Surface Water Treatment

Some countries are blessed with abundant natural water sources be it lakes or rivers. These are termed as surface waters. Unfortunately, surface waters are open to contamination from human and animal waste in addition to other natural pollutants. Consequently, they are particularly susceptible to contamination by organisms such as bacteria, viruses and parasites that can cause serious illness; or simply by mud during flood seasons. Orient Water Technologies offers sevel systems to treat each individual surface water in order to make it suitable for human consumption. Systems offered under this category include:

  • Flocculation, clarification, filtration and disinfection
  • Ultrafiltration
  • Microfiltration
  • Nanofiltration

Flocculation, Clarification, Filtration and Disinfection

A tremendous amount of time and technology is expended to make surface water safe. When water enters a treatment plant, the first step is coagulation, the rapid mixing of coagulants such as aluminum sulfate, ferric chloride and organic polymers into the water. This alters electrical charges surrounding the suspended, undesirable particles to make them attract and coagulate, or clump together, into larger particles known as flocs.

The next step is flocculation: water is gently agitated so the flocs or particles will collide with each other, stick together and entrap other suspended particles, forming larger, heavier particles that will settle out in the next step.

In the sedimentation phase, the flocculated water moves slowly through a basin or tank to allow the heavy floc particles to settle to the bottom, so they may be removed. Water is passed through a filter made of sand, coal particles or similar materials that removes particles such as silt, other very fine solids, and some pathogens not settled in the sedimentation process. Filtration further reduces turbidity and results in water that is crystal clear. Activated carbon also may be used to remove chemical contaminants. Rather than being trapped in the small passageways between grains of sand, contaminants stick to the surface of carbon and are removed, a process known as carbon adsorption.

At the disinfection stage, chlorine, chloramines, ozone or other disinfectants are added to the water to destroy potentially harmful germs such as bacteria, viruses, parasites and other organisms. During the treatment process, an effort is made to add enough disinfectant to leave a residual amount in the water to continue to kill any pathogens in the pipelines that convey the water to users.