WO2019195885A1

WO2019195885A1 - Process for the production of a microbial biomass

Info

Publication number: WO2019195885A1
Application number: PCT/AU2019/050319
Authority: WO
Inventors: Ian Bradley Nielsen
Original assignee: Airrat Pty Ltd
Priority date: 2018-04-12
Filing date: 2019-04-11
Publication date: 2019-10-17

Abstract

A process for the production of a microbial biomass, the process including culturing the microbial biomass in a liquid reservoir, at least some of the microbial biomass settling at the bottom of the liquid reservoir for harvesting, harvesting the settled microbial biomass from the bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir, the harvesting including traversing a harvesting device along the bottom of the reservoir, collecting the settled microbial biomass using the harvesting device and transferring the collected microbial biomass from the harvesting device to one or more settling tanks, dewatering the collected microbial biomass in the one or more settling tanks and drying the dewatered microbial biomass.

Description

PROCESS FOR THE PRODUCTION OF A MICROBIAL BIOMASS

Background of the Invention

[0001] The present invention relates to a process for the production of a microbial biomass, and in one example, to a continuous or semi-continuous process for the large-scale production of a microbial biomass in an open pond environment for use in or as an aquaculture feed.

Description of the Prior Art

[0002] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0003] The development of novel aquaculture feeds has been driven by the need to balance production output to meet the increasing protein needs of a growing population and environmental sustainability. It is recognised that the traditional reliance on fish meal and fish oil in the diet of many aquaculture species is unsustainable as fish meal and fish oil is sourced from wild caught species of fish that have been overfished. There is therefore a need to ensure improved utilisation of land-based feed solutions that can replace unsustainable sources of marine -based feeds.

[0004] Several years ago, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) developed a natural food source produced by marine microbes called Novacq™ which is used as an aquaculture feed ingredient, in particular for prawns. Use of Novacq™ feed sustainably boosts productivity for prawn farmers enabling them to grow bigger, healthier prawns sustainably, faster and cheaper. Prawns fed with Novacq™ grow on average 20-40 per cent faster, are healthier and can be produced with reduced wild fish products in their diet thereby providing improved feed conversion. This means more profit for prawn farmers and less pressure on precious marine resources. Novacq™ can help replace scarce fishery resources such as fish meal in diets, which is important for consumers, retailers and overall industry sustainability. The process for producing Novacq™ is described for example in Australian Patent Nos. 2008201886 and 2009225307.

[0005] The production and harvesting of Novacq™ to date has been performed as a batch process, which involves the periodic draining of production ponds to leave the Novacq™ as a residue to be harvested or collected and dried. Batch process production has a number of disadvantages and does not lend itself as an economically viable production process for commercial quantities of Novacq™ or microbial biomass more generally. In batch process production, the pond is required to be periodically drained which firstly creates an environmental problem in discharge and liquid disposal and subsequent re-filling. Water borne nutrients are also lost during draining and furthermore the microbial biomass is only grown and harvested at periodic intervals thereby making it difficult to be able to produce a constant supply of aquaculture feed for commercial use.

[0006] It would therefore be a more efficient and environmentally sustainable solution to harvest a microbial biomass such as Novacq™ as part of a continuous or semi-continuous production process.

[0007] It is against this background, and the problems and difficulties associated therewith, that the present invention has been developed.

Summary of the Present Invention

[0008] In one broad form an aspect of the present invention seeks to provide a process for the production of a microbial biomass, the process including: culturing the microbial biomass in a liquid reservoir, at least some of the microbial biomass settling at the bottom of the liquid reservoir for harvesting; harvesting the settled microbial biomass from the bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir, the harvesting including: traversing a harvesting device along the bottom of the reservoir; collecting the settled microbial biomass using the harvesting device; and, transferring the collected microbial biomass from the harvesting device to one or more settling tanks; dewatering the collected microbial biomass in the one or more settling tanks; and, drying the dewatered microbial biomass.

[0009] In one embodiment the process further includes feeding the liquid reservoir by transferring a mixture of culture ingredients to the liquid reservoir.

[0010] In one embodiment the feeding occurs periodically without draining the liquid reservoir at least one of: before a harvest; during a harvest; and, after a harvest.

