Forms of microbiological treatment:

    1. Treatment by aerobic biological method :

    A process using aerobic microorganisms to decompose the appropriate organic matter in wastewater in the condition of continuous oxygen supply.

The decomposition of organic matter by aerobic VSV can be described by the following reaction: (CHO) n NS + O 2 → CO 2 + H 2 O + NH 4+ + H 2 S + VSV + ∆H cells

Wastewater treatment processes by aerobic biological methods can occur in natural or artificial conditions. Depending on the different types of VSV, the artificial aerobic biological process is divided into:

• Aerobic biological treatment with suspended microorganisms

• Aerobic biological treatment with sticky microorganisms

    2. Treatment by anaerobic biological methods:

    L à measures decomposition of organic matter in anaerobic conditions. In the absence of oxygen, organic matter can be decomposed by microorganisms and the end product is CH4, CO2. The conversion of organic matter by anaerobic bacteria takes place mainly on the principle of fermentation through the following steps:

    Step 1: hydrolyze complex organic substances and fats into simpler organic substances such as monosaccharides, amino acids or other salts. This is the source of nutrition and energy for bacteria to function.

    Step 2: Groups of anaerobic bacteria carry out the acid fermentation process, converting simple organic substances into common organic acids such as acetic acid, glycerol, acetate, etc.

    Step 3: Groups of anaerobic bacteria force alkaline fermentation (mainly methane fermenters such as methanossarcian and methonaothrix) to convert acetic acid and hydrogen into CH4 and CO2.

    3. Treatment of waste water by anaerobic biological methods: 

    – Gas-deficient biodegradation, also called fermentation, is often used to treat nitrogen in wastewater with nitrification and denitrification processes. The principle of treatment of anoxic gas of nitrogen and phosphorus compounds is described as follows: 

    – Nitrate reaction process is described by the equation:

    NH3 -> NO3 -> NO2 -> NO -> N2O -> N2 (gas)

    – The phosphorite reaction process is described by the equation:

    PO4-3 Microogarnism (PO4-3) salt => slugde

    Typically, the lack of gas process will be equipped with a number of devices, such as:

• Water stirring pump: In order to create stability for anoxic environment, so that the lack of microorganisms can grow and develop well.

• Microbiological sludge return system

• The support system provides nutrition and substrate for anoxic microorganisms.

    4. Treatment by a combination of aerobic, anoxic and anaerobic process:

    Is a continuous biological treatment process, combining 3 microflora systems: anaerobic, anoxic, aerobic to treat waste water . Under the effect of decomposing pollutants of microorganisms, wastewater will be treated before being discharged into the environment. The combination of all three processes will minimize the disadvantages of each process, and the advantages of this process will complement the other process, helping to treat wastewater thoroughly. , minimizing the cost of wastewater treatment for businesses.