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The world energy scene is undergoing a period of transition. As the inevitability of exhaustion of fossil fuels is becoming increasingly intensive, efforts are exerted to find and use substitutes for energy. Bioethanol is one of the most substitute renewable fuels contributing to the reduction of the global warming effect and negative environmental impact. Bioethanol production generally utilizes derivatives from food crops such as corn grain and sugarcane. In Egypt, sugarcane molasses is mainly used as feedstock for bioethanol production. However, molasses contains a concentration of heavy metals. Heavy metals are presented in high concentrations in the fermentation medium causing a critical problem during fermentation. This study focuses on reducing heavy metals content in molasses to improve bioethanol fermentation using heating, centrifugation, sulfuric acid, and phosphoric acid. Heating and centrifugation were sufficient to decrease Ca with less effect on other metals. Sulfuric acid reduced heavy metals content and the reduction addition of phosphoric acid had less effect on lowering the levels of heavy metals in molasses. Pretreatment of molasses with 0.3% H2SO4 decreased the contents of various inhibitory metals: Ca, Cd, Cu, Fe, Ni, Pb, and Zn making molasses healthier for fermentation by yeast strains and increasing subsequent ethanol yield as well as high fermentation efficiency.

The recent developments in bioconversion of agricultural and industrial wastes to chemical feedstock led to extensive studies on cellulolytic enzymes produced by fungi and bacteria. Aspergillus niger is well known for its ability to produce cellulases. This study aimed to produce cellulolytic enzymes from A. niger. Thirteen isolates of Aspergillus niger were screened for cellulases production. A. niger 270 was the best one which formed the highest inhibition zone (9cm) with hydrolysis capacity of 1.32. This isolate was used for cellulases production and then optimization of endoglucanase and exoglucanase activities, in addition to protein and biomass production in broth by using response surface methodology. The Box-Behnken Design method with 3-factors and 3-levels was used. The maximum endoglucanase and exoglucanase activities were 10.37 and 6.81 IU/ml respectively, while protein and biomass reached 137.33 mg/ml and 14.39 g/l at the optimal conditions which were 7 days incubation period, 3% cellulose mixture concentration and 0.35% ammonium sulfate concentration.

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