Design and evaluation of black soldier fly larvae and frass compost separator

Abstract: Black Soldier Fly Larvae (BSFL) composting is a treatment procedure that generates two products: frass compost and BSFL. These products have different uses. BSFL can be used as animal feed and frass compost as soil fertiliser, and they need to be separated after the composting procedure has been finished. A separator of the vibrating sieve type, currently in use by a research group at SLU for separating BSFL from the frass compost generated by the composting process, was tested and evaluated in terms of fraction purity and separation time. It was found that the fraction purity was over 90% for the BSFL fraction, and that the separation time was approximately 1-1.5 minutes for 4 kg of material. Hotspots for improvement were identified and a new vibrating sieve was designed and built with the aim of providing flexibility for improving fraction purity, separation time and operator ergonomy for the end-customer. A CAD model of the new vibrating sieve was designed in SolidWorks with a complete set of technical drawings and purchasing components. These drawings were sent out for manufacturing at a workshop and the new vibrating sieve was built and tested. The new vibrating sieve was functioning properly, but its optimal mechanical settings need further research and testing. This separator design could be emulated by others, and also improved, and this research could be used for improving the process outcome for future BSFL separation processes.