JP5766643B2 - Water biological treatment equipment - Google Patents

Description

  The present invention relates to a biological treatment apparatus for water, and more particularly to an apparatus for biological treatment of raw water containing suspending substances (SS), ammonia, dissolved organic matter (DOC), and the like.

There are a wide variety of water sources such as river water, lake water, and groundwater, but the quality of the water source is not always good. In areas where agriculture and livestock industry are thriving upstream of the water source, or areas where factory wastewater is discharged with insufficient treatment, raw water may contain nitrogen, organic matter, phosphorus, and other chemical substances.

  Usually, water purification treatment and industrial water treatment are mainly composed of a combination of flocculation treatment, precipitation treatment, filtration treatment, and disinfection treatment because the main purpose is to remove suspended substances (SS). SS and phosphorus are removed by these processes, but contaminants such as ammonia (ammonium ions) and dissolved organic matter (DOC) are hardly removed.

  Biological treatment methods are available as methods for removing these contaminants. In the biological treatment method, activated carbon, anthracite, sand, ceramics, or a plastic filter medium (microorganism carrier) is filled in an apparatus, and raw water is passed through to grow microorganisms on the carrier for treatment. When the concentration of pollutants in the raw water is high, air is aerated from the bottom while passing the raw water to supply oxygen necessary for the treatment. If the pollutant concentration of raw water is higher, anaerobic treatment may be performed.

  There are a fixed bed type and a fluidized bed type as a contact method between raw water and a microorganism carrier in a biological treatment apparatus. The fixed bed type is excellent in application to raw water with less SS, and has the advantage that biological treatment and SS removal can be performed simultaneously. On the other hand, when applied to raw water with a high SS, the water flow resistance of the fixed floor easily rises, so there is a demerit that the frequency of washing the fixed floor increases and the water treatment efficiency decreases. The fluidized bed type has an advantage that the reaction tank volume can be reduced because the contact efficiency of the microorganism carrier and the raw water is high and the reaction rate is high. In addition, since most of the raw water SS passes through without being captured in the fluidized bed, continuous treatment for a long time is possible even when applied to raw water with high SS.

  In order to fully exhibit the high performance of the fixed bed and fluidized bed, it is important to uniformly supply water and air supplied to the apparatus to the entire tank so as not to cause dead space and drift. For this purpose, a gas-liquid distribution device for gas and liquid is provided at the bottom of the device, and structural contrivances are made so that water and air are uniformly discharged over the entire tank.

  A classic technique is to stack several types of gravel with different particle sizes at the bottom of the tank (gravel support floor), insert water and / or air introduction pipes into the gravel layer, and provide uniform discharge holes in the introduction pipes Has been. Furthermore, in recent years, there have been cases where a gas-liquid distribution structure instead of a supporting gravel floor is used, and the combined use of this with a gravel supporting floor is also recognized (Patent Document 1, Non-Patent Documents 1 to 3). These gas-liquid distributors are provided with an air introduction part, a water introduction part, an orifice, an internal partition, and the like, and a perforated plate or a granular material is laid on the upper part to prevent the filter medium from falling. Further, the water introduction part often serves as a water collection function for treated water. Such ingenuity makes it possible to discharge water and air uniformly. However, the continuous operation time required for water treatment equipment is not a short period but a long period of several years. As a result, even if the operation is stable on a monthly basis, there are cases where failures such as blockage of the gas-liquid distribution device and an increase in pressure loss occur with the operation of the annual operation. One reason for this is clogging by the raw water SS itself, but in many cases, it is the propagation of microorganisms inside the gas-liquid distributor, that is, microbial contamination. This type of obstacle is particularly likely to occur in upflow fixed beds and upward fluidized beds where raw water flows upward. The reason is due to contact with raw water before treatment having a high degree of contamination. As a means to prevent troubles caused by microbial contamination, water washing (water washing) is performed in such a manner that water flows at a high speed in the opposite direction to the inside of the gas-liquid distributor, and water washing is simultaneously performed while supplying a large amount of air (water washing ) And other physical cleaning operations are performed. As a result, the performance of the apparatus is restored, but the effect is limited to a temporary effect and often does not reach long-term stable operation. In that case, disassembly and cleaning of the gas-liquid distributor and chemical cleaning with a disinfectant and slime remover are necessary as the final means, and the apparatus must be stopped for a long time, increasing the cleaning cost.

