KR100460214B1 - Wastewater treatment method and wastewater treatment system using photosynthetic microorganisms - Google Patents

Abstract

The present invention relates to a wastewater treatment method using a photosynthetic microorganism and a treatment apparatus using the same, in particular, using a wastewater treatment apparatus consisting of an inlet source pipe, a sedimentation tank, a denitrification reaction tank, a final sedimentation tank, a treated water discharge tube, and a return pipe. The present invention relates to a wastewater treatment method and a treatment apparatus using the same by attaching a light source, an aeration device, and a stirring device to the denitrification reactor to efficiently remove nitrogen from the wastewater. In the wastewater treatment method of the present invention, by using photosynthetic microorganisms instead of using anaerobic microorganisms, nitrogen can be removed up to 95% or more by overcoming the disadvantage of low nitrogen removal rate of the activated sludge process commonly used in wastewater treatment. By eliminating the supply of organic carbon sources and the anaerobic tank, the process time can be shortened and the cost of sewage treatment can be reduced.

Description

Wastewater treatment method using photosynthetic microorganism and its treatment device {Wastewater treatment method and wastewater treatment system using photosynthetic microorganisms}

The present invention relates to a wastewater treatment method using a photosynthetic microorganism and a treatment apparatus using the same, in particular, using a wastewater treatment apparatus consisting of an inlet source pipe, a sedimentation tank, a denitrification reaction tank, a final sedimentation tank, a treated water discharge tube, and a return pipe. The present invention relates to a wastewater treatment method and a treatment apparatus using the same by attaching a light source, an aeration device, and a stirring device to the denitrification reactor to efficiently remove nitrogen from the wastewater.

Various wastewater treatment methods have been proposed to prevent river pollution caused by wastewater discharge due to industrialization.

Wastewater treatment methods are largely divided into physical, chemical and biological treatment methods. Physical wastewater treatment methods include sieve separation, filtration, ultra-fine filtration, dialysis, sedimentation, and distillation using properties such as particle size, specific gravity difference, and magnetic properties. And evaporation methods are used.

In addition, as the chemical treatment method, neutralization method, neutralization precipitation method, redox method, decomposition method, coagulation method, ion exchange method and incineration method using properties such as solubility, redox, hydrolysis, interfacial properties and ionicity are used.

Finally, biological treatment methods are widely used to treat wastewater containing a large amount of organic matter. Etc.

The general method for treating wastewater consists of two main steps: a primary treatment step for physically removing a certain amount of suspended solids contained in the wastewater and a second treatment step for biologically removing organic matter from the wastewater.

Wastewater treated in the secondary treatment step contains organic matter and nitrogen, and biologically activated sludge methods are commonly used to treat such wastewater. Conventional wastewater treatment systems require separate tanks for nitriding and denitrification processes. First, in the nitriding tanks, nitrites are oxidized by oxidizing organic nitrogen and ammonia-based nitrogen in wastewater introduced by the microorganisms causing nitrification and supplied oxygen. It is converted to nitrogen or nitrate nitrogen.

The nitrified wastewater is transported from the nitriding tank to the denitrification tank so that nitrogen is separated and released into the atmosphere by the respiratory action of the denitrification microorganism. The denitrified water is introduced into the settling tank and separated into activated sludge and water. The separated water is passed back to a high process or chlorinated and discharged out of the system and the activated sludge is recovered and introduced into the nitriding tank. However, in the biologically activated sludge treatment method, a large amount of excess sludge is generated, and additional facilities and costs are added to treat the excess sludge.

On the other hand, Korean sewage water has a relatively low proportion of carbon sources compared to nitrogen sources, so the wastewater treatment method using existing microorganisms has low nitrogen removal efficiency, and the activated sludge method can remove more than 90% of biochemical oxygen demand (BOD) from wastewater. But nitrogen can only remove about 20 to 50%. Therefore, to date, nitrogen has been removed by artificially increasing the ratio of C / N by supplying a separate organic carbon source such as ethanol or glucose, and this treatment is released to the stream without sufficient nitrogen contained in the wastewater. This can cause red tide, disrupt ecosystems and cause economic damage.

