Flotation clarifiers

In DAF, higher biosolids densities are obtained than in sedimentation. Even in shallow flotation clarifiers a satisfactory biosolids density is attainable. 

Several high-rate air flotation clarifiers (both DAF and dispersed air flotation) with less than 15 min of detention times have been developed for groundwater decontamination, industrial effluent treatment, resources recovery, and water reclamation. Both insoluble and soluble impurities such as... 

A common modification of this process is dissolved air flotation (DAF), in which air under pressure is injected into the wastewater. DAF units are more efficient than conventional flotation clarifiers because more air is introduced into the wastewater, thereby removing more solids.43 5-59... 

FIGURE 27.12 Improved activated sludge system with the installation of a secondary flotation clarifier (example). Note 1MGD = 0.0438 m3/s lppm-lmg/L 1 TPD = 37.8 kg/h. 

A typical overloaded conventional complete-mix activated sludge treatment plant (shown in Figure 27.11) has been described in Section 27.3.3. The same conventional treatment plant can be improved by the addition of a secondary flotation clarifier (shown in Figure 27.12). Some advantages of the improved activated sludge system are mathematically presented below. 

Full-scale trials with the secondary flotation clarifier were conducted in summer 1980, with excellent pilot results in solids removal, sludge consistency, and water clarity. Table 27.1 documents partial operational data. The following are the conclusions drawn from the investigation ... 

The secondary sludge in the secondary flotation clarifier is floating thus sludge rising is no longer a problem, and in fact, becomes a big plus. 

Another alternative involves the addition of a secondary flotation clarifier that parallels the existing secondary sedimentation clarifier in a conventional existing activated sludge wastewater treatment plant. 

The use of flotation clarifiers and fiber recovery facilities in paper mills may achieve near total water and fiber recycle and, in turn, accomplish the task of zero discharge [16]. 

Krofta, M. Wang, L.K. Improved biological treatment with a secondary flotation clarifier. Civil Engng. for Practicing and Design Engrs. 1983, 2, 307-324. 

Many books on the market are now printed on recycled paper containing almost 80% recycled fibers produced in a de-inking plant equipped with a dispersed flotation clarifier. 

Dissolved Air Flotation Clarifiers-Brief History of Development... 

CH2CHCONH2CH2CHCOO(CH2)2N(CH3)3rxXCr Empirical (CsHi6N02 C3HsNO)x xCI Uses Antistat, film-former in cosmetics dissolved air flotation clarifiers Features Low charge polymer Trade Name Synonyms Hartfloc C-475 [Huntsman http //www.huntsman.com] Polyquatemium-34... 

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