into feed, fuel and fertilizer
Scalable Biosystems for Sustainable Energy Production
Introduction: Concerns over rising energy demands and dependence on fossil fuels have led to a great deal of research into renewable energy. While sources like wind and solar show great potential for electricity generation, there will also be a need for renewable sources of liquid and solid fuels for both transportation and biomass gasification. Current sources of University generated waste can be diverted to displace 35%-50% of diesel fuel demand on campus, as well as contribute to biomass production for biomass gasification to supply steam to the West Campus. The objective of this project is to construct a scalable biosystem for conversion of food wastes into biodiesel fuel, renewable gasification feedstock, animal protein feed and compost.
This multi-faceted project aims to displace an additional 4,000 gallons of petro-diesel through algal and pupae lipid production, as well as divert 209,000 lbs of solid organic waste from Clemson University Facility and Maintenance Organization’s ( CU FMO) disposal. Its scalable design will allow further expansion and replication upon proof of concept. Mr. Tony Putnam, Director of Utility Services for Clemson University, has indicated his support for this project: “ University Facilities takes seriously our role to create, enhance and maintain a high quality learning environment. In particular, we strive to provide ‘living lab’ opportunities for students and faculty collaboration with our organization. This project is especially appealing to me since it examines multiple processes that can be immediately developed and implemented on our campus to minimize landfill waste as well as exploring alternatives to produce our own clean renewable energy to reduce our campus carbon footprint.“
Why BSF? Similar to the common “vermiculture digesters” utilized across many varying scales of production, this proposal offers an alternative to the use of earth worms and nightcrawlers. Instead, the larvae of black soldier fly, Hermetia illuscens, ubiquitous throughout North America, are voracious consumers of nitrogen-dominant decaying materials, such as kitchen food scraps or manures. Dried pre-pupae contain 42% protein and 35% fat, and as a component of a complete diet they can provide an excellent feed for chicks, swine, rainbow trout and catfish (reviewed in Newton et al. 2011). Additionally, BSF have been demonstrated to digest over 15 kilograms per day of waste per square meter of feeding surface area per day. According to a current Clemson Recycling Services study ~209,000 lbs of food waste could be collected annually from all dining halls on campus. Based on data from previous studies, this amount of dining hall waste could generate:
▪33,551 lbs of dried BSF pupae to process into oil and protein meal using existing equipment
▪45 tons of dry compost for use as a soil amendment at the Student Organic Farm
▪4,473 gallons of oil (based on 35% lipid content of pupae by weight) with a biodiesel value of $16,774 based on $3.75/gallon cost
▪10.9 tons of protein meal by-product from the oil processing procedure with a value of $5,500 based on value of fish meal
Dan Fleetwood and a group of Civil Engineering students helped with our project and put together this informative video: http://www.youtube.com/watch?v=a6QiE5j0Fpk&list=HL1336049837&feature=mh_lolz
This is our second week operating the system, and so far the critters have consumed over 400 lbs of cafeteria food waste. This number should increase exponentially as our BSF population increases. We started with 9000 young larvae from Pheonix Worms in Tifton, GA. After a spontaneous 38F night, we lost about 1/3 of our population. We made some adjustments to better control temperature, and utilize the adjacent greenhouse for supplemental heat, and since then, their population is soaring. We now have several adults lingering on the shredded paper which provides a nesting area for pupating larvae that don’t migrate into our harvest buckets.
We expect our population to reach 100,000 over the next two weeks, at which time we will begin harvesting larvae to press into oil and feed. We will test lipid for its Fatty Acid profile and conversion into biodiesel. We will test the feed for its nutrient and market value. The compost will not be harvested until the end of summer. This project is a collaboration between the Clemson Biosystems Engineering Program, the Student Organic Farm, and Facilities and Maintenance Organization.