CN103508564A - Embedded immobilized microorganism deep denitrification reactor and method - Google Patents

Abstract

The invention relates to a deep denitrification reactor and method for embedding immobilized microorganisms, which belong to the field of sewage treatment. The feature of the device is that the cube immobilized particles are put into the reactor, the reactor is fed with water from the bottom, and a stirring device is installed inside to fully mix the immobilized particles with the secondary effluent, and a grid is set on the top to prevent the embedded particles from leaking out with the water. Keep the number of immobilized particles in the reactor at a fixed value; the filling rate of cubic immobilized particles is 20%-30%, and the dispensing box for adding carbon source is connected to the reactor with a dosing pump, and the water inlet tank is connected to the reaction through an inlet pump device. When the immobilized embedded particles in the reactor are filled with 20%, and HRT=20min, the TN of the secondary effluent can be reduced to 5mg/L, and the denitrification rate is above 85%. Under the same substrate conversion rate, the required volume of the device is smaller than that of the denitrification biological filter, and the denitrification efficiency is higher than that of the denitrification biological filter, and it does not need backwashing or additional elevation, and is suitable for sewage treatment plants. Set it at the end of the treatment process for upgrading.

Description

A deep denitrification reactor device and method for embedded immobilized microorganisms

technical field

The invention relates to a deep denitrification reactor for embedded and immobilized microorganisms, which belongs to the field of sewage treatment.

Background technique

With the gradual enhancement of environmental protection awareness, in order to improve people's living environment, the country continues to put forward higher requirements for sewage discharge indicators. Many domestic sewage treatment plants are faced with how to use limited space and limited natural purification capacity. The most suitable method and process to realize the difficult problem of advanced treatment of sewage. At present, the technology adopted at home and abroad has played a certain role in the advanced treatment of wastewater, but there are still many problems. For example, the traditional biological denitrification technology usually uses microbial cultures to directly treat nitrogen-containing wastewater. After nitrogen treatment, subsequent processing steps such as precipitation, coagulation, and filtration are required. Moreover, because nitrifying bacteria are inorganic chemical energy autotrophic bacteria, their proliferation rate is slow, their generation cycle is long, they are sensitive to changes in environmental factors, they are easily eliminated by the treatment system, and it is difficult to maintain a high biological concentration, so the total hydraulic retention time of the system Longer, increased infrastructure investment and operating costs. Therefore, it is imperative to develop and use new processing technologies.

Immobilized microorganism technology is an emerging technology in the field of modern bioengineering. It is an inevitable development stage of wastewater biological treatment from biological natural purification, artificial cultivation of microbial flocs to artificial enhancement of high-efficiency and high-concentration microbial flocs. It localizes free cells or enzymes in a limited area to keep them active and reusable. In the 1970s, immobilization technology was applied to the water treatment industry. Sewage treatment plants generally adopt biological treatment technology to treat sewage, and strengthening the effect of biological treatment process is one of the main directions of sewage treatment research. The immobilization technology maintains the advantages of high efficiency, strong stability, and ability to purify and maintain high-efficiency bacteria, and has the advantages of fast reaction start, simple solid-liquid separation, strong poison resistance, and miniaturized sewage equipment. Embedding immobilization is currently the most studied immobilization technology, but also one of the most promising methods.

Compared with other denitrification processes, immobilized microorganism technology has the following advantages: (a) It can maintain a high concentration of biomass in the biological treatment device, improve the treatment capacity, start the reaction quickly, and reduce the volume of the treatment device; (b) sludge The output is small, and the remaining sludge output of immobilized cells is only 1/5 to 1/4 of that of ordinary activated sludge method; (c) can selectively immobilize dominant and high-efficiency bacteria to improve degradation efficiency; (d) has strong The ability to resist the toxic impact of toxic pollutants; (e) good stability to changes in water quality conditions such as pH; (f) good solid-liquid separation effect, no special solid-liquid separation device is needed; (g) stable operation, It is resistant to load impact and will not cause operational problems such as sludge bulking; (h) it provides a good retention method for slow-growing nitrifying bacteria, and the microorganisms are not easy to lose; (i) the mechanical strength of the cells is increased after immobilization.

Contents of the invention

The purpose of the present invention is to solve the problem of high TN concentration in the secondary effluent of sewage treatment plants; at the same time, in the process of water plant transformation, the problem of land shortage and high infrastructure costs, a deep denitrification device and method for immobilized embedded particles are proposed .

