Flotation or Foam Separation

One of the principal applications of vacuum and pressure (air) flotation is in commercial installations with colloidal wastes from soap and detergent factories [20,40-42]. Wastewaters from soap production are collected in traps on skimming tanks, with subsequent recovery floating of fatty acids.

Foam separation or fractionation [40,41,43-45] can be used to extra advantage: not only do surfactants congregate at the air/liquid interfaces, but other colloidal materials and ionized compounds that form a complex with the surfactants tend to also be concentrated by this method. An incidental, but often important, advantage of air flotation processes is the aerobic condition developed, which tends to stabilize the sludge and skimmings so that they are less likely to turn septic. However, disposal means for the foamate can be a serious problem in the use of this procedure [46]. It has been reported that foam separation has been able to remove 70-80% of synthetic detergents, at a wide range of costs [2]. Gibbs [17] reported the successful use of fine bubble flotation and 40 mm detention in treating soap manufacture wastes, where the skimmed sludge was periodically returned to the soap factory for reprocessing. According to Wang [47-49], the dissolved air flotation process is both technically and economically feasible for the removal of detergents and soaps (i.e., surfactants) from water.

Table 9 Effluent Limitations for Subpart I, Oleum Sulfonation

Effluent limitations [metric units (kg/1000 kg of anhydrous product)] Effluent Maximum for any 1 Average of daily values for 30 consecutive days characteristic__day__shall not exceed_

Table 9 Effluent Limitations for Subpart I, Oleum Sulfonation

Effluent limitations [metric units (kg/1000 kg of anhydrous product)] Effluent Maximum for any 1 Average of daily values for 30 consecutive days characteristic__day__shall not exceed_

(a) BPT

bod5

0.09

0.02

COD

0.40

0.09

TSS

0.15

0.03

Surfactants

0.15

0.03

Oil and grease

0.25

0.07

pH

a

a

(b) BAT

bod5

0.07

0.02

COD

0.27

0.09

TSS

0.09

0.03

Surfactants

0.09

0.03

Oil and grease

0.21

0.07

PH

a

a

(c) NSPS

bod5

0.03

0.01

COD

0.09

0.03

TSS

0.06

0.02

Surfactants

0.03

0.01

Oil and grease

0.12

0.04

ph

a

a

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