KR20050098051A - System for biological sewage treatment - Google Patents

Abstract

The present invention relates to a biological wastewater treatment apparatus that can effectively remove nutrients such as nitrogen contained in the wastewater without supply of an external carbon source.

Biological sewage treatment apparatus according to the present invention comprises a reaction tank having a predetermined space of a closed type; and a plurality of carriers provided in the reaction tank, the microorganism is attached to the surface; and one side of the reaction tank is provided with hydrogen gas into the reactor It characterized in that it comprises a hydrogen gas supply device for supplying.

Description

Biological sewage treatment device {system for biological sewage treatment}

The present invention relates to a biological wastewater treatment apparatus, and more particularly, to a biological wastewater treatment apparatus capable of effectively removing nutrients such as nitrogen contained in the wastewater without supplying an external carbon source.

Sewage treatment is aimed at removing contaminants contained in sewage and is classified into primary treatment, secondary treatment and tertiary treatment according to the treatment method. Primary treatment is a method of physically removing suspended solids or sedimentary substances in the sewage system, such as gravity sedimentation and flotation, which usually includes the process from the sewage treatment plant to the initial sedimentation basin. Secondary treatment is mainly used for biological treatment for the purpose of removing organic matter dissolved in sewage and organic solids not treated in the first treatment. Tertiary treatment is a highly advanced process that combines physical, chemical, and biological treatments to remove nutrients such as nitrogen and phosphorus in addition to organics not removed in the secondary treatment.

On the other hand, the tertiary treatment method for removing nutrients include a physical method, a chemical method and a biological method, the physical method and the chemical method is expensive to process, there is a problem of secondary pollution, and the operation process is complicated and advanced It is difficult to commercialize because it requires technology. For these economic and operational reasons, biological methods are widely used as nutrient removal methods.

Representative biological tertiary treatment is activated sludge method. Activated sludge is a wastewater treatment method applied for the secondary treatment of wastewater treated primarily or for complete treatment of wastewater not subjected to primary treatment. According to the general activated sludge method, as the waste water is continuously injected into the aeration tank, the microorganisms grow as the microorganism ingests and decomposes organic matter in the wastewater and proceeds to nitrification. Part of is returned to the aeration tank in the form of activated sludge, and some waste sludge is discarded, so that the amount of microorganisms in the aeration tank is maintained at an appropriate level to remove nitrogen, phosphorus, etc. together with organic matter decomposition in the waste water.

It has long been recognized that such activated sludge method has an excellent effect on the treatment of organic matter in wastewater, but it is not suitable to effectively remove organic matter and nitrogen from wastewater containing high concentrations of organic matter and nitrogen, and the amount of excess sludge increases. I have a problem. Therefore, in the sewage treatment plant based on the activated sludge method, organic matter is mainly removed, and nutrients such as nitrogen are discharged in an untreated state.

Various methods have been proposed to remove nutrients such as nitrogen, which can be broadly classified into A ₂ O (Anaerobic-Anoxic-Oxic) series, SBR (Sequencing Batch Reactor) series, carrier and media based methods. Most of these methods take the method of removing nitrogen depending on the organic load of the influent, and the process is briefly described as follows.

Ammonia contained in the influent decomposes nitrogen through nitrification and denitrification. First, ammonia is nitrified by nitrosomonas, an autotrophic bacterium. It is oxidized to nitrogen (NO ₂ ⁻ ) and the nitrite nitrogen is oxidized to nitric acid (NO ₃ ⁻ ) by a nitrobacter. Subsequently, in the denitrification process, the nitrate oxygen is converted into nitrate oxygen into nitrogen gas using heterogeneous bacteria as an electron acceptor in an anoxic tank.

Nitrification ^{_{process: NH 4 + -> NO 2}} - -> NO 3 -

^{_{Denitrification: NO 3 - -> NO 2}} - -> N 2

Recently, the nitrification-denitritation process which improved the nitrification-denitrification process and the Sharon process for nitrifying through selective growth of species by temperature and the ammonium and nitrite in association with the Sharon process The Anamox (ANAMOX) process, which proceeds with denitrification under conditions, has been proposed as a nitrogen removal method.

However, the biological treatment method for removing nitrogen depending on the organic load in this way has the following limitations. First, the nitrification process requires a large amount of oxygen (4.6 gO ₂ / g-NH ₄ -N) and slows the growth rate of nitrifying microorganisms. In addition, in order to denitrify after nitrification, a large amount of organic matter (about 4g-BOD / g-NO ₃ -N) is required, which is a big problem when BOD of sewage is low as in the case of Korea. In other words, the total nitrogen removal efficiency of the biological treatment method is determined by the ratio of organic carbon source / nitrogen and the return ratio.In case of lack of organic matter, an external carbon source must be supplied. In addition, there are disadvantages that are affected by various environments.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a biological sewage treatment apparatus that can effectively remove nutrients such as nitrogen contained in sewage or secondary treated water without supply of an external carbon source. have.

