Murdock, Jared (2014-05). Low Cost, Low Energy, Method of Dewatering Cultures of the Green Microalgae Nannochloris oculata: Electrocoagulation. Master's Thesis.
Microalgae have received a substantial amount of attention as an alternative fuel feedstock due to their ability to produce large quantities of lipids. The goal of this research was to determine the ideal operating parameters for electrocoagulation; a low cost, low energy method of dewatering cultures of microalgae. The objectives of this research focus on recognizing parameters that influence the overall efficiency of the process, effective electrode materials, and finally directional improvements in operating parameters contributing to a high reduction in optical density. Variables found to have a statistically significant effect on the efficiency of electrocoagulation were the electrode material, current, and duration. With no adjustment of the algae culture prior to electrocoagulation, iron and nickel were identified as the best performing electrode materials, in terms of optical density reduction. Of the materials tested, iron was found to achieve the greatest recovery of microalgae at the lowest power consumption, while staying below the threshold for animal feed tolerance. The most desirable operating parameters for electrocoagulation, within the confines of the experimental apparatus and using iron electrodes, were found to be a current of 0.3 amps and a 15 min reaction time. Increases in current and duration were found to provide the highest levels of optical density reduction. However, the average voltage, and therefore, power consumption are the highest when current and duration are maximized. Additional testing should be performed at higher currents and longer durations, in an attempt to find a peak in the optical density reduction.