WASTEWATER TREATMENTNOTES

TYPES OF POLLUTION

• Vegetable oil, salt, vinegar, food, dirt, soap, bacteria, nitrates, phosphates, heavy metals, human waste, litter, E. coli, chemicals, suspended solids

TREATMENT PROCESSPRIMARY TREATMENT: 1st Stage: Gets out the big stuff.

filtering and settling. Solids settle out and scum rises. Skimming the top of the tank removes the scum. Uses a screen, pools/ponds, settling tank.

STEPS:1. Goes through a screen to filter out big stuff2. Settling tank – heavy stuff sinks down, lighter stuff

floats.3. Sludge (stuff at bottom of settling tank) goes to ocean,

farm, is buried, or burned.4. Slow process

TREATMENT PROCESS

SECONDARY TREATMENT: 2nd Stage: Biological Process -- gets little stuff. Uses an aeration tank. Uses chlorine. Solids and microorganisms are separated.

STEPS:• Bacteria eat the waste in the Aeration tank.• Oxygen is supplied to bacteria so they have

plenty of DO. • Settling tank is used for dead bacteria to settle

out.

Wastewater treatment plant

Wastewater treatment plant

• Filtration – removing large particles• Sedimentation – sinking of the solid material

to the bottom of a tank. • Aeration – adding air to push out foul

smelling gases. • Disinfection – adding chlorine to kill disease-

causing organisms. • Distribution – releasing the treated water

into a stream.

WHY IS TREATMENT NECESSARY?

• Toxic to organisms, poisonous to organisms, smelly water, makes water easier to turn into drinkable water. Wastewater would increase turbidity, mess up pH, mess up DO, contains bacteria, contains heavy metals.