Biological and algae harvesting and cultivation systems and methods

An algae harvesting method for use with an algae harvesting system comprising:

• at least one treatment tank;
• at least one membrane filtration module positioned inside the at least one treatment tank, the at least one membrane filtration module including a plurality of hollow fiber membranes defining lumens;
• a permeate outlet in fluid connection with an inside of the lumens;
• a permeate suction source and a backwash pressure source in fluid connection with the permeate outlet;
• a permeate valve that can isolate the permeate suction source from the permeate outlet;
• and
• a backwash valve that can isolate the backwash pressure source from the permeate outlet;
• the method comprising:
• applying, by the backwash pressure source, a positive backwash pressure when the backwash valve is closed, such that when the backwash valve is opened, the backwash pressure is immediately applied to the permeate outlet and lumens;
• applying, by the permeate suction source, a permeate suction pressure when the permeate valve is closed such that when the permeate valve is opened a negative suction pressure is immediately applied to the permeate outlet and lumens;
• performing filtration of an algae slurry contained in the at least one treatment tank by pulling a substantially algae-free permeate through pores of the plurality of hollow fiber membranes so that the permeate flows inside the lumens of the plurality of hollow fiber membranes and a retentate of the algae slurry is produced outside the lumens of the plurality of hollow fiber membranes;
• and
• performing a backwash sequence in which a backwash fluid flows inside the lumens of the plurality of hollow fiber membranes and is pushed through the pores of the plurality of hollow fiber membranes.