Porous membranes for ballast water treatment from microalgae-rich seawater

The ballast waters from ships pose a major threat to oceans, notably because of the spread of microorganisms. The present study evaluates the techno-economic feasibility of implementing the membrane process to remove microalgae from seawater to be ballasted in a single step during planktonic bloom. The optimal conditions for the microfiltration of complex and reproducible synthetic seawater are a permeate flux and specific filtered volume of 100 L.h(-1).m(-2) and 75 L.m(-2).cycle(-1), respectively. Recovery of the membrane process represents about 76.6% and 62.7% of the annual cost for a cruise ship (5400 passengers) and liquefied natural gas (LNG) carrier (75,000 m3 of liquid natural gas), followed by the membrane replacement cost (13.4% and 21.9%, respectively). The treatment costs are competitive with conventional treatments, even when the membrane process is more feasible for cruise ships due to its smaller capital cost and footprint.