Important Stages of Waste Water Treatment

Utilities Tech Outlook | Tuesday, February 21, 2023

UV light wastewater treatment is typically used to control bacteria, preventing them from reproducing. Furthermore, it is capable of removing chlorine, chloramines, ozone, and bromine, making it ideal for producing extremely pure technical water.

FREMONT, CA: Wastewater treatment is divided into three stages: primary, secondary, and tertiary. Water is purified at each stage to a higher level. Some applications require only one or two stages. Based on the intended use of the water and the environment it will be discharged into, the level of treatment required varies.

Treatment in the primary stage: Sedimentation is the first step in wastewater treatment. Water is temporarily held in large sedimentation tanks to remove solids that settle.

Gravity causes heavier solids to sink to the bottom and lighter solids to rise to the top. As a coagulant, chemicals can also be added to remove more solids.

As a by-product of sedimentation, sewage sludge forms at the bottom of the tank; after this has settled, the treated water is released for secondary treatment. Alternatively, sludge may be used for anaerobic digestion or as a liming material.

Treatment in the second stage: During secondary treatment, organic matter solids that have escaped primary treatment are removed. As well as larger suspended solids, it also deals with smaller ones. 

There are several secondary treatment methods, including:

• Bioreactors which are a type of reactor

• Filter beds

• Aerated ponds

• Activated sludge 

• Biological contactors that rotate

In a membrane bioreactor, microorganisms consume organic matter for energy in order to remove organic contaminants. Solids are created by microorganisms replicating. The membrane filters solids to produce effluent.

Treatment at the tertiary level is the third step: Water is disinfected to the highest standard by tertiary treatment, also known as polishing. The purpose of this stage is to produce water that meets specifications, such as technical waters, and to treat wastewater for public water systems. Among the tertiary treatment methods are UV disinfection and Chemical disinfection.

Chemicals are not needed for UV disinfection, and they can replace them. As a result, additives do not require an extra filtering stage. Microorganisms are destroyed by UV light, but pH, appearance, taste, and smell do not change. 

UV light wastewater treatment is typically used to control bacteria, preventing them from reproducing. Furthermore, it is capable of removing chlorine, chloramines, ozone, and bromine, making it ideal for producing extremely pure technical water.

The process of chemical disinfection involves adding a chemical to the water. Chlorine is the most common. Bacteria and viruses are killed by chlorine. Iodine is another chemical used to disinfect water. Viruses and bacteria are equally killed by this method as by chlorine.