Hydrolysis acidification tank removal rate, the difference between pre acidification tank and hydrol

In general, the removal rate of hydrolysis acidification is directly related to the quality of wastewater. The removal rates of BOD and ammonia nitrogen are relatively high, but COD and TP are generally not high.

BOD can easily reach 30%, and better can reach 50%, or even more;

Ammonia nitrogen will increase after hydrolysis and acidification;

COD often falls below 30% or even below 10%;

TP usually cannot be lowered.

Seeing the relevant data, the removal rate of COD BOD ammonia nitrogen TP in the hydrolysis acidification tank is about 50%, and some related columns are also cited, I want to know what the removal efficiency of hydrolysis acidification in the actual project is...

It is recommended to be located behind the primary sedimentation tank, but the hydrolysis tank is usually not high, the removal rate of 20% is very good, and some wastewater will increase after hydrolysis, so the removal rate of hydrolysis is better set a little lower, otherwise it will not be very troublesome You need to emphasize the hydrolysis efficiency of the hydrolysis tank.

In general, the removal rate of hydrolysis acidification is directly related to the quality of wastewater. The removal rate of biochemical BOD and ammonia nitrogen is relatively high. BOD can easily reach 30%, and even better can reach 70-80% because of the decomposition of organic matter, ammonia nitrogen will increase after hydrolysis and acidification;

COD often falls below 30% or even below 10%;

TP usually cannot be lowered.

Hydrolytic acidification. The actual removal rate of COD in the pool is generally 30-40% is very high, but there is often such a removal rate that has anaerobic methane production.

In the case of the case, the low 10-20% or even almost none are removed.

However, the general purpose of our hydrolysis acidification is to break the chain macromolecules and improve the biodegradability of wastewater, and the removal rate of ten or twenty percent is not our main purpose, so for the hydrolysis acidification tank, we do not have to worry about how much COD is removed, but whether there is an effect, BOD? Do I need hydrolysis and acidification removal? If it's to remove BOD, then what do you have to spend money on hydrolysis and acidification?

Ammonia nitrogen. On the contrary, if the organic nitrogen content of the influent water is high, then it will be ammoniated, resulting in an increase in ammonia nitrogen in the effluent, which is also normal.

There is no removal rate of TP, and the general biological P removal relies on polyphosphate bacteria to absorb P excessively, and discharge it through mud discharge, so as to achieve the purpose of removing P.

Hydrolysis acidification is the first half of anaerobic, the pretreatment stage of anaerobic. In the anaerobic reaction tank, it is also necessary to undergo hydrolysis and acidification to produce acid and methane. As for the purpose of separating the hydrolysis acidification, it is generally for the purpose of using its broken chain macromolecular organic matter to improve the biodegradability of the wastewater, and in the actual hydrolysis acidification tank, it is actually difficult to completely control the hydrolysis acidification stage, and there is often a certain degree of methanogenic pre-acidification degree, which refers to the percentage of the total biotransformable COD of the macromolecular organic matter converted into volatile acid reached by the wastewater in the regulated pre-acidification tank.

Chinese name pre-acidification calculation formula vfa(meq l)*69 scod*100% main wastewater suitable pre-acidification degree about 30% 35%-pre-acidification degree calculation formula: pre-acidification degree = vfa(meq l)*69 scod*100%scod - influent cod(mg l); - The appropriate degree of pre-acidification is about 30% 35%, and the maximum can not exceed 50% - the pre-acidification is too high (VFA is high), the toxicity increases, which affects the growth and gas production of sludge granulation, causes the pH of the influent water to decrease, and inhibits the activity of methanogens, and the VFA is too high and even exceeds the treatment capacity of methanogens, resulting in the acidification phenomenon of the reactor - the pre-acidification is too low, which increases the load of the subsequent anaerobic units, resulting in the increase of COD and VFA in the effluent, and increases the possibility of acidification of the reactor.

There is no SS removal index in the hydrolysis acidification tank, and the effluent SS with stirring is 500-1000mg L, and the SS without stirring is generally less than 100mg L.

