JP2007509737A - Anaerobic wastewater treatment reactor - Google Patents

Abstract

An anaerobic wastewater treatment fixed bed reactor comprising a sheet-like carrier element for immobilizing microorganisms, wherein the carrier element is porous so that it can flow through and is thin compared to its area In a reactor having a width, the reactor is characterized in that the carrier elements are spaced apart such that a flow space having an average width in the spacing direction of 3.5-8 cm exists between the carrier elements.

Description

  The present invention relates to a fixed bed reactor for anaerobic wastewater treatment comprising a sheet-like carrier element for immobilizing microorganisms, the carrier element being porous so that it can flow through, and its region. Compared with a thin width.

  The reactor is characterized in that the carrier elements are spaced apart so that a flow space having an average thickness in the spacing direction of 3.5-8 cm exists between the carrier elements.

  It is well known to use an anaerobic process, ie, a wastewater treatment system that operates in an anaerobic manner, for the treatment of wastewater with a high organic pollutant load. When using anaerobic technology, the pollutant load contained in the wastewater is transferred to a regenerative energy carrier biogas that allows the stored energy to be stored with the help of the corresponding microorganisms. be changed.

  Municipal wastewater contains a relatively low pollutant load with a chemical oxygen demand (COD) of approximately 500 mg / liter and is generally treated by an aerobic activated sludge process. In the food processing industry, there are wastewaters with significantly higher organic pollutant loads that have a COD of 1000 mg / liter or more up to 100,000 mg / liter or more. High performance processes are utilized to clean up such waste water.

  The most common process is the so-called UASB process (upflow anaerobic sludge bed process). In the UASB reactor, internal biomass enrichment or fertilization is provided in the form of sludge that has very good granulation properties and forms. Microorganisms are grouped together to form so-called pellets. This allows for good biomass enrichment in the reactor. The reactor is operated in an upward flow manner. That is, the wastewater flows upward through the reactor from below. Due to the metabolically induced degradation of organic pollutants, a gas is created that adheres to the pellets in the form of bubbles. Therefore, the pellet rises upward. At the top of the UASB reactor is provided a separation system that is used to maintain pellets in the reactor. The disadvantage of this technique is that at high COD concentrations of about 20000-30000 mg / liter, the gas evolution is so strong that the pellets rise very quickly upwards and there is a considerable loss of biomass despite the separation system. Is to occur. This is called the spill effect.

  Another high performance process uses a fixed bed reactor. The fixed bed reactor is suitable for treating highly contaminated wastewater having a COD concentration of 10,000 mg / liter or more. In a fixed bed reactor, microorganisms settle on an inert carrier material in the form of a bulk material, a package or a fixed carrier material, for example an inert carrier material in the form of a plate-like carrier element. In order to achieve high biomass enrichment, the plates are currently arranged with a spacing of 1-2 cm. The plate-like carrier element usually has a membrane-like microbial growth having a thickness of 1 to 3 mm. The disadvantage of fixed bed reactors is that the support material constitutes a very large cost factor, especially when using high performance reactors.

  Inventors have found that, with relatively large carrier element spacings of 3.5 to 8 cm, preferably 4 to 6 cm, a bulky microbial mass is formed from which due to the intense agitation effect caused by the formation of the tuft. And found that an increase in the cross-sectional area of the mass can be observed. The hull can have a length of a few cm and a thickness of up to 1 cm. Its non-fixed end moves freely in the wastewater stream in the flow space. The wastewater thus flows around every side of the microorganism and supplies nutrients in an optimal way as well. This results in a particularly powerful microbial mass. Microorganisms are very effectively contacted with the wastewater to be treated. This bulky mass provides intense biomass enrichment with a relatively small number of carrier elements. This provides significant cost savings compared to conventional fixed bed reactors.

  With a carrier material that is porous so that it can flow through, the anchoring of the carrier element to the carrier element is so good that only very little biomass is removed.

