CN111410311A - Efficient denitrification method for coupling membrane filtration and anaerobic ammonia oxidation process - Google Patents

Abstract

The invention relates to a high-efficiency denitrification method for coupling membrane filtration and anammox processes, belonging to the technical field of water treatment. The method comprises the following steps: in a PN-ANAMMOX process, wastewater to be treated enters a nitrosation reactor for a cycle After the operation, the settling water is left to stand. The effluent enters the microfiltration membrane module with a pore size between 120 and 180 nm, and the nitrosation effluent enters from one side of the membrane and passes through the other side through the pressure difference to remove suspended solids and heterotrophic bacteria that enter the anammox influent water. , improve the water quality. Subsequently, the COD concentration in the nitrosation effluent is removed by 30%-50% through activated carbon, and then the anammox reaction is operated, so that the anammox runs stably and maintains an efficient nitrogen removal load. It forms a stable anammox process operation, reduces the impact of influent suspended solids or heterotrophic bacteria on the anammox operation, and is an efficient, energy-saving and stable wastewater denitrification treatment method.

Description

A high-efficiency denitrification method coupling membrane filtration and anammox process

technical field

The invention belongs to the technical field of water treatment.

Background technique

In recent years, anammox process has emerged as a new and promising wastewater treatment method to treat wastewater with high ammonium concentration and low COD content. In the traditional biological denitrification process, it includes two processes: nitrification and denitrification. In an aerobic environment, nitrifying bacteria use inorganic carbon as carbon source and oxygen as electron acceptor to oxidize ammonia nitrogen in wastewater to nitrate nitrogen; In an anaerobic/anoxic environment, denitrifying bacteria use organic carbon as carbon source and electron donor to reduce nitrate nitrogen to nitrogen. With the development of biological denitrification technology, new denitrification processes such as short-range-denitrification, aerobic denitrification, simultaneous nitrification-denitrification, and PN-ANAMMOX have been developed. The problem of difficult treatment of high ammonia nitrogen wastewater. In the PN-ANAMMOX process, the wastewater first goes through the nitrosation reaction and then enters the anammox process. Although after a period of static precipitation, there are still a small amount of suspended solids and heterotrophic bacteria that accompany the influent into the anammox process. In view of the characteristics of slow growth and long growth cycle of anammox bacteria, heterotrophic bacteria using organic carbon as raw materials will compete with anammox bacteria for survival in the reactor, which will adversely affect anammox bacteria. . Therefore, the introduction of a membrane filtration system is applied to the front end of the anammox process to intercept suspended solids and heterotrophic bacteria (even large particles of organic matter) in the influent water.

Now the common membrane technology application in anammox process is usually divided into the following three ideas:

One is the application of membrane bioreactor MBR as a back-end interception. Using the good retention performance of the membrane bioreactor, the bacteria are intercepted and fixed during the operation process, and the effluent quality is optimized while the bacteria are fixed. It is often used in experiments for enriching and cultivating obligate anammox bacteria, and experiments have shown that anammox bacteria are the dominant bacteria in the MBR reactor.

The second is the application of membrane aeration as a carrier in the reactor. In the process of research, we often need to control the concentration of dissolved oxygen in water. Membrane aeration can control dissolved oxygen and its diffusion efficiency is higher than that of ordinary aeration technology, while reducing volatile organic compounds and greenhouse gases in the gas to improve aeration quality. At the same time, in the membrane aeration system, a large surface area is provided for bacteria, allowing bacteria to enrich and grow on the surface.

The third is to perform pre-filtration at the front end of the reaction. The experiment comes from Imperial College London, Stuckey. The concept of nitrifying biofilms growing on the surface of the membrane is slightly modified, that is, ammonium diffuses through the tube side. Nitrifying bacteria grow on the shell side of the membrane module by continuously circulating the cell suspension through the shell side. In this way, nitrite can be controlled, cultivation is independent of wastewater flow, and concentrated cultivation can be developed on the shell side of the membrane module. This increases ammonium conversion efficiency and reduces aeration and reactor operating costs compared to existing treatment technologies.

SUMMARY OF THE INVENTION

The object of the present invention is to reduce the partial adverse effects on the anammox process in the existing PN-ANAMMOX process, provide a kind of optimization method maintaining the stable growth of anammox bacteria, and reduce the heterotrophic bacteria, Suspended solids enter the anammox process and compete with anammox bacteria under the promotion of the actual wastewater organic carbon source. At the same time, the organic carbon concentration in the water is reduced, and the partial inhibitory effect on the anammox bacteria caused by the high organic carbon concentration in the water is reduced.

