Different methods of wastewater treatment

Wastewater treatment is a procedure of removing all the pollutants in the form oforganic matter and cleaning domestic water and sewage. Water is treated with the purpose ofreusing the water either by humans or animals or for any other purposes.
　　
Water discharged from houses. factories. orindustries is made to enter sewers.Waterfrom rains enters stormwater sewers. Water from these sewers reaches the wastewater plant by means of gravity flow.
　　
With the increase in population, water resources have been impacted severelv. Innovative technologies are required to treat wastewater for pollution. There is an increased need of having oxidation methods chemicalnrecinitation adsorntion on various media etc to senarate contaminated nollutants from wastewater.

Various stages of wastewater treatment:
　　
1. Pre-treatment:
　　
Pre-treatment of wastewater is done prior to discharge from industries orfactories.This treatment is required to avoid the discharge of any chemicals surplus nutrients from the wastewater.
　　
2. Preliminary Treatment:
　　
Preliminary treatment is done to remove arge objects/debris and non-degradable objects from the wastewater. This treatment saves the equipment fron any kind ofdamage. The assemblyfor this treatment has a barscreen. mesh screen. and grit chamber to remove garbage
　　
3. Primary Treatment:
　　
lt is a physical process that is done to remove anv suspended sand particles from wastewater. The velocitv of wastewater is reduced so that all the suspended particles settle down due to gravity force. The settled material is called “Biosolids” or sludge.
　　
4.Secondary Treatment:
　　
It is a biological process that makes use ofmicrobes/bacteria and aleae to absorb the organic matter present in wastewater Microbes consume all the organicimpurities and converttheminto Carbon dioxide, water, or energy for their own growth.
　　
5.Disinfection:
　　
This is sometimes stated as the tertiary treatment.Generally, Chlorine andchloramines are used for the wastewater treatment for the disinfection proces. Sometimes, UV radiations are used to disinfect the water.
　　
6.Sludge (biosolids) Disposal:
　　
The final stage of wastewater treatment is removing sludge or biosolids.The by-products ofthese sludge are often used for agricultural purposes.
　　
Methods of wastewater treatment:
　　
1. Biological Wastewater Treatment:
　　
When we need water to be used for drinking orfor human consumption purposes, it needs to be cleaned extensively. To meet this requirement, the Biological treatment of wastewater is done. Biological treatment involves the use of micro bacteria that decompose the waste material or organic impurities and improve the quality of water to be used for households.
　　
There are three methods of biological treatment:
　　
· Aerobic Process:In the aerobic process, bacteria decompose and devour the organic impurities of wastewater and convert it to CO2 for reproduction and growth. Oxygen is required during this process.
　　
· Anaerobic Process: In the Anaerobic or fermentation process,waste orsludge present in the wastewater is fermented at a specified temperature. Oxygen is not required during this process.
　　
· Composting: Composting is a kind ofAerobic process, in which sludge orbiosolid is mixed with carbon sources in the presence of Oxygen to remove al the impurities.
　　
2. Physical Wastewater Treatment:
　　
Physical wastewater treatment uses physical approaches to remove impurities. There are three important physical methods that are used to clean waters
　　
· Sedimentation: Sedimentation is aprocedure ofremovinginsoluble debris from the water.The first unit of sedimentation tank is known as “primary sedimentation tank” or“primary settlingtanks”where solids or dense materialslike stones, dust particles, debris are removed by gravity force, and other less dense particles are carried to the next tank.
　　
· Aeration:In this method of water treatment, the air is made to circulate through the water to give it oxygen to increase its Bio-Oxygen Demand
　　
· Filtration: This method is used for filtering out impurities present in wastewater. A special filter with great capacity is used for this treatment. The most common filter used is Sand Filter.
　　
3. Chemical Wastewater Treatment:
　　
Chemical wastewater treatment uses variouschemicalsin order to clean water.Generally,Chlorine is used to treat sewage because it acts as an oxidizing chemical to kill harmfulbacteria.This process is known aschlorinationzone is alsoan oxidizing disinfectant that works to destrov viruses and harmful bacteria in the water. To treat industrial wastewater, the Neutralization method is used. In this method, base or acid is mixed with water till it reaches the ph value ofwater. Generally. lime is used as a base to neutralize acidic water