| 摘要 |
<p>PROBLEM TO BE SOLVED: To efficiently perform the treatment of waste water while reducing running cost by efficiently utilizing air in a relatively narraw treatment vol. by using reduced aeration power in a circulating type waste water treatment apparatus having a circulating tank using underwater floatable cylindrical carriers and controlled in the circulating number of times of waste water per hour. SOLUTION: A circulating tank is packed with cylindrical underwater floatable microorganism-immobilized carriers 11 with an apparent vol. density of 0.01-0.30 g/cm3 and divided by into an ascending flow part 2 and a descending flow part 3 by a partition means 4 so as to leave a space where waste water to be treated can freely circulate up and down and the circulating number of times of waste water to be treated in the tank is 100 times/hr or more and the cylindrical carriers 11 are characterized by that surface roughness Ra measured according to JIS is 30μm or more and the number of ridges per 1 cm of the outer surface of the cylinder of each of the carriers (the number of ridges with a height above an average line described in this inventive detailed explanation of 0.2 mm or more) is 3.0 or more.</p> |
