CN115677043A - A New Technology for Efficient Nitrogen Removal of Low Salt and Low C/N Wastewater - Google Patents

Abstract

The invention provides a new technology for high-efficiency denitrification of low-salt and low-C/N wastewater, which belongs to the technical field of biological denitrification. The sulfur autotrophic denitrification reactor is quickly started by the biological film-hanging method, and artificially prepared wastewater is fed into the wastewater. After adding a small amount of glucose, the system can well adapt to artificially prepared wastewater, the microorganisms grow rapidly, and the denitrification effect is good. Compared with the conventional heterotrophic denitrification process, it not only saves carbon sources, reduces sludge discharge and secondary pollution, but also forms a good sulfur autotrophic/heterotrophic synergistic denitrification system; when the HRT is set to 4h, the The removal effect of 30mg/L nitrate nitrogen can reach 96%, and the system is stable and efficient; under the condition of adding 2g/L of low salt, the system has no inhibitory effect and operates normally and efficiently; Significantly, it can be applied on a large scale.

Description

A New Technology for Efficient Nitrogen Removal of Low Salt and Low C/N Wastewater

technical field

The invention relates to the technical field of biological denitrification, in particular to a new technology for efficient denitrification of low-salt and low-C/N wastewater.

Background technique

The traditional biological denitrification process adopts nitrification and denitrification process, which has the disadvantages of high sludge output, additional carbon source and high operating cost. The principle of sulfur autotrophic denitrification is that some inorganic chemotrophic and phototrophic sulfur-oxidizing bacteria can use reduced sulfur (S ₀ , S ^2- , S ₂ O ₃ ^2- etc.) as an electron donor, obtain energy by oxidizing reduced sulfur, and use nitrate as an electron acceptor to reduce it to nitrogen, and use inorganic carbon (such as CO ₃ ^2- , HCO ₃ ^- ) to synthesize cells, thereby Realize autotrophic denitrification process. Sulfur autotrophic denitrification technology has the advantages of no need to add external carbon sources and low sludge production.

Elemental sulfur (S ₀ ), as a central intermediate in the sulfur cycle on Earth, has several advantages over other sulfur intermediates such as sulfide, thiosulfate, and sulfate: (1) It is an abundant resource on Earth ; (2) multifunctionality, allowing oxidation and reduction; (3) in the solid state, storage is safer and transportation costs are low. Therefore, exploiting the reducing and oxidizing properties of _S0 to treat wastewater has been widely reported in the past decades. Applications include S ₀ driven autotrophic denitrification (S ₀ AD), mediated by some S ₀ oxidizing bacteria (S ₀ OB). And in the common reduced sulfur, sulfide can inhibit the activity of aquatic microorganisms, and the preparation of thiosulfate is complicated, while elemental sulfur is non-toxic, insoluble in water, economical and effective, and has a good application prospect.

At present, the sulfur autotrophic denitrification technology using elemental sulfur as the electron donor has been widely used, but the reaction has the disadvantages of slow start-up time, low stability, unsatisfactory denitrification efficiency, and general salt tolerance. Therefore, the development of a system with quick start, good stability, excellent denitrification effect and salt tolerance is the focus of sulfur autotrophic denitrification technology research, and a new technology for efficient denitrification of low-salt and low C/N wastewater is needed .

Contents of the invention

The purpose of the present invention is to provide a new technology for high-efficiency denitrification of low-salt and low-C/N wastewater to solve the existing technical problems of slow start-up time, low stability, unsatisfactory denitrification efficiency and general salt tolerance. In the present invention, the reactor is started by the biofilm-hanging method, and artificial water distribution is introduced to form a good autotrophic/heterotrophic synergistic denitrification system. When the HRT is 4h, the removal effect of 30mg/L nitrate nitrogen can reach 96%. , Under the condition of 2% low salt, the system has no inhibitory effect, and operates normally and efficiently; it has the characteristics of quick start, low salt resistance, excellent denitrification effect, and stable system.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A new technology for efficient denitrification of low-salt and low C/N wastewater, comprising the following steps:

(1) Selection of the reactor: select a cylindrical upflow denitrification bioreactor, the material of the reactor is plexiglass, the inner diameter of the reactor is 8.6cm, the outer diameter of the reactor is 9.6cm, and the height of the reactor is 90cm, the effective volume of the reactor is 4L, the reactor is equipped with packing and artificially prepared waste water, the height of the packing is 22.5cm, and the volume of water is 2.2L;

(2) Start-up of the reactor: The reactor is started by the bio-filming method, and the reactor start-up situation is explored by monitoring the effluent water quality in the reactor and the operation effect of the reactor. The reactor start-up sludge is taken from domestic sewage activated sludge, By detecting the concentration of NO ₃ ^- , NO ₂ ^- , TN and other indicators in the water every day, the removal effect of NO ₃ ^- and TN has been determined to be over 90% for one week, and there is no accumulation of NO ₂ ^- , and obvious biofilm adhesion can be seen , indicating that the reactor started successfully;

