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Today we continue with the second part of the processes that are carried out in a wastewater treatment plant to improve water quality.
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Continuing with the processes we have...
This structure provides the necessary conditions for bacteria and/or microorganisms to live. They are responsible for digesting the contaminated organic matter that is present in the wastewater.
It is called an aeration tank because it is the only process to which oxygen is injected into the wastewater and why is it supplied with oxygen? Because bacteria begin to grow in contaminated water and therefore the biochemical demand for oxygen (BOD5) also increases, that is, as the number of bacteria grows, the amount of oxygen dissolved in the water decreases and as a consequence of this the bacteria begin to die and it is not what we want.
In the previous process, all the sludge generated is again agitated and it is in this tank where the conditions are given for the particles in suspension to settle again.
From this process, the water is much cleaner than when it enters the WWTP and can already be discharged into rivers and seas, it is worth mentioning that in some treatment plants chlorine compounds are added to bases to eliminate more contaminants that are present in the water to this is called chlorination.
A part of the sludge that has been generated is returned to the aeration tank, in order to maintain an adequate quantity of it in the system and another part goes on to the next process.
In this part all the sludge that is composed of organic matter and bacteria that are toxic to the environment is treated.
In these tanks, called biodigesters, the sludge spends approximately 20 days at a temperature of 35°C and thanks to this, an anaerobic process is produced (absence of oxygen) where a gas containing methane is generated, called biogas, which is usually used in the plants themselves to produce energy.
The other part of the sludge is used in agriculture as fertilizer for plants and/or to improve soil fertility.
The previous post.
Source of information
Source of information
Libro. Design elements for aqueduct and sewerage. Ricardo Alfredo López Cualla.