As such, conventional wastewater treatment systems require separate tanks for nitriding and denitrification processes and therefore require large installations. In addition, since the ammonia nitrogen in the nitriding tank is oxidized to produce nitrite or nitrate and the pH is considerably reduced, the growth of microorganisms is reduced, and it is pointed out that the problem is that alkali should be added and nitrogen removal rate from waste water is very low. have. Moreover, since heterotrophic microorganisms are generally used as denitrogen microorganisms, the cost of the wastewater treatment process is increased because a large amount of organic carbon sources such as ethanol and glucose are required.

In order to solve the above problems, the present inventors have developed a wastewater treatment apparatus composed of an inlet source pipe, a sedimentation tank, a denitrification reactor, a final sedimentation tank, a treated water discharge pipe, and a return pipe, and using the photosynthetic microorganism instead of anaerobic microorganisms, the nitrogen content The present invention has been completed by efficiently removing nitrogen from this high wastewater without adding a separate organic carbon source.

It is an object of the present invention to provide a wastewater treatment method and treatment apparatus which can reduce the wastewater treatment cost by efficiently removing nitrogen and shortening the treatment process in wastewater, in particular, wastewater having high nitrogen content.

1 shows a wastewater treatment apparatus for removing nitrogen from wastewater according to the wastewater treatment method using the photosynthetic microorganism of the present invention,

FIG. 2 shows an apparatus for removing nitrogen from a denitrification reactor in the wastewater treatment apparatus of FIG. 1 .

Figure 3a shows the result of culturing the microalgae by adding ammonia nitrogen to the denitrification reactor in the hape water treatment apparatus of the present invention ,

Figure 3b is a microalgae cultured in Figure 3a shows the result of reducing ammonia nitrogen,

Figure 4a shows the result of culturing the microalgae by adding nitrate nitrogen to the denitrification reactor in the wastewater treatment apparatus of the present invention,

Figure 4b is a microalgae cultured in Figure 4a shows the result of reducing the nitrate nitrogen,

Figure 5a shows the result of culturing the microalgae by adding nitrate nitrogen to the denitration reaction tank in the haep water treatment apparatus of the present invention by concentration,

Figure 5b shows the result of reducing the nitrate nitrogen added to the microalgae cultured in Figure 5a .

◆: 140 mg-N / L ■: 280 mg-N / L

▲: 700 mg-N / L ●: 1,400 mg-N / L

* Explanation of symbols for main parts of the drawing

1: inlet raw water pipe 2: sedimentation tank

3: denitrification reactor 4: final precipitation tank

5: treated water discharge pipe 6: return pipe

7 light source 8 stirring device

9: aeration device

In order to achieve the above object, the present invention provides a wastewater treatment method for removing nitrogen by using photosynthetic microorganisms in the wastewater.

In addition, the present invention provides a wastewater treatment apparatus using the wastewater treatment method consisting of the inlet source pipe, sedimentation tank, denitrification reaction tank, final sedimentation tank, treated water discharge pipe and return pipe.

Hereinafter, the present invention will be described in detail.

The present invention provides a wastewater treatment method for removing nitrogen using photosynthetic microorganisms in wastewater.

Wastewater treatment method of the present invention,

1) removing the material causing suspension from the sewage water;

2) removing nitrogen from the sewage using photosynthetic microorganisms; And

3) precipitating photosynthetic microorganisms in the final settling tank and releasing the treated water (see FIG. 1 ).

Step 1) is a step (1 and 2) of removing suspended solids from the influent sewage water, which is a physical treatment step, which is performed using a sieve separation, filtration, ultra-fine filtration, Dialysis, sedimentation, distillation and evaporation can be used. Since the present invention uses photosynthetic microorganisms that obtain an energy source and a carbon source through a photosynthetic reaction using light and carbon dioxide, the suspension material should be sufficiently removed.

Step 2) is a step in which nitrogen is removed by photosynthetic microorganisms from the sewage water from which the suspended matter is removed (3). The growth of photosynthetic microorganisms requires light, carbon dioxide, water, and nitrogen. Nitrogen is removed from the sewage in proportion to growth.

