Extensive pre-treatment of used process water is reasonable and necessary for both economic and legal reasons
Process water is needed in many production processes as a solvent, for production of material, or for cleaning purposes. Water is recirculated and reused for economical and environmental reasons. Grease, oil, fat, floating and suspended solids, settling material, and dissolved components need to be separated to provide good and uniform water quality. Recovery of valuable product from the water may be another additional objective.
Proper pre-treatment ensures that the applicable discharge standards for problematic substances (e.g. heavy metals, HC, AOX, etc.) are met and that the effluent discharge fee is minimized.
Conventional gravity clarifier sare often incapable to achieve sufficient pre-treatment for the reliable compliance with effluent standards or for extensive reduction of the contaminant load upstream of subsequent treatment stages.
Various types of flotation processes have been developed for such separation requirements, whereof dissolved air flotation with pressure water recirculation has proven most effective.
The use of a multistage rotary pump for recycle water saturation with air eliminates the need for costly pressure tanks with high maintenance requirements.
