CN102351309B - Azotification method by use of organic wastewater - Google Patents

Abstract

The invention belongs to the technical field of waste water recovery and utilization, and relates to a method for using organic waste water to fix nitrogen. The method includes the following steps: (1) adding the organic waste water into the reactor after being sterilized; (2) inserting photosynthetic bacteria into the reactor (3) Nitrogen gas is injected into the lower part of the reactor to make the air pressure in the reactor reach 0.1Mpa; (4) The organic wastewater is cultivated under light for not less than 96 hours; (5) After the cultivation, the liquid in the reactor is centrifuged, Dehydration and drying give solid organic nitrogen products. The present invention uses photosynthetic bacteria to convert the nutrients in the organic wastewater into nitrogen in the air by the nitrogen fixation of its own nitrogenase under anaerobic light conditions, thereby transforming the elemental nitrogen in the air into an organic state Form conversion fixes, providing the appropriate nitrogen source form.

Description

A kind of method utilizing organic waste water to carry out nitrogen fixation

technical field

The invention belongs to the technical field of waste water recycling and relates to a method for fixing nitrogen by using organic waste water.

Background technique

Nitrogen is an indispensable basic element for the growth of most animals, plants and microorganisms, and in most cases organisms are more likely to use organic nitrogen as a nitrogen source for their own metabolism. Although about 78% of the air is nitrogen, except for a few microorganisms and plants that have their own nitrogen fixation, most organisms cannot directly use nitrogen. At present, the utilization of air nitrogen source is mainly fixed conversion by chemical method (synthetic ammonia process), and the nitrogen in the air is converted into the form of ammonia for further utilization.

Photosynthetic bacteria are a type of archaea with a special growth and metabolism system, which can carry out growth and metabolism activities under different environmental conditions. Among them, under the conditions of anaerobic light and nitrogen deficiency under nutrient conditions, they can convert elemental nitrogen into what they need for their own growth and metabolism. Nitrogen source, this form of metabolism is an important part of the evolution of the Earth's atmosphere. Nitrogen fixation is a metabolic pathway of nitrogenase in photosynthetic bacteria. The nitrogen fixation process must be carried out under light conditions. Since the nitrogenase of photosynthetic bacteria is sensitive to oxygen, the presence of oxygen will lead to the inactivation of nitrogenase and the loss of nitrogen fixation activity. In order to use photosynthetic bacteria to fix and transform nitrogen in the air, the inhibitory effect of oxygen in the air must be eliminated.

Organic wastewater contains a large amount of carbon-rich organic matter, which consumes a large amount of oxygen in the process of metabolic decomposition, causing hypoxia and death of aquatic animals, which is an important cause of water pollution. The carbon-rich substances contained in organic wastewater are good carbon sources, which can provide energy sources for the growth and metabolism of a variety of microorganisms. Using the growth and metabolism characteristics of photosynthetic bacteria to convert and fix nitrogen in the air with organic wastewater as a carbon source under specific environmental conditions can not only purify organic wastewater, but also the nitrogen source converted and fixed by photosynthetic bacteria is also a nitrogen source for a variety of biological utilization form.

Contents of the invention

The purpose of the present invention is to provide a method for nitrogen fixation using organic waste water, which can obtain organic nitrogen products.

The present invention adopts following technical scheme:

A kind of method utilizing organic waste water to carry out nitrogen fixation, comprises the following steps:

(1) Add the organic wastewater to the reactor after sterilization; (2) Introduce photosynthetic bacteria into the reactor, and the inoculation amount of photosynthetic bacteria is 5-10% of the volume of the organic wastewater; (3) Inject nitrogen into the lower part of the reactor to make The air pressure in the reactor is up to 0.1Mpa; (4) The organic wastewater is cultivated under light for no less than 96 hours, the light intensity is controlled at 2000-3000 Lx, and the cultivation temperature is 25-30°C; (5) The liquid in the reactor after the cultivation is completed After centrifugation, dehydration and drying, solid organic nitrogen products are obtained.

