Raw water clarification

Raw water clarification has been a very traditional process step before filtration for both process and boiler feedwater applications. This applies to both river water sources/surface water sources in general as well as ground water sources.

Krofta DAF filtration of surface and ground water

Short setting time

For surface water sources, both traditional gravity clarifiers as well as DAFs have been used effectively. If there is sufficient open area available for upgrading of water processes or where the soils can support the required load bearing of clarifiers, gravity clarifiers are an effective solution. DAFs find their niche where space is limited and where the location for clarification requires pilings, etc. DAFs can accomplish the clarification in 3 to 5 minutes while a gravity clarifier needs longer setting time at the same flowrate.

Effective reduction of algae blooms

Krofta DAFs are also very effective in handling algae blooms that may be common in larger holding ponds when seasonal conditions are right for such algae blooms to occur. Small quantities of a coagulant and flocculant coupled with a DAF can be a very simple solution to solids reduction in general and for specific conditions such as algae blooms.

Effective dissolved metal reduction

DAF’s have been used very effectively for both the reduction of color caused by certain dissolved metals such as iron. Fe ions can be oxidized by a number of lower costs oxidizing agents. These can include oxygen from air as well as faster acting compounds such as sodium hypochloride. Once the Fe ion is oxidized forming an insoluble particle it can be floated using a DAF with appropriate chemistry. The reduction of iron from ground water sources can reduce the need for other chemicals in the papermaking process such as brighteners.

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