  Removal of microbial contamination generated at the bottom of a tank in a biological treatment apparatus is a difficult task. This is because chemicals used in chemical cleaning are sodium hypochlorite, sulfuric acid, sodium hydroxide, and the like, which are highly toxic to microorganisms. These chemicals cause great damage not only to contaminating microorganisms but also to microorganisms held on the carrier, and in the worst case, there is a risk of losing most of the functions of the biological treatment apparatus.

  Further, depending on the material of the carrier, the strength of the carrier itself may be impaired by chemicals, and secondary troubles such as collapse of the carrier may occur. For example, when activated carbon is used as a microbial carrier and sodium hypochlorite is used as a drug, sodium hypochlorite reduces not only the contaminating microorganisms but also the strength of the activated carbon itself, necessitating replacement of the activated carbon.

  In order to clean the gas-liquid distributor, inject sodium hypochlorite into the gas-liquid distributor via the liquid introduction line, drain after standing for a certain period of time, and flush the residual chemicals by washing with water several times. Has been done. However, chemicals always diffuse naturally. Therefore, in order to ensure the soundness of the microorganisms held on the carrier, it is difficult to treat with a sufficient concentration of chemicals for a sufficient time, and the resulting cleaning effect is often insufficient.

Japanese Patent No. 4299396

Water ing Co., Ltd. “Collector Trilateral” catalog Waterworks Kiko Co., Ltd. “Suioh Tetra Block” catalog Shinko Environmental Solution Co., Ltd. “Upward flow biological contact filtration equipment” catalog http://www.jsim.or.jp/newsPDF/kankyo05.pdf

  The present invention avoids or damages caused by microorganisms growing on a microorganism holding carrier and / or chemicals of the microorganism holding carrier when the gas-liquid distributor is chemically washed in a fixed bed type or fluidized bed type biological treatment apparatus. It is an object of the present invention to provide a water biological treatment apparatus that can minimize and maintain the function of the water treatment apparatus stably.

  According to the present invention, a water organism comprising: a microbial carrier layer filled with a microbial carrier therein; and a gas-liquid distribution device that uniformly introduces a gas and / or liquid into the microbial carrier layer. A treatment device, provided between the microorganism carrier layer and the gas-liquid distribution device, provided with a microorganism carrier protective layer that prevents the cleaning chemical solution from diffusing into the microorganism carrier layer; There is provided a water biological treatment apparatus characterized in that a water injection and flushing mechanism is provided.

  The microbial carrier protective layer is preferably made of a granular material and / or a perforated plate.

  According to the biological treatment apparatus for water of the present invention, the prevention of microbial contamination in the gas-liquid distribution apparatus and the cleaning recovery property thereof are improved. The present invention is effective for both a fixed bed and a fluidized bed, and provides a great effect particularly when applied to an upward flow water treatment.

FIG. 1 is a schematic explanatory view showing an embodiment of a water biological treatment apparatus according to the present invention. FIG. 2 is a schematic explanatory view showing another embodiment of the upward flow type fluidized bed biological treatment apparatus. FIG. 3 is a schematic explanatory view showing an embodiment of a downflow fixed-bed biological treatment apparatus. FIG. 4 is a schematic explanatory diagram showing a trilateral configuration that can be used as a gas-liquid distributor. FIG. 5 is a cross-sectional view of the trilateral shown in FIG.

