Ch. 11.3 Managing Our Water Systems

Treating Wastewater• wastewater – refers to water that has been used for

a purpose and is returned down a drain – most often we think of wastewater as being sewage, but

wastewater can also be the water that is used in a dishwasher, washing machine, to take a shower, etc.

Treating Wastewater• in urbanized parts of the developed world, our

wastewater leaves our house in a pipe and joins a network of pipes that lead the wastewater to a wastewater treatment facility

Treating Wastewater• this water that flows from our homes or

businesses contains soap, food residue, human waste material, rags, pharmaceuticals, and a number of other things that can accidentally or intentionally get flushed into the system

Treating Wastewater• if we were to put this wastewater back into

our lakes and rivers, we’d be contaminating our drinking water supply

• so, we treat our water before letting it re-enter the natural environment

Septic Systems• most rural homes dispose of their wastewater

with septic systems because they are not connected to a municipal wastewater treatment system

• septic system – a self-contained wastewater treatment facility

• septic tank – a tank in which wastewater from all indoor sources such as toilets, sinks, and bathtubs enter

Septic Systems• bacteria inside the septic tank immediately

begin to break down the waste• solid material settles on the bottom, while

lighter material (such as kitchen grease) float on the surface

• the liquid layer in between flow into pipes that lead out from the tank

• this wastewater contains nutrients such as nitrogen

Septic Systems• the pipes leading from the septic tank are

perforated (have holes) on the bottom, allowing water to seep into the soil

• leaching bed (or leach field) – are used to remove contaminants and impurities from the liquid that emerges from the septic tank

• once the water is in the soil, more bacteria digest and breakdown organic waste

• eventually, the liquid returns to the ground water supply

Septic Systems

Wetland Technology

• a wetland, such as a marsh or swamp, is land that is saturated with water for long periods of time

• water-loving plants that grow in wetlands can filter and purify water

• wetlands remove and recycle nutrients, while roots and soil filter out contaminants

Wetland Technology

The Wastewater Treatment Plant

• wastewater treatment plant – a large facility at which wastewater, brought to the facility from a large area (ie. a city) through pipes, is cleaned of contaminants and pollutants using physical, biological, or chemical procedures

The Wastewater Treatment Plant

• wastewater treatment plants are often the most expensive facilities in a community

• for instance, for a community of 50,000 people, a wastewater treatment facility may cost over $40 million to build and maintain

• a wastewater treatment plant includes the physical plant as well as underground pipes that bring wastewater from our homes to the facility

The Wastewater Treatment Plant

interactive WW

TP example

Protecting Drinking Water Sources

• the more we pollute our water systems, the more we need to treat them to make that water safe to drink

• all human activities that affect our water systems affect the sources that supply our drinking water

Testing Water Quality• for most of human existence, we have been unable

to answer questions as to why people sometimes became ill or died from drinking water

• water quality labs test water for contaminants and warn communities of water quality hazards to try and minimize the impact on consumers

When you flush your toilet, where is that wastewater

going?