NL2002207C2

NL2002207C2 - Upflow anaerobic sludge blanket reactor.

Info

Publication number: NL2002207C2
Application number: NL2002207A
Authority: NL
Inventors: Wilhelmus Thomas Leenders; Willem Maria Wiegant; Bernardus Johannes Maria Bisseling
Original assignee: Haskoning Nederland B V
Priority date: 2008-11-13
Filing date: 2008-11-13
Publication date: 2010-05-17

Description

No. NLP184510A

Upflow anaerobic sludge blanket reactor BACKGROUND

The invention relates to an upflow anaerobic sludge blanket (UASB) reactor.

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The upflow anaerobic sludge blanket (UASB) reactor is a reactor type for the anaerobic treatment of wastewater. It can be applied for both industrial and domestic wastewater. For tropical countries it is considered a cost-effective 10 treatment technology for the reduction of organic pollution. In the treatment of domestic wastewater, the UASB technology should often be regarded as a pre-treatment technique, requiring post treatment to attain the relevant effluent standards. Such reactors for the treatment of domestic 15 wastewater have been constructed in Portugal, Columbia, Brazil, India and Pakistan.

An upflow anaerobic sludge blanket reactor comprises, among other things, an upflow reactor vessel and a separating 20 devices in the top of the reactor vessel. Biogas is formed in the process of biological degradation of organic pollutants. This biogas will rise through the sludge bed or sludge blanket to the surface, where the biogas is collected by a separating device which comprises a gas collector and a 25 gas dome.

2 A significant number of patents on UASB reactors have been filed, a number of them relate to the gas-liquid separating device. However, most of these patents do not relate to 5 domestic wastewater, but mostly to industrial wastewater. Some patents describe various new ways of separating sludge from the treated water by adding parallel plates (lamellae) to the gas collector (WOO123062, W00238509, EP1408008), or by another gas collector setup as described earlier 10 (EP1291326), or multiple layers of gas collectors (JP2001269694, W02004035485, W02004035486, EP1860074.

EP1071636), sometimes in a spiral form (JP2000005793).

Repetitive structures have also been described, such as open 15 ISO containers, containing the elements of a gas-liquid-solids separation (W02005095288).

Usually the size and weight of the gas collectors for a UASB reactor, transport and installation costs are a predominant 20 factor in the total investment for such a reactor.

It is an object of the invention to provide an easy-to-construct, prefabricated part of the gas-liquid-solids separating device of the UASB.

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SUMMARY OF THE INVENTION

According to a first aspect, the invention provides an upflow anaerobic sludge blanket reactor, comprising an 30 upflow reactor vessel and a separating devices in the top of the reactor vessel, wherein the separating device comprises a gas collector and a gas dome, wherein the gas dome comprises a cover, wherein the cover comprises a closed upper wall and substantially downwards extending 35 longitudinal side walls and end walls, wherein the upper wall and/or the side walls are made from a flexible material.

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In an embodiment, the whole cover is made from a flexible material. In an embodiment, the cover is a prefabricated, flexible, reinforced plastic bag or tent.

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In an embodiment, the side or edge of the longitudinal side walls facing away from the upper wall is provided with weighting means. In an embodiment, the weighting means comprises a PVC pipe filled with a weighting material. In an 10 embodiment, the weighting material is sand or concrete.

In an embodiment, the gas dome is placed between concrete beams, wherein the longitudinal side walls are adjacent to the concrete beams. In an embodiment, the concrete beams are 15 arranged for holding and supporting effluent launders. In an embodiment, the effluent launders are directly connected to the concrete beams at a side of the concrete beams facing away from the gas dome.

20 In an embodiment, the reactor comprises a hatch on top of the gas dome which is connected to the concrete beams. In an embodiment, the gas dome is connected to the hatch.

In an embodiment, the hatch and/or at least one of the two 25 concrete beams is provided with clamps for releasable connecting the hatch with the at least one of the two concrete beams. In an embodiment, the hatch is releasable connected to both concrete beams at either side of the gas dome.

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In an embodiment, the hatch is hingedly connected to one of the two concrete beams. In an embodiment, the hatch and/or at least other one of the two concrete beams is provided with clamps for releasable connecting the hatch with the 35 other one of the two concrete beams.

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In an embodiment, the reactor further comprises an output pipe for the bio gas, which output pipe reaches into the gas dome from underneath the gas dome. In an embodiment, the output pipe reaches through an open bottom-side of the gas 5 dome.