Embodiment

Hereinafter, the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto.
FIG. 1 is a schematic explanatory view showing an embodiment of the present invention. In FIG. 1, a biological treatment apparatus 1 for water includes a microbial carrier layer 2 in which a microbial carrier is filled, and a gas-liquid distribution device that uniformly introduces a gas and / or liquid into the microbial carrier layer 2. And 5. The apparatus shown in FIG. 1 is provided with a gas-liquid distribution apparatus 5 at the bottom of the apparatus, the microorganism carrier layer 2 is positioned above the gas-liquid distribution apparatus 5, and raw water and air are introduced from the lower part of the apparatus so that the inside of the apparatus faces upward. This is an upward flow type fluidized bed biological treatment apparatus. The raw water inflow line 6 for supplying the raw water and the air inflow line 7 for supplying the air are connected so that the raw water and the air pass through the gas-liquid distributor 5. The air inflow line 7 is used not only for introducing cleaning air for cleaning the microorganism carrier 2 and the gas-liquid distribution device 5, but also for introducing air for aerobic treatment when the concentration of pollutants in the raw water is high. The Between the microorganism carrier layer 2 and the gas-liquid distributor 5, there is provided a microorganism carrier protective layer 3 that prevents the cleaning chemical solution from diffusing into the microorganism carrier layer 2. The microorganism carrier protective layer 3 is a porous plate material made of chemically resistant ceramics or reinforced plastic, and prevents the microorganism carrier from falling and disperses water and air from the gas-liquid distributor 5 to the microorganism carrier. A chemical injection line 10 for introducing a chemical solution for cleaning the gas-liquid distribution device 5 is connected between the microorganism carrier protective layer 3 and the gas-liquid distribution device 5. The gas-liquid distributor 5 is provided with a flushing mechanism for flushing the remaining chemical liquid. The flushing mechanism in the apparatus shown in FIG. 1 is a mechanism that flushes residual chemicals by supplying flushing water from a flushing line 11 connected to the raw water inflow line 6. This embodiment is suitable for supplying a cleaning chemical after draining water below the bottom of the microorganism carrier layer 2. In this case, the flushing water is supplied at a lower level than the bottom of the microorganism carrier layer 2 of the biological treatment apparatus 1. A discharge line 8 for discharging the waste water after the chemical liquid cleaning process of the gas-liquid distributor 5 and the waste water from the biological treatment apparatus 1 is also connected to the lower part of the apparatus where the gas-liquid distributor 5 is positioned. Reference numeral 9 denotes a chemical solution storage tank for storing the cleaning chemical solution, which is connected to the chemical injection line 10. Reference numeral 13 denotes an outflow line for treated water and washing waste water, which discharges overflow water from the biological treatment apparatus 1. Reference numeral 12 denotes an intermediate discharge line for washing waste water. The intermediate discharge line is used for shortening the drainage time when draining the cleaning wastewater staying at the top of the biological treatment apparatus 1 during normal cleaning of the microorganism carrier layer 2 (without using a chemical solution). .

  FIG. 2 is a schematic explanatory view showing another embodiment of the upward flow type fluidized bed biological treatment apparatus. In the biological treatment apparatus shown in FIG. 2, the description of the same configuration as that of the biological treatment apparatus shown in FIG. 1 is omitted. In FIG. 2, the microorganism carrier protective layer 3 is filled with inert particles such as gravel, ceramic particles, and reinforced plastic particles. Further, the flushing mechanism is connected to the cleaning chemical solution inflow line 10 and can flush not only the gas-liquid distributor 5 but also the cleaning chemical solution inflow line. This aspect is suitable for the case where flushing is performed after water is completely drained from the biological treatment apparatus 1. In this case, the flushing water is supplied at a lower level than the bottom of the microorganism carrier layer 2.

  FIG. 3 is a schematic explanatory view showing an embodiment of a downflow fixed-bed biological treatment apparatus. In the biological treatment apparatus 1A for water, raw water flows from the upper part of the biological treatment apparatus 1A via the raw water inflow line 6, and the treated water flows out from the lower part of the biological treatment apparatus 1A via the discharge line 8. Reference numeral 13 denotes an outflow line for washing wastewater, which discharges overflow water at the top of the biological treatment apparatus 1A. Reference numeral 14 denotes a washing water inflow line connected to the bottom of the biological treatment apparatus 1A. The cleaning chemical solution is supplied from the chemical injection line 10 and is passed through the washing water inflow line 14 to be used for cleaning the gas-liquid distributor 5. The

  As the microbial carrier that can be used in the biological treatment apparatus of the present invention, a microbial carrier used in a normal biological treatment apparatus can be used without particular limitation, and granular activated carbon, ceramics, zeolite, polyurethane foam, and the like can be preferably mentioned. .

