What is biological treatment?
Biological treatment is a treatment process that cleans the organic pollutants contained in wastewater by breaking down and metabolizing them with the help of natural organisms. This process takes place with the help of microorganisms, bacteria, fungi and other microbes and helps clean the wastewater. The biological treatment process is generally carried out in closed systems such as wastewater oxidation ponds or bioreactors and basically includes the following steps.
1. **Pre-Treatment:** Before wastewater enters the biological treatment plant, large solids, oils and other major contaminants need to be removed. This step is usually accomplished through physical processes, such as sedimentation tanks and filtration processes.
2. **Bio-Filtration or Biological Reactor:** Wastewater is pumped into large tanks or ponds called biological reactors. These reactors contain microorganisms that can break down and metabolize organic pollutants in the water. These microorganisms are usually a mixture of bacteria and activated sludge.
3. **Aeration and Mixing:** Microorganisms in biological reactors need oxygen to function properly. Therefore, the wastewater is oxygenated with aeration systems or mixers. This allows microorganisms to effectively break down organic pollutants.
4. **Sedimentation:** Water from biological reactors, where microorganisms and organic pollutants are broken down and metabolized, is then sent to sedimentation tanks. In these tanks, dissolved microorganisms and other solid residues in the water are allowed to settle.
5. **Disinfection (Optional):** Water that goes through the biological treatment process can be subjected to final disinfection. This process ensures the killing of pathogenic microorganisms and disease-causing bacteria in the water. Disinfection is usually achieved by methods such as chlorination, ultraviolet irradiation or ozonation.
Biological treatment is an effective method of purifying wastewater from organic pollutants and is commonly used in the treatment of municipal wastewater and industrial wastewater treatment. This method allows wastewater to return to the natural cycle without harming the environment and contributes to the protection of water resources.
6. **Nitrification and Denitrification:**
Some biological treatment systems include processes called nitrification and denitrification to remove nitrogen compounds found in wastewater. In these processes, nitrogen compounds are converted from the form of nitrite and nitrate into molecular nitrogen or gaseous nitrogen by certain microorganisms. This helps reduce the nitrogen load of wastewater and maintains the balance of the aquatic ecosystem.
7. **Phosphorus Removal:**
Some biological treatment systems include special processes to remove phosphorus compounds found in wastewater. Although phosphorus is an important nutrient for the aquatic ecosystem, excessive amounts of phosphorus waste can cause environmental problems. Therefore, biological removal or chemical removal of phosphorus is an important step during the purification process.
8. **Tertier Purification:**
In some cases, wastewater may need additional cleaning after biological treatment. This may require more complex purification technologies or chemical treatments. Tertiary treatment processes further improve the quality of wastewater, making it comply with environmental standards.
Biological treatment is an effective method that cleans wastewater through natural processes. This process is based on the use of natural microorganisms and represents an environmentally friendly approach. However, biological treatment systems must be carefully designed, operated and maintained to operate effectively. Additionally, different biological treatment systems should be selected based on factors such as the composition and quantity of wastewater.
