Ha

20 mg/L as COD

0.60 mg biomass COD/mg

COD removed 0.18 day 1

0.20 mg debris COD/mg biomass COD

0.24 mg biomass COD/mg

N oxidized 0.10 day 1

20 mg/L as COD

0.50 mg biomass TSS/mg

COD removed 0.18 day 1

0.20 mg debris TSS/mg biomass TSS 1.2 mg COD/mg TSS 0.77 day 1 1.0 mg/L as N 0.75 mg/L as 0: 0.20 mg biomass TSS/mg

N oxidized 0.10 day '

Conversion of YA to YArequires use of Eq. 8.48: 0.24

Thus, it can be seen that conversion between the various models and unit systems is very straightforward as long as the basic definitions of terms are considered.

Example 8.7.2

Historical data from a domestic wastewater treatment plant suggest that the heterotrophic biomass yield is 0.70 mg VSS formed/mg BODs removed. What would be the value of the yield if it were expressed in mg TSS formed/mg COD removed, i.e., as Y„ |?

This conversion can be made by using Eq. 8.47. Since we are not interested in YH (which is in COD/COD units) it can be eliminated and L0 xls, can be moved to the right side. From Table 3.1, i,,Xn.i has a value of 1.20 g COD/g TSS and ioxii.v has a value of 1.42 g COD/g VSS. Furthermore, since the wastewater is domestic, the value of the term (1 — 10 can be assumed to be 0.67. Finally, f,, has a value of 0.20. Therefore:

0 0