[0011] In one embodiment an initial feed is added to the liquid reservoir to begin the culturing and a further periodic feed is added whilst at least a portion of the microbial biomass is still being cultured.

[0012] In one embodiment the culture ingredients are combined in a mixing or agitation tank and at least one of: pumped to the liquid reservoir via a pipeline; and, delivered to the liquid reservoir via a tanker truck.

[0013] In one embodiment the step of culturing the microbial biomass in the liquid reservoir includes agitating the liquid in the reservoir by at least one of: aeration; circulation; and, mixing.

[0014] In one embodiment the agitation occurs at least one of: periodically, semi- continuously; and, continuously.

[0015] In one embodiment the agitation of the liquid in the reservoir is caused by deploying at least one fluid flow control device in the reservoir.

[0016] In one embodiment the fluid flow control device includes a baffle at least partially submerged in the fluid body, the baffle including: an inlet that in use is coupled to a fluid supply adapted to supply a second fluid; at least one outlet; at least one internal channel extending from the inlet to the at least one outlet to thereby allow second fluid to be expelled from the at least one outlet; and, an outer surface which acts with the at least one outlet to at least partially guide second fluid expelled from the outlet to induce flow within the fluid body and thereby agitate the fluid body. [0017] In one embodiment the fluid flow control device includes a platform that in use is provided on a surface of the fluid body, the platform including at least one mooring connector that in use is coupled to a mooring to thereby at least partially restrain movement of the platform in use, and wherein the baffle is attached to the platform.

[0018] In one embodiment a plurality of fluid flow control devices are positioned around the reservoir and configured to cause agitation that achieves optimum rates of culture growth.

[0019] In one embodiment the agitation at least partially causes matured microbial biomass to settle to the bottom of the reservoir for harvesting.

[0020] In one embodiment the agitation assists in directing movement of the matured microbial biomass towards the middle of the reservoir for settling and harvest.

[0021] In one embodiment the harvesting device includes: a plurality of suction head assemblies, each suction head assembly including a hollow suction head configured to cause agitation of solids settling in or around the suction head and to draw the solids entrained in a liquid flow into one or more outlets of the suction head; a manifold including a body having: one or more inlets coupled to the one or more outlets of each suction head to permit the collected solids entrained in the liquid flow to pass into the manifold, and, one or more discharge ports configured to expel the collected solids entrained in the liquid flow from the manifold; and, a pumping arrangement that draws in liquid and entrained solids from the suction head assemblies via the manifold and discharges the liquid and entrained solids via a discharge pipe.

[0022] In one embodiment the harvesting device includes: a plurality of suction head assemblies, each suction head assembly including a hollow suction head configured to cause agitation of microbial biomass settling in or around the suction head and to draw the microbial biomass entrained in a liquid flow into one or more outlets of the suction head; a manifold including a body having: one or more inlets coupled to the one or more outlets of each suction head to permit the collected microbial biomass entrained in the liquid flow to pass into the manifold, and, one or more discharge ports configured to expel the collected microbial biomass entrained in the liquid flow from the manifold; and, a plurality of buoyant collection tanks positioned to receive the collected microbial biomass entrained in the liquid flow from the one or more discharge ports of the manifold.

[0023] In one embodiment the collected microbial biomass is pumped from the collection tanks onboard the harvesting device to the one or more settling tanks.

[0024] In one embodiment the collected microbial biomass is transferred from the one or more settling tanks to a centrifuge.

[0025] In one embodiment the collected microbial biomass is passed through the centrifuge in order to dewater the collected microbial biomass.

[0026] In one embodiment the dewatered microbial biomass is transferred to a drying system including at least one of: a belt dryer; and, a rotary drum dryer.

[0027] In one embodiment a dried microbial biomass is produced and stored for subsequent use.

[0028] In one embodiment the microbial biomass is for use in or as at least one of aquaculture feed and agriculture feed.

