Environmental Engineering FOURTH EDITION

222 ENVIRONMENTAL ENGINEERING

Funnel

0

Figure 10-12. Buchner funnel test for determining specific resistance to filtration.

Table 10-3. Specific Resistance of Typical Sludges

Sludge type Specific resistance (m/kg)

~~

Raw Primary 10-30 x 1014

Mixed digested 3-30 x 1014

Waste activated 5-20 1014

Lime and biological sludge 1-5 x 1014

Lime slurry 5-10 1013

Alum 2-10 1013

Other test variables are:

P = pressure = 10 psi = 703 g/cm2,

p = viscosity = 0.0011 P = 0.0011 N x dm2,

w = 0.075 g/mL = 75 kg/m3, and

A = 44.2 cm2 = 0.00442 m2.

The data are plotted in Fig. 10-13. The slope of the line, b, is 5.73 dcm6 = 5.73 x

(100cm/m)6 = 5.73 x 10'~ s/m6

= 1.86 x 1013 mgkg.

(2) (6.9) (1 04) (0.00442) (5.73) ( 1 OI2)

(0.0011)(75)

r=

Specific resistance to filtration can be used to estimate the required loadings of a

filter. TheJiZter yield is described as the mass of dewatered (dry) solids produced by