| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate trouble generated by the sedimentation of a microbe adhered carrier by setting the density of the microbe adhered carrier to be precipitated at the rising speed of treated water at overflow outlets (carrier separating sections) of respective biological reaction tanks. SOLUTION: As far as the density of a microbe adhered carrier is in the given range, no particular restrictions are set, and a carrier can be a polymer containing gels or the like, and from the viewpoint of mechanical strength, a carrier composed of polyolefin foamed body such as polypropylene or polyethylene and having the density adjusted by, for example, an inorganic filler such as calcium carbonate and provided with the density of approximately 0.95-1.10 g/cm<3> is used. The density of the carrier is determined by the relation with the rising speed of treated water in a carrier separating section 4 of the biological reaction tank. Namely, when the rising speed is large, the density is set large, while the rising speed is small, the density is set small. As the oxygen feed speed is large and also the nitrification speed is large and the sedimentation of the microbe adhered carrier is not generated, the continuous operation can be carried out for a long period of time.</p> |