  As the gas-liquid distributor 5 that can be used in the biological treatment apparatus of the present invention, for example, a trilateral (water collector manufactured by Mizuing Co., Ltd.) shown in FIGS. 4 and 5 can be used. If it satisfies, it will not be limited to this. The trilateral is composed of a rectangular body 15 having a hollow interior. A plurality of slits 18 are provided on the upper surface of the rectangular body so that the microorganism holding carrier does not pass therethrough. A partition plate 19 provided with a through hole 19a is installed inside the rectangular body. The inflow line and the outflow line for water and air are positioned in the rectangular body 20 partitioned by the partition plate 19. That is, the water and air introduced into the rectangular interior 20 are configured to be uniformly ejected upward from the trilateral upper surface via the through holes 19 a and the slits 18. A cleaning liquid injection line 10 is disposed on the upper surface of the trilateral rectangular body. The cleaning chemical liquid injection line 10 has a plurality of holes 16 through which the chemical liquid is uniformly discharged. The discharged cleaning chemical is distributed into the biological treatment apparatus together with water and air ejected from the trilateral interior. The cleaning liquid injection line 10 may be directly installed on the trilateral upper surface, but may be installed several millimeters to several tens of millimeters away from the upper surface.

The chemical solution for cleaning the gas-liquid distributor varies depending on the properties of the raw water to be processed, but a normal cleaning chemical solution such as sodium hypochlorite or hydrogen peroxide can be used.
The flushing water is not particularly limited as long as it can wash away the residual chemical solution, and raw water, biologically treated water, purified water, or the like can be used.

The biological treatment apparatus of this invention is demonstrated using the Example which installed the biological treatment apparatus of this invention shown in FIG. 2 in the existing water purification plant.
The reaction system of the biological treatment equipment is an upflow type fluidized bed method. It is packed with granular activated carbon with an effective diameter of 0.4 mm and a uniformity coefficient of 1.3 as a microorganism carrier as a stationary bed height of 1.5 m, and the water flow rate (superficial velocity) is 320. It was set to 380 m / day. The raw water was river water contaminated with ammonia, and the ammonia concentration was 0.05 to 0.2 mg / L, SS was 5 to 50 mg / L, and DOC was 2 to 6 mg / L. A water collecting device “Tri-Lateral” (Mizuing Co., Ltd.) was laid as a gas-liquid distribution device at the bottom of the device, and 0.8 m of gravel was laminated on the upper surface to form a microorganism carrier protective layer. A porous pipe for supplying sodium hypochlorite was inserted at a position 0.2 m from the lower end of the gravel floor, and a sodium hypochlorite injection line (cleaning liquid inflow line) was connected. In the middle of the sodium hypochlorite injection line, a flushing water inflow line for residual chemical flushing was connected.

  Table 1 shows the operating conditions and progress of the biological treatment apparatus.

条件1は本発明に基づくもので、気液分配装置５と微生物担体保護層３との間の空間で所定の有効塩素濃度（1mg/L）となるように、次亜塩素酸ナトリウム希釈液を注入し、100分間の静置後に水流出ライン８から薬液を排出し、さらにフラッシングライン１１に生物処理水を通して洗浄薬液注入ライン１０をフラッシングした。薬品洗浄後は通水時の全体圧損が低下したことから、気液分配装置５及びその周辺部の閉塞がなくなったと推定された。また、薬品洗浄前後での生物処理機能の低下は特に認められなかった。さらに、薬品洗浄後の圧損増加は1年間認められなかった。

Condition 1 is based on the present invention. A sodium hypochlorite diluted solution is used so that a predetermined effective chlorine concentration (1 mg / L) is obtained in the space between the gas-liquid distributor 5 and the microorganism carrier protective layer 3. After injecting and leaving still for 100 minutes, the chemical solution was discharged from the water outflow line 8, and the cleaning chemical solution injection line 10 was flushed through the biological treatment water through the flushing line 11. It was estimated that the gas-liquid distribution device 5 and its peripheral portion were not blocked because the overall pressure loss during water passage decreased after chemical cleaning. In addition, there was no particular decrease in biological treatment function before and after chemical cleaning. Furthermore, no increase in pressure loss after chemical cleaning was observed for one year.