[0029] In one broad form an aspect of the present invention seeks to provide a continuous process for the production of a microbial biomass for use in or as an aquaculture or agriculture feed, the process including: feeding a liquid reservoir a mixture of culture ingredients; culturing the microbial biomass in the liquid reservoir, the step of culturing including agitating the liquid reservoir using a fluid flow control device; adding further feed to the liquid reservoir whilst at least a portion of the microbial biomass is still growing; harvesting a mature portion of the microbial biomass that has settled on the bottom of the liquid reservoir, the harvesting including: traversing a harvesting device along the bottom of the reservoir; collecting the mature microbial biomass that has settled using the harvesting device; and, moving the collected microbial biomass from the harvesting device to one or more settling tanks; dewatering the collected microbial biomass in the one or more settling tanks; and, drying the dewatered microbial biomass to thereby make it suitable for use as or in the aquaculture or agriculture feed.

[0030] In one broad form an aspect of the present invention seeks to provide apparatus for the production of a microbial biomass cultured within a liquid reservoir, the apparatus including: a harvesting device that harvests settled microbial biomass from a bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir by: traversing the bottom of the reservoir; collecting the settled microbial biomass; and, dewatering apparatus that dewaters the collected microbial biomass in the one or more settling tanks; and, a drying arrangement for drying the dewatered microbial biomass.

[0031] It will be appreciated that the broad forms of the invention and their respective features can be used in conjunction, interchangeably and/or independently, and reference to separate broad forms is not intended to be limiting.

Brief Description of the Drawings

[0032] Various examples and embodiments of the present invention will now be described with reference to the accompanying drawings, in which: -

[0033] Figure 1 is a flowchart of an example process for the production of a microbial biomass;

[0034] Figure 2A is a schematic plan view of an example of a production pond and associated plant equipment used in the production of the microbial biomass;

[0035] Figure 2B is a schematic plan view of an example of series of production ponds and associated plant equipment used in the production of the microbial biomass;

[0036] Figures 3A to 3D provide a sequence of plan views of a production pond for producing the microbial biomass at various stages of production;

[0037] Figure 4A is a schematic front view of an example of a harvesting device for harvesting the settled microbial biomass from the bottom of the production pond;

[0038] Figure 4B is a schematic sectional view of the harvesting device taken through section A-A of Figure 4A; [0039] Figure 4C is a schematic top view of the harvesting device of Figure 4A with the collection tanks removed for clarity;

[0040] Figure 4D is a schematic top view of the harvesting device of Figure 4A;

[0041] Figure 4E is a schematic cross sectional view of the harvesting device of Figure 4A;

[0042] Figure 5A is a schematic side view of an example of a fluid flow control device;

[0043] Figure 5B is a schematic front view of the device of Figure 5A;

[0044] Figure 6A is a schematic side view of an example of a platform;

[0045] Figure 6B is a schematic cross sectional view along the line A-A' of Figure 6A;

[0046] Figure 6C is a schematic plan view of the platform of Figure 6A;

[0047] Figure 7A is a schematic underside view of a specific example of a baffle;

[0048] Figure 7B is a schematic end view of the baffle of Figure 7A;

[0049] Figure 7C is a schematic plan view of the baffle of Figure 7A;

[0050] Figure 7D is a schematic side view of the baffle of Figure 7A;

[0051] Figure 7E is a schematic cross sectional view along the line B-B' of Figure 7A;

[0052] Figure 7F is a schematic cross sectional view along the line B-B' of Figure 7A showing the use of a secondary outlet;

[0053] Figure 8A is a schematic front view of a specific example of a support pillar;

[0054] Figure 8B is a schematic side view of the support pillar of Figure 8A;

[0055] Figure 9A is a schematic perspective plan view a fluid flow control device including a platform of Figure 6A, a baffle of Figure 7A and support pillar of Figure 8A;

[0056] Figure 9B is a schematic side view of the device of Figure 9A with the baffle in a partially raised position;

[0057] Figure 9C is a schematic side view of the apparatus of Figure 5A with the baffle in a lowered position;

[0058] Figure 10 is a flowchart of an example of a feed cycle process for use in producing the microbial biomass;

[0059] Figure 11 is a flowchart of an example of a harvest cycle process for use in producing the microbial biomass;

[0060] Figure 12A is a schematic front view of a second example of an apparatus for collecting solids settling at the bottom of a liquid reservoir;

[0061] Figure 12B is a schematic side view of the apparatus of Figure 12A; [0062] Figure 13 A is a schematic side view of a further example of an apparatus for controlling a flow of fluid within a fluid body; and,

[0063] Figure 13B is a schematic front view of the apparatus of Figure 13A.

