AbstractsBiology & Animal Science

ENGLISH ABSTRACT: In situ Informal Settlement Upgrading (ISU) was explored in this thesis, focussing on its relevance to waste service upgrading options immediately available and practically implementable for residents of Enkanini, a poorly serviced township (slum) in Stellenbosch, South Africa. Household food waste (kitchen scraps) was chosen as a key point of entry for exploring the context and viability of in situ improvement of solid waste management services in the area. This was done by investigating ways biological and social aspects of soil quality and food waste management can be incrementally improved in the settlement. Transdisciplinary methodology, Participatory Action Learning and Social Learning perspectives, combined with ecological thinking were used to explore different methods of managing food waste in Enkanini. A food waste collection pilot project was initiated in Enkanini by the Stellenbosch Municipality in 2012. The project was modified and continued in 2013, which served as the case study for this thesis. In 2013, food waste was collected by 56 households over five months. It was treated with Bokashi Effective Micro-organisms (Bokashi EM) containing yeasts, lactic acid bacteria, actinomycetes and photosynthetic bacteria. The Bokashi EM partially fermented the waste before it was used for composting or feeding to Black Soldier Fly (Hermetia illucens) larvae. Laboratory testing of food waste, compost, soils and larvae waste residue determined the safety, potential and sustainability of food waste for recycling and contribution to local urban agriculture by closing the organic waste loop, and for generating an income stream. A total of 5851kg food waste was collected, saving 6m3 landfill space. Households generated 5,2kg - 9,6kg food waste per week. Extrapolating this lower figure for all of Enkanini (about 2400 households), about 50,2 tonnes of food waste could be generated per month. If this were collected and recycled or composted, this would save 51,2m3 landfill space per month. The most commonly cited benefit of food waste collections by participants was reduction of vermin in or around their homes. Laboratory testing indicated that some samples had high levels of Escherichia coli (E. coli) bacteria. No traces of Salmonella were found in food waste, compost and soil samples, and most were within acceptable limits for heavy metals. It was cautioned that vegetables grown on soils or compost with high E. coli be washed or cooked before consumption. Following socially and ecologically sustainable management of Enkanini’s food waste requires a combination of waste management methods. Options include localised composting - burying EM treated food waste in soil; in situ container composting of waste and adding this to soil; processing of EM treated food waste by Black Soldier Fly larvae (and their subsequent use as feed for chickens or fish); and finally by anaerobic digestion for generation of biogas and effluent fertiliser in local …