Environmental Engineering Reference
In-Depth Information
TABLE 13.1
General Conversion Rates
Conversion Factor
(lb Solids/lb BOD Removal)
Process Type
Primary treatment
1.70
Trickling filters
1.00
Rotating biological contactors
1.00
Activated biosolids with primary
0.70
Activated biosolids without primary
Conventional
0.85
Extended air
0.65
Contact stabilization
1.00
Step feed
0.85
Oxidation ditch
0.65
4. Solids generated (lb) = BOD removed (lb) × Factor
5. Solids removed (lb/day) = Sludge pumped (gpd) × % Solids × 8.34 lb/gal
6. Effluent solids (mg/L) = Flow (MGD) × 8.34 lb/gal
■
Example 13.2
Problem:
A conventional activated biosolids system with primary treatment is oper-
ating at the levels listed below. Does the mass balance for the activated biosolids
system indicate that a problem exists?
Plant influent BOD = 250 mg/L
Primary effluent BOD = 166 mg/L
Activated biosolids system effluent BOD = 25 mg/L
Activated biosolids system effluent total suspended solids (TSS) = 19 mg/L
Plant flow = 11.40 MGD
Waste concentration = 6795 mg/L
Waste flow = 0.15 MGD
BOD In
BOD Out
Solids Out
Solids Removed
FIGURE 13.2
Comparison of BOD
in
and BOD
out
.
Search WWH ::
Custom Search