Wastewater Treatment Part One

What contaminants are removed from sewage in wastewater treatment?

Solids, BOD, nutrients such as nitrogen and phosphorus which promote algae growth, pathogenic microorganisms and harmful bacteria.

What is the purpose of wastewater treatment?

Wastewater treatment is necessary because it contains many contaminants that must be removed before returning the water to its natural environment.

Wastewater Treatment Steps:

Raw wastewater —>Screen (below is rakings for disposal)—> screened wastewater —> Grit separation (Grit leaves from the bottom) —>Degritted wastewater —> primary clarifier (port on bottom for primary sludge to digestion/disposal —>Biological processes —> Secondary clarifiers (port on the bottom for WAS) —>Tertiary treatment —> Disinfection

What is the purpose of primary treatment?

What is the purpose of secondary treatment? What are some options?

Primary Treatment: To settle out large and floatable materials to the top.

Secondary Treatment: Used to remove dissolved or unsettleable impurities such as BOD and suspended solids.

OPTIONS INCLUDE: Activated sludge process, Sequencing Batch Reactor (SBR), Trickling filters, Rotating Biological Contactors (RBC), Moving Bed Biological Reactor (MBBR), and aerated lagoons.

Describe Tertiary treatment:

Methods?

Mostly physical/chemical processes.

Can include: Chemical precipitation , Reverse osmosis, Carbon adsorption, Filtration, and Membrane filtration.