  The present invention provides the advantage of being able to treat wastewater having a higher pollutant load than in the case of a UASB reactor. A further advantage is that the release of biomass is substantially avoided without having a complex separation system to maintain the required biomass.

  The carrier elements that are arranged in the reactor according to the invention define a flow space between the carrier elements, where the bulk of the bulky microbial mass is spread. In the reactor according to the invention, microorganisms can be brought into contact with the wastewater to be treated in a particularly effective manner, so that the bulky mass allows for a high biomass enrichment, so highly contaminated wastewater is removed. Suitable for processing. Fewer support elements are required in the reactor according to the invention than the corresponding conventional fixed bed reactor. Thanks to the wide flow path, clogging or blockage due to, for example, solids intrusion, peeled biomass, flow path blockage growth, etc. is less likely. Thus, the reactor according to the present invention has a higher stable operation than a conventional fixed bed reactor.

  The average width of the flow path in the spacing direction, i.e. the opening distance between the carrier elements according to the invention, is 3.5 to 8 cm, preferably 4 to 6 cm. The average width of the flow space is understood here as the distance between the virtual center planes of two adjacent carrier elements minus the carrier element thickness.

  The carrier element has a flat plate shape. However, other shapes are conceivable as well, such as the shape that appears when the plate spreads out in a curvilinear or wavy or zigzag manner. The carrier element thickness may be the same for all carrier elements, or may vary for the carrier elements. In all cases, the average spacing is measured by subtracting the carrier material thickness between the virtual center planes. However, if the carrier element has prominent protrusions, these are ignored in measuring the spacing.

  If applicable with respect to the virtual center plane, the carrier elements are preferably arranged parallel to each other. The carrier element may be arranged in a cubic (cuboid) package.

  The carrier elements may be arranged in a fan-shaped package that can be arranged in a ring shape alongside each other. This ring-shaped arrangement of the fan-shaped carrier element package can (in general terms) be matched to the cylindrical reactor housing shape. The plate inside the package is arranged substantially in the tangential direction of the reactor.

  In the reactor, preferably wastewater having a chemical oxygen demand (COD) of 4000-120,000 mg / liter is scheduled to be treated during operation.

  The reactor according to the invention is preferably operated in an upflow mode. That is, the wastewater to be treated flows substantially upward from below through the flow space. This is due to the upward movement of bubbles formed by metabolism on the biofilm. At the upper end of the reactor, gas discharge means are provided in a conventional manner. It is therefore preferred to arrange the carrier elements substantially vertically.

  The reactor is preferably configured to be operated at an upward flow velocity of 5-10 m / h.

  The carrier element is arranged on a holding device. The carrier element is preferably rectangular and is supported at its corners. Furthermore, it is preferable that a holding device is provided which has a series of recesses and supports a plurality of carrier elements. The holding device comprises a rod, rail or cross section (eg U cross section) having a recess for receiving a carrier element therein. A preferred material for the cross section is stainless steel.

  The carrier element is made of a material that is porous to allow flow through. Preferably, the carrier element consists essentially of plastic particles and expanded clay particles, which are united by sintering. Polyethylene particles are preferred as plastic particles, and other plastic materials are possible as well. Microorganisms are deposited or inoculated in the pores between the particles, which can form a blocky mass on the carrier element. For example, in the case of a reactor failure due to a toxic impact, the microbial turf is reliably destroyed. However, the microorganisms quickly re-grow from the pores of the porous material and regenerate a membrane or stubby mass on the plate. The expanded clay particles have a pore size of approximately 1 to 100 μm. The microorganisms are preferably initially inoculated with smaller pores that constitute a protected space away from the flow. Inoculation begins with the smaller holes first, followed by the larger holes, and finally covers the entire structure. In the case of a malfunction, the micro-organisms in the small pores constitute a mass regeneration nucleus within a few days. Due to the fact that microorganisms also grow in the pores, a good fixation of the bushy mass is established.

  Adherent microorganisms can be inoculated or settled on the carrier element. In particular, the carrier element is inoculated with at least one bacterial genus of the group of the genus Citrophobacter, Citrophomas, Methanotrix, Methanosarcina and Methanococcus.