Detailed Description of the Preferred Embodiments

[0064] An example of a process for the production of a microbial biomass will now be described with reference to Figure 1.

[0065] In this example, at step 100, the process includes culturing (i.e. growing) the microbial biomass in a liquid reservoir. For the purpose of this example, the liquid reservoir is assumed to be a pond, tank, lagoon, lake, or the like, containing a liquid, typically water in which culture ingredients are added in order to grow the microbial biomass therein. In one preferred form, the liquid reservoir is a production pond for producing the microbial biomass in quantities suitable for commercial use as an aquaculture or agriculture feed ingredient.

[0066] It is to be understood that as the microbial biomass grows and the cell size and population density increases it will eventually begin to fall out of suspension and settle at the bottom of the liquid reservoir for harvesting. The settling process may also be assisted by one or more fluid flow control devices operating in the reservoir as will be described in further detail below

[0067] At step 110, the process includes harvesting the settled microbial biomass from the bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir. In this regard, it will be appreciated that the harvesting occurs in- situ without having to drain the liquid reservoir. The fully-grown microbial biomass that has settled can be harvested whilst biomass still growing remains in suspension.

[0068] The step of harvesting includes traversing a harvesting device along the bottom of the reservoir and collecting the settled microbial biomass using the harvesting device. The collected microbial biomass may be stored in collection tanks on-board the harvesting device such as one or more floating tanks. The collected microbial biomass is then transferred from the harvesting device to one or more settling tanks or silos that are typically based on-shore and in close proximity to the liquid reservoir.

[0069] At step 120, the collected microbial biomass in the one or more settling tanks is dewatered in order to further separate the solid microbial biomass from the liquid. In this regard, it is to be appreciated that the collected microbial biomass is typically a watery slurry or sludge that is collected from the bottom of the reservoir.

[0070] Finally, at step 130 the process includes drying the dewatered microbial biomass. The dried microbial biomass is then in a form suitable for use as an aquaculture feed ingredient and may be bagged and stored for subsequent use as such.

[0071] The above-described process provides a number of advantages. Firstly, it enables the microbial biomass to be produced in a continuous or semi -continuous process. Harvesting using the harvesting device occurs whilst the reservoir is still full which avoids the need to drain and excavate the pond in order to retrieve the microbial biomass. The reservoir can therefore be continuously used to culture microbial biomass with harvesting occurring periodically as required. This provides a more efficient production technique than conventional batch harvesting which enables large-scale commercial production to be achieved and ensures that more constant supply of aquaculture or agriculture feed can be produced.

[0072] A number of further features will now be described.

[0073] Typically, the process further includes feeding the liquid reservoir by transferring a mixture of culture ingredients to the liquid reservoir. In one example, the culture ingredients include a mixed population of microorganisms comprising microalgae and bacteria. Further information about an exemplary example of culture ingredients is described in Australian Patent Nos. 2008201886 and 2009225307 owned by the Commonwealth Scientific and Industrial Research Organization (CSIRO).

[0074] Typically, the culture ingredients are combined in a mixing or agitation tank and either pumped to the liquid reservoir via a pipeline or delivered to the liquid reservoir via a tanker truck. In this way, the liquid reservoir is able to be fed as frequently as required in order to ensure a steady production of microbial biomass.

[0075] The feeding may occur periodically without draining the liquid reservoir at least one of before harvest, during harvest, and, after harvest. In one example, further feed may be dispersed into the liquid reservoir between harvest cycles to ensure that there is always an amount of microbial biomass growing in the reservoir. In other words, there is a continuous process of growth and settling which occurs in the liquid reservoir which enables the reservoir to produce a steady supply of harvestable microbial biomass.

[0076] In one example, an initial feed is added to the liquid reservoir to begin the culturing and a further periodic feed is added whilst at least a portion of the microbial biomass is still being cultured. In this regard, the ponds may be fed at any suitable frequency to ensure that a steady supply of harvestable biomass is produced, and in one example the feed may occur one of every 1 day, 2 days, 3 days, 4 days, 5 days, 6 days or 7 days. Typically, the reservoir is fed daily.