In photosynthetic microorganisms such as Spirulina (Spirulina), Ana vena (Anabaena), cine Coco kusu (Synechococcus), cine Cauchy seutiseu (Synechocystis), know when seutiseu (Anacystis), no stock (Nostoc), come la thoria (Oscillatoria) Cyanobacteria and Chlorella , Dunalialla, Haematococcus, Isochrysis, Scenedesmus, Chlamydomonas, Porphyridium, etc. Microalgae of can be used, and metal ions such as phosphorus, iron, zinc, manganese, copper and aluminum, which are essential for their growth, do not need to be added to wastewater treated with activated sludge, but by artificially adding a small amount of these ions Photosynthetic microorganisms can also be cultured at high concentrations.

Step 3) is a step in which photosynthetic microorganisms are precipitated in the final settling tank and treated water is discharged (4 and 5). The sewage from which nitrogen is removed is transferred to the final settling tank (4), and then the photosynthetic microorganisms are settled by gravity and the return pipe ( 6) and only treated water is discharged. The precipitated microorganisms may be introduced back into the denitrification reactor through the return pipe 6, recycled or collected, and used as fertilizer or compost for livestock.

In addition, all types of nitrogen can be removed by introducing photosynthetic microorganisms using the wastewater treatment method in the existing wastewater treatment apparatus.

In addition, the present invention provides a wastewater treatment apparatus using the wastewater treatment method consisting of the inlet source pipe, sedimentation tank, denitrification reaction tank, final sedimentation tank, treated water discharge pipe and return pipe.

The wastewater treatment apparatus of the present invention specifically discharges an inlet source pipe into which wastewater is introduced, a settling tank for precipitating suspended substances, a denitrification tank for removing nitrogen by photosynthetic microorganisms, a final settling tank for precipitating photosynthetic microorganisms, and wastewater from which nitrogen is removed. The treated water discharge pipe, characterized in that consisting of a return pipe for transporting photosynthetic microorganisms from the settling tank to the denitrification reactor.

The sewage or untreated wastewater treated by the conventional method is transferred to the sedimentation tank 2 through the inlet raw water pipe 1, and the suspended matter or suspended matter is settled and removed, and the suspended matter is already removed by the existing activated sludge method. If it is, it is possible to proceed directly to the denitrification tank (3) without passing through the settling tank (2).

In the denitrification reactor, growth of photosynthetic microorganisms can be controlled by attaching a light source, aeration device, and agitation device according to the state of influent (see FIG. 2 ).

In order to supply light, the denitrification reactor 3 may be provided with a device 7 capable of introducing sunlight or artificial light. During the day, the solar light is collected in a light collecting device using a reflector or the like and supplied to the reactor 3 at high brightness, and artificial light may be added at night or on a day when solar light is insufficient to sustain the growth of photosynthetic microorganisms. As the artificial light, fluorescent lamps, xenon lamps, halogen lamps, tungsten, mercury lamps, sodium lamps, metal halide lamps and light-emitting diodes or LEDs may be used.

In addition, the aeration device 9 may be installed at the bottom of the denitrification reactor 3 to supply air. The photosynthetic microorganism uses 0.03% of carbon dioxide contained in the supplied air as a carbon source, and the growth rate of the photosynthetic microorganism can be controlled by controlling the aeration amount and the aeration rate. In particular, in the case of microalgae, nitrogen can be fixed without being limited to the C / N ratio in the influent by simply giving up air. In addition, aeration increases the opportunity for photosynthetic microorganisms to utilize light by stirring the influent in the reactor, and consequently, the effect of increasing light transmittance can be seen.

Finally, the stirring device 8 evenly mixes the photosynthetic microorganism and the influent in the reaction tank 3 so that the nitrogen removal occurs everywhere in the reaction tank. In addition, by increasing the number of cells receiving light from the light source also serves to increase the utilization efficiency of light.

In addition, all types of nitrogen can be removed by introducing photosynthetic microorganisms using the wastewater treatment apparatus in the existing wastewater treatment apparatus.

