Methods are provided for separating algae from an aqueous environment. An aqueous feed containing algae can be mixed in a turbulent manner in an aerated environment. The turbulent mixing can be sufficient to create a foam within the aqueous feed. The formation of the foam can also result in agglomeration of algae into larger size algae aggregates, which can then be filtered under pressure. Due to the larger size of the algae aggregates, the pressurized filtration can reduce/minimize the tendency to clog the filter, as the algae aggregates can generally be too large to fit within the pores of the filter. The filter can preferably be located at the bottom of the vessel holding the aqueous feed. This can assist in allowing the algae to remain in a cake above the filter, as opposed to having the algae dissolve back into the aqueous feed.