[0077] The step of growing the microbial biomass in the liquid reservoir includes agitating the liquid in the reservoir by at least one of aeration, circulation, and, mixing. Typically, a combination of these processes are used in order to promote growth of the microbial biomass. Agitation of the liquid and culture ingredients causes turbulence which is necessary in order to keep the microbial biomass in suspension so that it continues to grow. Mixing and circulation prevent the settling of cells, avoids thermal and oxygen stratification in the reservoir, and ensures that all cells in the population are equally exposed to the light and nutrients.

[0078] Once the reservoir is in production mode, agitation may occur periodically, semi- continuously; and, continuously. Preferably, some form of agitation occurs continuously in order to attain optimal production from the reservoir.

[0079] In one example, the agitation of the liquid in the reservoir is caused by deploying at least one fluid flow control device in the reservoir. Typically, the fluid flow control device includes a platform that in use is provided on a surface of the reservoir, the platform including at least one mooring connector that in use is coupled to a mooring to thereby at least partially restrain movement of the platform in use. The device further includes a baffle attached to the platform so that the baffle is at least partially submerged in the reservoir, the baffle including an inlet that in use is coupled to a fluid supply adapted to supply a fluid; at least one outlet; at least one internal channel extending from the inlet to the at least one outlet to thereby allow fluid to be expelled from the at least one outlet; and, an outer surface which acts with the at least one outlet to at least partially guide fluid expelled from the outlet to induce flow within the reservoir and thereby agitate the liquid in the reservoir.

[0080] The above described fluid flow control device provides a mechanism for inducing flow of liquid within the pond to thereby promote mixing and circulation of the culture ingredients to optimise growth of the microbial biomass. This is performed utilising a baffle having an internal channel allowing a fluid (e.g. gas) to be supplied from an inlet, which can be provided above or substantially near a surface of the pond, to an outlet provided at depth within the pond, with the depth being controlled based on an angle of inclination of the baffle. Additionally, the baffle can act to provide a guide surface guiding flow of fluids allowing this to be used to introduce directional fluid flow within the pond, which can in turn be used to agitate the liquid in the pond, and in particular, aerate and/or otherwise disturb the liquid in the pond.

[0081] Typically, a plurality of fluid flow control devices are positioned around the reservoir and configured to cause agitation that achieves optimum rates of culture growth. Furthermore, it will be appreciated that multiple fluid flow devices could be ganged together in order to increase the surface area over which they operate.

[0082] Whilst typically the fluid flow control device is used to promote mixing and circulation in order to keep the growing microbial biomass in liquid suspension, in other examples the agitation may at least partially cause matured microbial biomass to settle to the bottom of the reservoir for harvesting. In one example, the agitation assists in directing movement of the matured microbial biomass towards the middle of the reservoir for settling and harvest. This may be achieved by configuring the devices in the reservoir so that they direct flow towards the centre of the reservoir and away from turbulent regions. [0083] Alternatively, the baffle may be used to deflect flow so that energy is removed from the flow which may further assist in the settling of mature microbial biomass.

[0084] An example of a harvesting device will now be described in further detail. In one example configuration, the harvesting device includes a plurality of suction head assemblies, each suction head assembly including a hollow suction head configured to cause agitation of microbial biomass settling in or around the suction head and to draw the microbial biomass entrained in a liquid flow into one or more outlets of the suction head. The harvesting device also includes a manifold including a body having one or more inlets coupled to the one or more outlets of each suction head to permit the collected microbial biomass entrained in the liquid flow to pass into the manifold, and, one or more discharge ports configured to expel the collected microbial biomass entrained in the liquid flow from the manifold. Finally, the device additionally includes a plurality of buoyant collection tanks positioned to receive the collected microbial biomass entrained in the liquid flow from the one or more discharge ports of the manifold.

[0085] One or more harvesting devices may be deployed for use in the liquid reservoir as frequently as needed. In one example, a harvest cycle may occur at a frequency of one of: 1 week, 2 weeks, 3 weeks and 4 weeks dependent on the rate of microbial biomass growth and subsequent settling.

[0086] The collected microbial biomass may be pumped from the collection tanks on-board the harvesting device to the one or more settling tanks or silos disposed onshore. Accordingly, the harvesting device may further include a pump operable to pump the microbial biomass through a flexible pipeline running from the collection tanks to the settling silos. Alternatively, once the collection tanks are full, the harvesting device may be pulled from the reservoir so that the collection tanks can be emptied on land into the settling silos.

