Water Treatment Process – AP Enviro Science

Safe Drinking Water Act

The SDWA establishes maximum contaminant levels (MCLs) for 77 elements or substances in both surface water and groundwater used for public water systems in the USA.

Purpose of Treatment

Raw water from lakes and rivers contains suspended solids, dissolved minerals, and pathogenic microorganisms. The multi-stage process sequentially targets physical, chemical, and biological threats.

Coagulant Chemicals

Alum (Aluminum sulfate) neutralizes the negative electrical charges on dirt particles, allowing them to bind together into larger, heavier "flocs".

Tags

APESWater QualityPurificationPathogens

Treatment Timeline

Drinking water purification is a linear process. Advance through the stages to convert raw lake water into safe municipal drinking water.

0 Raw Water Intake

Lake or river water is pumped in, containing debris, silt, and bacteria.

1 Coagulation & Flocculation

Alum is added. Rapid mixing neutralizes particle charges. Slow mixing creates larger "flocs".

2 Sedimentation

Water flows slowly. Heavy iron/floc particles settle to the bottom as sludge.

3 Filtration

Water passes through sand, gravel, and activated carbon to remove remaining dissolved particles and odors.

4 Disinfection

Chlorine, Ozone, or UV light is applied to kill remaining pathogenic bacteria and viruses.