Abstract
M.Tech. (Chemical Engineering)
Third-generation feedstock such as algae is a key raw material in the sustainable production of bioenergy. Previous studies on bioenergy production from algae have majorly been on biodiesel production. The high carbohydrate content in algae can also be used in the production of bioethanol. However, the bioethanol yields have been very low, and previous studies have established that the pretreatment of algae can improve the bioethanol yield. There has not been any report that compare the effect of pretreatment on the bioethanol yield from the two major types of algae namely microalgae and macroalgae. This study compares the bioethanol yield of Spirulina Chlorella (a microalgae) and the Tarus Cape Kelp (a macroalgae) under different pre-treatment conditions. Acid pretreatment was used as the pretreatment method and the acid used for the pretreatment was Sulphuric acid. The effect of pretreatment acid concentration, temperature and time on Spirulina Chlorella (SC) and the Tarus Cape Kelp (TCK) on the hydrolyzed carbohydrates was evaluated and the resulting bioethanol yields were compared. The acid concentration results showed that an increase in acid concentration from 0.5N to 3N increased the amount of hydrolyzed carbohydrates from both Spirulina Chlorella and Tarus Cape Kelp. The highest amounts were 52oplato and 60.61oplato from the SC and TCK respectively obtained at 3N concentration. However, a further increase in acid concentration from 3N to 5N resulted in a reduction of hydrolyzed carbohydrates obtained from the Tarus Cape Kelp but was almost constant in Spirulina Chlorella. Increasing the pretreatment temperature increased the amount of hydrolyzed carbohydrates until the temperature of 120oc; 58.06oplato and 70.45oplato were achieved for Spirulina Chlorella and the Tarus Cape Kelp respectively. A further increase in temperature to 140oc was slightly beneficial for Spirulina Chlorella but had a lesser effect on Tarus Cape Kelp. The pretreatment time indicated to be most effective parameter on cell disruption as it gave the highest amount of hydrolyzed carbohydrates from both the Spirulina Chlorella and the Tarus...