  Reactors can be used for wastewater treatment of high load organic contaminants such as carbohydrates or proteins.

  In accordance with the present invention, organically highly contaminated wastewater from the beverage, feed, or food processing industries, particularly from starch processing factories and equipment, beverage factories, breweries, alcoholic breweries, dairy farms, etc. Waste water and waste water from meat processing plants and fish processing plants are treated. The process according to the invention and the reactor according to the invention are equally suitable for treating waste water from the paper and textile industries.

  The invention and preferred features of the invention will now be described by way of example with reference to the accompanying drawings.

  FIG. 1 shows a reactor 10 according to the present invention, which comprises a package assembly of carrier elements 20 that is inoculated with microorganisms for anaerobic treatment.

  The waste water 70 to be treated is supplied to the supply tank 60 via the sieve 71 and the oil separator 72. The supply tank is vented through the device 61. The supply tank further comprises waste water stirring means 62, pH value measuring means 63 and temperature measuring means 64. Sodium hydroxide or acid may be supplied via supply lines 66 and 67 in order to adjust the pH value to a physiologically appropriate range.

  The waste water to be treated is supplied to the line 30 via the line 50. This line 30 supplies fresh wastewater and circulating wastewater to the reactor 10. Supply from the supply tank 60 is controlled via a valve 51 and a pump 52. In order to bring the waste water to an appropriate temperature, the waste water is passed through the heat exchangers 53 and 54 on the way to the reactor 10. The heat exchanger 53 uses heat radiated from the outflow treatment wastewater drawn from the wastewater reactor 10 via the line 40. The wastewater pH value and temperature are sensed in line 30 using sensors 33 and 34, respectively. Acid or base may be supplied via line 37 to adjust the pH value. Alternatively, a passage vessel (not shown) may be provided between the supply tank 60 and the reactor 10, in which the pH of the sensor 33 is measured before the wastewater to be treated is supplied to the reactor. The pH value can be adjusted by adding acid or base in response to the value.

  In the reactor 10, wastewater flows vertically upward at a speed of 5-10 m / s, in this case through a plate package 20 of carrier material. Foam inhibitors and additional additives may be introduced into the reactor 10 via lines 16 and 17, respectively, as required. The biogas formed in the reactor accumulates at the top of the reactor 10. The gas can be withdrawn via line 18, and the gas is supplied for further processing or use, for example as a heat source for combustion. Waste water is circulated through line 30 with the help of a pump. The treated wastewater can be discharged via line 40.

  FIG. 2 illustrates a cubic package 20a of plate-shaped carrier elements 24a. The carrier element 24a is held at its corners using a U-section profile rail 22a which is part of the holding device.

  FIG. 3 illustrates a fan-shaped package 20b of a plate-shaped carrier element 24b. The carrier element 24b is held at its corners using a U-section profile rail 22b which is part of the holding device.

  FIG. 4 illustrates a partial view of the package illustrated in FIG. 3 (viewed from above), with the bottom of the rail facing to the right in the figure and the upper leg cut away. A cross-sectional outer rail 22b is shown. In this way, the lower legs of the U-section outer rail 22a with the recesses 26b supporting the carrier elements 24b with a mutual opening distance d can be seen from each other. This distance d constitutes the average width of the flow space. Thus, the flow space created between the carrier elements has a width d that is 3.5 to 8 cm according to the invention.

  However, the carrier element may be held by another holding device. In particular, it is conceivable that they are not supported at their corners but are supported at their vertical end surfaces by sliding them into the groove. These grooves may be U-shaped outer rail shapes that are interconnected horizontally using additional bars. Grooves may also be formed on or in the plate.

  The support side or bar may be part of the overall frame-like holding device.

  FIG. 5 illustrates an enlarged view of the carrier material 90. The carrier material consists of plastic particles 92 that are integrated with each other and the expanded clay particles 94 by sintering.