Biological wastewater treatment apparatus according to the present invention for achieving the above object is a reaction tank having a predetermined space of a closed type; and a plurality of carriers provided in the reaction tank, the microorganism is attached to the surface; and provided on one side of the reaction tank It characterized in that it comprises a hydrogen gas supply device for supplying hydrogen gas into the reactor.

Preferably, the carrier is made of porous synthetic resin, for example, may be composed of polyurethane.

Preferably, the hydrogen gas supply device is composed of a gas cylinder which is a hydrogen gas storage device, or an electrolysis device having an anode and a cathode and a membrane for preventing cation migration between the anode and the cathode. Can be.

Preferably, an acid pipe which is a hydrogen gas supply pipe is further provided between the reactor and the hydrogen gas supply device, and the acid pipe may be formed of a silicon tube or a membrane diffuser.

Preferably, it may be configured to further include a carbon dioxide supply device which is provided on one side of the reaction tank to selectively supply carbon dioxide into the reaction tank to adjust the pH in the reaction tank.

Preferably, it may be configured to further include a flow rate adjusting tank which is provided at the front end of the reaction tank to serve to control the flow rate of the waste water flowing into the reaction tank.

According to the characteristics of the present invention, by using the hydrogen gas in the form of molecules as an electron donor in performing the biological denitrification process, it is possible to effectively solve the problems such as lack of organic matter in the sewage, and the denitrification process according to the simplified denitrification process The amount of hydrogen gas that is introduced can be minimized.

Hereinafter, a biological sewage treatment apparatus according to the present invention will be described in detail with reference to the accompanying drawings. 1 is a block diagram of a biological sewage treatment apparatus according to the present invention.

First, as shown in FIG. 1, the biological sewage treatment apparatus 100 according to the present invention first includes a reaction tank 110 having a predetermined reaction space therein. Here, the reaction refers to the denitrification process by the microorganism. The carrier 110 is provided with a plurality of carriers 111 having a predetermined shape. The carrier 111 is a porous synthetic resin, for example, may be composed of a polyurethane material, and the preferred size of each carrier 111 is about 10 to 14 mm high, 10 to 14 mm long, and about 10 to 14 mm wide (see FIG. 3). ). Microorganisms such as autohydrogeno trophic denitrifiers are attached to the surfaces of the carriers 111. The autotrophic hydrogen denitrification bacteria grow on the surface of the porous carrier 111 by using the nitric acid component contained in the wastewater flowing into the reactor 110.

One side of the reaction tank 110 is provided with a hydrogen gas supply device 120. Hydrogen gas is supplied from the hydrogen gas supply device 120 into the reactor 110, wherein the hydrogen gas means hydrogen in a molecular form. In addition, between the hydrogen gas supply device 120 and the reactor 110, a hydrogen gas supply pipe is provided with an diffuser 114. The hydrogen gas supplied from the hydrogen gas supply device 120 has high reactivity, so stability is considered. Thus, the diffuser 114 may be composed of a silicon tube or a membrane diffuser.

Meanwhile, the hydrogen gas supply device 120 may use a cylinder, which is a conventional gas storage device, and may use an electrolysis device that may generate hydrogen gas in addition to the cylinder. When using an electrolysis device may have a configuration as shown in FIG. Referring to FIG. 2, an electrolysis apparatus according to the present invention includes an electrolytic cell 121 having an electrolytic space, and an anode 122 and a cathode 123 electrically decomposing water contained in the electrolytic cell 121. It consists of. Here, the cathode 123 may be made of a carbon material, and a predetermined film may be used to prevent oxygen ions generated from the anode 122 from being mixed with hydrogen ions generated from the cathode 123 by decomposition of the water. A cation exchange membrane 124 may be provided between the cathode 123 and the anode 122.

One side of the reaction tank 110 may be provided with a carbon dioxide supply device. The carbon dioxide supply device serves to adjust the pH of the reaction tank 110, specifically, the hydrogen gas flows into the reaction tank 110 from the hydrogen gas supply device 120 and between the hydrogen gas and the nitric acid material. During the chemical reaction process, the pH inside the reactor 110 is changed fluidly. Therefore, it is necessary to properly maintain the pH inside the reactor 110 and a predetermined amount of carbon dioxide is supplied from the carbon dioxide supply device 130 for a proper level of pH. On the other hand, exactly the front end of the reaction tank 110, the front end of the waste water supply pipe 112 is provided with a flow rate adjustment tank can be appropriately adjusted the amount of waste water flowing into the reaction tank (110). In addition, one side of the reaction tank 110 is provided with a treated water discharge pipe 113 for discharging the treated water is completed nitric acid process.

Looking at the operating principle of the biological sewage treatment apparatus 100 according to the present invention having such a configuration as follows.

First, in a state in which a plurality of carriers 111 are filled in the reaction tank 110 and the wastewater is supplied into the reaction tank 110 through the wastewater supply pipe 112, the hydrogen gas supply device 120 forms a molecular form. When hydrogen gas is supplied into the reaction tank 110 through the acid pipe 114, the nitric acid material contained in the wastewater by microorganisms attached to the surface of the carrier 111 is represented by <Formula 1> and <Formula 2> is reduced through the denitrification process.

