PRETREATMENT APPARATUS FOR ONLINE MEASUREMENT IN AQUEOUS SYSTEM, ONLINE MEASURING APPARATUS INCLUDING THE SAME, AND PRETREATMENT METHOD FOR ONLINE MEASUREMENT

摘要

PROBLEM TO BE SOLVED: To reduce maintenance frequency in online measurement by preventing fouling caused by a material having the size of about several millimeters and a fibrous material.SOLUTION: A pretreatment apparatus for online measurement includes a plurality of lengthy external pressure type hollow fiber membranes for filtering in a cross-flow filtration system, sample water introduced from an aqueous system whose water quality is to be online-measured, which are hollow fiber membranes each having a fixed first end forming a lower end in the used state.