JP4854401B2 - Wastewater treatment tank - Google Patents

Description

  The present invention relates to a wastewater treatment tank, and more particularly to a wastewater treatment tank that can efficiently purify a large amount of wastewater containing ammonia nitrogen.

  For example, an electrostatic precipitator that removes dust generated from a boiler of a thermal power plant by static electricity is cleaned periodically or as necessary. The waste water generated at this time contains a large amount of ammonia nitrogen.

  Thus, it is necessary to discharge the waste water containing a large amount of ammonia nitrogen after removing the ammonia nitrogen based on the standards defined by laws and regulations.

  Conventionally, a method using water vapor is well known as a method for removing ammonia nitrogen. This method gasifies ammonia nitrogen by discharging water vapor into the wastewater to be treated and drives it into the air to reduce the nitrogen content in the wastewater.

  Further, a treatment apparatus using aerobic bacteria is known as a wastewater treatment. As shown in FIG. 5, the waste water containing ammonia nitrogen is temporarily stored in the storage tank 102 from the receiving pipe 101, and the waste water stored in the storage tank 102 is treated using aerobic bacteria through the pipe 103. It transfers to the apparatus 104, This process apparatus 104 removes ammonia nitrogen content, and it discharges | emits it.

  However, the above-described treatment method using water vapor has an advantage that ammonia nitrogen removal efficiency is high, but has a problem that the treatment cost increases. Further, the apparatus shown in FIG. 5 has a problem that the waste water in the storage tank 102 can be treated only by a predetermined amount, and the treatment efficiency is low.

  For this reason, a technique that can efficiently purify a large amount of wastewater containing ammonia nitrogen at low cost is desired.

Means for solving the above-mentioned problems in the present invention are a storage tank for storing wastewater containing ammonia nitrogen and a nitrification by aerobic microorganisms for the stored wastewater, and in the wastewater taken from the storage tank. Microbubble generator that generates microbubble-containing wastewater containing microbubbles of aerobic gas, stirring member that is driven and rotated in the wastewater stored in the storage tank, and generated by the microbubble generator And a jetting device for guiding the microbubble-containing wastewater into the stirring member and jetting it into the tank from a plurality of jetting ports formed in the stirring member , wherein the jetting port of the jetting device is a bottom portion of the storage tank. directed to waste water treatment tank, wherein Rukoto is turbid debris aerobic microorganisms to accumulate in the storage tank bottom in the waste water A.

  According to the present invention, since denitrification treatment can be performed in a wastewater treatment tank in which a large amount of wastewater is stored, it is possible to purify a large amount of wastewater at a time, and to treat wastewater containing microbubbles with a microbubble generator. Since it is discharged into the tank and agitated, oxygen can be sufficiently dissolved in the wastewater, and aerobic bacteria can be promoted to remove nitrogen content in the wastewater with high efficiency.

  Embodiments of a wastewater treatment tank according to the present invention will be described below with reference to FIGS. In this example, the waste water treatment tank 10 is used as a waste water treatment facility for a thermal power plant, and treats waste water from an electrostatic precipitator, cleaning water for a smoke pipe, and ammonia production facility.

  FIG. 1 is a schematic diagram showing a wastewater treatment facility using a wastewater treatment tank according to an embodiment.

  In this example, as shown in FIG. 1, the thermal power plant has three waste water treatment tanks having the same configuration, that is, a first waste water treatment tank 10-1 and a second waste water treatment device. A treatment tank 10-2 and a third wastewater treatment tank 10-3 are provided. In this example, waste water containing ammonia nitrogen is treated by sequentially using these three waste water treatment tanks 10-1, 10-2, 10-3. And in each waste water treatment tank 10-1,10-2,10-3, storage tank 20-1,20-2,20-3, microbubble generating part 30-1,30-2,30-3, Denitrification tanks 50-1, 50-2, 50-3, which are denitrification apparatuses, are arranged, and storage tanks 20-1, 20-2, 20- are provided by valves 60-1, 60-2, 60-3. 3 is selected to allow drainage to flow.