In order to achieve the above object, the technical scheme provided by the invention is as follows:

A high-efficiency denitrification method for coupling membrane filtration and anammox process, characterized in that the method comprises: in the PN-ANAMMOX process, the wastewater to be treated enters a nitrosation reactor for a cycle of operation, and then settles the effluent . The effluent enters the membrane system module with a pore size between 120 and 180 nm, and the nitrosation effluent enters from one side of the membrane and passes through the other side through the pressure difference to remove suspended solids and heterotrophic bacteria that enter the anammox influent water. , improve the water quality. Subsequently, the COD concentration in the nitrosation effluent is removed by 30%-50% through activated carbon, and then enters the anammox reaction operation, so that the anammox runs stably and maintains an efficient nitrogen removal load. Above, a stable anammox process operation is formed, the influence of influent suspended solids or heterotrophic bacteria on the anammox operation is reduced, and it is an efficient, energy-saving and stable wastewater denitrification treatment method.

The membrane system component is placed at the front end of the anammox process to filter the anammox feed water. In the existing PN-ANAMMOX process, the membrane module can be applied to the intermediate position of partial nitrosation and anammox. Then some activated carbon was added to remove part of the activated carbon concentration.

The membrane system component adopts a microfiltration membrane system, and the membrane pore size is between 120 and 180 nm; the bottom layer is a non-woven fabric, and the non-woven fabric is covered with a PVDF active layer by a phase inversion method; the contact angle is between 75 and 80 . It can effectively remove suspended solids and heterotrophic bacteria in water, and the removal rate can reach more than 90%, which has a good effect on improving the water quality of anammox influent.

In the anammox reaction, 10-30g of activated carbon is put into every 200ml of actual waste water, so that the organic carbon removal rate reaches 30%-50%, and the inhibition of high-concentration activated carbon on the operation of the anammox process is reduced.

The scope of application of the method includes, but is not limited to, thermal hydrolysis sludge digestion liquid, industrial wastewater with high nitrogen content and high organic matter, etc., and is suitable for industrial wastewater with high nitrogen concentration, high COD concentration and complex composition.

The PN-ANAMMOX process can be operated by SPR process in the whole process. After precipitation and standing, the nitrosation effluent will pass through the membrane module, which can reduce the pollution of SS in the water to the membrane module, improve the membrane flux, and prolong the service time of the membrane module.

Compared with the prior art, the present invention has the following characteristics and beneficial effects:

1. Use the microfiltration membrane module at the front end of the anammox process to filter suspended solids and heterotrophic bacteria to remove suspended solids and heterotrophic bacteria that may affect the anammox bacteria. Compared with the anammox process without membrane filtration, which is commonly used in UN, it can reduce the abnormal bacteria that may compete with anammox bacteria in the influent, so as to improve the stable growth of anammox bacteria and maintain the anaerobic bacteria. The ammonia oxidation process operates stably for biological nitrogen removal.

2. Activated carbon is used to remove part of the COD concentration in wastewater. In the anammox process of treating high COD concentration, the COD concentration is removed by activated carbon, which improves the water quality. Compared with wastewater without activated carbon to remove COD content, anammox bacteria are produced. less adverse effects.

3. Compared with the traditional nitrification-denitrification, the anammox process can reduce the organic carbon source by 100%, reduce the oxygen demand by 60% _{, and} reduce the excess sludge production by 90%.

Description of drawings

Fig. 1 is the process flow diagram of the high-efficiency denitrification process and method of coupling membrane filtration and anammox process of the present invention;

Detailed ways

The high-efficiency denitrification method of coupling membrane filtration and anammox process of the present invention specifically includes the following steps (as shown in Figure 1):

The first step is that the sewage enters the nitrification reaction tank, and after aerobic stirring and anaerobic stirring, the ratio of ammonia nitrogen: nitrite nitrogen in the nitrosation effluent is close to 1:1.32, which meets the requirements of the subsequent reaction, and the effluent is left to settle. into the membrane module.

In the second step, the effluent enters the microfiltration membrane module with a pore size between 120 and 180 nm, and the nitrosation effluent enters from one side of the membrane and passes through the other side through the pressure difference to remove the suspended solids entering the anammox influent water. , Heterotrophic bacteria, improve the water quality.

The third step is to add 10-30g of activated carbon per 200mL of nitrosation effluent to make the COD removal rate reach 30%-50%.

The fourth step is to remove part of the COD concentration in the water, and then enter the back-end anammox process to operate so that the anammox reactor operates stably and maintains medium and high total nitrogen removal loads.

