CN105152479B - Modified granular activated carbon coupling membrane bioreactor and heavy metal-containing wastewater treatment method - Google Patents

Abstract

The invention discloses a modified granular activated carbon coupling membrane bioreactor and a heavy metal-containing wastewater treatment method, the modified granular activated carbon coupling membrane bioreactor comprises an aeration activated sludge reaction tank and a membrane component, the aeration activated sludge reaction tank is provided with a water inlet and a water outlet, the bottom is provided with a sludge discharge pipe, and the bottom of the aeration pipe is provided with an aeration pipe connected with an aeration pump, and the modified granular activated carbon component comprises a filter screen supported by a bearing and hanging framework and modified granular activated carbon filled in the filter screen, the modified granular active carbon component is arranged in the aeration activated sludge reaction tank, the membrane component is arranged outside the aeration activated sludge reaction tank, the water outlet is connected with the inlet of the membrane module through a water pump, and the membrane module is also connected with the aeration activated sludge reaction tank through a sludge return pipe. Compared with the conventional membrane bioreactor, the invention can improve the treatment effect on the wastewater, has strong adaptability and simple and convenient operation.

Description

Modified granular activated carbon coupling membrane bioreactor and heavy metal-containing wastewater treatment method

technical field

The invention relates to a heavy metal-containing wastewater treatment device and method, in particular to a modified granular activated carbon coupled membrane bioreactor and a heavy metal-containing wastewater treatment method.

Background technique

In recent decades, with the rapid development of human social economy and modern industry and the impact of human social activities, heavy metal pollution has become more and more serious, among which heavy metal pollution in water bodies is the most serious. Heavy metal pollution itself is difficult to control. Once heavy metal pollutants enter the surface water body and underground water system, such heavy metals and their compounds are highly stable and refractory, which will pose a great threat to the environment and human life.

For example, cadmium is a typical heavy metal element that exists widely in the environment. Once metal cadmium enters the human body and causes metal poisoning, the main manifestations are osteoporosis and softening, liver and kidney failure, and pain all day long. Due to the toxicity of cadmium to the human body, it has attracted great attention from all over the country and even the world. The National Environmental Protection Law clearly stipulates that cadmium is a class of pollutants, and a single physical method (such as dilution method) cannot be used instead of targeted treatment. The concentration of cadmium in the cadmium-containing wastewater discharged from the factory shall not be higher than the national standard before it is treated. The cadmium-containing wastewater must be treated and checked to be below the national standard before it can be directly discharged.

At present, the practical methods for the treatment of heavy metal-containing wastewater include hydroxide precipitation, sulfide precipitation, ion exchange, adsorption, redox, iron oxidation, membrane separation, and biochemical precipitation. At present, although the technology of removing heavy metals from water has made great progress, there are still big problems in theory and application. On the one hand, the above-mentioned various methods are mainly based on physical and chemical precipitation, which produces a large amount of metal sludge, and the secondary discharge will have a great impact on the environment; on the other hand, although the technology based on membrane separation has high development and application However, due to serious membrane fouling and polarization problems, the widespread use of separation technology is affected.

Therefore, how to improve the treatment effect of wastewater and incorporate the removal of heavy metals into the wastewater treatment system to improve the overall removal rate is a technical bottleneck that needs to be solved in the treatment of wastewater containing heavy metals, and it is very important to solve the current ubiquitous problem of heavy metal pollution in water Significance and development and application prospects.

Biological treatment technology is a widely used wastewater treatment technology at present, but it has certain limitations in the treatment of some metal-containing wastewater. With the development of treatment technology and the improvement of water quality requirements, membrane bioreactor, which combines membrane separation and biological treatment technology, has a very high effect and development and application trend on wastewater treatment. Membrane bioreactor (MBR) is a new water treatment process combined with membrane separation and microbial treatment technology. It has many advantages incomparable to conventional water treatment processes such as high treatment efficiency, good effluent quality, short process flow, and small footprint. , is considered to be the most promising water treatment technology in the 21st century. At present, membrane bioreactor technology has been widely studied and used in water treatment. Membrane bioreactor can improve the effect of wastewater treatment, and the quality of effluent water is better. However, due to the toxicity of heavy metals to most organisms, there is no future Research and application reports on the application of membrane bioreactors to the removal of heavy metal-containing wastewater. As an adsorbent, activated carbon is widely used in water treatment, especially in the application of physical adsorption technology in the removal of heavy metals in water. However, due to the limitation of adsorption capacity, adsorption is generally only used for advanced treatment, and it is difficult to use activated carbon and other adsorption technologies in wastewater treatment. Therefore, it is of great significance to research and develop a wastewater treatment technology and device suitable for the application of membrane bioreactors to effectively remove heavy metal pollution.