In an embodiment, the gas collector comprises a gas collector frame which consists of a prefabricated inverted "V" or triangular structure for carrying sides walls of the 10 gas collector. In an embodiment, the gas collector frame comprises longitudinal beams.

In an embodiment, the frame is made using pipes and elbows or bend parts. In an embodiment, the collector frame is 15 further provided with longitudinal beams, which are connected to the pipes via a T-piece or branche pipe, or a cross piece or four-way junction.

In an embodiment, the frame is made from a non-corrosive 20 material. In an embodiment, the frame is made from plastic pipes. In an embodiment, the frame is made from PVC pipes.

In an embodiment, the side walls are made from a flexible, non-corrosive material. In an embodiment, the side walls are 25 made from a plastic sheet.

According to a further aspect, the invention relates to a method of constructing an upflow anaerobic sludge blanket reactor as described above, wherein said method comprises 30 the step of building the separating device on site using prefabricated parts comprising a least a prefabricated flexible cover.

According to a third aspect, the invention relates to a 35 separating devices intended and suitable for use in an upflow anaerobic sludge blanket reactor as described above.

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The proposed structure and embodiments may, among others, provide one or more of the following advantages: i. a complete UASB reactor can be constructed in a modular form, using the gas dome structures (see Figure 8) 5 are the main repeating unit; ii. the triangular structures of the sides of the gas collectors (see Figure 2) can be simple put in place onsite; iii. these structures allow for simple mounting of the 10 flexible sides (see Figure 3) of the gas collector structure; iv. based on these units, the feed inlet structures can also be constructed in a modular form; v. the repeatability of the structures may lead to a 15 simple and cost-effective way of construction; vi. the low weight of the proposed structures allows for easy, on-site, construction of a whole UASB plant; vii. ease of maintenance is greatly enhanced by the proposed structure, because the hatch top of the gas 20 collector structure can easily be removed to allow for maintenance activities; and viii. gas pipes do not have to be disconnected upon cleaning the gas dome structures.

25 The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent 30 applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of 35 an exemplary embodiment shown in the attached drawings, in which:

Figure 1 shows a schematic view in cross-section 6 of a UASB reactor,

Figures 2A and 2B show a schematic view of a gas collector frame according to the invention,

Figure 3 shows a schematic view of the gas 5 collector frame of figure 2 with screens for guiding the biogas,

Figure 4A shows a schematic view of a gas dome, Figure 4B shows a schematic view of the gas dome of figure 4A on top of the gas collector of figure 3, 10 Figure 5 shows a schematic view of the gas collector of figure 4B with attached effluent launders and scum baffle,

Figures 6A and 6B show a schematic view of further embodiment of a gas dome, 15 Figures 7A and 7b show a schematic view of the closed and opened state of the gas dome of figure 6, and

Figure 8 shows a schematic view of the gas dome of figure 6B on top of the gas collector of figure 3.

20 DETAILED DESCRIPTION OF THE INVENTION

A generic and schematic representation of a UASB reactor is presented in Figure 1. The UASB reactor comprises a reactor vessel having a bottom wall 1 and the bottom wall 1 25 surrounding side walls 2.

The wastewater from a feed pipe 11, enters the reactor vessel through distribution boxes 12, which divide the wastewater evenly over the feed inlet points 13, which 30 themselves are distributed evenly over the bottom of the reactor. The biological sludge lays in the lower part of the reactor, and it is called the sludge bed 14 and if the concentration is lower, than it may be referred to as the sludge blanket 15. The wastewater passes through the sludge 35 bed 14 or blanket 15, and due to the contact with the sludge, organic pollution is removed by both biological conversion and by sedimentation.

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As an alternative, feed inlet may be applied through the bottom of the reactor instead of over the top, but for domestic wastewater, with its tendency for clogging of inlet 5 piping, it is not recommended.

Biogas 16 is formed in the process of biological degradation of organic pollutants. This biogas 16 will rise through the sludge bed 14 or sludge blanket 15 to the surface. On its 10 way up, the biogas 16 is guided via deflector beams 17 and baffles 18 into gas collectors 19, to be collected on top of the gas collector 19 in the gas domes 20. Usually, the weight of the gas collectors 19 and or the gas collector 19 are high to withstand the gas pressure and/or the withstand 15 the upward pressure of the gas collected by the gas collector and the gas dome. For example, the gas collector and/or gas dome can be fabricated using concrete. The invention, as described in more detail below, provides a light-weight alternative construction 20

The biogas 16 lead out of the gas domes 20 via an output pipe 21.

