| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the frequency of washing work and to improve the efficiency of each cleaning work by burning a filler for biological filtration which contains quartz sand and bentonite as main components and has a specified value of true specific gravity and a specified effective particle size by using powdery foundry sand or waste sand as a raw material. SOLUTION: A filler for biological membrane filtration contains quartz sand and bentonite as main components and may be a product prepared by a process in which used powdery foundry sand is added with water, and the mixture is kneaded, molded, and sintered. The sintered material has a true specific gravity of 1.5-1.8 and an effective particle size of 2.0-5.0 mm. Its shape is preferably spherical, though complete sphericity is not required, in consideration of granulation and uniform filling. In a filter bed column 1 to be used, the lower part is filled with gravel 20 to make a support layer 2, and a number of filter mediums 21 are piled on the layer 2 to form a filter medium layer 3. In this way, washing frequency to solve clogging is reduced, and discharge due to the lifting of the filter mediums 21 by washing work is decreased to enable efficient operation.</p> |
