The printers that I have dealt with in Louisville, KY have been able to
discharge directly to the POTW sewers without any pretreatment, regardless
of whether ipa was in the fountain solution or not. However, they do have
a pretreatment permit and have to meet POTW standards. Their permits however
deal primarily with silver from photoprocessing, or at least this has been
their and the POTW's biggest concern.