JP2018015728A - Organic wastewater treatment method and organic wastewater treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment method allowing for suppression of effluence of sludge from a settling tank caused by ozone supply to an activated sludge tank in an activated sludge process.SOLUTION: The organic wastewater treatment method for clarifying organic wastewater by an organic wastewater treatment system is provided. The organic wastewater treatment system comprises: an activated sludge tank for decomposing organic substances included in organic wastewater using activated sludge including aerobic microorganisms; and a settling tank for receiving sludge including decomposed organic substances and the organic wastewater from which the organic substances has been decomposed and settling the sludge. The organic wastewater treatment method includes a decomposing step of supplying ozone to the activated sludge tank and decomposing the organic substances included in the organic wastewater using the activated sludge, and a settling step of crushing and settling floating sludge which includes gas bubbles and floats on the water surface, out of the sludge in the settling tank.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic wastewater treatment method and an organic wastewater treatment system.

  An activated sludge method is an example of a method for purifying organic wastewater. In the activated sludge method, first, organic substances contained in organic wastewater are decomposed in an activated sludge tank in which activated sludge containing aerobic microorganisms is accumulated. The water in which the organic matter is decomposed is sent to the settling tank together with the sludge containing the decomposed organic matter. In the sedimentation tank, the sludge contained in the water sent from the activated sludge tank is precipitated, and the supernatant water is discharged as treated water. Moreover, the sludge settled in the settling tank is returned to the activated sludge tank. In order to improve the efficiency of the purification process by the activated sludge of an activated sludge tank like the following patent document 1, the process which supplies ozone to an activated sludge tank is also performed.

JP 2006-314911 A Japanese Patent Laid-Open No. 6-305991 Japanese Patent No. 4593537

  The inventors have discovered that when ozone is supplied to the activated sludge tank, the sludge may float to the sedimentation tank. If the sludge that floated in the sedimentation tank is left unattended, the sludge that floated along with the treated water will also flow out, so the quality of the treated water will deteriorate.

  Then, one side surface of the technique of an indication makes it a subject to provide the processing method of the organic waste_water | drain which can suppress the outflow of the sludge from the sedimentation tank produced by the supply of ozone to an activated sludge tank in an activated sludge method.

  One aspect of the disclosed technology is exemplified by the following organic wastewater treatment method. An organic wastewater treatment method for purifying organic wastewater by an organic wastewater treatment system, wherein the organic wastewater treatment system decomposes organic matter contained in organic wastewater by activated sludge containing aerobic microorganisms. A tank, and a sedimentation tank that receives organic wastewater in which the organic matter is decomposed together with the sludge containing the decomposed organic substance from the activated sludge tank and precipitates the sludge. The organic wastewater treatment method supplies ozone to the activated sludge tank, decomposes the organic matter contained in the organic wastewater with the activated sludge, and floats on the water surface including bubbles in the sludge in the sedimentation tank. And a precipitation step of crushing and sedimenting the floating sludge.

  When ozone is supplied to the activated sludge tank, the floating sludge containing bubbles rises on the water surface of the settling tank. According to such a method for treating organic wastewater, the floating sludge that has floated in the precipitation step is crushed and air bubbles are removed. Since the floating sludge from which the bubbles have been removed settles in the settling tank, the outflow of the floating sludge to the treated water is suppressed.

Furthermore, the organic wastewater treatment method may have the following characteristics. The precipitation step further includes a step of agitating the water in the precipitation tank by aeration of the precipitation tank and crushing the floating sludge by bubbles generated by aeration. According to such an organic wastewater treatment method, floating sludge is crushed by bubbles generated by aeration. Furthermore, the inside of the precipitation tank is agitated by aeration, so that the sludge accumulated in the bottom of the precipitation tank without being returned to the activated sludge tank can be lifted and crushed and then precipitated again. Therefore, the efficiency of returning the sludge accumulated at the bottom of the settling tank to the activated sludge tank is increased.

  Furthermore, the organic wastewater treatment method may have the following characteristics. The precipitation step includes a step of discharging water to the sludge that has floated. According to such an organic wastewater treatment method, the floating sludge can be crushed by water discharge.