Contents of the invention

In view of the above problems, the present invention researches and designs a modified granular activated carbon coupling membrane bioreactor and a wastewater treatment method. The technical means adopted in the present invention are as follows:

A modified granular activated carbon coupling membrane bioreactor, including an aerated activated sludge reaction tank and a membrane module, the aerated activated sludge reaction tank is provided with a water inlet and a water outlet, the bottom is provided with a sludge discharge pipe, and the bottom is An aeration pipe connected to the aeration pump is provided, and a modified granular activated carbon assembly is provided. The modified granular activated carbon assembly includes a filter screen supported by a suspension frame and a modified granular activated carbon filled inside the filter screen. The modified granular activated carbon module is arranged in the aerated activated sludge reaction tank, the membrane module is arranged outside the aerated activated sludge reaction tank, the water outlet is connected to the inlet of the membrane module through a water pump, and the membrane module is also passed through The sludge return pipe is connected with the aerated activated sludge reaction tank.

Further, the modified granular activated carbon assembly is a plate structure, the outside is a hanging frame, the hanging frame is made of stainless steel, and the inner hanging is a filter screen made of nylon mesh. The modified granular activated carbon assembly The amount of modified granular activated carbon is 1-4g/L, and the modified granular activated carbon components are installed in the aerated activated sludge reaction tank at an interval of less than 10cm.

Further, the thickness of the modified granular activated carbon assembly is 1-3 cm.

Further, the specific surface area of the modified granular activated carbon is between 1363.8-1548.3m ² /g.

Further, the water inlet is arranged at the lower part of one side of the aerated activated sludge reaction tank, and the water outlet is arranged at the other side of the aerated activated sludge reaction tank.

A modified granular activated carbon-coupled membrane bioreactor treatment method for heavy metal-containing wastewater, using the modified granular activated carbon-coupled membrane bioreactor of the present invention, comprising the following steps:

① Discharge the wastewater from the water inlet into the aerated activated sludge reaction tank, and turn on the aeration pump;

② After the sewage reacts in the aerated activated sludge reaction tank, it enters the membrane module through the outlet;

③The sewage discharged from the aerated activated sludge reaction tank is discharged after being treated by the membrane module, and the sludge in the membrane module is returned to the aerated activated sludge reaction tank through the return pipe.

Further, in step ②, the concentration of microorganisms in the aerated activated sludge reaction tank is maintained at 2500mg/L-3500mg/L, the pH value is maintained between 6.5-8.5, and the retention of sewage in the aerated activated sludge reaction tank The time is 3.5-4.5 hours.

Compared with the prior art, a modified granular activated carbon coupling membrane bioreactor and wastewater treatment method of the present invention have the following beneficial effects:

(1) Compared with conventional membrane bioreactors, the present invention can improve the treatment effect on heavy metal-containing wastewater, has strong adaptability, and is simple and convenient to operate.

(2) The present invention effectively couples multiple functions of modified granular activated carbon adsorption, bioabsorption and metabolism, biosorption, etc., to achieve the purpose of effectively removing heavy metals in water, has strong adaptability, is suitable for the treatment of heavy metal-containing wastewater, and has a good effect of removing heavy metals ;

(3) The present invention promotes the formation and growth of bacteria micelles by means of the lotus root effect of modified granular activated carbon, increases the contact area, promotes the cohesion of bacteria micelles, improves the sedimentation performance of sludge, and reduces the discharge of sludge;

(4) The present invention reduces the sludge concentration entering the membrane module by means of the aggregation of granular activated carbon, and reduces the pollution of the membrane;

(5) The present invention adopts modified granular activated carbon to be coupled in membrane bioreactor, has improved the adaptability and treatment effect of waste water;

(6) The present invention can be operated intermittently or continuously, and is not only suitable for batch treatment with small water volume, but also suitable for continuous treatment, and has strong operability;

(7) Modified granular activated carbon is constructed into a frame-suspended filter screen sheet in the present invention, which is easy to replace and regenerate;

(8) The invention has advanced technology, stable operation, simple operation, easy management and operation of equipment, and strong practicability and economy.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

