WO2017106907A1

WO2017106907A1 - Biofilm reactor wastewater treatment module

Info

Publication number: WO2017106907A1
Application number: PCT/AU2016/051202
Authority: WO
Inventors: Jim TANNER; Rhys Eddy
Original assignee: Envirostream Solutions Pty Ltd
Priority date: 2015-12-24
Filing date: 2016-12-07
Publication date: 2017-06-29
Also published as: AU2016374651B2; CN108430938A; CN108430938B; AU2016374651A1

Abstract

A biofilm reactor wastewater treatment module, comprising: a filtration core in the form of a sleeve of flexible, oxygen permeable and water impermeable material, an interior of the sleeve defining an air channel and the sleeve being spiral wound around a generally vertical central air duct through which air is introduced into the sleeve, wherein a wastewater passage is defined between adjacent layers of the sleeve and the sleeve is configured to support a biofilm on an exterior surface thereof for treating wastewater passing through the wastewater passage, and wherein the sleeve is sealed along at least an upper edge thereof and there is provided means for pressuring the sleeve with air so that air passes along the sleeve and through walls of the sleeve and into contact with the biofilm; a housing in which the filtration core is disposed, a lower portion of the housing defining a reservoir beneath the core; and a wastewater distribution system for distributing wastewater over an upper portion of the filtration core and into the wastewater channel so that the wastewater can pass over the biofilm for treatment; wherein the reservoir is in liquid communication with the distribution system for returning water from the reservoir to the distribution system to progressively treat the wastewater.

Description

BIOFILM REACTOR WASTEWATER TREATMENT MODULE FIELD OF THE INVENTION The present invention relates to a biofilm reactor wastewater treatment module. BACKGROUND OF THE INVENTION

It has previously been proposed to use microorganisms (bacteria) to produce enzymes that catalyse the degradation of unwanted material in water for treating wastewater such as sewerage. One way to achieve this is by providing a oxygen permeable and water impermeable membrane on which a biofilm is supported so as to promote aerobic treatment of wastewater passing over the membrane. This technology has been used in many differently configured systems with varying results. Some previous systems have been difficult to operate and control, expensive to install and provide variable results. Due to the large treatment area required to efficiently treat wastewater, and a desire to minimise the size of equipment required, filtration cores can be closely packed, often resulting in clogging during use. For example, some previous arrangements use a closely packed sleeve filled with wastewater that is prone to blocking and can be difficult to clean. Other arrangements use a planar sheet that requires manual assembly and a large treatment area.

US3558549, which issued 6 May 2003 to Zeonon Environmetal Inc., describes a membrane module having an oxygen permeable but liquid impermeable membrane with aerobic and anoxic biofilm for treating wastewater. Although this membrane can be spirally wound to be mounted in a tank or pipe, given the passive nature of the system, it can be difficult to reliably treat wastewater of varying composition to a required standard.

Similarly, US2003/0104192, which published 5 June 2003, discloses an apparatus for removal of organic substances and/or nitrogen sources from an aqueous medium, the apparatus having a sheet for passage of air and that can be spiral wound to form a gap through which wastewater can pass. Again, given the passive nature of the system, it can be difficult to reliably treat wastewater of varying composition to a required standard.

To address the issues of clogging membranes, US2009/0250394, which published 8 October 2009, proposes the use of planar membranes arranged side by side, however, such an arrangement can require a large amount of space to implement.

US8,940, 171, which issued 27 January 2015 to Emefcy Limited, involves the use of treatment units including a spiral wound generally horizontal wastewater pathway, between layers of which is defined a vertical airflow passageway. A plurality of like units are stacked vertically to provide sufficient treatment volume. Although a greater treatment area can be provided, in addition to the wastewater pathway being difficult to manufacture in that it must remain watertight, and it being prone to clogging due to its small size, maintaining and controlling a microbial population can be difficult, thereby making it difficult to reliably control the treatment effectiveness of the wastewater treatment system.

The inventors have observed that passing wastewater through a closely packed sleeve is an inefficient solution that can be difficult to maintain and can provide variable results, particularly as previously proposed treatment systems allow only a single pass through the treatment system, thereby requiring multiple units in parallel to ensure sufficient treatment is achieved. Also, most aerobic systems use blowers to supply air to the suspended biomass, which can be less efficient that water pumps.

Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previous biofilm reactor wastewater treatment modules.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a biofilm reactor wastewater treatment module, comprising: a filtration core in the form of a sleeve of flexible, oxygen permeable and water impermeable material, an interior of the sleeve defining an air channel and the sleeve being spiral wound around a generally vertical central air duct through which air is introduced into the sleeve, wherein a wastewater passage is defined between adjacent layers of the sleeve and the sleeve is configured to support a biofilm on an exterior surface thereof for treating wastewater passing through the wastewater passage, and wherein the sleeve is sealed along at least an upper edge thereof and there is provided means for pressuring the sleeve with air so that air passes along the sleeve and through walls of the sleeve and into contact with the biofilm;

a housing in which the filtration core is disposed, a lower portion of the housing defining a reservoir beneath the core; and

a wastewater distribution system for distributing wastewater over an upper portion of the filtration core and into the wastewater channel so that the wastewater can pass over the biofilm for treatment;

wherein the reservoir is in liquid communication with the distribution system for returning water from the reservoir to the distribution system to progressively treat the wastewater.

According to a preferred embodiment of the present invention, the module further comprises an inlet within the reservoir through which treated water is collected for discharging from the module, the inlet being arranged for collecting treated water from an upper portion of the reservoir.

The inlet may be floating within the reservoir. Preferably, the inlet is selectively openable to treat wastewater in batches.

Preferably, the module further comprises a recirculation pump disposed in the reservoir for returning treated water to the distribution system. The filtration core can be supported above the reservoir by support members extending radially outwardly from the air duct. Preferably, the sleeve is open along a lower edge. In other embodiments, it can be sealed along upper, lower and outermost edges. Preferably, the air duct is formed with a longitudinally extending slot in communication with the sleeve. In some embodiments, the housing has an outer portion formed of HDPE plastic.

According to another aspect of the present invention, there is provided a wastewater treatment plant comprising a plurality of modules of the above described type. According to another aspect of the present invention, there is provided a batch process for treating wastewater, comprising the steps of:

providing at least one module of the above described type;

filling the reservoir of the module with wastewater to be treated;

cycling the wastewater through the module to progressively treat the wastewater; and

after a predetermined amount of time has passed, discharging treated water from the module.

Preferably, at least 5% of the reservoir volume is retained in the reservoir for mixing with wastewater in a subsequent batch.

In some embodiments, the process can include the step of passing the treated water through a clarifier. In alternative embodiments, the process further including the step of allowing the treated water to settle in the reservoir and discharging treated water from an upper portion of the reservoir.

Preferably, the treated water is discharged through a floating pick up, floating on treated water within the reservoir. Preferred embodiments of the invention provide an integrated module for treating wastewater that can operate independently with little external infrastructure being required. As such, the module can be used in remote locations in emergency situations when existing infrastructure is unavailable, in connection with temporary housing or settlement projects, or in disaster recovery situations. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be further described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective sectional view of a biofilm reactor wastewater treatment module of one embodiment of the invention, with the filtration core removed for clarity;

Figure 2 is another perspective sectional view of the module, with an upper portion of the housing removed to illustrate a wastewater distribution system and illustrating the core in situ;

Figure 3 is a sectional side schematic view of the module;

Figure 4 is a close sectional view of the filtration core, illustrating air channels and wastewater passages;

Figure 5 is a side view of a filtration core of the module;

Figure 6 is a sectional view of the core of Figure 5; and

Figures 7 to 10 are different sectional plan views of the filtration core of Figure 5.

DETAILED DESCRIPTION

With reference to Figure 1, there is shown a wastewater treatment module 10. The module 10 uses a biofilm reactor for treatment of the wastewater.

As illustrated in Figures 1 to 3, the module 10 includes a filtration core 12 (refer Figure 2), a housing 14, a wastewater distribution system 16, means, in the form of a fan 18, for pressuring the filtration core 12, and a reservoir 20 for collecting treated water. The filtration core 12 is in the form of a sleeve 13 of flexible, oxygen permeable and water impermeable material. An interior of the sleeve 13 defines an air channel (refer 22 in Figure 4). To form the filtration core 12, the sleeve 13 is spiral wound around a central air duct 24 through which air is introduced into the sleeve 13. A wastewater passage 26 is defined between adjacent layers of the sleeve 13 and the sleeve 13 is configured to support a biofilm on an exterior surface thereof for treating wastewater passing through the wastewater passage 26.

The sleeve 13 is sealed along at least an upper edge thereof and there is provided means, in the form of fan 18, for pressuring the sleeve 13 with air so that air passes along the sleeve 13 and through walls of the sleeve 13 and into contact with the biofilm to provide oxygen to the biofilm and support the aerobic treatment of the wastewater as it passes through the wastewater passage 26. To supply air to the fan, an air inlet 19 is formed in an upper portion of the housing 14. Fan 18 is preferably a low pressure induction fan, though it will be appreciated that other devices for circulating air may also be used. In another form, the module 10 may be simply provided with a source of pressurised air.

