Abstract: There is provided is a blower installed at a manhole opening, with which it is possible to facilitate an entry or an exit of a worker or an import or an export of an article. The present invention provides a ventilation system in a pipe conduit using the blower. Provided is a blower comprising: a ring-like or circular arc-like frame; a nozzle installed continuously or discontinuously along the frame; and compressed air supplying means for supplying the nozzle with compressed air, wherein the compressed air supplied from the compressed air supplying means is emitted while swallowing up air in the nozzle or near the nozzle, whereby, an airflow to a normal direction of a disk surface of which the flame is periphery is generated. The nozzle may be a nozzle for exhausting an air flown from an entry port of a cylindrical flow channel to an exit port of the cylindrical flow channel, and a plurality of the nozzles may be discontinuously installed along the frame.

Abstract: A regional water purifier collects blue green algae continuously by using a water flow produced by the operation of a water flow generator, and continuously and efficiently processes the algae to make it inactive by irradiating ultrasonic waves thereon. Thus, regional water purification is performed efficiently at a far lower cost than the conventional method through the blue green algae processing. The purifier includes a blue green algae processing duct 2, which is disposed under water where blue green algae breed in large quantities, and has an ultrasonic wave transmitter 3 therein for transmitting ultrasonic waves to process the blue green algae with the ultrasonic waves. Both ends of the duct 2 are open, and a water flow generator 4 produces a suction flow for sucking water containing blue green algae into the blue green algae. processing duct 2 from a first end 2a and a discharge flow for discharging the water from the second end 2b.