A deep denitrification reactor for embedded and immobilized microorganisms, characterized in that: cubic immobilized particles with a volume of 3×3×3 mm are put into the reactor, the reactor is fed with water from the bottom, and a stirring device is installed inside to make the immobilized particles The particles are fully mixed with the secondary effluent, and a grid is set on the top to prevent the embedded particles from leaking with the effluent, and keep the number of immobilized particles in the reactor at a fixed value; the filling rate of the immobilized particles in the cube is 20%-30%, and the dispensing box passes The reactor is connected with the dosing pump, and the water inlet tank is connected with the reactor through the water inlet pump;

Preparation method of the immobilized particles used:

1) Dissolve the prepolymer polyethylene glycol and the accelerator tetramethylethylenediamine in water to obtain a mixed solution A;

2) Mix the mixed liquid A with the denitrification sludge that has been enriched and cultivated;

3) Add the initiator potassium persulfate to start the polymerization;

4) After the polymerization is completed, the formed gel-like solid is cut into cubes of 3×3×3mm;

100 ml of the obtained cubes contained 10 g of polyethylene glycol, 0.5 g of accelerator, 0.25 g of initiator and 0.4 g of enriched denitrification sludge.

Applying the method for embedding immobilized microorganism deep denitrification reactor, characterized in that

The influent is the secondary effluent of the sewage plant, the TN load of the influent is 1.8kg/(m ³ ·d), the hydraulic retention time of the reactor is 20min; the organic matter is supplemented by adding an external carbon source, and the COD value in the water is controlled at 130mg/L.

This device has the following characteristics:

1) Fast start up. It takes time for immobilized particles to adapt to the treatment of sewage. Under the conditions of water temperature of about 25°C, pH of about 7.2, and HRT of 70min, fill 30% of embedded particles (v/v) in the reactor for 7 to 9 days Able to achieve successful domestication, the embedded particles not only have a good treatment effect on nitrate nitrogen and TN in sewage, but also have obvious changes in sensory perception.

2) High denitrification efficiency. Under the conditions of water temperature of about 25°C, pH of about 7.2, filling of immobilized particles at 20% (v/v), HRT of 20min, and influent TN load of 1.8kg/(m ³ ·d), the immobilized package Buried particles can reduce the nitrate nitrogen in the influent water from about 25mg/L to less than 1mg/L, and the average removal rate of TN reaches 86.6%. When the influent TN load is 2.5kg/(m ³ ·d), the average removal rate of 65% TN can still be achieved. Under the same conditions, the denitrification biological filter reduces TN to below 5mg/L, and the acceptable TN load is 1.2kg/(m ³ ·d), which is lower than the 1.8kg/(m ³ ·d)TN determined in this experiment load.

3) Easy to control. The reaction of immobilized particles using sodium acetate as an external carbon source can reduce nitrate nitrogen to 0.84mg/L in 15 minutes; in the whole denitrification process, the pH first increases and then does not change, and an inflection point appears in 15 minutes; ORP continues to decrease ;The inflection point of pH appears, and in stable operation, it is found that the pH of the effluent is generally 0.6-0.8 higher than that of the influent, so the online pH monitoring equipment can be used as the control parameter for the denitrification effect of the actual reactor.

4) Small footprint. In this process device, the immobilized particles are artificially strengthened with high-efficiency and high-concentration microbial flocs, and the higher the TN load is treated, the more energy-saving, consumption-reducing and cost-reducing purposes can be achieved.

Description of drawings

Fig. 1 is a schematic diagram of the present invention

In the figure, 1—water inlet tank, 2—medicine dispensing tank, 3—water inlet peristaltic pump, 4—dosage delivery peristaltic pump, 5—immobilized embedded particles, 6—grid, 7—agitator, 8—water outlet tank.

Figure 2 Abundant microorganisms observed on the surface of embedded particles after acclimation by SEM electron microscope.

Detailed ways

The immobilized embedding reaction device is made of plexiglass. The height of the reactor is 0.7m, of which the bottom 0.2m is an inverted triangular cone, the inner diameter of the reactor is 200mm, and the effective volume is 17L. The reaction pool is filled with cubes of 3×3×3mm, and the filling ratio is 20% (v/v). The filler in the reactor, the color of the immobilized embedded particles is black; it is a regular cube with clear edges and corners; the density (1.04) Close to water; the carrier is polyethylene glycol; the molecular chain constituting the polymer is a three-dimensional network structure, and its mesh size is nanometer (7nm), in which bacteria proliferate at high density and fully volatilize their activity. as shown in picture 2.

