Upflow sludge blanket anaerobic digestion reactor

Abstract

The present application relates to a kind of upflow residual sludge separation anaerobic digestion reactor, belongs to sludge treatment device.It includes three series water pools of separation pool, water distribution pool and digestion pool.Utilize the difference of digestible sludge and indigestible sludge in separation pool in sedimentation velocity, using fluidized bed technology, indigestible sludge with sedimentation velocity greater than or equal to the upflow velocity of fluidized bed sewage empty bed in separation pool or is detained in fluidized bed layer, or is settled to separation pool bottom.Digestible sludge with sedimentation velocity less than the upflow velocity of fluidized bed sewage empty bed in separation pool is brought into water distribution pool by upflow sewage, and digestible sludge and indigestible sludge are completely separated.Digestible sludge brought into water distribution pool enters digestion pool for digestion reaction through water distributor inlet pipe under water distribution pool.The present application completely separates digestible sludge and indigestible sludge, improves the concentration of digestible sludge in digestion reaction pool and digestion reaction speed, and reduces the volume of digestion reaction pool.

Description

Technical Field

[0001] This invention relates to an upflow anaerobic digestion reactor for separating excess sludge, which belongs to the field of sludge treatment devices. Background Technology

[0002] Because the residual sludge discharged from urban wastewater treatment plants contains approximately 40% undigested sludge, including organic debris and inorganic particles, current anaerobic digestion systems can only degrade 40%–45% of the digestible organic matter in the residual sludge. This results in minimal sludge reduction, low levels of harmlessness, and poor dewatering performance of the digested sludge. If anaerobic digestion were to be used to degrade over 95% of the digestible organic matter in the residual sludge discharged from urban wastewater treatment plants, the investment in such a system would be enormous. Therefore, reducing the investment in anaerobic digestion systems, increasing the depth of sludge digestion, and reducing the concentration of digestible sludge in the post-digestion sludge are pressing technical challenges that need to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide an upflow anaerobic digestion reactor for separating waste sludge, consisting of two stages of upflow reaction tanks connected in series. By allowing waste sludge to undergo a separation reaction within this reactor, digestible and indigestible sludge are separated. The separated digestible sludge is then concentrated, increasing the digestion rate and reducing the volume of the reaction tanks. The separated indigestible sludge contains a low content of digestible sludge, exhibits good dewatering properties, is essentially harmless, and causes minimal environmental pollution.

[0004] The present invention solves the above-mentioned technical problems by means of the following technical solution:

[0005] An upflow anaerobic digestion reactor for separating excess sludge includes a reactor, which is divided into three series-connected pools: a separation pool, a distribution pool, and a digestion pool, by two vertically installed baffles.

[0006] A sludge inlet water distributor is installed at the sludge inlet pipe in the middle of the separation tank, a return water distributor is installed at the bottom, and a sludge discharge pipe is installed at the bottom.

[0007] The water inlet pipe of the water distribution tank is connected to the water distributor at the bottom;

[0008] A water distributor is installed at the bottom of the digester, and a baffle plate and an outlet pipe are installed at the top. A reflux pump is installed below the water surface of the digester, and the outlet pipe of the reflux pump is connected to the reflux water distributor.

[0009] A biogas exhaust pipe is installed at the top of the reactor;

[0010] The excess sludge flows continuously through the sludge inlet pipe into the sludge distributor in the middle of the separation tank. After being evenly distributed by the sludge distributor, it flows upward from the middle of the separation tank into the separation tank. The return water enters the return water distributor and, after being evenly distributed by the return water distributor, flows upward from the bottom of the separation tank into the separation tank. The flow rate of the return water is adjusted to form a fluidized bed of undigested sludge in the separation tank.

[0011] Undigested sludge with a settling velocity greater than or equal to the empty bed flow velocity of the fluidized bed in the separation tank either remains in the fluidized bed or settles to the bottom of the separation tank and is discharged from the reactor through the sludge discharge pipe.

[0012] Digestible sludge with a settling velocity lower than the upflow velocity of the fluidized bed wastewater in the separation tank is carried into the distribution tank by the upstream wastewater, where digestible sludge and non-digestible sludge are completely separated. The digestible sludge carried into the distribution tank enters the distributor through the inlet pipe of the distributor at the bottom of the distribution tank. After being evenly distributed by the distributor, it enters the digestion tank in an upward flow to carry out the digestion reaction.

[0013] Because the upward flow velocity of the wastewater in the digester is very low, the digestible sludge cannot be carried out of the digester by the upward flow of wastewater. The digestible sludge remains in the digester until it is completely digested. The wastewater carried into the reactor by the residual sludge is separated from the scum by the baffle plate and then discharged from the reactor through the effluent pipe.