  Condition 2 is a method that does not use the present invention as a method for injecting a sodium hypochlorite solution. Specifically, wash water having a predetermined effective chlorine concentration (1 mg / L) was applied from the raw water inflow line 6 to the upper end of the gravel support floor, left standing for 100 minutes, and then the chemical solution was discharged from the water outflow line 8. . Thereafter, flushing was performed by repeating the operation of filling and discharging water containing no chemical from the raw water inflow line 6 three times. As a result, the pressure loss decreased to almost the same as Condition 1, so it can be said that there was a corresponding cleaning effect. Although there was no particular decline in the biological treatment function thereafter, pressure loss began to increase 2 months after washing, so it was necessary to perform chemical washing again.

  Condition 3 was based on the result of condition 2 and the effective chlorine concentration was increased to 3 mg / L. Other conditions were the same as those of condition 2. As a result, the pressure loss decreased after washing, but the biological treatment function was reduced by about 20%, and ammonia remained in the biologically treated water. It took a month to recover.

  The cause of the difference between Condition 1 and Condition 2 is considered to be the difference in the cleaning effect of the gas-liquid distributor. That is, in condition 1 (the present invention), cleaning was performed almost completely, but in condition 2, the cleaning was insufficient and contaminated microorganisms remained inside the gas-liquid distributor. The pressure loss was thought to have increased again in two months. Condition 3 was carried out by increasing the chemical concentration by a factor of 3 based on the reflection, but resulted in a decrease in biological treatment function. This was thought to be due to the disinfection of some of the microorganisms on the carrier that had contributed to the treatment, although some chemicals diffused into the microorganism carrier in 100 minutes, even though the chemical solution was applied to the upper surface of the support floor. .

  The biological treatment apparatus of the present invention can reliably clean the gas-liquid distributor of the biological treatment apparatus to avoid an increase in pressure loss during water flow, and does not involve a decrease in biological treatment function. Therefore, according to the present invention, it is possible to stably maintain the performance of the biological treatment apparatus over the medium to long term.

Claims (2)

A microbial carrier layer filled with a microbial carrier inside;
A liquid dispensing device than the microorganism carrier layer is positioned downward, the uniformly dispersed gas and / or liquid is introduced into the microorganism carrier layer,
Microbial support protection layer is provided, cleaning solution suppresses the diffusion to the microbial support layer, consisting of granules and / or perforated plate between the microorganism carrier layer and the gas-liquid distribution device,
A raw water inflow line connected to the gas-liquid distributor for supplying raw water as an upward flow;
A chemical injection line connected between the gas-liquid distributor and the microorganism carrier protective layer, for introducing a cleaning chemical for cleaning the gas-liquid distributor;
A flushing mechanism connected to the raw water inflow line and provided in the gas-liquid distributor , supplying flushing water at a lower level than the bottom of the microorganism carrier layer, and flushing residual chemicals ;
It is provided with a biological treatment apparatus of water upflow characterized by. A microbial carrier layer filled with a microbial carrier inside;
A gas-liquid distribution device that is positioned below the microbial carrier layer and uniformly introduces the gas and / or liquid into the microbial carrier layer, and
A microbial carrier protective layer comprising a granular material and / or a perforated plate, which is provided between the microbial carrier layer and the gas-liquid distributor, and prevents the cleaning chemical solution from diffusing into the microbial carrier layer ;
A raw water inflow line connected to the gas-liquid distributor for supplying raw water as an upward flow;
A chemical injection line connected to the gas-liquid distributor and for introducing a cleaning chemical for cleaning the gas-liquid distributor;
A flushing mechanism connected to the chemical injection line and provided in the gas-liquid distributor, supplying flushing water at a lower level than the bottom of the microorganism carrier layer, and flushing residual chemicals;
An upward-flow-type biological treatment apparatus for water.

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