The escalating prices on the world market, depreciation of fossils fuel reserves and environmental concerns has lead to the quest for the alternatives sustainable renewable energy sources. The past decades have witnessed innovations developed to produce biodiesels from various sources such as Groundnuts, Soya beans, Palm oils, Canola, Sunflower, Castor nuts and Jatropha plants and animal fats. However, most of these raw materials are competitive as food sources in human food chain. This research assesses the use of Used Cooking Oils (UCOs) from food outlets in Kitwe Town, Zambia as source for biodiesel production. Of equal importance is the assessment of environmental impact of the current waste management practices employed in disposal of UCOs. Data was obtained by administering questionnaires to various food outlets. The study revealed that approximately 8500 L/year of UCO would be generated from the sampled area. Fast food outlets accounted for 76% of the overall UCOs production in the sampled area. It was found that UCOs were mainly disposed through drainage into Municipal Sewers with the possibility of fatberg generation. Reuse of the UCO by the correspondents was a common practice and any leftover was disposed into the environment. The results of this study indicated the UCOs could be a major source material for biodiesel production.

Jarosite formation is undesirable in bioleaching processes as it depletes the needed ferric reagent for the oxidation of most sulfide minerals. Although it creates kinetic barriers thereby retarding the leach rates of most minerals, jarosite serves as support for the attachment of bioleaching microbes, facilitating biooxidation rate. Microbial ferrous-oxidation by mesophilic microbe was studied in a recently reported novel packed-column bioreactor with a view to investigate the potential of using solution pH to manage jarosite accumulation in the bioreactor in addition to establishing a base case data for the bioreactor. Experiments were conducted in the bioreactor packed with glass balls (15mm diameter) at constant temperature of 38.6 °C, residence time of 18 hours, airflow rate of 20 mLs-1 and pH values of 1.3, 1.5 and 1.7. The results showed that the amount of jarosite accumulation is proportional to the solution pH, and to the duration of operation of the bioreactor. Jarosite precipitation concentrations of 4.95, 5.89 and 7.08 gL-1 were obtained after 10 days of continuous operation at solution pH values of 1.3, 1.5 and 1.7 respectively, while after 15 days the precipitations concentrations increased to 5.50, 7.90, 9.98 gL-1 respectively. The results also showed that 33% and 52% precipitate reduction could be achieved by gradual decrease in the bioreactor solution pH to 1.5 and 1.3 after being continuously operated for 10 days at pH 1.7 respectively after an addition of 5 days. A maximum ferrous oxidation rate (), 6.85 mmol.L-1.h-1 and the affinity kinetic constants (,), of 0.001 and 0.006 for Hansford and Monod models respectively. Although a directly relationship exist between jarosite formation and pH, the results of this study may be relevant in bioleach heaps or at least in column bioreactors to manage/control jarosite accumulation thereby improving the leach kinetics of mineral sulfides.

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