As the renewable fuel industry seeks to meet the demands of an ever-growing population, new methods and energy sources must be identified.  Algae have been established as an ideal biodiesel feedstock because of their high oil yield and carbon neutrality.  It follows that efficient, environmental-friendly, and cost-effective harvesting methods need to be discovered.  Flocculation and sedimentation are commonly used procedures for harvesting the algae that must be enhanced before they can support a sustainable algal biofuel industry.  If the energy and chemical requirements of these procedures are lowered, net energy benefits can be improved.  In this research project, the effectiveness of algae removal through the use of ultrasonic treatment and chitosan, a biodegradable polymer, is studied.  The traditional flocculation test performed in the laboratory involves a rapid mixing stage and a slow mixing stage.  Since ultrasound is capable of flocculating suspended algae particles, the rapid mixing stage was replaced by ultrasonic treatment in this study.  Two coagulants or flocculation agents are investigated: aluminum sulfate (Al2(SO4)3), also known as alum, and chitosan.  Alum is a widely used flocculation agent, while chitosan is an emerging candidate.  Chitosan is a biodegradable polymer that is derived from the shells of crustaceans.  The use of biodegradable polymers in water treatment is attractive since conventional coagulants can cause environmental hazards.  The effects of coagulant dosage, power levels, and pH are investigated. The percent removal of algae is calculated using both turbidity and optical density measurements.  In addition, variations in pH, total dissolved solids, and electrical conductivity are observed.

Ultrasonic-chitosan enhanced flocculation of algal turbid waters

247th National Meeting (2014)

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