The reactor is usually provided with an overflow system 25 comprising effluent gutters 22 for leading away the treated water 23. Furthermore, a sludge withdrawal system 24 is provided.

Even without the use of biogas it is essential that the gas 30 16 is collected, because the zone between the gas collectors is used as a settling zone 21 for sludge particles, which can fall back in the reactor compartment.

The invention relates to an easy-to-construct, prefabricated 35 part of the gas-liquid-solids separating device of the upflow anaerobic sludge blanket (UASB) reactor. The prefabricated parts consist of 8 (1) a frame, wholly prefabricated or to be mounted from prefabricated elements, which will act as the structure to support the sides of a gas collector, which themselves consist of 5 (2) flexible, non-corrosive sheet and (3) a prefabricated gas dome in the form of a prefabricated bag-like structure, connected to a hatch which is also used to keep the dome in its place (4) Eventually prefabricated influent distribution 10 boxes may also be used for the simple and modular construction of the UASB reactor.

The parts (1) to (3) together are repetitive units that can be used for the construction of gas collectors with effluent 15 launders attached of a variety of sizes. With the use of these modules, construction of UASB reactors can be less costly, more effective and faster than is common practice today. Separate descriptions of the elements are presented below.

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Gas collector frame

The proposed gas collector frame 31 is depicted in Figure 2A. It consists of a prefabricated inverted "V" or 25 triangular structure 32, which can be further provided with longitudinal beams 33. In an embodiment, the angle between the horizontal and the sides is substantially 45°.

In an embodiment for construction on-site, as shown in 30 figure 2B, the frame 31 is made of inverted "V" or triangular elements 34, for example using pipes 35 and elbows or bend parts 36. The collector frame 31 can be further provided with longitudinal beams 37, which are connected to the pipes 35 via a T-piece or branche pipe 38, 35 or a cross piece or four-way junction 39.

The frame 31 can be used to support the sides of the gas 9 collector 40, as shown in figure 3. These sides 40 can be of a flexible, non-corrosive material (for instance, plastic sheet) to allow the gas to be collected at the top 30 of the structure 31 and to act as the sides of a sedimentation zone 5 in between two gas collectors.

The proposed structure 31 is both simple to construct and light, and can be used repeatedly to construct longer gas collectors.

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Gas domes

Gas domes may also be constructed in modules. The proposed module is illustrated in Figure 4A.

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The proposed substantially box-shaped module 41 can be placed on top of the gas collector, to form a gas-liquid-solids separating device. The biogas that is guided by the sides 40 of the gas collector 31, can enter the gas dome 20 module 41 via the open bottom-side 42 of the module 41, as schematically shown in figure 4B.

The gas dome 41 are placed in between concrete beams 43. These concrete beams 43 will also be used for holding and 25 supporting the effluent launders. In an embodiment the effluent launders 44 are directly connected to the concrete beams 43, as is illustrated in Figure 5.

Preferably the gas dome will be constructed in the form of a 30 prefabricated, flexible cover 51, such as a prefabricated, flexible, reinforced plastic bag. The cover 51 comprises a closed upper wall 52 and substantially downwards extending longitudinal side walls 54 and end walls 53. At least the side of the longitudinal side walls 54 facing away from the 35 upper wall 52 is provided with weighting means, such as a PVC pipe 55 filled with a proper material, as to act as a weight to put it in its place substantially below the water 10 level in the reactor. In Figure 6A, the proposed structure is depicted.

The gas dome 51 are provided with loops 56 allowing for 5 connection onto a hatch 61 on top of them, as shown in figure 6B. The gas dome 51 may be connected to the hatch 61 (glass reinforced plastic or comparable) with tie-wraps, allowing for easy mounting. The gas dome 51 is kept in place by the hatch 61 on top of it. Furthermore, the gas dome 51 10 is caught between the concrete beams 43 on either side of the dome 51

The hatches 61 themselves are connected to one of the two concrete beams 43a, with hinges to allow for opening of the 15 whole gas dome 51 as shown in figure 7B. Furthermore, the hatches 61 and/or the other one of the two concrete beams 43b is provided with clamps 62 to keep the gas dome 51 in its place under normal conditions, as shown in Figure 7A.

2 0 The biogas will be removed via an output pipe 63 which reaches into the gas dome 51 from underneath the gas collectors, in stead of on the top of them.

The outlet of the biogas will be kept below the gas domes, 25 in stead of on top of them. The complete proposed structure is illustrated in Figure 8.