  In the reactor 10, a hexagonal arrangement of fan-shaped packages of carrier material plates is provided. The hexagonal arrangement has a diameter of 1 m and a height of 1.5 m. The carrier material is a composite material composed of expanded clay particles and polyethylene which are porous so as to be flowable through and integrated by sintering. The spacing d between the carrier elements (ie the plates) is 4 cm. In a test run to test the equipment capacity, the reactor was operated in a circulation with an upward flow rate of 5-10 m / s. In the test run, wastewater flowing in with a COD of 4025-117500 mg / liter was treated and the measured COD value of the treated wastewater was 580-5500 mg / liter.

  Inspection of the carrier element plate revealed that a bacterial bulky mass had formed on the plate. Compared to conventional fixed bed reactors with similar operating parameters, the surface area of the plate can be reduced by about 50%, and the reduction of the surface area significantly reduces equipment costs. Furthermore, the risk of partial or complete clogging of the flow path could be prevented without problems in test runs over several months.

1 shows a schematic diagram of a wastewater treatment facility incorporating an embodiment of a reactor according to the present invention. Figure 2 shows a plan view of a cubic package of carrier elements. Fig. 4 shows a plan view of a fan-shaped package of carrier elements. Figure 2 shows a partial view of a carrier element package. Figure 2 shows an enlarged view of the carrier element.

Explanation of symbols

10 reactors 16 lines 17 lines 18 lines 20 carrier elements 20a cubic packages 20b fan-shaped packages 22a U-section outer rails 22b U-section outer rails 24a carrier elements 24b carrier elements 30 lines 33 pH measurement sensors 34 temperature measurement sensors 37 lines 40 lines 50 lines 51 valve 52 pump 53 heat exchanger 54 heat exchanger 60 supply tank 61 equipment 62 stirring means 63 pH measurement means 64 temperature measurement means 66 supply line 67 supply line 70 waste water 71 sieve 72 oil separator 90 carrier material 92 plastic particle 94 expansion Clay particles

Claims (13)

An anaerobic wastewater treatment fixed bed reactor comprising a sheet-like carrier element for immobilizing microorganisms, wherein the carrier element is porous to be able to flow through and has a thickness smaller than that of the region. In a reactor having
Reactor characterized in that the carrier elements are spaced apart such that a flow space having an average width in the spacing direction of 3.5-8 cm exists between the carrier elements.   Reactor according to claim 1, characterized in that the flow space existing between the carrier elements has an average width in the spacing direction of 4-6 cm.   The reactor according to claim 2, wherein the carrier element has a substantially flat plate shape.   Reactor according to any one of the preceding claims, characterized in that a carrier element arranged in a cubic package is provided.   4. A carrier element arranged in a fan-shaped package that is placed side by side in a ring, the carrier element extending substantially tangentially. The reactor described.   The reactor according to any one of claims 1 to 5, characterized in that, during operation, the reactor is scheduled to treat wastewater having a chemical oxygen demand (COD) of 4000 to 120,000 mg / liter. Reactor.   Reactor according to any one of the preceding claims, characterized in that the reactor is adapted to be operated at an upward flow velocity of 5 to 10 m / h.   Reactor according to any one of the preceding claims, characterized in that the carrier element has a rectangular shape and is supported at its corners.   Reactor according to any one of the preceding claims, characterized in that a holding device is provided, each having a series of recesses and holding a plurality of carrier elements.   Reactor according to any one of the preceding claims, characterized in that it is provided with a carrier element consisting essentially of plastic particles and expanded clay particles that are integral with each other.   11. The reactor according to claim 1, wherein the reactor is scheduled to be operated with at least one bacterium of the group of the genera Citrophobacter, Citrophomas, Methanox, Methanosartina and Methanococcus during operation. A reactor according to claim 1.   12. A method of using a reactor according to any one of claims 1 to 11 for anaerobic wastewater treatment of equipment in the beverage industry, feed industry or food processing industry. A method of using a reactor according to any one of claims 1 to 11 for the treatment of anaerobic wastewater in equipment of the paper industry or textile industry.

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