The preparation steps of the nitrogen gas are as follows: sending organic waste water with a COD of 4000-6000 mg/L into the deoxygenation reactor; adding aerobic activated sludge with an organic waste water quality of 1/15-1/20 in the deoxygenation reactor; The bottom of the deoxygenation reactor is fed with air, and the air flows from bottom to top in the deoxygenation reactor. Oxygen participates in the reaction and is consumed, and the gas discharged from the deoxygenation reactor removes carbon dioxide to obtain nitrogen.

The deoxygenation reactor includes a shell, an aerator is provided at the bottom of the shell, the inlet of the aerator is connected to the air intake pipe, and the inner wall of the shell above the aerator is vertically spaced and staggered with downward-sloping and upward-sloping Baffle plate, there is a gap between the far end of the baffle plate and the inner wall of the opposite shell; the top of the shell is provided with a shower, the inlet of the shower is connected to the bottom of the shell through a circulation pipe, and the entrance of the circulation pipe is set There is a circulating pump, the top of the casing is provided with an air outlet pipe, the upper part of the casing is provided with a water inlet pipe, the bottom of the casing is inclined, and the bottom surface of the casing is provided with a sewage outlet; the casing is provided with an overflow pipe; Between the second baffle plate and the third baffle plate.

The present invention uses photosynthetic bacteria to convert the nutrients in the organic wastewater into nitrogen in the air by the nitrogen fixation of its own nitrogenase under anaerobic light conditions, thereby transforming the elemental nitrogen in the air into an organic state Form conversion fixes, providing the appropriate nitrogen source form.

In the process of the present invention, the organic waste water needs to be sterilized before entering the reactor, so as to prevent the pollution of miscellaneous bacteria and reduce the inhibitory effect of air oxygen on photosynthetic bacteria. The present invention can not directly use air as the nitrogen source of organic wastewater metabolic reaction, this is because the oxygen in the air has inhibitory effect on nitrogenase, so the nitrogen used must be the air after deoxygenation, if the trace oxygen exists, the cultivation time should be increased , so that photosynthetic bacteria firstly carry out aerobic respiration to consume the trace oxygen that exists and then switch to nitrogen fixation metabolism.

The nitrogen fixation process of the present invention is simple, and its main cost lies in the power consumption of light for light cultivation. If sunlight is used as a natural light source, the production cost can be greatly reduced by properly extending the cultivation time to compensate for the influence of periodic changes in sunlight. After adopting the method of the present invention to fix nitrogen, nitrogen mainly exists in the culture medium in the form of bacterial protein and photosynthetic pigment. After centrifugation, the bacterial protein and bacterial pigment can be used as animal feed protein and fish feed, and can also be used as animal feed after inactivation. A supplementary nitrogen source for biological fermentation, such as a supplementary nitrogen source for anaerobic fermentation of straw. The present invention uses organic waste water to obtain nitrogen. The principle is that air is used as an oxygen source for the degradation of organic matter in organic waste water. The process of organic matter degradation and metabolism consumes oxygen to eliminate oxygen in the air. Finally, carbon dioxide and water are removed to obtain a nitrogen concentration of 95. % of nitrogen products.

When utilizing organic waste water to obtain nitrogen in the present invention, organic waste water COD needs to be controlled, and this is because when the organic waste water COD is too low, the oxygen contained in the air cannot be completely eliminated, and when the organic waste water COD is too high, there is a large amount of CO _2. The generation of new impurity gases such as CO not only increases the consumption of the absorbed lye but also affects the purity of the obtained nitrogen. Controlling COD keeps the degradation and metabolism of organic wastewater at the aerobic and micro-aerobic level, avoiding the generation of more miscellaneous gases in the anaerobic state of organic matter. The method of obtaining nitrogen by using organic waste water is simple and low in energy consumption. While obtaining nitrogen, it also has a certain purification effect on organic waste water. The nitrogen concentration (volume percentage) in the gas obtained by using the method of the present invention can reach about 95%. It also contains a small concentration of oxygen and carbon monoxide gas, which can be used as a precursor gas for obtaining high-purity nitrogen.