In order to investigate the degree to which nitrogen is removed by photosynthetic microorganisms using the wastewater treatment apparatus including the denitrification reaction tank of the present invention as described above, a wastewater containing nitrogen is prepared and a microalga Chlorella kessleri ( Chlorella kessleri) is prepared. The degree of nitrogen removal was measured by incubating for 10 days.

When ammonia nitrogen was added at 140 mg / L, the concentration of chlorella cesery gradually increased, and at 10 days of incubation, the nitrogen concentration decreased to 24 mg / L to about 1/7 of the initial concentration ( FIGS. 3A and 3A ) . In the case of adding nitrate nitrogen at 140 mg / L, the concentration of Chlorella Kessler was gradually increased and the concentration of nitrogen decreased to about 1/14 of the initial concentration at 10 mg / L on the 10th day of culture. (See FIGS . 4A and 4B ). In addition, even when high concentrations of nitrate nitrogen were added at 140 mg / L, 280 mg / L, 700 mg / L and 1,400 mg / L, the growth of Chlorella Kessler was not inhibited and the higher the concentration of nitrate nitrogen was, Cell concentration was high and nitrogen removal was also high (see FIGS . 5A and 5B ).

As such, the present invention can effectively remove nitrogen without supplying additional organic carbon sources from wastewater containing a large amount of nitrogen by using a wastewater treatment apparatus including a denitrification reactor and photosynthetic microorganisms, as well as omitting an existing anaerobic tank. Sewage treatment costs can be reduced.

Hereinafter, the present invention will be described in detail by way of examples.

The following examples are merely illustrative of the present invention, but the content of the present invention is not limited to the following examples.

Example 1 Removal of Ammonia Nitrogen

In order to investigate the nitrogen removal rate using the wastewater treatment apparatus of the present invention, the following experiment was performed.

Artificial wastewater containing no carbon source was prepared by mixing metal ions such as ammonia nitrogen, phosphorus, iron, zinc, manganese, copper and aluminum of 140 mg NH ₄ -N / L.

The denitrification reactor of the present invention was filled with 400 ml of the wastewater prepared as described above, and then inoculated with a microalga Chlorella Kessler at a concentration of 1 × 10 ⁶ cells / ml. A fluorescent lamp was installed in the light source input device to irradiate 200 μmol m ⁻² sec ⁻¹ light, and aeration device was attached to supply air to the denitrification reactor at a rate of 400 mL / min.

225 mg / L phosphorus essential for the growth of Chlorella Kesslerley, 1.5 mg / L, 0.7275 mg / L, 3.6031 mg / L, 0.4657 mg / L and 0.2103 mg of iron, zinc, manganese, copper and aluminum as metal ions, respectively. It was added at a concentration of / L and incubated for 10 days at room temperature. 3A and 3B show the amount of ammonia nitrogen removed from the wastewater as the concentration of cultured Chlorella Kessler increased.

As shown in Figure 3a , Chlorella Kessler increased cell concentration after inoculation and grew to a concentration of 5 × 10 ⁷ cells / ml on day 10. In addition, as shown in Figure 3b the ammonia nitrogen in the waste water of the denitrification reactor gradually decreased with the number of days of cell culture, and decreased to about 1/7 to less than about 24 mg / L on day 10.

This is because Chlorella Kesselli causes a photosynthetic reaction using ammonia nitrogen in the wastewater of the denitrification tank and carbon dioxide and fluorescent light in the air introduced through the aeration device, so that ammonia nitrogen decreases with increasing cell concentration.

Example 2 Removal of Nitrate Nitrogen

In order to investigate whether the wastewater treatment apparatus of the present invention can remove other types of nitrogen, the following experiment was performed.

Wastewater preparation was prepared in the same manner as in Example 1 except that 140 mg NO ₃ -N / L of nitrate nitrogen was added instead of ammonia nitrogen. Chlorella Kessler was inoculated at a concentration of 1 × 10 ⁶ cells / ml at room temperature under the same conditions as in Example 1, incubated in a denitrification reactor for 10 days, and nitrate nitrogen was removed from the wastewater according to the concentration of the cultured Chlorella Kesslery. The amount is shown in FIGS . 4A and 4B .