  Here, each storage tank 20-1, 20-2, 20-3 is a substantially cylindrical hollow structure capable of storing 1500 tons of waste water. In this example, the waste water from the thermal power plant is discharged in sequence by the opening / closing operation of the valves 60-1, 60-2, 60-3, the first storage tank 20-1, the second storage tank 20-2, 3 is stored in the storage tank 20-3, and waste water treatment is sequentially performed. That is, wastewater is stored in the first storage tank 20-1, and when the first storage tank 20-1 is full, the microbubble generator 30-1 is operated to perform processing, and this processing is necessary. It is performed for a long time, for example, several tens of hours, and the purification process is terminated and discharged.

  The waste water generated during the purification process of the first storage tank 20-1 is stored in the second storage tank 20-2, and when the storage tank 20-2 becomes full, Purify wastewater stored in Similarly, during the purification of the waste water in the second storage tank 20-2, it is stored in the third storage tank 20-3, and when the storage tank 20-3 becomes full, the purification process is performed. First, the waste water is stored in the first storage tank 20-1 that has been emptied after the purification process is completed. In this manner, the storage and purification processes are sequentially performed in the first wastewater treatment tank 10-1, the second wastewater treatment tank 10-2, and the third wastewater treatment tank 10-3. As a result, the waste water from the power plant can be continuously stored and purified. Next, each waste water treatment tank 10 will be described.

  FIG. 2 is a schematic diagram illustrating a configuration of the wastewater treatment tank according to the embodiment.

  The waste water treatment tank 10 according to this example includes a storage tank 20 in which waste water containing ammonia nitrogen is stored, and a microbubble of air as a gas containing oxygen in the waste water taken from the storage tank 20. A microbubble generating unit 30 that creates microbubble-containing wastewater, an ejection device 40 that ejects the microbubble-containing wastewater to the storage tank 20, and a denitrification device that denitrifies the wastewater from the storage tank 20 with anaerobic bacteria. And a denitrification tank 50. In this example, the ejection device 40 is provided with a stirring pipe 45 that is driven to rotate in the storage tank 20 and serves as a stirring member for stirring the waste water.

  The storage tank 20 is provided with a receiving pipe 11 at an upper portion thereof, and wastewater to be treated flows into the storage tank 20 from the receiving pipe 11.

  Further, the wastewater in the storage tank 20 is guided to the microbubble generating unit 30 through the pipe 12 and is further ejected from the ejection device 40 to the storage tank 20.

  The storage tank 20 is provided with a discharge pipe 13 at a lower portion thereof, and the waste water treated in the storage tank 20 is guided from the discharge pipe 13 to the denitrification tank 50. Then, the waste water denitrified in the denitrification tank 50 is transferred to a subsequent waste water treatment device through the pipe 14.

  The microbubble generator 30 includes a microbubble generator 31 and a pump 32 that takes in the wastewater into the microbubble generator 31.

  The microbubble generating unit 30 uses air as an aerobic gas, and generates microbubble mixed wastewater in which microbubbles of air are mixed into the wastewater.

  Here, the microbubble is “a very fine bubble having a bubble diameter of about 10 to 40 μm at the time of generation”. For example, the publication “Water Engineering Papers” (issued by the Japan Society of Civil Engineers, No. 46, No. 1163). 1168, issued February 2002). Such microbubbles, unlike ordinary air bubbles of a millimeter size or larger, remain in water for a long time and have a large surface area, so that oxygen in the microbubbles dissolves in water efficiently. For this reason, the reproduction of aerobic bacteria in water can be made extremely good.

  The microbubble generator 31 is well known, and for example, in a high centrifugal force field generated by rotating a liquid, air and liquid are mixed to generate microbubble mixed waste water.

  FIG. 3 is a schematic view showing the internal structure of the waste water treatment tank according to the embodiment, and FIG. 4 is a cross-sectional view corresponding to the line CC in FIG. 3 showing the structure of the stirring pipe.

  The ejection device 40 includes a pipe 41 for leading out microbubble mixed wastewater generated by the microbubble generator 30 and a jet pump 42 for discharging the wastewater mixed with microbubbles at high pressure. In addition, the ejection device 40 is provided with a rotary base 43 disposed on the bottom 21 of the storage tank 20, a rotary shaft 44 standing on the rotary base 43, and radially arranged in four directions from the rotary shaft 44. The stirring pipe 45 is provided.