[0087] The step of dewatering the collected microbial biomass typically includes transferring the biomass which is in slurry like form from the one or more settling tanks to a centrifuge. The collected microbial biomass is then passed through the centrifuge in order to dewater the collected microbial biomass and separate the solid material from the liquid. Other suitable dewatering apparatus could be used in this step, however a high-speed centrifuge is a preferable option.

[0088] The dewatered microbial biomass is then transferred to a drying system including at least one of a belt dryer; and, a rotary drum dryer. The drying system may be located adjacent the centrifuge or alternatively at another part of the production plant or offsite in a factory where the product may be dried and bagged. Accordingly, it will be appreciated that after drying, a dried microbial biomass is produced which is typically bagged and stored for use in or as an aquaculture feed. Typically, the microbial biomass is used as an ingredient in an aquaculture feed.

[0089] In another broad form, there is provided a continuous process for the production of a microbial biomass for use in or as an aquaculture feed, the process including feeding a liquid reservoir a mixture of culture ingredients; culturing the microbial biomass in the liquid reservoir, the step of culturing including agitating the liquid reservoir using a fluid flow control device; adding further feed to the liquid reservoir whilst at least a portion of the microbial biomass is still growing; harvesting a mature portion of the microbial biomass that has settled on the bottom of the liquid reservoir, the harvesting including traversing a harvesting device along the bottom of the reservoir; collecting the mature microbial biomass that has settled using the harvesting device; and, moving the collected microbial biomass from the harvesting device to one or more settling tanks; dewatering the collected microbial biomass in the one or more settling tanks; and, drying the dewatered microbial biomass to thereby make it suitable for use as or in the aquaculture feed.

[0090] Referring now to Figure 2A, an example of a production plant 200 for producing the microbial biomass will be described. The production plant 200 includes a liquid reservoir which in this example is an open water pond 210 that is typically filled with water, such as fresh water, sea water, or water with any concentration of salt. From hereon in in this description, the term "pond" or "production pond" will be used to refer to the liquid reservoir. In the example shown, the pond 210 has a rectangular configuration, although circular ponds or other suitable configurations may also be used. The plant 200 further includes an agitation or mixing tank 220 disposed nearby the pond 210 in which the culture ingredients (liquid, powder etc.) are mixed prior to feeding or fertilizing the pond 210. In the example shown, a pipeline 225 extends between the mixing tank 220 and the pond 210 through which the culture ingredients can be pumped in order to disperse to the pond 210 as often as desired. Although the mixing tank 220 is shown in close proximity to the pond 210 in this example, this need not be the case and in other examples the feed may be prepared off-site and delivered to the pond 210 in a tanker truck or the like.

[0091] After the culture ingredients have been dispersed in the pond 210, in order to grow the microbial biomass it is important to keep the biomass in suspension. This may be achieved through a combination of mixing, aeration and circulation of the water in the pond 210. In order to achieve desired levels of agitation, one or more fluid flow control devices 202 may be operated in the pond 210. The fluid flow control devices 202 may be operated on a continuous basis in order to achieve optimum growth of the microbial biomass. Although fluid flow control devices 202 are shown operating independently in Figure 2A, in practice multiple devices 202 may be ganged together in order to increase the surface area over which they operate. In the schematic diagram shown, the fluid flow control devices 202 are shown operating around the periphery of the pond 210 in order to assist in circulating water around the pond 210, however this need not be the case and the devices 202 may be positioned elsewhere in the pond 210 where mixing/aeration is required.

[0092] Eventually, as the microbial biomass continues to grow and mature the cell size will become large enough so that it begins to fall out of suspension and settle on the bottom of the pond 210. In this regard, the microbial biomass (MB) may be encouraged to settle in the middle of the pond for harvesting. This may be encouraged through use of the fluid flow control devices 202. For example, if the devices 202 operate around the periphery of the pond 210 then microbial biomass in proximity to the devices 202 will largely continue to remain in suspension, whereas microbial biomass in the middle of pond 210 and away from the agitation will begin to settle. Furthermore, the flow control devices 202 can be used to direct flow towards the centre of the pond 210 to thereby allow the microbial biomass to settle in that region for ease of harvest. [0093] Once a layer of microbial biomass MB has formed on the bottom of the pond 210, one or more harvesting devices 204 may be introduced to the pond 210 and traversed along the bottom above the settled layer of microbial biomass. The harvesting device 204 is configured to agitate the settled layer and suck the microbial biomass into a manifold which draws the collected microbial biomass to the surface whereby it is discharged into one or more buoyant collection tanks. The collected microbial biomass may then be pumped via a flexible pipeline 207 to one or more on-shore settling tanks or silos 230. Alternatively, once the collection tanks on-board the harvesting device 204 become sufficiently full, the harvesting device 204 may be pulled ashore so that the collection tanks can be directly emptied into the settling tanks 230.

