Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/02—Aerobic processes
  • C02F3/12—Activated sludge processes
  • C02F3/1205—Particular type of activated sludge processes
  • C02F3/1221—Particular type of activated sludge processes comprising treatment of the recirculated sludge
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/18—Treatment of sludge; Devices therefor by thermal conditioning
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/28—Anaerobic digestion processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

• the invention relates to a method for conditioning and sanitizing sewage sludge and the like, with a container having a plurality of chambers, in which method the fresh sewage sludge is preheated and introduced into a first chamber and further heated there and thereby sanitized and / or hydrolyzed, then into a first Retention chamber is admitted and left there for a predetermined time to the hygienization temperature, then cooled by heat exchange with fresh sewage sludge and finally converted into digested sludge in one or more stages.
• Sewage sludge is a liquid that is highly contaminated with organic substances.
• Fresh sewage sludge is understood to mean the material to be treated which is introduced for the first time in the described method, even if it was subjected to a pretreatment before being introduced into the method.
• a treatment method for sewage sludge has proven itself in practice, in which the sewage sludge is first hygienized and hydrolyzed by heating to a temperature of 60 ° C. for about 24 hours.
• European patent 0 053 777 of UTB reactor Buchs AG relates to a process which has become known under the name "UTB AEROTHERM”.
• the sewage sludge is heated by biodegradation by introducing air into the sewage sludge, which causes the aerobic activity thermophilic bacteria is supported in such a way that temperatures of about 70 C are reached. An increased temperature is maintained as long as enterobacteria and worm eggs are killed.
• the batch to be discharged is discharged into a receiver and left there for about half an hour. This prevents traces of untreated sewage sludge which still contain dangerous enterobacteria, for example Salmonella, from being removed with the treated sewage sludge. The dwell time of half an hour is enough to kill any remaining enterobacteria.
• the sewage sludge is largely degassed. So carbon dioxide, nitrogen and some oxygen are separated.
• the separated gases do not get into the sewage gas of the subsequent digestion stage, which leads to an increase in the quality of the sewage gas.
• the sewage sludge pumped out of the receiver into the digestion stage is passed through a flow-through heat exchanger through which fresh sewage sludge is fed to the reactor in counterflow.
• the hot sewage sludge is brought to the optimum temperature for the digestion before entering the digestion stage and, at the same time, the fresh sewage sludge which is fed to the reactor is preheated.
• a disadvantage of the described method is that it requires a relatively large amount of equipment and the space required is correspondingly large.
• the isolation of the template and the relatively long supply lines is relatively expensive and can hardly meet the requirements, especially in severe winters.
• European patent application 0 217 739 from UTB scrub ⁇ technik Buchs AG describes a process in which the fresh sewage sludge is first hygienized and / or hydrolyzed by increasing the temperature in a reactor, then further hygienized and degassed in a template and finally in one or more stages Sludge is converted.
• the temperature of the sewage sludge in the feed is maintained by heat from the reactor.
• the template is arranged inside the reactor.
• a flow-through heat exchanger is again provided, through which the treated sewage sludge from the receiver and the fresh sludge are passed in countercurrent. Flow-through heat exchangers are relatively expensive and also require a relatively large amount of maintenance.
• Another disadvantage is that a relatively large amount of space is used for the reactor and heat exchanger. In existing wastewater treatment plants, however, the space is often very tight, so that there is a considerable need for compact plants. It is therefore an object of the present invention to provide a method for conditioning and sanitizing sewage sludge which has a minimal need for apparatus and at the same time enables a very compact design of the device for carrying out the method. A compact design should also reduce investment costs and heat losses.
• this is achieved in a method according to the type mentioned at the outset by introducing the fresh sewage sludge for preheating into a further dwell chamber, which is adjacent to the first dwell chamber, so that heat is exchanged through a chamber wall , whereby the fresh sewage sludge is preheated and the hot sewage sludge is cooled.
• This method has the advantage that it enables a very compact design of the device for conditioning and sanitizing sewage sludge, because it does not require the usual separate receiver or a flow-through heat exchanger.
