Overview
Here we outline the design process our team went through order to find and eventually build a sustainable, cheap and efficient way to farm Black Soldier Flies. Many different prototypes and sketches were drawn and improved to obtain our BSF bin design.
Final Design
This was our groups final design. We ditched all use of adhesives to improve longevity and avoid any contamination of the larvae. In this design two PVC pipes are placed through a hole cut in the side of the compost container. As the eggs hatch the larvae will eventually crawl up the tubes to lay eggs where they will then fall in the collection bins. We found this design to be the most simplistic, the cheapest, and the most effective at harvesting the BSFL.
Results of Our 1st Prototype and Design Considerations for another Design
After creating our plastic bin design we filled it with compost, added our soldier fly larvae, and then left it at the experimental farm. We periodically went to check on it, and to add more compost. We found a few larvae that had made it into the collection tray during our first few visits, but the last time we checked on it we found that the collection tray had filled with rain and killed all the larvae. We set out to create a new prototype to address the issues of rainwater pooling and the difficulty the larvae had crawling up the center bucket. Our new prototype model features a plastic bin with angled tubes for the larvae to crawl up.
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Decision Matrix
Prototype
Our prototype consists of a 27 gallon plastic bin which contains the compost and larvae. Inside the bin we glued upside down buckets over a 10 inch diameter hole we cut in the bottom. Underneath the bin we have a collection tray to collect the larvae which crawl up the edge of the buckets and fall down. The supplies to build the prototype including the price of Black Soldier Fly larvae was about $45. In the future we plan to make the collection bin more secure from any predators which would want to eat the larvae, we also plan to insulate the outside of the bin to help with temperature regulation. Lastly we are keeping an eye on the structural integrity of our project to ensure that the Gorilla Glue does its job and holds everything together.
Design
The final bin design that our team developed for our prototype model comprises of small plastic bin, plastic bowl, collection tray put in place by a strong adhesive. The bowl acts as a barrier between larvae in the collection tray and the Black Soldier flies mating in the compost. These materials were chosen as a cheap alternative to building a wooden or metal prototype. Dimensions depend on the individual space available to each individual when constructing the project.
Materials: (1) plastic bin (1) plastic bowl (1) plastic tray (2) wooden spacers (4) screws (1) black paint
Previous Drafts
In our third design we include spacers that support the bin. We incorporate a large bin to collect the larvae. We decide to remove the bin and replace it with a collection tray for space and efficiency. The bowl trap is reincorporated in this version of the design.
In our second design we introduce the bowl trap as a way of separating the mating black soldier flies and compost from the larvae. The circular edges of the bowl act as a barrier while the larvae crawl and fall into the collection bin. This design incorporates the use of two large bins which would be superimposed on each other. We had planned to paint the exterior black to promote heat absorption but after talking to Pete he pointed out that white paint actually might be better because of its resistance to absorbing and emitting radiation.
In our first design we incorporate a slanted wooden plate inside two bins where the larvae and black soldier flies would remain. The bin would entirely be constructed out of wood and the outside painted black to promote solar absorption. The slope act as a barrier between the mating soldier flies in the compost and larvae who will crawl up the sides and drop down to be collected. The doors would either swing or be detachable in order to collect the larvae that drop dow. This design was abandoned because of the financial cost of using wood as a material for the prototypes and the inefficiency of the the larvae collection.
Other Factors
Longevity and durability of our design is increased through our use of rugged plastic containers and simplistic construction.
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Our design is relatively cheap and can be built for less than $40.
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The design needs to shelter the larvae from the elements as well as providing them some form of protection from predators.