The filtration core 12 is disposed in a housing 14. A lower portion of the housing 14 defines a reservoir 20 beneath the core and in which treated water can be collected. The filtration core 12 may be supported above the reservoir 20 by support members 30 extending radially outwardly from the air duct 24.

The housing 14 has an outer portion formed of HDPE plastic, though it will be appreciated that other commercially available materials may similarly be used. Advantageously, the module 10 can be formed as a sealed and integral unit, cost effectively and with existing manufacturing technologies. Offensive odours from the module 10 can be reduced and the module 10 can include all necessary equipment for operation, requiring little or no external infrastructure for operation.

The wastewater distribution system 16 is configured for distributing wastewater over an upper portion of the filtration core 12 and into the wastewater channel 26 so that the wastewater can pass over the biofilm for treatment. In some embodiments, the distribution system 16 distributes a small amount of wastewater so that the module 10 can operate as a trickle down filter. The distribution system 16 includes a generally annular conduit extending within the housing 14 and above the core 12 for distributing wastewater generally evenly over the core 12. The distribution system 16 is provided with a plurality of nozzles (not shown) for spraying the wastewater from a manifold (not shown) at sufficient water velocity to be self cleaning as the biofilm grows. Advantageously, clogging of the distribution system 16 and wastewater channels 26 can be reduced and potentially avoided.

The reservoir 20 is in liquid communication with the distribution system 16 for returning water from the reservoir 20 to the distribution system 16 to progressively treat the wastewater. In this regard a conduit 32 is provided, extending upwardly within the air duct 24 from the reservoir 20 to the distribution system 16. A recirculation pump 34 is disposed in the reservoir 20 for returning treated water to the distribution system 16. The operating specifications of the recirculation pump 34 will be selected having regard to the size of the module 10, the required flow rate through the wastewater treatment passages 26 and pressure required at the nozzles.

An inlet (not shown) within the reservoir 20 is provided, through which treated water is collected for discharging from the module 10. The inlet is arranged for collecting treated water from an upper portion of the reservoir 20 and may be in the form of a floating inlet, which floats on treated water within the reservoir to ensure treated water is collected from an uppermost portion of the reservoir 20 to reduce the amount of sediment in water discharged from the module 10. The inlet is selectively openable to treat wastewater in batches.

In this regard, in operation the module 10 is filled with wastewater, which is cycled through the module 10 and progressively treated. After a predetermined amount of time has passed, the recirculation pump 34 may be stopped and water allowed to settle before being discharged via a secondary pump (not shown). In another form, the treated water may be discharged directly after the recirculation pump 34 has stopped, i.e. without settling, and transferred to a clarifier or other similar apparatus to assist in the removal of sediment.

In use, at least 5%, and preferably between 5% and 10%, of the reservoir volume is retained in the reservoir as activated sludge for processing the next batch. Advantageously, treatment of the wastewater can be improved due to a reduction in the time required to establish the microbial population with a new batch. Removal of accumulated sludge may be performed by operating the recirculation pump and diverting the outlet to expel sediment rich water from the module 10. It will be appreciated that the secondary pump may also be configured for this use and that a further pump may also be provided for this purpose. Alternatively, the module 10 may be provided with an access hatch to allow for manual extraction of the sludge from the module 10.

The filtration core 12 is configured so that air passes along the air passages 22. In some embodiments, the sleeve 13 is sealed along upper, lower and outermost edges so that air passes from the air duct 24 under action of the fan 18, through the along the sleeve 13, through the membrane and to the biofilm. The air duct 24 is formed with a longitudinally extending slot 25 in communication with the sleeve 13 to facilitate passage of air from the air duct 24 into the sleeve 13. In other embodiments, the sleeve 13 is open along a lowermost edge, thereby simplifying manufacturing and allowing air to come up through the wastewater from the base in addition to passing along the sleeve 13.