  In this example, the rotary base 43 is configured by arranging a passage through which pressurized microbubble mixed waste water from the jet pump 42 can be conducted to the stirring pipe 45. The rotation base 43 is configured to rotationally drive four stirring pipes 45 attached to the rotation shaft 44 in a predetermined direction at a predetermined rotation speed. Thereby, the waste water in the storage tank 20 is agitated as shown by an arrow b in FIG.

  The stirring pipe 45 is formed with a plurality of substantially cylindrical ejection nozzles 46 which are ejection ports, and the ejection nozzles 46 are lowered downward by θ (for example, 45 °) from the horizontal direction as shown in FIG. Directed and ejected microbubble-containing wastewater is jetted in the direction of arrow a in FIGS. 3 and 4 toward the bottom 21 of the storage tank 20.

  By ejecting the microbubble-mixed waste water toward the bottom portion 21, the aerobic bacterial debris that tends to settle on the bottom portion 21 is rolled up above the storage tank 20 and becomes turbid in the waste water, and accumulates in the bottom portion 21. do not do. Moreover, the waste water in the storage tank 20 is further agitated by the jet flow from the ejection nozzle 46.

  In this example, since a large amount of oxygen is dissolved from the microbubbles in the waste water in the storage tank 20, aerobic bacteria propagate well. For this reason, ammonia nitrogen in the waste water is decomposed with high efficiency into nitrite nitrogen and further nitrate nitrogen by aerobic bacteria.

  In addition, such decomposition of ammonia nitrogen is performed in a single stroke for a large amount of wastewater stored in the storage tank 20, and a large amount of wastewater can be processed at a time.

  When the nitrification by the storage tank 20 is completed, the waste water is discharged to the denitrification tank 50.

  The denitrification tank 50 denitrifies the treated waste water. That is, in the denitrification tank 50, a denitrifying bacterium which is a kind of facultative anaerobic bacterium in an oxygen-free state reduces nitrite nitrogen and nitrate nitrogen to nitrogen gas and the like, and denitrifies the waste water. As a result, the nitrification and denitrification treatment of the wastewater is completed, and the nitrogen in the wastewater is reduced to a reference value or less.

  As described above, according to the wastewater treatment tank of the present invention, a large amount of wastewater can be treated with high efficiency in a thermal power plant, and it can be implemented at low cost without using a steam generator or the like.

  In the above example, the case where three wastewater treatment tanks are arranged and used sequentially has been described, but the wastewater can be purified with one wastewater treatment tank.

  In the above example, the ejection nozzle is provided in the stirring pipe which is the stirring member. However, the ejection nozzle may be provided separately from the stirring member.

It is a schematic diagram which shows the waste water treatment facility which uses the waste water treatment tank which concerns on embodiment. It is a schematic diagram which shows the structure of the waste water treatment tank which concerns on embodiment. It is a schematic diagram which shows the structure inside the waste water treatment tank which concerns on embodiment. It is sectional drawing equivalent to the CC line in FIG. 3 which shows the structure of an ejection pipe. It is a schematic diagram which shows the example of the conventional waste water treatment equipment.

Explanation of symbols

10 Wastewater treatment tank 20 Storage tank 21 Bottom 30 Microbubble generator (microbubble generator)
40 Jetting device 45 Stirring pipe (stirring member)
50 Denitrification tank (denitrification equipment)

Claims (3)

A storage tank for storing wastewater containing ammonia nitrogen and nitrifying the stored wastewater with aerobic microorganisms;
A microbubble generator for generating microbubble-containing wastewater containing microbubbles of aerobic gas in wastewater taken from the storage tank;
A stirring member that is driven and rotated in the wastewater stored in the storage tank;
A jetting device that guides the microbubble-containing wastewater generated by the microbubble generating device into the stirring member and jets it into the tank from a plurality of jets formed in the stirring member;
And a jet port of the jetting device is directed to the bottom of the storage tank, and the debris of aerobic microorganisms accumulated at the bottom of the storage tank is turbid in the drainage. The wastewater treatment tank according to claim 1, wherein the aerobic gas is air. The wastewater treatment tank according to claim 1 or 2 , further comprising a denitrification device that performs a denitrification treatment with a facultative anaerobic microorganism on the nitrified wastewater.

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