ENVE 420Industrial Pollution Control

Wastewater Treatment ProcessesDr. Aslıhan Kerç

Primary – Secondary Treatment

• Primary and secondary treatment handle non-toxic wastewaters.

• If ww contains toxic compounds, they have to be pretreated before these processes.

Primary Treatment

• Preparation of wastewater for biological treatment

• Removal of large solids by screening, grit removal

• Equalization: Levels out the hour to hour variations in flows and concentrations.

• Spill Pond: Retain slugs of concentrated wastes that could upset the downstream processes.

Primary Treatment

• Neutralization: Follows equalization. Streams of different pH neutralize each other

• Oil and grease, SS removal by flotation, sedimentation or filtration

Secondary Treatment

• Biological degredation of soluble organic compounds

Biotreatment:- Aerobic- Anaerobic

In-plant Treatment

• Necessary for biological treatment.• Heavy metals, pesticides pass through primary

treatment and inhibit biological treatment.• Effective for low volume streams with high

concentration of non-degredable materials. • Easier to treat a specific pollutant from a small

and concentrated stream than a large dilute stream.

In-plant Treatment

• Precipitation• Activated carbon adsorption• Chemical oxidation• Air or stream stripping• Ion exchange• Reverse osmosis• Electrodialysis• Wet air oxidation