Mass Balance and Measuring Plant Performance - Basic Mathematics for Water and Wastewater Operators - page 192

VM in VM out

74% 54%

59% VM Reduction

FIGURE 13.5 Illustration for Example 13.5.

p erCent v olatile M atter r eduCtion in s ludge
The calculation used to determine percent volatile matter reduction is more compli-
cated because of the changes occurring during biosolids digestion:

( ) ×

%VM − % M 100

in out

%VMreduction = (13.2)

( )

%VM − VM × %VM out

in in

■ Example 13.5
Problem: Using the digester data provided below, determine the percent volatile
matter reduction for the digester (see Figure 13.5).

Raw biosolids volatile matter = 74%
Digested biosolids volatile matter = 54%

Solution:

( ) × 0.74

0.74

− 054 . 100

%VMreduction = = 59%

( )

− 0.74 × 0.54