(3) Stable operation stage of the reactor: In the stable operation stage of the reactor, artificially prepared wastewater is used for the influent water. The wastewater formula is: for every 1L of tap water, add 0.033g of glucose, 0.182g of sodium nitrate, 0.0045g of potassium dihydrogen phosphate and trace element nutrients 1mL/L, set the HRT to 10h on the 0-5 day, set the HRT to 7h on the 5-10 day, set the HRT to 4h on the 10-25 day, during the HRT of 4h, the removal effect on NO ₃ ^- and TN It can reach 95%, and there is no accumulation of NO ₂ ^- and NH ₄ ⁺ , which realizes quick startup and stable operation of the system;

(4) After 15 days of stable operation, add 2g/L NaCl to the distribution water to observe whether the sulfur autotrophic/heterotrophic synergistic system can inhibit the denitrification efficiency under low-salt conditions. The results show that low-salt has no effect on the reaction system. No effect, the system operates normally, and the removal efficiency of NO ₃ ^-N and TN reaches 96%.

Further, in step (1), the filler in the reactor is sulfur and limestone particles, the volume ratio of sulfur and limestone particles is 1:1, the particle diameter of sulfur is 3-4mm, and the particle diameter of limestone particles is 2- 3mm.

Further, in step (2), the index concentration of domesticated wastewater is: NO ₃ ⁻ -N=20 mg/L, NO ₂ ⁻ -N=9 mg/L, NH ₄ ⁺ -N=3 mg/L, TN=30 mg /L, COD=30mg/L, pH value is 7.5.

Further, in step (2), the starting water consumption of the reactor is: 0-7 days HRT is 10 h, and 7-15 days HRT is 7 h.

Further, in step (3), the index concentration of wastewater quality is: COD=30±2mg/L, PO ₄ ³⁻ =1±0.2mg/L, NO ₃ ⁻ =30±1mg/L, and the pH value is 7.0-7.2.

The present invention has the following beneficial effects due to the adoption of the above technical solution:

In the present invention, the reactor is started by the biofilm-hanging method, and artificial water distribution is introduced to form a good autotrophic/heterotrophic synergistic denitrification system. When the HRT is 4h, the removal effect of various nitrogen can reach 96%. Under 2% low-salt conditions, the system has no inhibitory effect and operates normally and efficiently; it has the characteristics of fast start-up, low-salt resistance, excellent denitrification effect, and stable system.

Description of drawings

Fig. 1 is the change figure of the nitrogen index of start-up and stable operation of the present invention;

Fig. 2 is a pH and COD change figure in the stable operation stage of the present invention;

Fig. 3 is the effluent SO ₄ ^2- concentration in the stable operation stage of the present invention;

Fig. 4 is the change diagram of nitrogen concentration in the 2g/L NaCl stage (HRT=4h) of the present invention;

Fig. 5 is the change figure of COD concentration and pH value of 2g/L NaCl stage (HRT=4h) of the present invention;

Fig. 6 is a graph showing the variation of sulfate concentration in effluent in the 2g/L NaCl stage (HRT=4h) of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many of the details listed in the specification are only for readers to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

As shown in Figure 1-2, a new technology for efficient denitrification of low-salt and low-C/N wastewater includes the following steps: including the following steps:

(1) Selection of the reactor: select a cylindrical upflow denitrification bioreactor, the material of the reactor is plexiglass, the inner diameter of the reactor is 8.6cm, the outer diameter of the reactor is 9.6cm, and the height of the reactor is 90cm, the effective volume of the reactor is 4L, the reactor is equipped with packing and artificially prepared waste water, the height of the packing is 22.5cm, and the volume of water is 2.2L; the packing in the reactor is sulfur and limestone particles, sulfur and limestone particles The volume ratio of the sulfur is 1:1, the particle size of the sulfur is 3-4mm, and the particle size of the limestone particles is 2-3mm; using the upflow water inlet operation mode, the smaller the particle size is, the larger the specific surface area of the filler is, and the microorganisms can attach to it. Sulfur and limestone fillers consume sulfur to generate energy, part of which is used for the process of denitrification, and part of which is used for the growth of bacteria themselves.

(2) Start-up of the reactor: The reactor is started by the bio-filming method, and the reactor start-up situation is explored by monitoring the effluent water quality in the reactor and the operation effect of the reactor. The reactor start-up sludge is taken from domestic sewage activated sludge, By detecting the concentration of NO ₃ ^- , NO ₂ ^- , TN and other indicators in the water every day, the removal effect of NO ₃ ^- and TN has been determined to be over 90% for one week, and there is no accumulation of NO ₂ ^- , and obvious biofilm adhesion can be seen , indicating that the reactor was started successfully; the index concentration of domesticated wastewater is: NO ₃ ^- -N=20mg/L, NO ₂ ^- -N=9mg/L, NH ₄ ⁺ -N=3mg/L, TN=30mg/L, COD=30mg/L, pH value is 7.5; the water consumption for reactor start-up is: 0-7 days HRT is 10h, 7-15 days HRT is 7h; inoculation wastewater contains a large number of various microorganisms, which can shorten the cultivation and domestication of microorganisms time.

