Effluent Treatment Plant

Effluent is any substance that create pollution, such as municipal sewage or industrial liquid waste that flows out of a treatment plant, septic system, pipe, etc. Effluent can be the outflow from a sewage treatment facility or the wastewater discharge from industrial facilities. Effluents are being produced in large amounts from a number of industries, and it is posing a serious threat to our environment. Handling of such type of effluents is quite necessary to prevent our environment from being further threatened by such dangers.

The effluent treatment plant may follow any of these processes available today, such as conventional method, modern technology. Here we will concentrate on the conventional method used for the effluent treatment plant. The conventional method consists of three main stages, which includes:

• Primary Treatment
• Secondary Treatment
• Tertiary Treatment

Primary Treatment
The primary treatment process consists of three processes including, physical treatment, chemical treatment, and biological treatment. The physical treatment includes the separation of solid and semi-solid materials from the the effluent. This phase use equipment, such as grit chamber and bar screen. After the physical processing is over, the effluent is treated chemical, which includes the processes like coagulation and flocculation. After the removal of solid materials and chemical treatment, the effluent is passed through a biological treatment process.

Secondary Treatment
The secondary treatment includes the following processes in the entire treatment including, Activated Sludge Process, Aerobic/Anaerobic Digestion, Sequence Batch Reactor, Tricking Filter, Oxidation Pond. These two are the major ones :

• Activated Sludge Process: This process uses dissolved oxygen to promote the growth of biological floc which helps in removing the organic material. It can convert ammonia to nitrite and nitrate and ultimately to nitrogen gas. This process is also capable of trapping particulate material.
• Aerobic/Anaerobic Digestion: Aerobic biological processes are used to decompose the biological content of the sewage like food waste, soaps, detergent and human waste. Bacteria and protozoa are introduced to convert the biodegradable soluble organic contaminants into floc.

Tertiary Treatment
Tertiary treatment of wastewater is essential to further enhance its quality. Some popular methods used in this stage are filtration, lagooning, removal of chemicals like nitrogen and phosphorus etc. Various treatment processes are used to remove nitrogen and phosphorus. The ammonia present in the wastewater is changed to nitrite and it is followed by denitrification. Phosphorus can be removed by using specific bacteria, called polyphosphate that collects large quantities of phosphorus within their cells. They are removed from the water and are used as fertilizer.