In the figure: 1. Aerated activated sludge reaction tank; 2. Water inlet; 3. Drainage outlet; 4. Water outlet; 5. Aeration pipe; 6. Aeration pump; 7. Membrane module; 8. Modified particles Activated carbon component; 9. Water pump; 10. Sludge discharge pipe; 11. Sludge return pipe; 12. Activated sludge; 13. Suspension frame; 14. Filter screen.

detailed description

As shown in Figure 1, a modified granular activated carbon coupling membrane bioreactor includes an aerated activated sludge reaction tank 1 and a membrane module 7, and the aerated activated sludge reaction tank 1 is provided with a water inlet 2 and a drainage Port 3, the bottom is provided with a mud discharge pipe 10, and the bottom is provided with an aeration pipe 5 connected to the aeration pump 6, and also includes a modified granular activated carbon assembly 8, which includes a suspension frame 13 The suspended filter screen 14 and the modified granular activated carbon filled inside the filter screen 14, the modified granular activated carbon assembly 8 is arranged in the aerated activated sludge reaction tank 1, and under certain hydraulic and airflow impacts, the filter screen 14 and the modified granular activated carbon inside can be suspended within a certain range in the aerated activated sludge reaction tank 1, and the modified granular activated carbon can be replaced and regenerated at any time. The membrane module 7 is arranged outside the aerated activated sludge reaction tank 1, the outlet 3 is connected to the inlet of the membrane module 7 through the water pump 9, and the membrane module 7 is also connected to the aerated activated sludge through the sludge return pipe 11. Mud reaction tank 1 is connected.

The modified granular activated carbon assembly 8 is a plate-shaped structure, and the suspension frame 13 is made of stainless steel, and the inner suspension is a filter screen 14 made of nylon mesh. The modified granular activated carbon assembly 8 The amount of modified granular activated carbon is 1-4g/L, and the modified granular activated carbon components are installed in the aerated activated sludge reaction tank 1 at an interval of less than 10cm.

The thickness of the modified granular activated carbon assembly 8 is 1-3 cm.

The specific surface area of the modified granular activated carbon is between 1363.8-1548.3m ² /g.

The water inlet 2 is arranged at the lower part of one side of the aerated activated sludge reaction tank 1 , and the water outlet 3 is arranged at the other side of the aerated activated sludge reaction tank 1 .

A method for treating wastewater containing heavy metals in a modified granular activated carbon coupled membrane bioreactor, using the modified granular activated carbon coupled membrane bioreactor described in this embodiment, comprising the following steps:

① Discharge the waste water from the water inlet into the aerated activated sludge reaction tank 1, and turn on the aeration pump 6;

② After the sewage reacts in the aerated activated sludge reaction tank 1, it enters the membrane module 7 through the outlet 3;

③ The sewage discharged from the aerated activated sludge reaction tank 1 is discharged through the water outlet 4 after being treated by the membrane module 7, and the sludge in the membrane module 7 is returned to the aerated activated sludge reaction tank 1 through the return pipe.

In step ②, the concentration of microorganisms in the aerated activated sludge reaction tank 1 is maintained at 2500mg/L-3500mg/L, the pH value is maintained between 6.5-8.5, and the retention of sewage in the aerated activated sludge reaction tank 1 The time is 3.5-4.5 hours.

In this example, the granular activated carbon is first modified to increase its specific surface area (the specific surface area is between 1363.8-1548.3m ² /g) and the proportion of surface micropores, and at the same time, carbon oxide groups will be generated on the surface. In the aerated activated sludge reaction tank, the modified granular activated carbon can, on the one hand, absorb heavy metals in water through the huge specific surface area and surface porosity, and on the other hand, promote the aggregation of bacterial micelles through the carbon oxygen groups generated on the surface. It increases the chance of contact between activated sludge and pollutants in water, accelerates mass transfer, promotes the metabolism and absorption of pollutants by sludge, and at the same time changes the sedimentation performance of activated sludge, and reduces the adhesion and deposition of sludge on the membrane surface, so as to realize the Effective treatment and effective separation and removal of heavy metals in water, while changing the sedimentation performance of sludge and reducing the amount of sludge discharged. A large amount of activated sludge grown in the aerated activated sludge reaction tank can absorb heavy metals in water and participate in the metabolism of microorganisms. At the same time, sticky metabolites such as polysaccharides on the surface of activated sludge can absorb heavy metals in water; modified granular activated carbon aggregates Sludge can reduce the concentration of sludge entering the membrane module, reduce membrane pollution, and prolong the service life of the membrane.

