FROTH FLOTATION HARVESTING OF ALGAE FIG. 2a. Algalfoam produced byfrothflotation harvesting FIG. 2b. Comparison of harvest, feed, andwaste offrothflotation process. Fromleft to right cylinders contain harvest,feed, andwaste. Tolerance of Chlorella to low pH. In a scaled-up froth flotation harvesting process, it is likely that the algae will have to endure low pH for approximately l a hr.