Three Biological Wastewater Treatment Units Clarimar MF-2 and five MF-3 were mounted on total eight ferry boats in Croatia . The systems are approved to IMO MEPC 227 (64) resolution and use Bio-Sword filtration technology. This process doesnt need any chemicals, but is based on the aerobic bacteria which break down the organic material into carbon dioxide, water and inert non-organic material. Clean water can be discharged either in the sea or recycled back into ship.