for extracting phosphorous from algae - in a body of water , the algae are deposited into a sealable tank that is then evacuated , thereby rupturing the algal cell walls . the ruptured algae are then moved to a second tank , mixed with water and bacterial cultures , and allowed to settle until the lipids rise to the top and the oil - less debris settles to the bottom . the second tank also contains sacrificial and rusted electrodes . the phosphorous from the algae combines with the rust . the lipids and debris are then removed . next , an electrical source causes the rust to be removed from the rusted electrodes and settle . in addition , a phosphorous - rich scum floats to the top . these components are placed in storage containers for later use and the water is returned , thereby reducing its phosphorous content .