[0014] Furthermore, the flow velocity of the fluidized bed wastewater in the separation tank is controlled between 1 and 3 meters per hour.

[0015] The empty bed outflow velocity of wastewater in the digester is controlled below 0.3 m / h.

[0016] The surface area of ​​the digester is 8-10 times that of the separation tank.

[0017] The upflow anaerobic digestion reactor for waste sludge separation provided by this invention consists of two vertically installed baffles, dividing the reactor into three series-connected tanks: a separation tank, a distribution tank, and a digestion tank. Because digestible sludge has a smaller specific gravity and particle size than indigestible sludge, its settling velocity is also lower. This invention utilizes the difference in settling velocity between digestible and indigestible sludge in the separation tank, employing fluidized bed technology. Indigestible sludge with a settling velocity greater than or equal to the upflow velocity of the fluidized bed wastewater in the separation tank is either retained in the fluidized bed or settles to the bottom of the separation tank. Digestible sludge with a settling velocity less than the upflow velocity of the fluidized bed wastewater in the separation tank is carried into the distribution tank by the upflow wastewater, where the digestible and indigestible sludge are completely separated. The digestible sludge carried into the distribution tank enters the digestion tank through the water distributor inlet pipe below the distribution tank for digestion.

[0018] The technical effects of this invention are as follows:

[0019] 1. Within the separation tank, fluidization technology is used to fluidize undigested sludge (plastics, fibers, inorganic particles) with a settling velocity greater than the upstream velocity of the wastewater in the separation tank. This fluidizes the sludge, which is suspended in the upstream flowing wastewater or settles to the bottom of the separation tank. Meanwhile, digestible sludge with a settling velocity less than the upstream velocity of the wastewater in the separation tank is carried out of the separation tank by the upstream wastewater. This method results in fast separation speed, high separation efficiency, and a simple separation tank structure.

[0020] 2. In the digester, upflow technology is used to ensure sufficient contact and reaction between the digestible sludge and the anaerobic and facultative anaerobic microorganisms, thereby increasing the mass transfer rate and digestion rate between the digestible sludge and the microorganisms in the digester. This allows the sludge loading rate in the digester to reach 3 kg VSS / m³ under normal temperature anaerobic digestion conditions. 3 •d or above, reduce the volume of the digester and the investment in the sludge treatment system.

[0021] 3. The undigested sludge discharged after separation treatment has a moisture content of 98%, while the digestible sludge content is less than 5%. The sludge has excellent dewatering performance and is odorless and tasteless. After mechanical dewatering treatment, the amount of sludge to be disposed of can be reduced by more than 96%. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the upflow separation digester of the present invention;

[0023] In the diagram: 1. Return water distributor; 2. Sludge inlet water distributor; 3. Sludge inlet pipe; 4. Separation tank; 5. Water distribution tank; 6. Return pump; 7. Biogas exhaust pipe; 8. Sludge baffle plate; 9. Water outlet pipe; 10. Digestion tank; 11. Water distributor; 12. Sludge discharge pipe. Detailed Implementation

[0024] The upflow anaerobic digestion reactor for separating excess sludge of the present invention includes a reactor, which is divided into a separation tank 4, a water distribution tank 5 and a digestion tank 10 by two vertically installed baffles.

[0025] The separation tank 4 is equipped with a sludge inlet distributor 2 in the middle, a return water distributor 1 in the lower part, and a sludge discharge pipe 12 at the bottom of the tank.

[0026] The water inlet pipe of the water distributor 11 is connected to the lower part of the water distribution tank 5.

[0027] A water distributor 11 is installed at the bottom of the digester 10, and a baffle plate 8 and an outlet pipe 9 are installed at the top. A return pump 6 is installed below the water surface of the digester 10, and the outlet pipe 9 of the return pump 6 is connected to the return water distributor 1. A biogas exhaust pipe 7 is installed at the top of the reactor.

