APES UNIT 8.11 - Sewage Treatment

septic system

Small waste water system used by a single home or business.

Three layers in a septic tank

scum (oils) , effluent (clear liquid), sludge (solids)

What breaks down sludge in septic tank?

natural bacteria

sewage treatment plant

centralized systems in large municipalities in developed countries

primary treatment of sewage

physical removal of solids.

-flows through bar screens (big stuff) and grates (small stuff) to remove solids

-then comminutor grinds remaining

-Grit chamber=settling of sand to gravel size particles

-waste settles at bottom of tank

Secondary treatment of sewage

-the amount of biodegradable materials is reduced and broken down by adding air to encourage microscopic organism growth (aerobic bacteria)

• This is typically done using microorganisms, such as bacteria, that consume the organic matter and convert it into biomass. Secondary treatment is usually done in aerated lagoons or activated sludge tanks.

Tertiary treatments of sewage

-disinfection using chlorine, UV light, ozone, peroxide, reverse osmosis

Manure lagoon

Human-made pond lined with rubber built to handle large quantities of manure produced by livestock.

Activated Sludge Tanks

Activated sludge tanks are large, aerated tanks used in wastewater treatment plants to treat sewage. Microorganisms in the tank break down organic matter and remove pollutants from the water.

Clean Water Act (CWA)

The Clean Water Act (CWA) is a federal law enacted in 1972 that regulates pollution discharges into U.S. waters with the goal of maintaining and restoring the chemical, physical, and biological integrity of these waters. It sets standards for wastewater treatment plants, controls point source pollution from industries, and protects wetlands.

National Pollutant Discharge Elimination System (NPDES)

The National Pollutant Discharge Elimination System is a program under the Clean Water Act that regulates point source pollution by requiring permits for any entity discharging pollutants into U.S. waters.

Septic Tank

A septic tank is an underground wastewater treatment system commonly used in rural areas or homes not connected to municipal sewage systems. It separates solid waste from wastewater and allows natural processes to break down the waste before it enters the drain field.

Safe Drinking Water Act (SDWA)

The Safe Drinking Water Act (SDWA) is a federal law in the United States that sets standards for drinking water quality and regulates public water systems. It aims to protect public health by ensuring safe drinking water for all citizens.

Leach Field

A leach field is a part of a septic system that consists of underground pipes or trenches filled with gravel. It is designed to allow wastewater from the septic tank to slowly percolate into the soil, where it undergoes natural filtration and treatment.

Sludge

 Sludge refers to the thick, semi-solid material that accumulates at the bottom of wastewater treatment systems like septic tanks or during industrial processes. It contains a mixture of organic and inorganic matter.