Development and Field Testing of a Solar-Powered Glass Tumbler for Waste Glass Processing in Cape Maclear, Malawi

This thesis addresses the accumulation of imported glass waste in Cape Maclear, Malawi, driven by population growth and tourism, by developing and field-testing a solar-powered glass tumbler that converts sharp shards into smooth, marketable sea glass. Building on an earlier prototype, a tumbler using a repurposed gas-cylinder drum was powered by a direct-current motor connected to a mobile solar panel, avoiding battery storage. Trials compared water alone, silicon grit, and locally sourced sand as abrasive media, quantifying edge smoothing via photographic brightness analysis. The tumbler processed 20 kg batches, achieving the best finish after 10 hours, with local sand performing nearly as well as silicon grit. Financial analysis showed a break-even price below $5 per 100 kg over a five-year amortization, indicating decentralized glass tumbling is technically and economically viable.