It is to be understood that the above description is included to illustrate the operation of the preferred 30 embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present invention.

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Claims

An up-flow anaerobic sludge blanket reactor, comprising an up-flow reactor vessel (1, 2) and a separator (19, 20) at the top of the reactor vessel (1, 2), the separator (19, 20) a gas collector (19 ) and comprises a gas dome (20), characterized in that the gas dome (41, 51) comprises a cover, the cover comprising a closed top wall (52) and substantially downwardly extending longitudinal side walls (54) and end walls (53), wherein at least the top wall (52) and / or the side walls (54) are made of a flexible material.

An up-flow anaerobic silage blanket reactor according to claim 1, wherein the entire cover (52, 53, 54) is made of a flexible material.

An up-flow anaerobic sludge blanket reactor according to claim 2, wherein the cover (52, 53, 54) is a prefabricated, flexible bag or tent made of reinforced plastic.

An up-flow anaerobic silage blanket reactor according to claim 1, 2 or 3, wherein the side or edge of the longitudinal side walls (54) remote from the top wall (52) is provided with weighting means (55).

5. Upward-flow anaerobic mud blanket reactor according to claim 4, wherein the weighting means comprises a PVC tube (55) filled with a weighting material.

6. Upward flow anaerobic mud blanket reactor according to claim 5, wherein the weighting material is sand or concrete.

An up-flow anaerobic sludge blanket reactor according to any one of the preceding claims, wherein the gas dome (41, 51) is disposed between concrete beams (43), the longitudinal side walls (54) being adjacent to the concrete beams (43).

An up-flow anaerobic silage blanket reactor according to claim 7, wherein the concrete beams (43) are arranged to hold and support discharge troughs (44).

An up-flow anaerobic sludge blanket reactor according to claim 8, wherein the discharge troughs (44) are directly connected to the concrete beams (43) on a side of the concrete beams (43) remote from the gas dome (41, 51).

An up-flow anaerobic mud blanket reactor according to any one of the preceding claims, wherein the reactor comprises a hatch (61) placed on top of the gas dome (41, 51) and connected to the concrete beams.

The up-flow anaerobic mud blanket reactor according to claim 10, wherein the gas dome (41, 51) is connected to the hatch (61).

12. Upward flow anaerobic sludge blanket reactor according to claim 10 or 11, wherein the hatch (61) is hingedly connected to one of the two concrete beams (43a).

13. Upward flow anaerobic mud blanket reactor according to claim 10, 11 or 12, wherein the hatch (61) and / or at least one of the two concrete beams (43b) is provided with closing hooks (62) for releasably connecting the hatch (61) with the at least one of the two concrete beams.

14. Upward-flow anaerobic sludge blanket reactor according to any one of the preceding claims, wherein the reactor further comprises an outlet tube (63) for the biogas, the outlet tube (63) from the underside of the gas dome (41, 51) in the gas dome (41 , 51), preferably through an open bottom side (42) of the gas dome (41, 51).

An up-flow anaerobic sludge blanket reactor according to any one of the preceding claims, wherein the gas collector comprises a gas collector frame (31) consisting of a prefabricated inverted "V" or a triangular structure (32) for supporting side walls (40) of the gas collector.

An up-flow anaerobic silage blanket reactor according to claim 15, wherein the gas collector frame (31) comprises longitudinal beams (33).

The up-flow anaerobic silage blanket reactor according to claim 15 or 16, wherein the frame (31) is made of tubes (35) and bends or curved parts (36).

18. The upflow anaerobic sludge blanket reactor according to claim 17, wherein the collector frame (31) further comprises longitudinal beams (37) connected to the tubes (35) via T-pieces or branch tubes (38), or a cross piece or four-way split (39).

An up-flow anaerobic sludge blanket reactor according to any one of the preceding claims 15-18, wherein the frame (31) is made of a non-corrosive material, preferably of plastic tubes, preferably PVC tubes.

An up-flow anaerobic silage blanket reactor according to any one of the preceding claims, wherein the side walls (40) are made of. a flexible, non-corrosive material, preferably a plastic sheet.

A method of building an up-flow anaerobic sludge blanket reactor according to any one of the preceding claims, wherein the method comprises the step of constructing the separator 30 on site using prefabricated parts comprising at least one prefabricated flexible cover.

A separation device intended and suitable for an upward flow anaerobic silage blanket reactor according to any one of the preceding claims 1-20. 9 πποολ-