A new method for treating fluorine wastewater to reduce sludge and running costs

Reduction of the sludge generated in fluorine wastewater treatment is a critical problem for the semiconductor industry. We have developed a new method for treating fluorine wastewater in order to reduce sludge and running costs. This method utilizes a small amount of Al(OH)/sub 3/ not only as an aggregator for CaF/sub 2/ generated from fluoride ions in the wastewater but also as an effective fluorine adsorbent. The Al(OH)/sub 3/ as fluorine adsorbent is used repeatedly through an AI(OH)3 reclamation process. This method can effectively treat the concentrated fluorine wastewater to achieve an exceedingly low concentration in one-step treatment. We constructed a practical treatment system using this method by modifying part of an existing conventional system. This new treatment system is able to reduce both the total sludge and running costs to about one-tenth those of a conventional system.