What is aerobic biochemical treatment? Characteristics of aerobic biological treatment

According to the different requirements of microbial growth for oxygen environment, biochemical treatment can be divided into two categories: aerobic biochemical treatment and anoxic biochemical treatment, and anoxic biochemical treatment can be divided into facultative oxygen biochemical treatment and anaerobic biochemical treatment. In the process of aerobic biochemical treatment, aerobic microorganisms must grow and multiply in the presence of a large amount of oxygen and reduce the organic matter in the wastewater; In the process of facultative oxygen biochemical treatment, facultative microorganisms only need a small amount of oxygen to grow and reproduce and degrade the organic matter in the wastewater, if there is too much oxygen in the water, the facultative oxygen microorganism does not grow well and thus affects its treatment efficiency of organic matter.

Aerobic treatment refers to the biochemical process in which organic matter is degraded and converted into humus-like substances with the participation of microorganisms under suitable conditions such as carbon-nitrogen ratio, moisture content and oxygen. Aerobic treatment technology is considered to be an effective method for organic solid waste treatment because it can achieve the treatment goals of solid waste reduction, harmlessness and resource utilization. After a series of biochemical reactions, the energy is released step by step, and finally stabilized with low-energy inorganic substances to meet the requirements of harmlessness, so that they can be returned to the natural environment or further processed.

The characteristics of aerobic treatment: the reaction speed is fast, the required reaction time is short, and in the reaction process, there is basically no odor, more hygienic, and it is more suitable for wastewater with BOD5 concentration below 600mg L. However, aerobic treatment must meet the requirements for water quality.

1. Dissolved oxygen: The dissolved oxygen in the wastewater should be between, and aerobic bacteria and facultative bacteria can carry out aerobic respiration at this time.

2. PH value: For aerobic treatment, the pH value should be between 6 and 9.

3. Temperature: The water temperature is between 20 and 40. Nutrients such as carbon, nitrogen, energy, growth factors (vitamins), inorganic salts (potassium, calcium, magnesium, iron, etc.), and water are necessary for the growth of microorganisms.

4. Toxic substances: most heavy metals, such as zinc, copper, lead, chromium, etc., contain toxicity, which is not conducive to the survival of microorganisms. However, if the concentration of toxic substances is gradually increased, it is possible to adapt them to the new environment to a certain extent and improve the treatment efficiency.

5. The concentration of organic matter in the influent water: the concentration of BOD5 in the influent water is generally 100 600mg L.

6. Biodegradability of wastewater: The biodegradability of wastewater is generally expressed by BOD5 COD value.

When BOD5 COD >, the effect of biological treatment was obvious. Bod5 COD <, it is not suitable to use biological treatment.

Aerobic biological treatment:

A treatment method in which aerobic microorganisms (including facultative microorganisms) are biologically metabolized in the presence of oxygen to degrade organic matter and make it stable and harmless. Microorganisms use the organic pollutants present in the water as substrates for aerobic metabolism, and after a series of biochemical reactions, the energy is released step by step, and finally stabilized with low-energy inorganic substances to meet the requirements of harmlessness, so as to return to the natural environment or further treatment. In addition, under the condition of sufficient oxygen supply, the nitrification of aerobic autotrophic bacteria oxidizes NH3-N(NH4+) to NO3-

In turn, it provides NO3- to anaerobic heterotrophic bacteria.

Anaerobic Biological Treatment:

Heterotrophic bacteria in the anoxic section hydrolyze suspended pollutants such as starch, fiber, carbohydrates and soluble organic matter in sewage into organic acids, decompose macromolecular organic matter into small molecule organic matter, and convert insoluble organic matter into soluble organic matter. In the anoxic section, heterotrophic bacteria ammoniate proteins, fats and other pollutants (N on the organic chain or amino groups in amino acids) to release ammonia (NH3, NH4+), and reflux to the anaerobic section through the aerobic stage, and under anoxic conditions, the denitrification of isoxic bacteria reduces NO3- to molecular nitrogen (N2) to complete the cycle of C, N, and O in the ecology.

In actual application, A and O are mostly mixed, and A is mostly first.

Biochemical treatment basis:

Microbe. The different requirements of the oxygen environment for growth can be divided into two categories: aerobic biochemical treatment and anoxic biochemical treatment, and anoxic biochemical treatment can be divided into facultative biochemical treatment and.

Anaerobic. Biochemical treatment. In the process of aerobic biochemical treatment, aerobic microorganisms must grow and multiply in the presence of a large amount of oxygen and be reduced.

Wastewater. organic matter; In the process of facultative oxygen biochemical treatment, facultative microorganisms only need a small amount of oxygen to grow and reproduce and degrade the organic matter in the wastewater, if there is too much oxygen in the water, the facultative oxygen microorganism does not grow well and thus affects its treatment efficiency of organic matter.

Facultative microorganisms can adapt to wastewater with high COD concentration, and the COD concentration of influent water can be increased to more than 2000mg L, and the COD removal rate is generally 50-80%; The aerobic microorganisms can only adapt to the wastewater with low COD concentration, the COD concentration of the influent water is generally controlled below 1000-1500mg L, the COD removal rate is generally 50-80%, and the time of facultative oxygen biochemical treatment and aerobic biochemical treatment is not too long, generally 12-24 hours. People take advantage of the differences and the same advantages between facultative biochemistry and aerobic biochemistry to combine facultative biochemical treatment and aerobic biochemical treatment, so that wastewater with higher COD concentration is treated with facultative biochemical treatment first, and then let it.

Oxygen tank. The treated effluent is used as the inlet water of the aerobic pond, so that the combined treatment can be reduced.

Biochemical pools. The volume not only saves environmental protection investment but also reduces daily operating costs.

The principle and function of anaerobic biochemical treatment and facultative biochemical treatment are the same. The difference between anaerobic biochemical treatment and facultative biochemical treatment is that no oxygen is required during the reproduction and growth of anaerobic microorganisms and their degradation of organic substances, and anaerobic microorganisms can adapt to wastewater with higher COD concentrations (4000-10000 mg L).

The disadvantage of anaerobic biochemical treatment is that the biochemical treatment time is very long, and the residence time of wastewater in the anaerobic biochemical tank generally takes more than 40 hours.

According to the different requirements of microbial growth for oxygen environment, sewage biochemical treatment can be divided into two categories: aerobic biochemical treatment and anoxic biochemical treatment, and anoxic biochemical treatment can be divided into facultative oxygen biochemical treatment and anaerobic biochemical treatment. The difference between aerobic biochemical treatment and facultative biochemical treatment: in the process of aerobic biochemical treatment, aerobic microorganisms must grow and multiply in the presence of a large amount of oxygen and reduce the organic matter in the wastewater; And in the process of biochemical treatment.

Facultative microorganisms can adapt to wastewater with high COD concentration, and the COD concentration of influent water can be increased to more than 2000mg L. Aerobic microorganisms can only adapt to wastewater with low COD concentration, and the COD concentration of influent water is generally controlled below 1000-1500mg L.