(3) Stable operation stage of the reactor: In the stable operation stage of the reactor, artificially prepared wastewater is used for the influent water. The wastewater formula is: for every 1L of tap water, add 0.033g of glucose, 0.182g of sodium nitrate, 0.0045g of potassium dihydrogen phosphate and trace element nutrients 1mL/L, set the HRT to 10h on the 0-5 day, set the HRT to 7h on the 5-10 day, set the HRT to 4h on the 10-25 day, during the HRT of 4h, the removal effect on NO ₃ ^- and TN It can reach 95%, and there is no accumulation of NO ₂ ^- and NH ₄ ⁺ , which realizes rapid startup and stable operation of the system; the index concentration of wastewater quality is: COD＝30±2mg/L, PO ₄ ^3- ＝1±0.2mg/ L, NO ₃ ⁻ =30±1 mg/L, pH value is 7.0-7.2. After adding glucose organic carbon source, the system can well adapt to artificial water distribution, rapid microbial growth, and good denitrification effect. Compared with conventional heterotrophic denitrification process, it saves carbon source, reduces sludge discharge and secondary pollution, A good sulfur autotrophic/heterotrophic synergistic denitrification system has also been formed; the advantages of coupling sulfur autotrophic denitrification and heterotrophic denitrification are: ① It can reduce the addition of alkalinity and reduce costs; ② Under the strengthening of carbon sources, heterotrophic denitrification The denitrification reaction bears part of the NO ₃ ^- -N load, which not only effectively improves the denitrification efficiency, but also ensures that the content of organic matter in the effluent is low.

(4) After 15 days of stable operation, add 2g/L NaCl to the distribution water to observe whether the sulfur autotrophic/heterotrophic synergistic system can inhibit the denitrification efficiency under low-salt conditions. The results show that low-salt has no effect on the reaction system. No effect, the system operates normally, and the removal effect of NO ₃ ^-N and TN can reach 96%.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (5)

1. A new technology for efficient denitrification of low-salt and low-C/N waste water, characterized in that: comprising the following steps: (1) Selection of the reactor: select a cylindrical upflow denitrification bioreactor, the material of the reactor is plexiglass, the inner diameter of the reactor is 8.6cm, the outer diameter of the reactor is 9.6cm, and the height of the reactor is 90cm, the effective volume of the reactor is 4L, the reactor is equipped with packing and artificially prepared waste water, the height of the packing is 22.5cm, and the volume of water is 2.2L; (2) Start-up of the reactor: The reactor is started by the bio-filming method, and the reactor start-up situation is explored by monitoring the effluent water quality in the reactor and the operation effect of the reactor. The reactor start-up sludge is taken from domestic sewage activated sludge, By detecting the concentration of NO ₃ ^- , NO ₂ ^- , TN and other indicators in the water every day, the removal effect of NO ₃ ^- and TN has been determined to be over 90% for one week, and there is no accumulation of NO ₂ ^- , and obvious biofilm adhesion can be seen , indicating that the reactor started successfully; (3) Stable operation stage of the reactor: In the stable operation stage of the reactor, artificially prepared wastewater is used for the influent water. The wastewater formula is: for every 1L of tap water, add 0.033g of glucose, 0.182g of sodium nitrate, 0.0045g of potassium dihydrogen phosphate and trace element nutrients 1mL/L, set HRT to 10 hours for 0-5 days, set HRT for 7h for 5-10 days, set HRT for 4h for 10-25 days, and remove NO ₃ ^- and TN during HRT of 4h The effect can reach 95%, and there is no accumulation of NO ₂ ^- and NH ₄ ⁺ , which realizes quick startup and stable operation of the system; (4) After 15 days of stable operation, add 2g/L NaCl to the distribution water to observe whether the sulfur autotrophic/heterotrophic synergistic system can inhibit the denitrification efficiency under low-salt conditions. The results show that low-salt has no effect on the reaction system. No effect, the system operates normally, and the removal efficiency of NO ₃ ^-N and TN reaches 96%. 2. A new technology for efficient denitrification of low-salt, low-C/N waste water according to claim 1, characterized in that: in step (1), the filler in the reactor is sulfur and limestone particles, sulfur and The volume ratio of limestone particles is 1:1, the particle size of sulfur is 3-4mm, and the particle size of limestone particles is 2-3mm. 3. A new technology for efficient denitrification of low-salt, low-C/N wastewater according to claim 1, characterized in that: in step (2), the index concentration of domesticated wastewater is: NO ₃ ^- -N= 20mg/L, NO ₂ ^- -N=9mg/L, NH ₄ ⁺ -N=3mg/L, TN=30mg/L, COD=30mg/L, pH value is 7.5. 4. A new technology for efficient denitrification of low-salt, low-C/N wastewater according to claim 1, characterized in that: in step (2), the water consumption for reactor start-up is: 0-7 days HRT is 10h, 7-15 days HRT is 7h. 5. A new technology for efficient denitrification of low-salt, low-C/N wastewater according to claim 1, characterized in that: in step (3), the index concentration of wastewater quality is: COD=30±2mg/ L, PO ₄ ^3- = 1±0.2 mg/L, NO ₃ ^- = 30±1 mg/L, pH value 7.0-7.2.

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