MEPC 44/INF.9
ANNEX
UTILIZATION OF MIXER PIPE FOR THE TREATMENT OF SHIP'S BALLAST WATER
The Japan Association of Marine Safety
Introduction
Research and development efforts have been made in various countries in the world to develop measures to replace the exchange of ballast water. Japan has also been engaged in studies to find alternative measures, and the Japan Association of Marine Safety (JAMS) presented during MEPC 43 an electrochemical processing method, which was favorably accepted as a means highly effective in killing marine organisms without polluting the environment. This time, JAMS would like to propose a completely different method using mixer pipes. The mixer pipe, simple in structure, has the effects of physically destroying particles existing in sea water and of mixing seawater and gas effectively. The device is intended to be integrated into the ballast pipe system, and to sterilize sea water upon its passage through it during ballasting and/or deballasting operations. This method can be adopted without changing usual ballasting operations and, furthermore, does not require much energy or special maintenance. JAMS considers the method excellent since it is environmentally friendly, easy in maintenance and economical in operation.
Receiving a subsidy from The Nippon Foundation, JAMS conducted an experiment in a shore facility, using a small prototype device (treatment of about 20 m 3 of water/hour). On the basis of the experiment, JAMS is studying a proper structure and system to introduce the method for actual application on board vessels. JAMS report on the mixer-pipe method, centering around results of the shore experiment, which showed encouraging effects of killing plankton.
1 Structure of Mixer Pipe
The mixer pipe consists of three main parts: 1) a revolution section where introduced water is given a spiralling motion; 2) a gas injection pipe which supplies gas to the revolution section; and 3) a projections section which promotes mixture of water and gas.
The prototype mixer pipe manufactured for the experiment had the structure as shown in Fig. 1, with the pipe fitted with projections having an inside diameter of slightly less than 40 mm.
Fig. 1 Structure of mixer pipe