[0094] During harvesting, the harvesting device 204 is typically actuated by a winch system. In one example, the winch system includes a hauling winch 206 located on one side of the pond 210 and a tensioning winch 208 located on an opposing side of the pond 210 that are coupled to the harvesting device 204 and operable to traverse the harvesting device 204 across the pond 210 in order to collect the settled microbial biomass.

[0095] The collected microbial biomass settles in the settling tanks 230 (typically of conical configuration) and once a certain density is reached, the microbial biomass is transferred from the bottom of the settling tanks 230 to a dewatering apparatus which typically is a high speed centrifuge 240. This process further increases the concentration of the microbial biomass and removes further liquid from the wet slurry that is removed from the pond 210. The dewatered microbial biomass is then transferred to a drying system 250 which in the example shown is a slow speed belt dryer. Any other suitable drying system may be used such as a rotary drum dryer for example.

[0096] The dried product is then bagged and stored, although typically this occurs off-site at a warehouse or factory from which the end-product is shipped to customers.

[0097] Referring now to Figure 2B, a series of production ponds 210A, 210B, 210C for producing microbial biomass are shown. In this schematic, a mixing or agitation tank 220 is shown in which the culture ingredients are mixed prior to feeding the ponds. A single pipeline 225 is routed from the mixing tank 220 to each pond 210A, 21 OB, 210C to thereby deliver the feed to each respective production pond.

[0098] Each pond 210A, 21 OB, 210C has a plurality of fluid flow control devices 202 A, 202B, 202C in operation in the same manner as previously described for mixing, aerating and circulating water around the respective pond to keep the growing microbial biomass in suspension. At harvest, each pond also utilises a harvesting device 204A, 204B and 204C which operates as previously described to collect the settled microbial biomass from the bottom of the pond once it is mature. The collected microbial biomass in each pond 210A, 210B, 210C is then transferred via a respective pipeline to on-shore settling tanks or silos 230A, 230B, 230C associated with each pond. After further settling in the settling tanks 230A, 230B, 230C, the microbial biomass is transferred via a common pipeline 207 to a centrifuge 240 where the solid concentration of microbial biomass harvested form all of the ponds is increased by separating the liquid from the solids. Finally, the dewatered microbial biomass is transferred from the centrifuge 240 to a drying system 250 such as a belt conveyer as previously described.

[0099] An example of a sequence of production steps for use in producing the microbial biomass is graphically illustrated with respect to Figures 3A to 3D. In Figure 3A, the culture ingredients are mixed together in mixing tank 220 and pumped via pipeline 225 into the pond 210 where it is dispersed into the water. The fluid flow control devices then agitate the water in the pond 210 to mix, aerate and circulate water in order to promote growth of the microbial biomass.

[0100] In Figure 3B, as the mixing, aeration and circulation continue, eventually the microbial biomass begins to mature and settling begins to occur. In this example, the settling is promoted in the middle of the pond and a layer of settled microbial biomass begins to form.

[0101] Eventually, the settled microbial biomass layer becomes large enough for harvest and the harvesting device 204 is deployed in the pond 210 to collect the layer of settled microbial biomass from the bottom of the pond 210 as shown in Figure 3C and as previously described. [0102] In Figure 3D, another feed cycle is initiated whilst the pond 210 is being harvested. Further culture ingredients are mixed in the mixing tank 220 and delivered to the pond 210 via pipeline 225. The fluid flow control devices continue operating to aerate, mix and circulate water in the pond 210. In this way, microbial biomass is cultured in a continuous manner such that there is always microbial biomass growing in the pond 210, even when mature microbial biomass is being harvested. Although in this example, a feed cycle is shown commencing during harvest, it is to be appreciated that this is an example only, and a feed cycle could be initiated before harvest, or after a harvest as well depending on the production parameters that have been set for the pond. Feed and harvest cycle parameters will typically be determined to ensure continuous production of microbial biomass is achieved in the pond. Once in production, it will be appreciated that microbial biomass will always be present in the pond at varying states of growth. Typically, there will be at least some microbial biomass that has reached maturity and is settling whilst younger culture is still growing and in suspension. By periodically feeding the pond, new culture is constantly being added which ensures that a steady supply of microbial biomass is being produced in the pond.

