WHAT IS SEPTIC TANK? ITS FUNCTIONS, ADVANTAGES AND DRAWBACKS.


A septic tank is an underwater sedimentation tank made of concrete, fiberglass, or plastic through which domestic waste water used. Waste water treatment through by the different process of biological decomposition and drainage.  



Grease Trap and Septic System Cleaning in Baltimore | Freedom ...


Function of septic tank :

  • A septic tank will digest organic matter and separate float able matter(e.g., oils and grease) and solids from the wastewater 
  • A septic tank will be connected with two pipes (for inlet and outlet). 
  • The inlet pipe is used to transport the water waste from the house and collect it in the septic tank. It is kept here long enough so that the solid and liquid waste is separated from each other.
  • The second pipe is the outlet pipe. It can also call the drain field. This pipe moves out the pre-processed wastewater from the septic tank and spreads it evenly in the soil and watercourses.
  • When waste water has been collected after a while it will begin to, separate into 3 layers. (as shown in the image above)
  • The top layer is oils and grease and floats above all the waste. This commonly referred to as "scum".
  • The middle layer contains wastewater along with waste particles.
  • The third and bottom layer consists of particles that are heavier than water and form a layer of sludge.
  • Bacteria inside the tank does it's best to break down the solid waste, which then allows liquids to separate and drain away easily.
  • What is left at the bottom of the tank is what needs to be periodically removed as part of general maintenance. This is one of the reasons why a septic tank is only a basic form of sewage treatment.

Advantages of septic tank :
1. Cost of construction is less.
2. Ease in construction.
3. Large cleaning period can be allowed.
4. It removes considerable amount of BOD.
5. The maintenance of the septic system is very economical.
6. You need a small space compared to other water treatment systems.
7. It is an excellent option for rural communities.
8. It reduces the deterioration of surface water bodies.


Drawbacks of septic tank :
1. Since septic systems require large drain fields, they are unsuitable for densely built areas.
2. It emits bad odor and generate carbon dioxide and methane gas which is harmful for environment.
3. Waste water treatment system is very costly.
4. Improperly maintained and failed septic systems contribute to surface water pollution near water bodies.
5. Excessive water entering the system may overload it and cause it to fail.
6. Roots from trees and shrubbery protruding above the tank or drain field may rupture them.
7. The effluents from the septic tank is highly toxic and BOD and need to proper disposal.
8. Foul smelling discharge due to anaerobic digestion.
9. Clogged drains by oil, grease, fats, and other materials that may be thrown into toilets, sinks, and showers causing obstruction.
10. There is a risk in rainy seasons that the septic system overflows bringing sewage to the surface

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