| 摘要 |
<P>PROBLEM TO BE SOLVED: To make organic material-containing water subjected to a biological treatment by adding phosphorus as a nutrient, and to prevent membrane contamination in filtering with a membrane the biologically treated liquid so obtained. <P>SOLUTION: The biologically treated liquid flowed out from a biological treatment tank 21 is flocculated in a coagulation/sedimentation tank 22. The phosphoric acid concentration of the flocculated liquid obtained is measured by a densitometer 43 for phosphoric acid, with the addition of phosphoric acid adjusted so that the measurement value becomes ≤2 mg/L. The phosphoric acid is allowed to remain at ≤2 mg/L in the flocculated liquid. A phosphoric acid solution may be added to some excess so that no phosphoric acid runs short in the biological treatment in the biological treatment tank 21. <P>COPYRIGHT: (C)2009,JPO&INPIT |