• the compact design also allows the device or system to be largely standardized and cheaper.
• the fresh sewage sludge is gelatinous at rest and therefore no significant convection currents can develop in it. In the idle state, the fresh sewage sludge is therefore only heated in the area of the warm container walls and can therefore initially not extract much heat from the reaction chamber or from the dwell chamber for the hot sewage sludge.
• the treated sewage sludge is first discharged into a receiver before it is discharged into the digester and there for a predetermined time, e.g. half an hour. If, according to one embodiment of the invention, the fresh sewage sludge is only introduced into the second retention chamber after the predetermined time has elapsed, the treated sewage sludge in the first retention chamber is not cooled by fresh sewage sludge in the second retention chamber during the required retention time.
• the contents of these chambers are expediently moved by an agitator in each case.
• This circulation results in a good heat exchange, so that the treated sewage sludge reaches the lower temperature desired for the subsequent digestion in a relatively short time and the fresh sewage sludge is preheated in the reactor chamber for its further treatment.
• the fresh sewage sludge in the reactor chamber is expediently heated further by biodegradation.
• the sewage sludge can be circulated in the reactor with a feed pump and aerated with an oxygen-containing gas during circulation with an ejector. This ventilation adds the oxygen required for aerobic thermophilic degradation to the sewage sludge.
• the sewage sludge from the reactor chamber is advantageously circulated using a feed pump. By selecting the appropriate circulation rate, it can be ensured that the sewage sludge slowly flowing through the fixed bed does not create any shear forces that could disrupt the symbiosis of the acidifying and methanogenic bacteria.
• the circulation is expediently carried out through a fixed bed which has a multiplicity of channels, the walls of which serve as settlement areas for microorganisms, for example acidifying and methanogenic bacteria.
• a fixed bed clearly defined flow conditions are achieved which counteract a reduction in cross section caused by deposits.
• the carpet of microorganisms that forms on the walls of the channels is fully effective, so that the organic matter of the sewage sludge is quickly conditioned.
• fresh sewage sludge can then be let into a first dwell chamber and, after the anaerobic treatment, still hot sewage sludge can be let into a second dwell chamber, whereby the fresh sewage sludge is preheated and the hot sewage sludge is cooled. Afterwards, the freshly prewarmed sewage sludge can be conveyed into the reactor chamber and the cooled treated sewage sludge into a stacking room.
• the invention also relates to a device for conditioning and sanitizing sewage sludge.
• This device has a container which has a reactor chamber for heating the sewage sludge.
• the device is characterized in that the means mentioned have a retention chamber for hot sewage sludge and a retention chamber for fresh sewage sludge in the same container in which the reactor chamber is also located. This leads to a very compact construction of the device.
• At least one agitator is advantageously arranged in each dwell chamber. Thereby, heat exchange between the chambers is promoted during the time when heat exchange is desired.
• the retention chamber for the fresh sewage sludge is arranged between the reactor chamber and the retention chamber for the hot sewage sludge. With this arrangement, heat is transferred to the fresh sewage sludge both from the reactor chamber and from the dwell chamber for the hot sewage sludge.
• Another embodiment of the invention provides that the retention chamber for the hot sewage sludge is arranged between the reactor chamber and the retention chamber for the fresh sewage sludge. With this arrangement, heat transfer from the reactor chamber to the fresh sewage sludge in the residence chamber is avoided. This also has the advantage that the hot sewage sludge is cooled down more before it is fed into the digester.
• Dwell chamber and reactor chamber are advantageously arranged one above the other. This results in a very compact and space-saving design, especially if the container is a vertically arranged cylindrical container.
• the container expediently has thermal insulation in order to avoid radiation losses.
• Each chamber is expediently provided with a ventilation line. The gas generated in the reactor chamber during anaerobic operation can be fed to a methane-forming fouling stage.
• At least one bundle of tubes is advantageously arranged in the reactor chamber in order to form the fixed bed with a plurality of practically vertical channels.
