Browsing by Author "Stoffberg, Dirk"
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- ItemWaste to protein: nutrient cycling through integrated farming(Stellenbosch : Stellenbosch University, 2021-12) Stoffberg, Dirk; Pieterse, Elsje; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.ENGLISH ABSTRACT: This study addressed the sustainability of our food system with specific focus on nutrient wastage and the treatment or recycling thereof. Black soldier fly (BSF) farming is a well-known method for treating organic waste to produce protein, fat, and fertilizer. Using BSF to recycle wasted nutrients has been proven effective. The complex problem is that insects are not considered as food in most South African diets. Aquaponics involves the simultaneous cultivation of plants and fish in a recirculating aquaculture system. In this project, the integration of aquaponics and black soldier fly farming was proposed as an instrument to recycle organic waste into food production systems , growing food that are well accepted in the South African market. This project entailed the design, construction, and operation of two identical aquaponics systems and a BSF rearing unit. The control aquaponics unit (termed the two-tier system) received a pelleted BSF diet as input while the integrated BSF and aquaponics unit (termed the three-tier system) received live BSF larvae and a filler feed as input. The BSF larvae were reared on a formulated diet made from raw materials in the feed industry and not organic waste. Both systems were primed for 12 weeks before being operated for a trial period of 31 days. Both system were compared considering the performance of African sharp-tooth catfish (Clarius gariepinus) and the culinary herb, basil (Ocimum basilicum L.). Both systems showed comparable results in terms of fish growth rates, feed conversion as well as plant growth curves and biomass yields. The environmental parameters monitored for both systems were indicative of a stable nitrogen conversion cycle and resilience against abrupt environmental stimuli in the form of power outages and changes in temperature, pH and dissolved oxygen. The integrated black soldier fly and aquaponics system displayed technical feasibility for Nutrient recycling through the integration of BSF farming and aquaponic farming. This farming method proved to be feasible in recycling food waste to food production on a small scale and shows promise for scalability to large scale food waste recycling. The project also showed potential in decentralised community food production systems on the same scale or smaller units.