Technical introduction: Hydrolysis refers to the biochemical reaction carried out outside the cell before organic matter enters the microleakage reflux biological cells. Microorganisms complete biocatalytic reactions by releasing extracellular free enzymes or immobilized enzymes attached to the outer wall of the cell.

Acidification is a typical fermentation process, and the metabolites of microorganisms are mainly various organic acids.

Mechanistically speaking, hydrolysis and acidification are two stages of the anaerobic digestion process, but the treatment purpose of hydrolysis acidification is different in different processes. The purpose of hydrolysis in the hydrolysis acidification-aerobic biological treatment process is mainly to convert the insoluble organic matter in the original wastewater into Xiaochai dissolved organic matter, especially in industrial wastewater, mainly to convert the organic matter that is difficult to biodegrade into easily biodegradable organic matter, so as to improve the biodegradability of the wastewater and facilitate the subsequent aerobic treatment. Considering the energy consumption of the subsequent oxygen treatment, hydrolysis is mainly used for the pretreatment of low-concentration refractory wastewater.

The purpose of hydrolysis acidification in the mixed anaerobic digestion process is to provide a substrate for methane fermentation in the mixed anaerobic digestion process. The acid-producing phase in the two-phase anaerobic digestion process separates the acid-producing and methanogenic phases in the mixed anaerobic digestion to create their own optimal environment. <>

1.The function of the hydrolysis acidification tank: to improve the biodegradability of wastewater, it can convert macromolecular organic matter into small molecules.

2.To remove COD from wastewater, since it is a heterotrophic microbial bacteria, it is necessary to draw nutrients from the environment, so some organic matter must be degraded and synthesized into its own cells.

3.Operation process of hydrolysis acidification tank: The anaerobic fermentation process can be divided into four stages: hydrolysis stage, acidification stage, acid degradation stage and methanation stage.

4.In the hydrolysis acidification tank, the reaction process is controlled in two stages: hydrolysis and acidification.

5.In the hydrolysis stage, the composite filler can degrade solid organic matter into soluble substances and macromolecular organic matter into small molecule substances.

6.During the acid-producing phase, carbohydrates and other organic compounds are degraded into organic acids, mainly acetic acid, butyric acid, and propionic acid.

7.Hydrolysis and acidification reactions proceed relatively quickly, and it is often difficult to separate them.

8.The main microorganisms at this stage are hydrolytic acidifying bacteria.

The role of the hydrolysis acidification tank is to improve the biodegradability of wastewater, and the second is to remove COD in wastewater.

The hydrolysis acidification tank can convert macromolecular organic matter into small molecules as early as possible, and after the sewage enters the hydrolysis acidification tank, the ammonia nitrogen in the effluent of the hydrolysis tank is higher than that of the inlet water. According to the actual operation of the sewage treatment plant, the hydraulic retention time of the hydrolysis acidification tank is small, the sludge age is about 6d, the average ammonia nitrogen removal rate of the hydrolysis acidification tank reaches out, the Kjeldahl nitrogen removal rate and the total nitrogen removal rate are.

Since it is a heterotrophic microbial bacteria, it must draw nutrients from the environment, so some organic matter must be degraded to synthesize its own cells.

Hydrolysis acidification tank structure

The hydrolysis acidification tank is divided into sludge bed area and clear water layer area, and the sewage to be treated and the remaining microbial film shed during the backwashing of the filter tank enter the tank from the bottom of the reactor, and are quickly and evenly mixed with the sludge bed through the water distributor with the retracer. The sludge bed is thicker, similar to a filter layer, which quickly retains and adsorbs particulate matter and colloidal matter in the influent water.

Due to the high concentration of facultative microorganisms in the sludge bed, under the condition of anoxic conditions in the tank, the trapped organic matter is hydrolyzed into soluble substances under the action of a large number of hydrolysis-acid-producing bacteria, and macromolecules and substances that are difficult to biodegrade are converted into substances that are easy to biodegrade.

The above content reference: Encyclopedia - Hydrolysis and acidification.