Owing to the flexibility of the sleeve 13, it acts as a membrane bladder that expands once pressurised. It will be appreciated that the sleeve 13 is configured so that when inflated there is sufficient space for the wastewater passages 26 to allow a desired flow of wastewater to be obtained and a targeted treatment volume to be achieved. As illustrated in Figure 4, air channel supports 36 are provided within the sleeve 13 so as to maintain the air channel 22 in an open condition. Also, wastewater passage supports 38 are provided between adjacent layers of the sleeve 13 to maintain the wastewater passage 26 in an open condition. It will be appreciated that wastewater passage supports 38 are configured so as to reduce clogging of the wastewater passage due to sediment in the wastewater. Figures 5 to 10 illustrate the Filtration core 12 in more detail. With reference to Figure 7, it can be seen that a lower plate 40 is provided, the lower plate 40 having a plurality of slots 42 formed therein to allow the passage of water after it has passed through wastewater passages 26 for treatment. The filtration core 12, as illustrated in Figure 9, rests upon plate 40 in use.

A top distribution plate 44 having a plurality of apertures formed therein can also be provided as an alternative to a spray system for distributing water over an upper portion of the core 12. With distribution plate 44, water to be treated may simply be pumped upwardly by pump 34 and onto the plate 44 allowing even distribution over the core 12 without requiring a spraying system. It will be appreciated that the number and size of apertures are selected to provide a predetermined flow rate of water to the core 12.

Figure 10 illustrates a base 46 of the filtration core 12. The base 46 has a plurality of supports 48, which in the illustrated embodiment number 6 though different numbers of supports (either more or less) could similarly be used. The supports 48 extend from a central cylindrical portion 50 that defines a lower portion of air duct 24 and in which pump 34 may be disposed. Module 10 can provide an integrated wastewater treatment solution requiring little external infrastructure. Module 10 may be provided with a solar panel (not shown) for operating the fan 18, the recirculation pump 34 and the secondary pump. Recirculation pump 34 and/or the secondary pump may be provided for drawing wastewater into the module 10 so that only an inlet conduit or hose is required for connection of the module 10 to a source of water to be treated.

The module 10 can be used as a stand alone unit or a plurality of units may be combined to form a wastewater treatment plant if additional treatment capacity is required. Due to this modular nature, a user is provided with greater flexibility in establishing a wastewater treatment facility and greatly reduced capital outlay for commissioning a small scale facility that can be later upgraded. The disclosed embodiments can provide an integrated module for treating wastewater that can operate independently with little external infrastructure being required. As such, the module can be used in remote locations in emergency situations when existing infrastructure is unavailable, in connection with temporary housing or settlement projects, or in disaster recovery situations.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention disclosed.

Claims

1. A biofilm reactor wastewater treatment module, comprising:

a filtration core in the form of a sleeve of flexible, oxygen permeable and water impermeable material, an interior of the sleeve defining an air channel and the sleeve being spiral wound around a generally vertical central air duct through which air is introduced into the sleeve, wherein a wastewater passage is defined between adjacent layers of the sleeve and the sleeve is configured to support a biofilm on an exterior surface thereof for treating wastewater passing through the wastewater passage, and wherein the sleeve is sealed along at least an upper edge thereof and there is provided means for pressuring the sleeve with air so that air passes along the sleeve and through walls of the sleeve and into contact with the biofilm;

2. A module according to claim 1, further comprising an inlet within the reservoir through which treated water is collected for discharging from the module, the inlet being arranged for collecting treated water from an upper portion of the reservoir.

3. A module according to claim 2, wherein the inlet is floating within the reservoir.

4. A module according to claim 2 or claim 3, wherein the inlet is selectively openable to treat wastewater in batches.

5. A module according to any preceding claim, further comprising a recirculation pump disposed in the reservoir for returning treated water to the distribution system.

6. A module according to any preceding claim, wherein the sleeve is sealed along upper, lower and outermost edges.

7. A module according to any preceding claim, wherein the means for pressurising the sleeve is a fan.

8. A module according to any preceding claim, wherein the filtration core is supported above the reservoir by support members extending radially outwardly from the air duct.

9. A module according to any preceding claim, wherein the air duct is formed with a longitudinally extending slot in communication with the sleeve.

10. A module according to any preceding claim, wherein the housing has an outer portion formed of HDPE plastic.

11. A wastewater treatment plant comprising a plurality of modules according to any preceding claim.

12. A batch process for treating wastewater, comprising the steps of:

providing at least one module according to any one of claims 1 to 11;

filling the reservoir of the module with wastewater to be treated;

13. A process according to claim 12, wherein at least 5% of the reservoir volume is retained in the reservoir for mixing with wastewater in a subsequent batch.

14. A process according to claim 12 or claim 13, further including the step of passing the treated water through a clarifier.

15. A process according to any one of claims 12 to 14, further including the step of allowing the treated water to settle in the reservoir and discharging treated water from an upper portion of the reservoir.

16. A process according to claim 15, wherein the treated water is discharged through a floating pick up, floating on treated water within the reservoir.