DI water for rinse zones in surface pre-treatment of alloy wheels

The alloy wheels produced by a large European wheel manufacturer are distinguished by their superior optics, excellent stability and exceptionally long lifetimes. Being able to meet the high standards of automotive manufacturers an ultra-modern surface treatment technology is of outmost importance, including a chrome-free pretreatment as well as powder coating based on durable and environmentally friendly coating variants. The water treatment solution for the pre-treatment consists of the following parts:

Water saving: A properly designed water recycling process reduces the demand for fresh water as well as the demand for waste water treatment. The water from the rinse zone is reused/recycled through bag filter, automatic gravel filter and two parallel automatic demineralizers for continuous operation and returned to the DI-rinse zones after being disinfected in UV unit.

Demineralized rinse water: In all water based pre-treatment systems there is a need to add fresh make-up water due to evaporation, drag-over, renewal of the water in the different baths, etc. In this case, the distillate from a vacuum distillation system serves as one source for the make-up water. However, the main source is chlorinated municipal drinking water treated in the following steps: bag filter, activated carbon filter, antiscalant dosing and reverse osmosis unit with water saving technology.