<Equation 1>

^{_{(1): 2NO 3 - +}} 2H 2 => 2NO 2 - + 2H 2 O

<Equation 2>

^{_{(2): 2NO 2 - +}} 3H 2 + 2H + => N 2 + 4H 2 O

<Equation 3>

(1) + (2): 2NO 3 - + 5H 2 + 2H + => N 2 + 6H 2 O

It can be seen that the hydrogen gas serves as an electron donor through the processes of <Equation 1> to <Equation 3>, referring to <Equation 3> which is the total reaction of <Equation 1> and <Equation 2>, nitrate material of 1g ^- of the hydrogen gas required to remove (NO ₃ -N) the amount it can be seen that not only about 0.357g. These results indicate that in the conventional nitrification-denitrification process, about 4 g of organic matter is required for nitrification of 1 g of ammonium and about 4 g of organic matter for denitrification of 1 g of nitric acid material. In addition, the denitrification process of <Equation 1> and <Equation 2> is significantly simplified compared to the conventional nitrification and denitrification process NO ₃ ^- => NO ₂ ^- => NO => N ₂ O => N ₂ Able to know.

The mechanism of hydrogen generation and denitrification by electrolysis according to the present invention is expressed in terms of stoichiometry, as shown in FIGS. 5 and 6 below.

<Equation 4>

^{_{2NO 3 - + 5H 2 + 2H}} + => N 2 + 6H 2 O

<Equation 5>

_{10e + 10H 2 O => 5H} 2 + 10OH - (Cathodic reaction)

_{^{10e + 2NO 3 - + 12H +}} => N 2 + 6H 2 O

5H ₂ O => 5 / 2O ₂ + 10H ⁺ 10e (Anodic reaction)

<Equation 6>

^{_{Net reaction: 2NO 3 - + 2H}} + => N 2 + 5 / 2O 2 + H 2 O

On the other hand, according to the biological sewage treatment apparatus 100 according to the present invention can achieve a high denitrification rate of about 90% or more over time as shown in FIG.

The biological sewage treatment apparatus according to the present invention has the following effects.

In the biological denitrification process, the use of molecular hydrogen gas as an electron donor can effectively solve problems such as lack of organic matter in sewage water, and minimize the amount of hydrogen gas required for denitrification by simplifying the denitrification process. can do.

In addition, the use of the electrochemical method facilitates the control of the reaction and prevents the problem of secondary contamination due to the organic material injection.

1A is a perspective view of a biological sewage treatment apparatus according to the present invention.

1B is a front view of the biological sewage treatment apparatus according to the present invention.

Figure 2 is a cross-sectional configuration of the electrolysis device applied to the present invention.

Figure 3 is a photograph showing the real of the carrier applied to the present invention.

Figure 4 is a graph showing the denitrification rate measured using a biological sewage treatment apparatus according to the present invention.

Figure 5 is a reference diagram for explaining the mechanism of hydrogen generation and denitrification process by electrolysis according to the present invention.

Description of the main parts of the drawing

100: biological sewage treatment apparatus

110 reactor 111 carrier

112: wastewater supply pipe 113: treated water discharge pipe

114: diffuser 120: hydrogen gas supply device

121: electrolytic cell 122: anode

123: cathode 124: membrane

130: carbon dioxide supply unit

Claims (10)

Reactor having a predetermined space of the closed type; A plurality of carriers provided in the reaction tank and having microorganisms attached thereto; Biological wastewater treatment apparatus is provided on one side of the reaction tank comprises a hydrogen gas supply device for supplying hydrogen gas into the reaction tank. The biological sewage treatment apparatus according to claim 1, wherein the carrier is made of a porous synthetic resin. 3. The biological sewage treatment apparatus according to claim 1 or 2, wherein the carrier is made of polyurethane. The biological sewage treatment apparatus of claim 1, wherein the hydrogen gas supply device comprises a gas cylinder which is a hydrogen gas storage device. The biological wastewater treatment apparatus of claim 1, wherein the hydrogen gas supply device comprises an electrolysis device having an anode and a cathode and a membrane for preventing cation migration between the anode and the cathode. 6. The biological sewage treatment apparatus of claim 5, wherein the cathode is made of carbon material. The biological sewage treatment apparatus according to claim 1 or 5, further comprising an acid pipe which is a hydrogen gas supply pipe between the reactor and the hydrogen gas supply device. 8. The biological sewage treatment apparatus of claim 7, wherein the diffuser comprises a silicon tube or a membrane diffuser. The biological sewage treatment apparatus of claim 1, further comprising a carbon dioxide supply device provided at one side of the reactor to selectively supply carbon dioxide into the reactor to adjust pH in the reactor. . 2. The biological sewage treatment apparatus of claim 1, further comprising a flow rate adjusting tank provided at a front end of the reaction tank to adjust a flow rate of the wastewater flowing into the reaction tank.