As shown in 4a , the cell growth gradually increased with the cultivation days, and on the 10th day, the cells were grown at a concentration of about 8 × 10 ⁷ cells / ml. In addition, as shown in FIG . 4B , the nitrate nitrogen in the wastewater of the denitrification reactor gradually decreased with the days of cell culture, and decreased to about 1/14 at 10 days or less at 10 days. This indicates that as Chlorella Kessler grows, it caused a photosynthetic reaction and consumed nitrate nitrogen in the wastewater.

Example 3 Removal of Nitrate Nitrogen Added by Concentration

By increasing the concentration of nitrate nitrogen in the wastewater of Example 2 was investigated the growth rate of Chlorella Kessler and the decrease rate of nitrate nitrogen.

The experiment was conducted in the same manner and in the same manner as in Example 2, except that the concentration of nitrate nitrogen in the wastewater was 140 mg NO ₃ -N / L, 280 mg NO ₃ -N / L, 700 mg NO ₃ -N / L, and 1,400, respectively. Four kinds of wastewater were prepared by adding MG NO ₃ -N / L. Each wastewater was inoculated with Chlorella Kessler at a concentration of 1 × 10 ⁶ cells / ml and incubated at room temperature for 10 days.

As a result, as shown in Fig . 5a , the higher the concentration of nitrate nitrogen, the more active the cell growth, and the highest the cell concentration in the wastewater containing 1,400 mg NO ₃ -N / L. In addition, as shown in FIG . 5B , nitrate nitrogen gradually decreased with cell growth, and when nitrate nitrogen was added at 1,400 mg NO ₃ -N / L and 700 mg NO ₃ -N / L, respectively, after 10 days of 250 Nitrate nitrogen concentrations were reduced to 1/17 and 1/25 of the initial concentrations, respectively, with mg NO ₃ -N / L and 180 mg NO ₃ -N / L. When nitrate nitrogen was added at 280 mg NO ₃ -N / L and 140 mg NO ₃ -N / L, the concentration decreased to 20 mg / L and 10 mg / L, respectively. Decreased to 1/7.

This is because the higher the concentration of nitrate nitrogen, the more active the growth of photosynthetic microorganisms, the cell concentration increases and proportionally decreases the nitrate nitrogen.

As described above, the wastewater treatment method and treatment apparatus of the present invention provides a wastewater treatment apparatus including a denitrification reactor and uses photosynthetic microorganisms to supply nitrogen without supplying additional organic carbon sources from the wastewater containing a large amount of nitrogen. Not only can it remove more than 95%, but it can reduce the cost of sewage treatment by omitting the existing anaerobic tank, which can be useful for sewage treatment.

Claims (11)

1) removing the material causing suspension from the sewage water; 2) Anavena (Anabaena),Spirulina(Spirulina), Shineko Cocous (Synechococcus),Cinecossis(Synechocystis),Anassistis(Anacystis),Northstock(Nostoc)And Oscillatoria(Oscillatoria)Cyanobacteria; And chlorella (Chlorella),Dunariella(Dunalialla),Hematococcus(Haematococcus),Isocrysis(Isochrysis),Senedesmus(Scenedesmus),Chlamydomonas(Chlamydomonas),Porphyridium(Porphyridium)Removing nitrogen by culturing a photosynthetic microorganism selected from the group consisting of microalgae; And 3) sewage water treatment method comprising the step of precipitating the photosynthetic microorganisms in the final sedimentation tank and removing the treated water, wherein the nitrogen component is removed from the sewage water with low C / N ratio. The wastewater treatment according to claim 1, wherein the removal of the material causing suspension in step 1) is performed using a method selected from the group consisting of sieving, filtration, ultrafine filtration, dialysis, sedimentation, distillation and evaporation. Way. The method of claim 1, wherein the photosynthetic microorganism of step 2) is Chlorella keseri. delete delete delete delete delete delete delete delete