If rapid COD and online TOC measurements cannot measure the true COD value why does anyone make these measurements?
The reason for using these analytical techniques is speed of analysis. Its takes at least 2½ hours to collect, prepare, digest, cool and read a true COD value; online TOC analysis can give a result in under 10 minutes and do this automatically. If there is a problem with the waste treatment then the rapid analysis allows intervention to be made quickly – e.g. incorrectly treated waste can be diverted to a holding tank rather than being discharged to a watercourse.