  Furthermore, the above-described technical idea disclosed for the organic wastewater treatment method can be applied to an organic wastewater treatment system as long as no technical defects occur.

  This organic wastewater treatment method can suppress the outflow of sludge from the sedimentation tank caused by the supply of ozone to the activated sludge tank in the activated sludge process.

FIG. 1 is a diagram illustrating an example of a configuration of an organic wastewater treatment system according to an embodiment. FIG. 2 is a diagram illustrating an example of an organic wastewater treatment system before the start of ozone supply by the ozone supply device. FIG. 3 is a diagram illustrating an example of an organic wastewater treatment system in which ozone is supplied to an activated sludge tank by an ozone supply device. FIG. 4 is a diagram illustrating an example of a state in which the supply pipe supplies air to the settling tank. FIG. 5 is a diagram illustrating an example of an organic wastewater treatment method by an organic wastewater treatment system. FIG. 6 is a diagram showing an example of the processing flow of the first embodiment. FIG. 7 is a diagram showing an example of the processing flow of the second embodiment. FIG. 8 is an example of a view of the sedimentation tank according to the modification viewed from the side. FIG. 9 is an example of a top view of a sedimentation tank according to a modification. FIG. 10 is a diagram illustrating an example of a sludge scraper.

  Hereinafter, an organic wastewater treatment system according to an embodiment will be described with reference to the drawings. The configuration of the embodiment described below is an exemplification, and the disclosed technology is not limited to the configuration of the embodiment.

<Embodiment>
FIG. 1 is a diagram illustrating an example of a configuration of an organic wastewater treatment system 1 according to an embodiment. The organic wastewater treatment system 1 includes a flow rate adjustment tank 11, an activated sludge tank 12, and a sedimentation tank 13. The organic wastewater treatment system 1 is an example of an “organic wastewater treatment system”.

  The organic wastewater which becomes the treatment target of the organic wastewater treatment system 1 flows into the flow rate adjusting tank 11. The flow rate adjusting tank 11 includes a pump 14a. The pump 14 a sends an amount of organic waste water that can be treated in the activated sludge tank 12 and the settling tank 13 to the activated sludge tank 12.

  The activated sludge tank 12 performs a decomposition process of organic substances contained in the organic waste water sent from the flow rate adjusting tank 11 by activated sludge containing aerobic microorganisms. In the activated sludge tank 12, the aerobic microorganism group is propagated by aeration, and the activated sludge suitable for the treatment of organic waste water is maintained. Ozone is supplied to the activated sludge tank 12 by the ozone supply device 20 in order to increase the efficiency of the purification treatment with activated sludge. The water in which the organic matter is decomposed by the activated sludge is sent to the settling tank 13.

  The sedimentation tank 13 precipitates the activated sludge contained in the water sent from the activated sludge tank 12, and drains the supernatant water as treated water. The sedimentation tank 13 is provided with a wall portion 13c formed in a cylindrical shape and an inclined portion 13b inclined in a mortar shape from the wall portion 13c toward the bottom surface central portion 13a. The bottom center portion 13 a is connected to the bottom portion of the activated sludge tank 12 by a return sludge pipe 15. The angle of the inclined portion 13b is 60 degrees or more with respect to the horizontal direction. A pump 14 b is provided between the sedimentation tank 13 and the activated sludge tank 12 on the return sludge pipe 15. The sludge precipitated in the settling tank 13 is collected in the bottom center part 13a along the inclined part 13b, and returned to the activated sludge tank 12 as return sludge via the return sludge pipe 15 by the pump 14b. The settling tank 13 is provided with an aeration device 21 and a water discharge device 22. The aeration device 21 is provided in the approximate center in the top view of the precipitation tank 13 and aerates the water in the precipitation tank 13. The water discharge device 22 discharges water toward the water surface stored in the settling tank 13.

  FIGS. 2 to 4 are views showing an example of the state of the organic waste water treatment system 1 in which ozone is supplied to the activated sludge tank 12. Hereinafter, the state of the organic waste water treatment system 1 supplied with ozone will be described with reference to FIGS.

