Evaluation of new technology for shipboard wastewater treatment

In 2000, the Alaska Cruise Ship Initiative found that traditional marine sanitation devices (MSD) on passenger ships, both large and small, were unable to effectively treat sewage (blackwater). In addition, untreated shower and galley water (graywater) contained bacteria and suspended solids concentrations equal to or exceeding blackwater. Since that discovery, cruise ship owners and operators operating in Alaska have worked aggressively to improve the performance of traditional MSDs or replace them with new treatment technologies to meet new Federal and state effluent standards. The efforts to improve the traditional MSD proved unsuccessful so large ships moved toward replacing them. Member lines of the North West Cruise Ship Association (NWCA) evaluated different technologies and systems and shared the lessons learned in the interest of developing an accelerated program to treat both blackwater and graywater discharge. Five different treatment methods were strenuously tested or evaluated. As of 2003, shipboard systems employing a combination of biological aerobic digestion and fine filtration were the most commonly employed systems capable of meeting stringent Federal standards for continuous discharge. These new technologies have improved the quality of wastewater discharged into Alaska water and have potential to reach other applications within and outside the marine industry.