Contact clarifiers

Softening lime-soda (high-rate, solids-contact clarifiers) 3.7... 

If a solids-contact clarifier is required, the surface-area requirement must exclude the area taken up by the reaction chamber. The reaction chamber itself is normally sized for a detention time of 15 to 45 min, depending on the type of treatment and the design of the unit. 

Figure 11. Solids contact clarifier without sludge blanket filtration. ...

Operation of slurry-recirculation solids contact units is typically controlled by maintaining steady levels of solids in the reaction zone. Design features of solids contact clarifiers should include ... 

The source of water samples was a 4-m3/h pilot plant on the Seine River located upstream from Paris, France. The background organic concentration ranged from 2 to 3 mg/L. The process, shown in Figure 1, included an upflow solids contact clarifier (Pulsator, Degremont, Rueil Malmaison, France) followed by rapid sand filtration (RSF). The effluent of the RSF was then split into four lines, which received various levels of ozonation followed by granular activated carbon (GAC) adsorption. Postchlorination (0.2 mg/L residual after 1 h) was used for bacterial control. 

Solids-contact clarifiers (also known as "upflow" clarifiers) typically have four treatment zones ... 

Cold lime and lime-soda softening is conducted in a solids-contact clarifier (see Chapter 8.1.1.). Cold lime softeners are typically followed by filtration and sodium softening to remove the balance of hardness from the water. 

In practice, two types of plants are generally used for chemical precipitation hardness removal One type uses a sludge blanket contact mechanism to facilitate the precipitation reaction. The second type consists of a flash mix, a flocculation basin, and a sedimentation basin. The former is called a solids-contact clarifier. The latter arrangement of flash mix, flocculation, and sedimentation were discussed in previous chapters on unit operations. 

FIGURE 10.1 Solids-contact clarifier. (Courtesy of Infilco Degremont, Inc.)... 

Solids-contact clarifier—A clarifier that uses a sludge blanket contact mechanism to facilitate the precipitation reaction. 

Clarification (after 30-min flocculation) Softening lime-soda (high-rate, solids-contact clarifiers) Softening lime-sludge 5-10 20-45 0.6-2.5 1-1.3 3.7... 

Solids-Contact Clarifiers When desirable, mixing, flocculation,... 

FIGURE 7.57. Typical solids-contact clarifier. (With permission of Japan Soda Industry Association.)... 

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