  FIG. 2 is a diagram illustrating an example of the organic wastewater treatment system 1 before the ozone supply device 20 starts supplying ozone. On the bottom of the sedimentation tank 13, a sludge 30 containing activated sludge that flows in from the activated sludge tank 12 together with water is precipitated. The sedimented sludge 30 is collected along the inclined portion 13 b at the bottom center portion 13 a and is returned to the activated sludge tank 12 via the return sludge pipe 15. However, not all the sludge 30 that has settled is collected in the bottom center part 13a along the inclined part 13b. The sludge 30 may remain at a boundary portion between the inclined portion 13b and the wall portion 13c of the sedimentation tank 13, an unspecified portion of the inclined portion 13b, or the entire inclined portion 13b. At least a part of the sludge 30 remaining in the sedimentation tank 13 without being returned to the activated sludge tank 12 stays at the bottom of the sedimentation tank 13, and as a result, contact with oxygen is reduced. 31.

  FIG. 3 is a diagram illustrating an example of the organic wastewater treatment system 1 in which ozone is supplied to the activated sludge tank 12 by the ozone supply device 20. By supplying ozone to the activated sludge tank 12, the efficiency of decomposing organic substances contained in the organic waste water from the activated sludge tank 12 is increased. The ozone supplied to the activated sludge tank 12 flows into the settling tank 13 together with the water treated by the activated sludge tank 12. When ozone flows into the settling tank 13, a part of the septic sludge 31 floats on the surface of the water stored in the settling tank 13. The mechanism of the rise of the septic sludge 31 is that the absolute anaerobic bacteria of the septic sludge 31 decrease and the facultative anaerobic bacteria grow, and bubbles are included in the septic sludge 31 due to the denitrification reaction by the propagated facultative anaerobes This is probably because of this. The rotting sewage sludge 31 has a size of about several centimeters to several tens of centimeters square, and the hardness thereof is, for example, about the same as that of cotton tofu. The septic sludge 31 is an example of “floating sludge”.

  FIG. 4 is a diagram illustrating an example of a state in which the aeration apparatus 21 has aerated the sedimentation tank 13. By aeration by the aeration device 21, bubbles 21a are generated in the water of the settling tank 13. The aeration apparatus 21 supplies air that can agitate the entire water stored in the settling tank 13. Moreover, the aeration apparatus 21 supplies air in such a degree that bubbles 21a having a diameter of about 10 centimeters to about 30 centimeters can be generated. In the sedimentation tank 13, the air bubbles 21 a collide with each other, or the water in the sedimentation tank 13 collides with the septic sludge 31 by stirring, so that the septic sludge 31 is crushed. The septic sludge 31 is crushed to remove the adhering bubbles. Further, the water in the sedimentation tank 13 is agitated, so that the rise of the septic sludge 31 remaining at the bottom of the sedimentation tank 13 is promoted. The aeration apparatus 21 is an example of “crushing means”.

FIG. 5 is a diagram illustrating an example of an organic wastewater treatment method performed by the organic wastewater treatment system 1. In FIG. 5, the description starts from the point where ozone is supplied to the activated sludge tank 12. In the treatment method illustrated in FIG. 5, the inflow of organic wastewater into the activated sludge tank 12 is stopped. Therefore, the treatment method illustrated in FIG. 5 is performed at a time when the organic wastewater flowing into the flow rate adjustment tank 11 is small so that the organic wastewater flowing in while being stopped can be stored in the flow rate adjustment tank 11. It is preferable. For example, if organic wastewater from a factory is processed from Monday to Friday, ozone supply will start on Friday night, and organic wastewater will flow into the activated sludge tank 12 from Saturday to Monday morning. Is stopped. Hereinafter, an example of a method for treating organic wastewater by the organic wastewater treatment system 1 will be described with reference to FIG.

