| 摘要 |
<p>PURPOSE:To enable aeration and agitation or only agitation by providing an impeller for scraping up water and an agitation impeller to an aerator, and making the aerator rotatable in the normal and the reverse direction. CONSTITUTION:An impeller 3 for scraping up water and an agitation impeller 15 are furnished to an aerator 14, and the agitator is made rotatable in the normal and the reverse direction. With said aerator, aeration and agitation are carried out when the aeration is needed, and only agitation can be carried out when the aeration is not needed or when the agitation is needed.</p> |
