| 摘要 |
PROBLEM TO BE SOLVED: To avoid generation of harmful trihalo-methane and to prevent deterioration of water quality in a pretreatment of raw water fed to a reverse osmosis membrane treatment device. SOLUTION: Pipe lines from an intake pump 14 to a first stage membrane module 17 of the reverse osmosis membrane treatment device 2 (pipe lines equipped with a sand filter device 8 and a safety filter 9, etc.), are provided for a closing pipe line. A flocculant addition device 7 for adding a flocculant solution into sea water flowing in the first pipe line 6, a pH adjusting agent addition device 11 for adding a pH adjusting mineral acid solution to a primary filtrate flowing in a second pipe line 10, and a sterilizing agent addition device 13 for adding a sterilizing purpose mineral acid solution to a secondary filtrate flowing in a third pipe line 12 are provided for the device. |