  At T <b> 1, organic wastewater flows from the flow rate adjustment tank 11 into the activated sludge tank 12. In the activated sludge tank 12, ozone is supplied to the inflowing organic waste water. The amount of ozone to be supplied is appropriately determined based on the amount of inflowing organic waste water. The organic matter contained in the organic wastewater by activated sludge is decomposed. In the activated sludge tank 12 to which ozone is supplied, a process for decomposing the organic matter in the organic waste water by the activated sludge is performed. The treatment in which T1 ozone is supplied and the organic matter in the organic wastewater is decomposed by the activated sludge is an example of the “decomposition step”.

  At T2, the water flowing from the flow rate adjustment tank 11 into the activated sludge tank 12 is stopped after a predetermined waiting time has elapsed until the outflow of the septic sludge 31 from the T1 to the treated water begins. The treatment of T2 may be limited to the amount of water that flows in to such an extent that the treated water does not flow out of the sedimentation tank 13 without stopping the inflowing water. At T3, it is determined whether or not the septic sludge 31 has floated in the sedimentation tank 13. When the septic sludge 31 emerges, the process proceeds to T4. When the septic sludge 31 does not rise, the process of T3 is repeated.

  At T4, the settling tank 13 is aerated by the aeration apparatus 21. By aeration, bubbles 21a are generated in the water of the precipitation tank 13, and the inside of the precipitation tank 13 is further stirred. By the agitation of the sedimentation tank 13, the septic sludge 31 containing air bubbles that have settled in the sedimentation tank 13 rises. The septic sludge 31 is crushed by a collision with the bubbles 21 a or a collision between the septic sludges 31. Air bubbles are removed from the smashed septic sludge 31 and precipitate. The process of T4 is an example of a “precipitation process”.

  When a predetermined ascent time has elapsed in which it is determined that all the septic sludge 31 that has settled in the agitated settling tank 13 has floated (YES in T5), the process proceeds to T6. If the predetermined ascent time has not elapsed (NO in T5), the process returns to T5. The predetermined ascent time can be determined, for example, by performing a test operation of the organic waste water treatment system 1 and actually measuring it.

  At T6, aeration of the sedimentation tank 13 by the aeration apparatus 21 is stopped. When the septic sludge 31 that has not been precipitated by the process of T4 is present, the septic sludge 31 that is still floating can be precipitated by the process of T6. The process of T6 is an example of a “precipitation step”.

  When a predetermined settling time has elapsed in which almost all the septic sludge 31 that has floated in the settling tank 13 has settled (YES in T7), the process proceeds to T8. If the predetermined settling time during which almost all the septic sludge 31 is settled has not yet elapsed (NO in T7), the process of T7 is repeated. The predetermined settling time can be determined, for example, by performing a test operation of the organic wastewater treatment system 1 and actually measuring it. In addition, when all the septic sludge 31 from which bubbles have been removed by the treatment of T4 can be precipitated, the predetermined settling time at T7 is “0”. The process of waiting for the elapse of the predetermined precipitation time at T7 is an example of a “precipitation step”.

  If there is a septic sludge 31 that has floated in the settling tank 13 after a predetermined settling time has elapsed (YES in T8), the process proceeds to T9. If there is no septic sludge 31 floating in the settling tank 13 after the predetermined settling time has elapsed (YES in T8), the process proceeds to T10.

  At T <b> 9, the water discharge device 22 discharges water toward the settling tank 13. By the water discharge by the water discharge device 22, the septic sludge 31 still floating in the settling tank 13 is crushed, and bubbles are removed from the crushed sewage sludge and settled on the bottom of the settling tank 13. The time from the start of water discharge by the water discharge device 22 until the septic sludge 31 is settled can be determined, for example, by performing a test operation of the organic waste water treatment system 1 and actually measuring it. The process of T9 is an example of a “precipitation step”. At T10, the inflow of water from the flow rate adjustment tank 11 to the activated sludge tank 12 is resumed. The water discharge device 22 is an example of “crushing means”.

  According to the organic wastewater treatment system 1, the septic sludge 31 that floated in the settling tank 13 was crushed by aeration of the aeration device 21 and water discharge of the water discharge device 22. The crushed septic sludge 31 was precipitated after the bubbles were removed. As a result, according to the organic waste water treatment system 1, the outflow of the septic sludge 31 to the treated water can be suppressed.

