Description
The rising demand for energy, anticipated depletion of fossil fuels reserves, and detrimental impacts on the environment from the use of fossil fuels have increased research on renewable energy sources. Algae biofuel can be one of the resources to meet the requirements of future energy needs. The major challenges faced by the algae biofuel industry is the lack of energy-efficient and cost-effective methods to disrupt algae cells for the separation and extraction of bioproducts. The goal of this research was to investigate the feasibility of using two copper-based chemicals, copper sulfate and copper ethanolamine complex commonly known as Cutrine plus for the pretreatment of algal biomass to improve lipid extraction. In this research, one of the most widely researched microalgae species Chlorella Vulgaris was used. Several experiments were conducted, and the data were analyzed based on chemical dosage, contact time, algae cell viability, and lipid extraction yield. A suspension of 0.02% algae dosed with 200, 300 and 400 mg Cu /L of Cutrine plus for 72-hour contact time resulted in 30, 45 and 60% cell disruption respectively. Moreover, algae dosed with 200, 300 and 500 mg Cu /L of copper sulfate resulted in 38, 47, 70% cell disruption respectively. By pretreating 10% algae paste with 100 mg of Cu per g of dry algae of Cutrine plus after 24-hours of contact time, 19 to 33% increase in extracted lipid contents were observed. Similarly, pretreating with copper sulfate chemical lead to 20 to 31% increase in lipid extraction. In addition to lipid extraction yield, energy requirement and greenhouse gas (GHG) emission were estimated to assess the environmental impact of the proposed technique. There was approximately 79 to 99% decrease in specific energy requirement and 97 to 99% reduction in CO2 emission using proposed chemical when compared with existing pretreatment algae cell disruption techniques. Despite these advantages, the adaption of copper sulfate and Cutrine plus as algal cell disruption methods may be limited by the 24-hour contact time needed to achieve a significant increase in lipid extraction yield. Therefore, it is recommended that future research efforts be focused on addressing this challenge.