The deoxygenation reactor used to obtain nitrogen from organic wastewater has a simple structure design, reasonable layout, and baffles, which can make the air fully baffle from bottom to top in the reactor, ensuring that the oxygen in the air is degraded and metabolized by organic matter to the greatest extent. Use up.

Description of drawings

Fig. 1 is the structural representation of used deoxygenation reactor among the present invention;

Figure 2 is a schematic structural diagram of the system when the deoxygenation reactor is in use.

Detailed ways

The test uses the waste water produced by the malt sugar factory as a sample, part of which is used as a nutrient substrate for photosynthetic bacteria after being sterilized by ultraviolet light, and part of which is used as an air deoxygenation medium.

The deoxygenation reactor, as shown in Figure 1, includes a shell 1, the bottom of the shell 1 is provided with an aerator 2, the inlet of the aerator 2 is connected to the air intake pipe 3, and the inner wall of the shell 1 above the aerator 2 is vertical The baffles 4 inclined downwards and upwards are staggered to the interval, and there is a gap between the far end of the baffles 4 and the inner wall of the opposite housing 1; the top of the housing 1 is provided with a shower 5, and the shower 5 The inlet of 5 is connected to the bottom of the housing 1 through the circulation pipe 6, and a circulation pump 7 is provided at the inlet of the circulation pipe 6. During operation, the circulation pump 7 circulates the organic waste water at the bottom to the sprayer 5, so that the inside of the housing 1 The organic waste water is continuously circulated, and the excess waste water is discharged through the overflow pipe 11; the top of the shell 1 is provided with an air outlet pipe 8, and the upper part of the shell 1 is from top to bottom between the second baffle plate 4 and the third baffle plate 4 A water inlet pipe 9 is arranged between them, through which organic waste water is constantly replenished. The casing 1 is provided with an overflow pipe 11, the bottom of the casing 1 is inclined, and the bottom surface of the casing 1 is provided with a sewage outlet 10.

When the deoxygenation reactor is in use, as shown in Figure 2, the air inlet pipe 3 of the deoxygenation reactor is connected with the air storage tank 20, the air storage tank 20 is connected with the air compressor 23, and the air outlet pipe 8 of the deoxygenation reactor is connected with the alkaline absorption box 21 is connected, and the gas outlet of the alkaline absorption box 21 is connected with the dehydration box 22.

The organic wastewater used in the air deoxidation medium part is adjusted (COD is 5550mg/L), enters the shell 1 of the deoxidation reactor through the water inlet pipe 9; Add the aerobic activated sludge of organic wastewater quality 1/20 in the reactor; Utilize the air compressor 23 to press the air into the air storage tank 20, the air is dispersed at the bottom of the deoxygenation reactor through the air inlet pipe 3 and the aerator 2, and Gather at the relatively higher end of the baffle 4, and with the increase of air flow, the collected air diffuses to the lower end of the baffle 4 and then continuously diffuses upward, and the air gradually deoxidizes under the action of the baffle 4 The top of the reactor moves, the air is in the process of baffle, and the contained _O2 participates in the degradation reaction of organic matter to achieve the elimination effect, and finally the gas is discharged from the outlet pipe 8 at the top of the shell 1. Most of the air discharged from the air outlet pipe 8 is nitrogen, and also contains the carbon dioxide contained in the air itself and the degradation of organic matter, and continues to pass into the alkaline absorption tank 21 to be absorbed by the lye to remove carbon dioxide, and finally dehydrated in the dehydration tank 22 to obtain nitrogen. . The measured components in nitrogen are: N ₂ : 97.2%, O ₂ : 0.8%, CO ₂ : 0%, CO: 0.4%, and the measured COD in the organic wastewater flowing out of overflow pipe 11 is 4100mg/L. During operation, the circulation pump 7 circulates the organic waste water at the bottom to the sprayer 5 through the circulation pipe 6, so that the organic waste water in the shell 1 is continuously circulated, and the organic waste water is continuously replenished by the water inlet pipe 9, and the excess waste water passes through the overflow pipe 11 discharge; after running for a period of time, close the air and circulation pump 7, open the sewage outlet 10 to discharge the sewage, remove the sludge particles in the reactor, and start the operation of the next process after cleaning.