  In the organic wastewater treatment system 1, the aeration device 21 and the water discharge device 22 are used for crushing the rot sludge 31 that has surfaced. In order to provide an aeration apparatus in an existing organic wastewater treatment system, a pump for sending air and a pipe for supplying air to the settling tank 13 may be installed. Moreover, what is necessary is just to provide a water discharge hose toward the sedimentation tank 13 in order to provide the water discharge apparatus 22 in the existing organic waste water treatment system. That is, the organic waste water treatment system 1 can be easily installed with respect to the existing organic waste water treatment system.

  In the organic wastewater treatment system 1, the inside of the sedimentation tank 13 is agitated by aeration, so that the septic sludge 31 accumulated in the sedimentation tank 13 is floated without being returned to the activated sludge tank 12, and is crushed and precipitated. . Therefore, according to the organic drainage system 1, the efficiency of returning the septic sludge accumulated in the settling tank 13 to the activated sludge tank 12 can be increased.

  In the embodiment, the rotted sludge 31 that floated was crushed by air bubbles 21 a generated by aeration of the aeration device 21 and water discharge by the water discharge device 22. The rotting sludge 31 that floated was crushed to remove bubbles and settled. However, the method of crushing the rot sludge 31 that has surfaced is not limited to these. The method of crushing the rotted sludge 31 may be, for example, irradiating the septic sludge 31 with air spray or hitting the septic sludge 31 with a rod rotating around an axis.

<Example>
Hereinafter, an example in which the organic waste water treatment system 1 is tested and the predetermined waiting time, the predetermined ascent time, and the predetermined settling time are determined will be described.

<First embodiment>
In the first embodiment, an organic wastewater treatment system 1 is constructed in a certain wastewater treatment plant, and ozone is supplied by the ozone supply device 20 after operation without supplying ozone for 4 months. FIG. 6 is a diagram showing an example of the processing flow of the first embodiment. Hereinafter, the first embodiment will be described with reference to FIG.

  In T11, the organic waste water treatment system 1 is operated without supplying ozone for four months. At T12, the ozone supply device 20 of the organic wastewater treatment system 1 starts supplying ozone to the activated sludge tank 12. After 14 hours from the start of ozone supply by the ozone supply device 20, the rise of the septic sludge 31 was confirmed in the sedimentation tank 13, and after 16 hours, the septic sludge 31 enough to cover the surface of the sedimentation tank 13 was confirmed. . Therefore, the septic sludge 31 was discharged together with the treated water discharged from the settling tank 13.

  At T13, the supply of ozone from the ozone supply device 20 of the organic waste water treatment system 1 to the activated sludge tank 12 is stopped. The operation of the organic waste water treatment system 1 is continued for 7 days while the supply of ozone is stopped. At T14, supply of ozone from the ozone supply device 20 to the activated sludge tank 12 was started, but the rise of the septic sludge 31 in the sedimentation tank 13 was not confirmed.

  At T15, the supply of ozone from the ozone supply device 20 of the organic waste water treatment system 1 to the activated sludge tank 12 is stopped. The operation of the organic wastewater treatment system 1 is continued for 10 days with the supply of ozone stopped. At T16, supply of ozone from the ozone supply device 20 to the activated sludge tank 12 was started, and the rise of the septic sludge 31 in the sedimentation tank 13 was confirmed.

  In the facility used in the first example, it was found that if the ozone supply was stopped within 7 days, the rotting sludge 31 did not rise even if the ozone supply was resumed. Therefore, when the period in which the ozone supply was stopped was within 7 days, when the organic wastewater treatment was continued without aeration to the sedimentation tank 13, the rise of the septic sludge 31 in the sedimentation tank 13 was confirmed. There wasn't.

  In the facility used in the first example, it was found that the septic sludge 31 emerged in the sedimentation tank 13 after about 14 hours had passed since the start of the supply of ozone to the sedimentation tank 13 in which the septic sludge 31 accumulated on the bottom. That is, it can be seen that the predetermined waiting time at the facility used in the first example is less than 14 hours.