• Fig. 1 is a schematic representation of a system for
• Fig. 2 shows a container with two retention chambers and a reactor chamber, in which a fixed bed is arranged.
• the container 11 provided with thermal insulation 14 has three chambers 13, 15 and 17. It is advantageously upright and of cylindrical shape, the chambers 17, 15 and 13 being arranged one above the other. This design takes up very little space. However, it would also be possible to give the container 11 a different shape and, for example, to arrange it horizontally.
• the fresh sludge is supplied from the sewage treatment plant via line 21, in which the feed pump 23 and the valve 25 are arranged.
• the chamber 15 is the retention chamber for the fresh sewage sludge.
• the line 27 leads from the dwell chamber 15 for the fresh sewage sludge to the upper part of the reactor chamber 13. In the line 27 the valve 29 and the feed pump 31 are arranged. There are various options for aerating the sewage sludge in the reactor chamber 13.
• a circulation pump 33 is provided for ventilation, which causes the contents of the reactor chamber 13 to be circulated via the line 35, the oxygen-containing gas then being fed through the injector 37 to the sewage sludge.
• a support heater 39 is provided to heat the sewage sludge if necessary.
• a valve 36 is advantageously provided with which the air supply can be regulated. It is also possible to provide a gas circuit from the reactor chamber 13 back to the reactor chamber 13 via the line 38, the valve 40 and the injector 37.
• One agitator 43, 45 is used to circulate the contents of the chamber 15 and 17 respectively.
• the lines 47, 48 and 49 serve to vent the chambers 13, 15 and 17.
• the lines 47, 48 and 49 are for this purpose to a collecting line 51 connected, which is connected to an exhaust fan 53.
• the lines 47, 48, 49 also serve as emergency overflow lines, the emergency overflow taking place in a collecting line 55.
• the lines 72 between the digestion chamber 65 and the chamber 17 and the line 74 from the chamber 17 to the stacking chamber 66 are provided for the variants of the method in which heat is exchanged between digested sludge and fresh sewage sludge.
• Valves 50, 52, 54, 56 and 62 are used in particular to switch from one process variant to another.
• the conditioning and hygienizing process is controlled by electronic control device 67, for example, which switches pumps, valves, agitators, etc.
• the system In operation for the heating of fresh sewage sludge with hot. Sewage sludge from the reactor chamber 13, the system operates as follows: After the reactor chamber 13 has been filled with sewage sludge, the circulation pump 33 circulates the reactor contents; the injector 37 aerates the sludge mixture. The action of the thermophilic bacteria causes the sewage sludge to biodegrade in the reactor, with the temperature in the reactor rising above 60 ° C. At these temperatures, dangerous enterobacteria, e.g. Salmonella, killed after some time. The controller 67 then opens the valve 59 so that a batch of hot sewage sludge can flow into the dwell chamber 17. The sewage sludge is left there for about half an hour.
• a charge of fresh sewage sludge is pumped into the dwell chamber 15 by the feed pump 23.
• the agitators 43 and 45 are set in motion, so that the contents of the chambers 15, 17 are circulated.
• a heat exchange takes place through the chamber wall 12, so that the hot sewage sludge cools down in the chamber 17.
• the sewage sludge cooled and degassed to about 40 ° C is discharged from the dwell chamber 17 via lines 58, 64 and the opened valves 60, 61 from the feed pump 63 to the subsequent sludge treatment stage, e.g. a digester 65, pumped.
• the fresh sewage sludge from preheating chamber 15, which has now been preheated to approximately 20 ° C., is pumped by the feed pump 31 into the reactor chamber 13 via the opened valve 29.
• a new cycle can now take place which begins with the loading of the dwell chamber 17 with hot sewage sludge from the reactor 13.
• the digestion sludge can be discharged into the stacking space 66 at a temperature of approximately 35 ° C. by opening the valve 50.
• the fresh sewage sludge is preheated in two stages, namely first by heat exchange with digested sludge and then by heat exchange with hot sewage sludge from the reactor chamber 13.
