Environmental Engineering Reference
In-Depth Information
Conclusion for DCs: No need to use more than primary treatment.
Influent (typical)
BOD
Sus. Solids
Grease/Oils
=
=
=
240 mg/l
300 mg/l
30 mg/l
Complete Treatment
3.0
BOD
Sus. Solids
Grease/Oils
=
=
=
20 mg/l
30 mg/l
5 mg/l
Primary Treatment
1.0
Eff BOD
Eff Sus. Solids
Eff Grease/Oils
=
=
=
160 mg/l
200 mg/l
10 mg/l
Eff = Effluent
1900
1950
2000
FIGURE 4.9
Schematic drawing showing effluent standards requirements for disposal
of municipal sewage to inland/confined coastal waters where DO is not and significant
ambient parameter.
Disposal to open unconfined waters where ambient DO
is not significant
Up to 1980: Primary treatment only
Since 1980: Primary and secondary
New technology: since 1985
Relative Cost
1
1 + 2 = 3
Floatables
- Use microscreening in lieu of primary treatment removes
floatables not settleables.
- Scientific research has shown that for disposal to open marine
waters, only floatables need to be removed.
- Recommendation for DCs = Floatables removal only because
ocean environment completely assimilates BOD/suspended solids.
Floatables Removal (by microscreening)
Floatables
FIGURE 4.10
Schematic drawing showing effluent standards requirements for disposal
of municipal sewage to unconfined marine waters (where access to open ocean is feasible
and DO is not a significant parameter).