Embodiment one

Reaction target solution volume: 160L

Activated sludge concentration in aerated activated sludge reaction tank: 3400mg/L;

Reaction target solution temperature: 25°C;

The initial concentration of pollutants in the reaction target solution: COD _Cr is 400mg/L, and Cd ²⁺ is 2.5mg/L;

The initial pH value of the solution is 8.3;

The amount of modified granular activated carbon in the modified granular activated carbon component is 0-4g/L (where 0 means no modified granular activated carbon is added, and only biological treatment is used in the reactor);

The residence time of the aeration reaction tank is 4h;

The cadmium-containing wastewater was treated in batches. At different concentrations of modified granular activated carbon, the removal of cadmium-containing wastewater is shown in Table 1.

Table 1: Treatment effect of modified granular activated carbon coupled with membrane bioreactor for treating cadmium-containing wastewater (initial cadmium content is 2.5mg/L, residence time is 4h)

Concentration of modified granular activated carbon in components (g/L) Cd ²⁺ (cadmium) removal rate (%) COD _Cr removal rate (%) 0 98.0 89.5 0.05 98.2 89.7 0.1 98.4 90.5 0.2 98.6 91.3 0.4 98.8 92.0 0.6 98.8 92.0 0.8 99.4 93.5 1.0 99.7 95.5 1.5 99.8 96.3

2.0 99.9 97.0 3.0 99.9 97.5 4.0 99.9 98.3

It can be seen from the examples that the installation of the modified granular activated carbon module has greatly improved the removal effect of the membrane bioreactor on cadmium and COD _Cr , and has a good adaptation effect on pollutants. In the treatment of cadmium-containing wastewater by modified granular activated carbon coupled with membrane bioreactor, there is adsorption effect of modified activated carbon, but the adsorption effect is not large. Modified activated carbon mainly improves the sedimentation performance of sludge, changes the concentration of activated sludge and promotes Flocculation, increase mass transfer and other functions, improve the treatment effect of wastewater and reduce the water content of sludge, and reduce the amount of sludge discharge.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (3)

1. A modified granular activated carbon coupled membrane bioreactor, composed of an aerated activated sludge reaction tank and a membrane module, the aerated activated sludge reaction tank is provided with a water inlet and a discharge port, and a sludge discharge pipe is provided at the bottom , and the bottom is provided with an aeration pipe connected to the aeration pump, which is characterized in that: a modified granular activated carbon assembly is provided in the aeration active reaction tank, and the modified granular activated carbon assembly is filled with a filter screen and a suspension frame The modified granular activated carbon inside the filter screen is composed of the modified granular activated carbon module set in the aerated activated sludge reaction tank, the membrane module is set outside the aerated activated sludge reaction tank, and the outlet is connected by a water pump and The inlet connection of the membrane module, and the membrane module is also connected to the aerated activated sludge reaction tank through the sludge return pipe; The modified granular activated carbon assembly is a plate structure, the outside is a hanging frame, the hanging frame is made of stainless steel, and the inner hanging is a filter screen made of nylon mesh. The modified granular activated carbon assembly is modified The amount of granular activated carbon is 1-4g/L, and the modified granular activated carbon components are installed in the aerated activated sludge reaction tank at an interval of less than 10cm; The thickness of the modified granular activated carbon assembly is 1-3cm; The specific surface area of the modified granular activated carbon is 1363.8-1548.3m ² /g, and the surface has carbon-oxygen groups; The water inlet is arranged at the lower part of one side of the aerated activated sludge reaction tank, and the water outlet is arranged at the other side of the aerated activated sludge reaction tank. 2. A method for treating heavy metal-containing wastewater in a modified granular activated carbon coupled membrane bioreactor, using the modified granular activated carbon coupled membrane bioreactor as claimed in claim 1, characterized in that: comprising the steps: ① Discharge the wastewater from the water inlet into the aerated activated sludge reaction tank, and turn on the aeration pump; ② After the sewage reacts in the aerated activated sludge reaction tank, it enters the membrane module through the outlet; ③The sewage discharged from the aerated activated sludge reaction tank is discharged after being treated by the membrane module, and the sludge in the membrane module is returned to the aerated activated sludge reaction tank through the return pipe. 3. The modified granular activated carbon coupling membrane bioreactor according to claim 2 contains heavy metal wastewater treatment method, characterized in that: in step 2., the concentration of microorganisms in the aerated activated sludge reaction tank is maintained at 2500mg/L- 3500mg/L, the pH value is maintained between 6.5-8.5, and the residence time of sewage in the aerated activated sludge reaction tank is 3.5-4.5 hours.