Water and Wastewater Treatment

One Water Concept

A holistic approach to water management that integrates the management of drinking water, wastewater, and stormwater as interconnected resources for sustainable use and environmental protection.

Potable water sources

Groundwater, surface water (rivers and lakes) and treated water.

Advantages of Groundwater

Low turbidity, microorganisms and low amounts of high molecular weight organics.

Disadvantages of Groundwater

Potentially high volatiles organics, hardness, total dissolved solids.

Advantages of Surface Water

Low volatiles organics, and hardness

Disadvantages of Surface Water

Potentially high turbidity, microorganisms, high molecular weight organics and total dissolved solids.

Sanitary Sewer

Collects wastewater from indoor plumbing and transports it to a wastewater treatment plant.

Domestic Wastewater

Used water from residential sources (flushing toilets, bathing, doing laundry)

Industrial Wastewater

Contaminated water from industrial processes such as manufacturing, power plants, and mining.

Storm sewer

A sewer that carries excess water in times of heavy rain.

Combined sewer overflow

When a combined sewer system (storm sewer and sanitary sewer) overflows due to excess rainfall and a mixture of storm water and untreated sewage flows out.

Problem with combined sewers

They oveflow during periods of heavy rainfall leading to a mixture of untreated sewage and stormwater flowing out of the sewer.

1974 Safe Drinking Water Act

Authorizes the EPA to enforce national regulations to ensure drinking water quality.

Primary drinking water standards

Enforced, health based

Secondary drinking water standards

Not enforced, aesthetically based

Screen

remove large material (logs, fish, etc.)

Aeration/Ozonation

Add air/ozone. Remove H2S, VOCs, and add O2.

Coagulation/Flocculation

• Add particles and mix

• Particles aggregate

• Coarse particle removal (sludge)

• Hydrophobic colloidal material

Chemical Addition

• To remove colloidal particles

• Disrupts charges and allows particles to agglomerate

Sedimentation

Remove solids/turbidity

Softening

Remove hardness (multivalent cations). Chemicals added are lime (CaOH2) and soda ash (Na2CO3). Calcium and magnesium rich sludge is formed.

Activated carbon adsorption

Activated carbon (very high surface area). Remove organics, best for non-polar, high molecular weight compounds.

Chemical Addition

Disinfection, leave residual disinfectant, corrosion control.