• the system then works as follows: After the reactor chamber 13 has been filled with sewage sludge, it rolls Circulation pump 33 around the reactor contents, the temperature in the reactor rising due to the action of the thermophilic bacteria. After a certain temperature has been reached, the valve 52 is first opened and a batch of digested sludge from the digesting chamber 65 is let into the dwell chamber 17. Fresh sewage sludge is pumped into the dwell chamber 15 by opening the valve 25 and actuating the feed pump 23. The two agitators 43 and 45 are then set in motion.
• the fresh sewage sludge is heated and the digested sludge is cooled by the heat exchange through the chamber wall 12.
• the cooled digested sludge is then conveyed into the stacking space 66 by the feed pump 63 or by gravity via the lines 58 and 74.
• the control then closes the valve 61 and opens the valve 59, so that a batch of hot sewage sludge can flow into the residence chamber 17.
• the sewage sludge is then left there for about half an hour.
• the contents of the chambers 15, 17 are then circulated in order in turn to bring about an intensive heat exchange through the chamber wall 12.
• the fresh sewage sludge already preheated by the digested sludge is preheated further.
• the sewage sludge which has been cooled and degassed to about 40 ° C., is then pumped from the dwell chamber 17 via line 58 and the open valves 54, 61, 62 by the feed pump 63 into the digester 65. A new cycle can then begin again.
• the fresh sewage sludge is preheated by anaerobically treated ones Sewage sludge, so-called digested sludge.
• the plant then operates as follows: after the reactor chamber 13 has been filled with sewage sludge, the circulating pump 33 circulates the reactor contents, the temperature in the reactor rising as a result of the action of the thermophilic bacteria. After a certain temperature has been reached, the feed pump 63 pumps hot sewage sludge into the anaerobic stage 65 when the valves 54, 61 and 62 are open. By opening the valve 52, a batch of anaerobically treated sewage sludge flows into the dwell chamber 17.
• FIG. 2 shows a fixed bed 71 inserted into the reactor space 13. Otherwise, the plant is constructed practically the same as that of FIG. 1, so that reference can be made to the description of FIG. 1 for details.
• a fixed bed is particularly advantageous for anaerobic operation, but can also be used for aerobic operation.
• the fixed bed 71 consists of a tube bundle 73, the tubes 75 of which are fed with sewage sludge through a distribution device 77.
• the tubes 75 form a multitude of channels, the walls of which serve as settlement areas for microorganisms.
• a circulation pump 33 is provided, which causes the contents of the reactor chamber 13 to be circulated via the line 35 and the distribution device 77.
• a support heater 39 is used, if necessary, for the additional heating of the sewage sludge.
• the system provided with a fixed bed 71 practically the same as the system previously described. In anaerobic mode, however, there is no ventilation.
• the gas then produced can then be fed via line 51 to the digester 65.
• the distribution device 77 distributes the sewage sludge practically uniformly over the individual channels of the fixed bed 71.
• the filling level of the reactor chamber 13 is controlled in such a way that the individual channels are not filled to the top. As already described in the introduction, a risk of constipation is counteracted.
• the lines 72 and 74 and the valves 50, 52, 54, 56 can be omitted if the system only has to be able to heat the fresh sewage sludge from the reactor chamber 13 using hot sewage sludge.
• Other lines and valves can be omitted if the system is only to work according to a different process variant.
• the arrangement of the chambers 15 and 17 can be interchanged, for example.

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• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Microbiology (AREA)
• Biodiversity & Conservation Biology (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Treatment Of Sludge (AREA)

Applications Claiming Priority (2)

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• 1987
  • 1987-04-15 CH CH1477/87A patent/CH672780A5/de not_active IP Right Cessation
• 1988
  • 1988-04-13 WO PCT/CH1988/000077 patent/WO1988007978A1/de not_active Application Discontinuation
  • 1988-04-13 EP EP88902783A patent/EP0333774A1/de not_active Withdrawn

Non-Patent Citations (1)

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