METHOD OF PURIFYING LACUSTRINE WATER AND FILTHY WATER PURIFICATION BOAT

A method enabling thorough purification of lacustrine water with simple operation in an energy-saving manner within a short period of time and being free from the possibility of secondary public nuisance, and further a filthy water purification boat for implementing said method. According to this invention, while operating filthy water purification boat having an electrolyzing device for calcium fluoride, DC current power source, and coagulant pouring device mounted thereon on lakes or marshes, the electrolyzing device is operated and coagulant is fed into a pipe having a coagulant pouring nozzle. Lacustrine water, while passed through electrodes, is fed with fluorine ion and coagulant, and polluting substances coagulate and turn into flocks of a large diameter. These diametrally large flocks are recovered into the boat by a flock recovering device or adapted to sink to the bottom of lakes or marshes after volume reduction caused by hydrophobic action of the flocks, and purified water is returned to lakes or marshes.