After ultraviolet sterilization, the organic wastewater used as the nutrient substrate of photosynthetic bacteria is added to the nitrogen fixation reactor; (2) the photosynthetic bacteria with an inoculation amount of 5% of the organic wastewater volume are inserted into the nitrogen fixation reactor, and the photosynthetic bacteria are spherical red pseudomonas Bacteria and Rhodospirillum rubrum; (3) The lower part of the reactor passes through the nitrogen gas discharged from the dehydration tank 22 of the deoxygenation reactor to make the air pressure in the nitrogen fixation reactor reach 0.1Mpa; (4) Use incandescent lamps to treat organic wastewater Carry out light cultivation for no less than 96 hours, adjust the distance between the incandescent lamp and the reactor to control the illuminance to 2000 Lx, and the cultivation temperature to 25°C; (5) After the cultivation, the liquid in the reactor is centrifuged, dehydrated and dried to obtain solid organic nitrogen products.

Before the test, the nitrogen content in the photosynthetic bacteria inoculum was tested to be 325 mg/L, and the nitrogen content in the wastewater was 97 mg/L. After 4 days of continuous culture, the nitrogen content in the organic wastewater was determined to be 780 mg/L. From this, the photosynthetic bacteria after continuous culture were calculated. The total fixed nitrogen is 5.851g, that is, the fixed nitrogen amount per unit effective volume is 680.35 mg/L.

Claims (3)

1. method of utilizing organic waste water to carry out fixed nitrogen may further comprise the steps:

(1) organic waste water sterilization back adds in the reactor drum; (2) in reactor drum, insert photosynthetic bacterium, the photosynthetic bacterium inoculum size is the 5-10% of organic waste water volume; (3) feeding nitrogen in the bottom of reactor drum makes the air pressure in the reactor drum reach 0.1MPa; (4) organic waste water is carried out illumination cultivation and be no less than 96h, the control illuminance is 2000-3000 lx, and culture temperature is 25-30 ℃; (5) cultivate to finish liquid in the post-reactor through spinning, dehydrate and obtain solid organic nitrogen product.

2. the method for utilizing organic waste water to carry out fixed nitrogen as claimed in claim 1 is characterized in that, the preparation process of said nitrogen is: with COD is that the organic waste water of 4000-6000mg/L is sent in the deoxidation reactor; The aerobic activated sludge that in deoxidation reactor, adds organic waste water quality 1/15-1/20; By deoxidation reactor bottom bubbling air, air in deoxidation reactor from bottom to top in the flow process oxygen participate in reaction and be consumed, the gas of discharging deoxidation reactor remove behind the carbonic acid gas nitrogen.

3. the method for utilizing organic waste water to carry out fixed nitrogen as claimed in claim 2; It is characterized in that; Said deoxidation reactor comprises housing, and housing bottom is provided with aerator, the import of aerator and air inlet pipe coupling; The vertical interleaved of inner walls of aerator top is provided with downward-sloping and acclivitous traverse baffle, leaves the space between the far-end of traverse baffle and the relative inner walls; Case top is provided with spray thrower, and the import of spray thrower is connected with housing bottom through circulation tube, and the ingress of circulation tube is provided with recycle pump, and case top is provided with escape pipe, and housing top is provided with water inlet pipe, and housing bottom is skewed, and the housing bottom surface is provided with sewage draining exit; Housing is provided with upflow tube; Water inlet pipe is located at from top to bottom between second traverse baffle and the 3rd traverse baffle.

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