A study was carried out in an Automotive Manufacturing Company to reduce chloride and fluoride level in final discharge water where the chloride level exceeded 2000ppm and fluoride discharge is not consistent. Existing system is using calcium chloride in fluoride treatment, thus contributing to high chloride and scaling in pipeline & final discharge tank. The scaling is in the form of calcium fluoride (CaF2) and calcium phosphate (Ca3PO4). By using calcium chloride, floating floc was observed frequently and resulted in sludge carry over into treated water tank.

 

Furthermore, fluoride exchange resin was found with high calcium scaling and has to be regenerated more frequently. Phosphate also competes with fluoride and interferes in ion exchange performance causing inconsistent fluoride discharge.

Based on the findings, calcium chloride (CaCl2) was found not suitable to be used to treat their wastewater. Frequent maintenance and unnecessary manpower were required to remove scaling and floating sludge in order to run the fluoride treatment. Due to high sludge, sludge holding tank keep overflowing and filter press has to be run more frequently.

To solve all these problems, a new chemical, Hyfor-F1 was introduced to replace Calcium Chloride (CaCl2) in fluoride treatment. Referring to the Table 1 & Table 2, the chloride level is reduced significantly as well as the fluoride & phosphate. Besides, the sludge generation was reduced about 30% and regeneration of exchange resin reduced from twice a week to once a week.