<Second embodiment>
In the second embodiment, the organic wastewater treatment system 1 is operated in the same facility as that used in the first embodiment. FIG. 7 is a diagram showing an example of the processing flow of the second embodiment. Hereinafter, the second embodiment will be described with reference to FIG.

  At T <b> 21, ozone is supplied to the activated sludge tank 12 by the ozone supply device 20. In T22, the inflow water from the flow rate adjustment tank 11 to the activated sludge tank 12 is stopped 12 hours after the ozone supply. The time of 12 hours is that the rising of the septic sludge 31 in the sedimentation tank 13 was confirmed 14 hours after the start of ozone supply in the first embodiment. This is the time determined so that the inflow can be stopped. Further, after 14 hours from the ozone supply, the septic sludge 31 rises in the settling tank 13.

  In T23, the aeration apparatus 21 performs aeration to the settling tank 13. By stirring the inside of the sedimentation tank 13 by aeration, the septic sludge 31 is crushed and air bubbles are removed. Further, the septic sludge 31 remaining at the bottom of the settling tank 13 is floated, and the septic sludge 31 that has been lifted is crushed and the attached bubbles are removed. When the aeration to the settling tank 13 was continued for 2 hours, the rising of the new septic sludge 31 was not confirmed.

  In T24, aeration by the aeration apparatus 21 is stopped. One hour after the aeration was stopped, precipitation of almost all the septic sludge 31 was confirmed. About the septic sludge 31 still floating, almost all the septic sludge 31 was settled by discharging water for about 1 hour with respect to the septic sludge 31 surfaced by the water discharger 22. At T25, the inflow of water from the flow rate adjustment tank 11 to the activated sludge tank 12 is resumed.

  According to the second embodiment, it can be seen that the predetermined ascending time at which all the septic sludge 31 in this facility is determined to rise is 2 hours after the start of aeration. Moreover, it turns out that the predetermined settling time in which almost all the septic sludge 31 in this facility settles is 1 hour after aeration stop.

According to the first and second examples, the predetermined waiting time, the predetermined ascent time, and the predetermined settling time were determined. Based on these information, the organic wastewater treatment system 1 can be automatically operated in the facility used in the embodiment. Furthermore, according to the first embodiment, it has been found that if the period in which the supply of ozone is stopped is 7 days, the rotting sludge 31 does not rise. Therefore, when the automatic operation is performed, for example, when the period during which the ozone supply is stopped is within 7 days, stoppage of the inflow water to the activated sludge tank 12, aeration and discharge in the settling tank 13 are not performed. Good.

<Modification>
In the embodiment, the sedimentation tank 13 having the inclined portion 13b provided with an inclination of 60 degrees or more with respect to the horizontal direction is used. In the modified example, a sedimentation tank in which the slope of the bottom surface is formed more gently than the sloped portion 13b will be described. 8 and 9 are diagrams showing an example of the sedimentation tank 43 according to the modification. FIG. 8 is an example of a view of the sedimentation tank 43 according to the modification as viewed from the side. FIG. 9 is an example of a top view of a sedimentation tank 43 according to a modification. The sedimentation tank 43 has a substantially square shape when viewed from above, and has a bottom center part 43a and an inclined part 43b. Similarly to the sedimentation tank 13 of the embodiment, the return sludge pipe 15 is connected to the bottom center part 43a, and the sludge 30 collected in the bottom center part 43a is transferred to the activated sludge tank 12 via the return sludge pipe 15. It is supposed to be returned. At the corners of the four corners of the precipitation tank 43, an aeration device 21 for aeration of the precipitation tank 43 is provided. The inclined portion 43b of the settling tank 43 is gentler than the inclined portion 13b of the settling tank 13 of the embodiment. Therefore, it is difficult to collect the sludge 30 in the bottom center part 43a by the inclination of the inclined part 43b. Therefore, the settling tank 43 is provided with a sludge scraping machine 44 that collects the precipitated sludge 30.

  FIG. 10 is a diagram illustrating an example of the sludge scraper 44. The sludge scraper 44 has a shaft 44a and a scraper 44b. The sludge scraper 44 rotates the scraper 44b around the shaft 44a to scrape the sludge 30 accumulated on the bottom of the settling tank 43 into the bottom center 43a of the settling tank 43.

