Recycling a nonionic aqueous-based metal-cleaning solution with a ceramic membrane: Pilot-scale evaluation

The effectiveness of a zirconium dioxide (ZrO2) membrane filter was evaluat ed for recycling a nonionic aqueous metal cleaning bath under real-world co nditions. The pilot-scale study consisted of four 7- to 16-day filtration r uns, Each processed a portion of the cleaning bath during immersion cleanin g of aircraft engine and motor parts. The results indicated that the filter aas effective in removing contaminants such as oil and grease and suspende d solids from the process solution, thus extending the life-span of the bat h up to three times. The process bath, however, bad to be replenished with, surfactant additives to compensate for those removed by the filter. The fo uled membrane could be effectively cleaned with its permeability fully rest ored for reuse.