What is the purpose of the Septic tank vent?

Any empty tank is really a tank full of air. If you want water to go into a tank or pipe or drain then you have to allow the air to escape out of it. We allow the air to escape through a "vent pipe," connected to the tank. When refering to septic tanks, this pipe is called a "septic tank vent." Unless we use a zeocarbon filter on the "septic tank vent", the vile air coming out smells like a combination of rotten eggs and ammonia. Some septic tanks are upgraded to include aeration systems where electric or solar powered aerators bubble air into the liquid in the septic tank. Although these systems treat water faster and produce cleaner treated wastewater you still need a "septic tank vent," to let the air escape from the tank so water can go into it.