Shipowners may run into both heavy fines and imprisonment as a consequence of lacking international rules for organic load in sewage plants. Many sewage plants may simply be too small. The issue was discussed at the Royal Institution of Naval Architects (RINA) conference earlier in March.
As of 1st January 2010, much stricter guidelines on treatment of black water have placed equally stricter demands on shipowners. The guidelines, outlined in the MARPOL 73/78 rules under the IMO MECP 159(55) Resolution, restrict treated sewage contents of BOD5, TSS, COD, thermo-tolerant coliform bacteria and chlorine. It might appear that the stricter guidelines should not pose a problem to shipowners with a sewage plant approved by a major classification society such as DNV or Bureau Veritas. However, the new guidelines pose a significant threat as even shipowners with newly approved sewage plants run the risk of both fines and imprisonment. The reason is that there is a significant risk that the sewage plant is too small.
A quote for a sewage treatment plant is normally requested by specifying the number of persons onboard. However, a sewage plant is not approved based on the number of persons, but rather on hydraulic load (litres per day) and organic load (kg of BOD5 per day). Shipowners and designers should ensure that their sewage plant is in order by specifying organic and hydraulic loads.