The cultivation method of enriched denitrification sludge is as follows:

The sludge is taken from the return sludge of the secondary settling tank of Gaobeidian Wastewater Treatment Plant, and put into the SBR reactor for cultivation, which runs 2 cycles a day, stirring for 3 hours in each cycle, and standing for the rest of the time. Using sodium acetate as carbon source, maintain COD=300mg/L, and the sludge obtained by running for 3 weeks under the condition of carbon-nitrogen ratio 4:1.

Enrichment culture is a routine technique and is not limited to the denitrification sludge cultured with the specific parameters mentioned above.

Referring to shown in Figure 1 of the description, the specific implementation process of the present invention is:

The sodium acetate carbon source is added from the dispensing box 2, and the secondary effluent and carbon source are pumped into the reactor by the dosing pump 3 and the water inlet pump 4 respectively. The reactor is filled with 20% (v/v) immobilized particles 5, and after stirring The reactor 7 is evenly mixed, the top of the reactor is discharged, and the grid 6 is set to prevent the leakage of the immobilized particles 5. The outlet water first enters the outlet tank 8 and then is discharged. The outlet tank 8 is to prevent accidents from happening. The fixed particles leak from the reactor and settle at 8, which is the second protection measure to prevent the leakage of the immobilized particles. In this experiment, the HRT of the reactor was controlled by controlling the flow rate of the influent pump. Its characteristics are that the acclimatization period is completed within one week, the effluent is stable, and the startup is successful; the purpose of deep denitrification can be achieved under a relatively high TN influent load.

The device has the advantages of fast domestication, high denitrification efficiency, large biomass, low sludge output and certain tolerance to water quality changes.

Implementation example: Taking the secondary effluent of a large urban sewage treatment plant as the research object, the secondary effluent, reactor influent and effluent were sampled and analyzed. The test results show that the system can obtain stable process performance after continuous operation:

(1) The filling rate is an important factor affecting the denitrification effect of the reactor. During the test, the filling rate of the immobilized embedded particles was changed, and when it was gradually reduced from 30% to 20%, the TN removal rate could reach more than 80%; the filling rate was low At 20%, the removal rate of TN decreases with the decrease of filling rate. The experiment determined that the optimum filling rate of embedding immobilized particles was 20%.

(2) After domestication is successful, at a water temperature of about 25°C and a pH of about 7.2, fill with immobilized particles at 20% (v/v), HRT for 20min, add sodium acetate carbon source, and control the COD value in the water to 130mg/L Left and right, to ensure that the organic matter that microorganisms can use is sufficient. The average concentration of nitrate nitrogen in the influent is 25.5mg/L, the concentration of nitrate nitrogen in the effluent is lower than 1mg/L, the average concentration of TN influent is about 27mg/L, the effluent can be controlled within 5mg/L, and the average removal rate of TN reaches 86.6%.

Claims (2)

1. A deep denitrification reactor for embedded and immobilized microorganisms, characterized in that: cube immobilized particles with a volume of 3 × 3 × 3mm are put into the reactor, and the reactor is fed with water from the bottom, and a stirring device is arranged inside, so that The immobilized particles are fully mixed with the secondary effluent, and a grid is set on the top to prevent the embedded particles from leaking with the effluent, and keep the number of immobilized particles in the reactor at a fixed value; the filling rate of the immobilized particles in the cube is 20%-30%. The dispensing box for external carbon source is connected to the reactor through the dosing pump, and the water inlet tank is connected to the reactor through the water inlet pump; Preparation method of the immobilized particles used: 1) Dissolve the prepolymer polyethylene glycol and the accelerator tetramethylethylenediamine in water to obtain a mixed solution A; 2) Mix the mixed liquid A with the denitrification sludge that has been enriched and cultivated; 3) Add the initiator potassium persulfate to start the polymerization; 4) After the polymerization is completed, the formed gel-like solid is cut into cubes of 3×3×3mm; 100 ml of the obtained cubes contained 10 g of polyethylene glycol, 0.5 g of accelerator, 0.25 g of initiator and 0.4 g of enriched denitrification sludge. 2. the method for applying a kind of embedded immobilized microorganism deep denitrification reactor according to claim 1, is characterized in that: The influent is the secondary effluent of the sewage plant, the TN load of the influent is 1.8kg/(m ³ ·d), the hydraulic retention time of the reactor is 20min; the organic matter is supplemented by adding an external carbon source, and the COD value in the water is controlled at 130mg/L.

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