  In FIG. 9, the area | region which the sludge scraper 44 rotates and the sludge 30 can be collected is illustrated as the rotation area | region 44a. Since the rotation area 44a in which the sludge scraper 44 rotates is circular, the four corner areas of the settling tank 43 are dead areas 43c, which are areas where the sludge 30 is not scraped by the sludge scraper 44. In the dead region 43c, the sludge 30 that has not been scraped is deposited, and thus the septic sludge 31 is likely to be generated.

  In the sedimentation tank 43, the aeration apparatus 21 is provided in the four corner regions as described above. The four corner areas are dead areas 43c where the septic sludge 31 is likely to be generated. The sludge 30 and the septic sludge 31 accumulated in the dead area 43 c are carried out of the dead area 43 c by bubbles generated by aeration by the aeration apparatus 21 and a water flow in the settling tank 43. The sludge 30 and the septic sludge 31 carried to the outside of the dead area 43 c are collected by the sludge scraper 44 to the bottom center portion 43 a. Moreover, when the septic sludge 31 floats in the sedimentation tank 43, the septic sludge 31 which floated by the air bubbles from the aeration device 21 is crushed and the bubbles attached to the septic sludge 31 are removed as in the embodiment. As a result, the septic sludge 31 that has surfaced settles and is collected by the sludge scraper 44 on the bottom center portion 43a.

  The embodiments and modifications disclosed above can be combined. For example, you may provide the sludge scraper 44 of a modification in the sedimentation tank 13 of embodiment.

DESCRIPTION OF SYMBOLS 1 ... Organic waste water treatment system 11 ... Flow control tank 12 ... Activated sludge tank 20 ... Ozone supply device 13, 43 ... Precipitation tank 13a, 43a ... Bottom center part 13b, 43b ... Inclined part 13c ... Wall part 21 ... Aeration device 21a ... Bubble 22 ... Water discharge device 14a, 14b ... Pump 15 ... Return sludge pipe 30 ... Sludge 31 ...・ Septic sludge 43c ... Death area 44 ... Sludge scraping machine 44a ... Shaft 44b ... Scraping part

Claims (6)

An organic wastewater treatment method in which organic wastewater is purified by an organic wastewater treatment system,
The organic wastewater treatment system is
An activated sludge tank for decomposing organic matter contained in the organic wastewater with activated sludge containing aerobic microorganisms;
A settling tank for receiving the organic waste water in which the organic matter is decomposed together with the sludge containing the decomposed organic matter from the activated sludge tank, and precipitating the sludge,
The organic wastewater treatment method is
While supplying ozone to the activated sludge tank, a decomposition step of decomposing organic matter contained in the organic wastewater by the activated sludge,
In the settling tank, including a precipitation step of crushing and precipitating floating sludge that floats on the water surface including bubbles among the sludge,
Organic wastewater treatment method. The settling step further includes a step of agitating the settling tank to stir the water in the settling tank and crushing the floating sludge with bubbles generated by aeration.
The processing method of the organic waste_water | drain of Claim 1. The precipitation step includes a step of discharging water to the levitated sludge.
The processing method of the organic waste_water | drain of Claim 1 or 2. An activated sludge tank for decomposing organic matter contained in organic wastewater by activated sludge containing aerobic microorganisms;
An organic wastewater treatment system comprising: a settling tank that receives the organic wastewater in which the organic matter is decomposed together with the sludge containing the decomposed organic matter from the activated sludge tank, and precipitates the sludge,
An ozone supply device for supplying ozone to the activated sludge tank;
In the settling tank, further comprising crushing means for crushing the floating sludge that floats on the water surface including bubbles in the sludge,
Organic wastewater treatment system. The crushing means includes an aeration apparatus that agitates the settling tank to stir the water in the settling tank and crushes the floating sludge by bubbles generated by aeration.
The organic wastewater treatment system according to claim 4. The crushing means includes a water discharge device for discharging water to the levitated sludge.
The organic wastewater treatment system according to claim 4 or 5.

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