The first step is that the sewage enters the nitrosation stage to run. In this stage, the influence of water quality and other reasons on the nitrosation operation can be adjusted and improved by optimizing the operation, and the concentration ratio of ammonia nitrogen in the waste water: nitrite nitrogen is maintained. Close to 1:1.32, which satisfies subsequent reaction runs.

The second step is that the water after nitrosation treatment enters the membrane system after standing and settling, and the membrane module is made of non-woven material and the pore size of 120-180nm, which has a good ability to remove suspended solids in water and heterotrophic bacteria. Effect.

The third step is to add an appropriate dose of activated carbon to the nitrosation effluent after membrane filtration to reduce the COD concentration in the water through physical adsorption. Reduce the adverse effect of COD on anammox operation process.

The fourth step is to enter the nitrosation reaction effluent through membrane filtration into the anaerobic ammonia oxidation process, and by removing suspended solids and heterotrophic bacteria in the water, the anaerobic ammonia oxidation influent water may be detrimental to bacterial derivation. Affected suspended matter.

The embodiment of the present invention will be further described below with reference to FIG. 1 .

Example:

The process running in a factory is a two-stage PN-ANAMMOX process. The ammonia nitrogen concentration of the thermally hydrolyzed sludge digested biogas slurry is 1500-2000mg/L, the COD concentration is 2000-2500mg/L, the biogas slurry enters the nitrification process and the effluent ammonia nitrogen concentration is 400-700mg/L, and the effluent nitrous nitrogen concentration is also It is 400-700mg/L, and the effluent COD concentration is 1200-1700mg/L. The nitrosation effluent directly enters the ammonium hydroxide oxidation process. After the anammox process, the ammonia nitrogen concentration in the effluent is 100-150mg/L, the nitrous nitrogen concentration in the effluent is 0-10mg/L, and the anammox operation load is 0.4kgN/L. m3/d.

In the two-stage PN-ANAMMOX process, a membrane module is added to remove suspended solids and heterotrophic bacteria, and an appropriate amount of activated carbon is added to the nitrosation effluent filtered by the membrane module. The removal rate of the membrane module for suspended solids and heterotrophic bacteria is as high as 92%-97%. Activated carbon can remove COD concentration up to 30%-50%. When the nitrosation effluent after membrane filtration and activated carbon adsorption enters the anammox process, the anammox process can run more stably, and the nitrogen removal load is increased by 10%-30%.

Claims (2)

1. A high-efficiency denitrification method for a coupled membrane filtration and anaerobic ammonia oxidation process is characterized by comprising the following steps: in the PN-ANAMMOX process, the wastewater to be treated enters a nitrosation reactor to be treatedStanding and settling the effluent after the periodic operation. And enabling the effluent to enter a membrane system assembly with the aperture of 120-180 nm, enabling nitrosation effluent to enter from one side of the membrane and penetrate out from the other side of the membrane through pressure difference, removing suspended matters and heterotrophic bacteria in the anaerobic ammonia oxidation influent, and improving the quality of the influent.Subsequently, the process of the present invention,removing 30-50% of COD concentration in the nitrosation effluent by using activated carbon, and then performing anaerobic ammonia oxidation reaction operation, so that the anaerobic ammonia oxidation stably operates and high-efficiency nitrogen removal load is maintained. The method forms a stable anaerobic ammonia oxidation process operation, reduces the influence of inflow suspended matters or heterotrophic bacteria on the anaerobic ammonia oxidation operation, and is a high-efficiency, energy-saving and stable wastewater denitrification treatment method.

2. The method for high efficiency denitrification with coupled membrane filtration and anammox process of claim wherein the steps are performed by:

the first step is that sewage enters a nitrosation reaction tank, and ammonia nitrogen in nitrosation effluent is enabled to be: the ratio of nitrite nitrogen is close to 1:1.32, meeting the requirements of subsequent reaction, standing to precipitate water, and allowing the water to flow into a membrane module;

the second step, the effluent enters a microfiltration membrane component with the aperture of 120-180 nm, nitrosation effluent enters from one side of the membrane through pressure difference, and penetrates out from the other side of the membrane, so that suspended matters and heterotrophic bacteria in the anaerobic ammonia oxidation influent are removed, and the quality of the influent is improved;

step three, adding 10-30 g of activated carbon into every 200m of L nitrosation effluent to ensure that the removal rate of COD reaches 30-50%;

and step four, after removing part of COD concentration in the water, the anaerobic ammonia oxidation reactor is operated in a rear-end anaerobic ammonia oxidation process to ensure that the anaerobic ammonia oxidation reactor is stably operated, and the removal load of medium and high total nitrogen is maintained.

Images