[0028] The excess sludge flows continuously through the sludge inlet pipe 3 into the sludge distributor 2 in the middle of the separation tank 4. After being evenly distributed by the sludge distributor 2, it flows upward into the separation tank 4. Return water enters the return water distributor 1, and after being evenly distributed by the return water distributor 1, it flows upward from the bottom of the separation tank 4. The flow rate of the return water is adjusted to form a fluidized bed of undigested sludge in the separation tank 4. Undigested sludge with a settling velocity greater than or equal to the upward velocity of the empty bed of the fluidized bed in the separation tank 4 either remains in the fluidized bed or settles to the bottom of the separation tank 4, and is then discharged from the reactor through the sludge discharge pipe 12. Digestible sludge with a settling velocity lower than the upward flow velocity of the fluidized bed wastewater in separation tank 4 is carried by the upstream wastewater into distribution tank 5. It then enters distribution tank 11 through the inlet pipe at the bottom of distribution tank 5, and after being evenly distributed by distribution tank 11, it flows upwards into digestion tank 10 for digestion. Since the water surface area of ​​digestion tank 10 is 8-10 times that of separation tank 4, the upward flow velocity of wastewater in digestion tank 10 is as low as 0.3 m / h or less. Therefore, the digestible sludge cannot be carried out of digestion tank 10 by the upstream wastewater and remains in digestion tank 10 until it is completely digested. Wastewater carried into the reactor by the remaining sludge is separated from the reactor by baffle plate 8 and discharged through outlet pipe 9.

[0029] Based on research and experimentation, the following formula of this invention can meet the requirements for the effective volume of the designed reactor:

[0030] V = W / q

[0031] In the formula: V is the effective volume of the reactor, m 3 W represents the amount of residual digestible sludge digested, kgVSS / d; Q represents the volumetric loading rate of the reactor, kgVSS / m³. 3 ·d.

[0032] The volumetric loading rate q in the above formula varies depending on the composition of the sludge being treated. For the residual sludge from urban wastewater treatment plants, the volumetric loading rate q in the above formula is 3 kgVSS / m.

Claims

1. An upflow anaerobic digestion reactor for separating excess sludge, characterized in that, The reactor is divided into three series-connected pools: a separation pool (4), a distribution pool (5), and a digestion pool (10) by two vertically installed baffles. A sludge inlet water distributor (2) is installed at the sludge inlet pipe (3) in the middle of the separation tank (4), a return water distributor (1) is installed at the bottom, and a sludge discharge pipe (12) is installed at the bottom. The water distribution tank (5) is connected to the water inlet pipe of the water distributor (11) at the bottom; A water distributor (11) is installed at the bottom of the digester (10), and a baffle plate (8) and an outlet pipe (9) are installed at the top. A reflux pump (6) is installed below the water surface of the digester (10), and the outlet pipe (9) of the reflux pump (6) is connected to the reflux water distributor (1). A biogas exhaust pipe (7) is installed at the top of the reactor. The excess sludge flows continuously through the sludge inlet pipe (3) into the sludge inlet distributor (2) in the middle of the separation tank (4). After being evenly distributed by the sludge inlet distributor (2), it flows upward from the middle of the separation tank (4) into the separation tank (4). The return water enters the return water distributor (1). After being evenly distributed by the return water distributor (1), it flows upward from the lower part of the separation tank (4) into the separation tank (4). The flow rate of the return water is adjusted so that the undigested sludge in the separation tank (4) forms a fluidized bed. Undigested sludge with a settling velocity greater than or equal to the fluidized bed flow velocity in the separation tank (4) will either remain in the fluidized bed layer or settle to the bottom of the separation tank (4) and be discharged from the reactor through the sludge discharge pipe (12). Digestible sludge with a settling velocity lower than the upflow velocity of the fluidized bed wastewater in the separation tank (4) is carried into the distribution tank (5) by the upstream wastewater, and the digestible sludge and non-digestible sludge are completely separated; the digestible sludge carried into the distribution tank (5) enters the distributor (11) through the inlet pipe of the distributor (11) at the bottom of the distribution tank (5), and after being evenly distributed by the distributor (11), it enters the digestion tank (10) in an upward flow mode for digestion reaction; Because the upstream flow velocity of the sewage in the digester (10) is very low, the digestible sludge cannot be carried out of the digester (10) by the upstream sewage in the digester (10). The digestible sludge stays in the digester (10) until it is completely digested. The sewage carried into the reactor by the residual sludge is separated from the scum by the baffle plate (8) and discharged from the reactor through the outlet pipe (9).

2. The upflow anaerobic digester for separating excess sludge according to claim 1, characterized in that, The flow velocity of the fluidized bed wastewater in the separation tank (4) is controlled between 1 and 3 meters per hour.

3. The upflow anaerobic digester for separating excess sludge according to claim 1, characterized in that, The empty bed flow velocity of sewage in the digester (10) is controlled to be below 0.3 m / h.

4. The upflow anaerobic digester for separating excess sludge according to claim 1, characterized in that, The water area of ​​the digester (10) is 8-10 times that of the separation tank (4).

Images