Traditional Water Treatment

Traditional water treatment processes are designed to remove particulates and unwanted chemicals from water.
Water Treatment

Coagulation – The process of using chemical and/or physical techniques to promote particulate settling by reducing net electrical repulsion forces between particles.

Flocculation – The process of agglomerating particles in water or wastewater to promote settling by using high-molecular-weight materials such as polymers, starches, and multiple charged ions.

Sedimentation – A process that allows the flocculated or coagulated particles time to settle by gravity in a sedimentation tank. Typically, a hydraulic residence time of 4 hours is desired to allow sufficient time for settling. Sedimentation is common in wastewater treatment and water pretreatment.

Filtration – A process that removes solids from the water by passing water through a porous medium. Coarse, medium, and fine filters can be utilized depending on the degree of treatment. Two types of filters commonly used are gravity and pressure filters. To remove accumulated solids from the the filter bed, backwashing is required. Backwashing is the process of reversing the direction of flow through the filter, removing solids from the filter bed.

Activated carbon absorption – A physical process that is typically applied as tertiary treatment to remove low concentrations of contaminants from water that are difficult to remove by other means. Activated carbon has been processed to make it extremely porous, thereby creating a very large surface area available for adsorption of contaminants. Activated carbon may have a surface area as great as 1500 m2/g (7.3 million ft2/lb).

Pressurized Filtration Technologies

Microfiltration – A membrane filtration technique that is used to remove sand, silt, clay, algae, and bacteria. The membrane pore sizes range from 0.03 to 10 μm.

Ultrafiltration – A membrane filtration technique that is used to remove sand, silt, clay, algae, and bacteria. The membrane pore sizes range from 0.01 to 0.03 μm.

Nanofiltration – A membrane filtration technique that is used to remove natural organic matter and synthetic organic chemicals. The membrane has pore sizes of 0.001 μm or 1 nm.

Reverse osmosis – A membrane filtration technique that removes virtually all contaminants from water.

Chemical Processes

Hardness removal – Hardness in water can lead to scaling of piping and plumbing equipment.

Lime softening – A series of chemical reactions that change the soluble calcium and magnesium compounds in water into insoluble calcium carbonate and magnesium hydroxide. These are the least soluble calcium and magnesium compounds and will precipitate from solution at relatively low concentrations.

Ion exchange softening – The process of using either natural or synthetic ion exchange resins to remove hardness from water. The resins exchange non-hardness-causing sodium ions for hardness-causing calcium and magnesium ions. The water becomes enriched with sodium and depleted in calcium and magnesium, while the resin becomes enriched with calcium and magnesium and depleted in sodium.

Disinfection – The purpose of water disinfection is to destroy organisms that cause disease. Common water disinfection methods include chlorination, ozonation, and ultraviolet radiation. Biological material may also clog pipes in cooling systems.

Chlorination – A water treatment method that destroys harmful bacteria, parasites, and other organisms. Chlorination also removes soluble iron, manganese, and hydrogen sulfide ions from the water.

Ozonation – A water treatment process that destroys harmful bacteria and other microorganisms through an infusion of ozone. Ozone (O3) is a gas created when oxygen molecules are subjected to high electrical voltage.

Ultraviolet radiation – A disinfection process for water and wastewater treatment that involves passing ultraviolet (UV) light through water or wastewater. UV light kills microorganisms.