Harvesting Device

[0103] An example of a harvesting device 204 for harvesting the microbial biomass settling at the bottom B of the liquid reservoir will now be described with reference to Figures 4A to 4E.

[0104] In this example, the harvesting device 204 includes a plurality of suction head assemblies 410, each suction head assembly 410 including a hollow suction head 411 configured to cause agitation of microbial biomass settling in or around the suction head 411 and to draw the microbial biomass entrained in a liquid flow into one or more outlets 412 of the suction head 111.

[0105] The harvesting device 204 further includes a manifold 420 including a body having one or more inlets 422 coupled to the one or more outlets 412 of each suction head 111 to permit the microbial biomass entrained in the liquid flow to pass into the manifold 420. The manifold 420 further includes one or more discharge ports 424, 426 configured to expel the microbial biomass entrained in the liquid flow from the manifold 420.

[0106] A plurality of buoyant collection tanks 430, 440 are positioned to receive the collected microbial biomass entrained in the liquid flow from the one or more discharge ports 424, 426 of the manifold 420. The collection tanks 430, 440 are typically configured to float at or near the surface level SL of the liquid reservoir with the suction head assemblies 410 operating underneath collecting the settled microbial biomass from the bottom B of the liquid reservoir. When the collection tanks 430, 440 are filled, the collected microbial biomass may be pumped from the tanks 430, 440 to off-shore settling silos as previously described. Alternatively, the harvesting device 204 may be moved to a bank of the liquid reservoir so that the collected microbial biomass can be transferred to the settling silos.

[0107] The above described harvesting device 204 provides a number of advantages. Firstly, it enables the microbial biomass to be harvested in-situ while the pond remains filled. It is therefore not necessary to drain the pond prior to harvest which enables continuous production of the microbial biomass (instead of the traditional batch production). Furthermore, the harvesting is efficient and environmentally sustainable which enables large- scale commercial production and harvest of the microbial biomass to be achieved.

[0108] The harvesting device 204 is particularly efficient as it integrates multiple suction heads into a single device. This enables a greater surface area of the bottom of the pond to be traversed by the apparatus, thereby increasing efficiency of harvest.

[0109] Each suction head assembly is connected to a common manifold having discharge ports to expel the collected microbial biomass entrained in the liquid flow into the collection tanks. Microbial biomass collected by each suction head assembly is therefore drawn into a single manifold. This provides a simplified construction which is scalable in line with the size of the production pond. In the present arrangement, the common manifold permits any desired number of suction head assemblies to be coupled thereto.

[0110] The harvesting device 204 further includes an air supply such as a compressed air source, an air supply line 460 connected to the air supply and a plurality of air diffusers 470, each air diffuser 470 positioned within a respective suction head 411 and interconnected to the air supply line 460 to enable air from the air supply to be introduced into each suction head 411 to thereby agitate the settled microbial biomass.

[0111] The air supply line 460 includes a horizontal section 462 that is configured to run parallel to the manifold 420 outside of each suction head 411. Air intake tubes 468 are coupled between outlets of the horizontal section 462 of the air supply line and inlets of an air diffuser 470 disposed within each suction head 411. Each air diffuser 470 has a generally elongate body having an upper surface in which the inlets are disposed at opposing ends thereof. A plurality of apertures are positioned between the inlets in the upper surface for allowing air bubbles to escape therefrom into the suction head 411 in order for a suction pressure to be created in the head 411 as will be described in more detail below.

[0112] The relative position of the air supply line 460 to the manifold 420 and suction heads 411 is shown in Figures 4B and 4C. In this example, each suction head 411 has a generally dome shaped housing. The horizontal segment of the manifold 420 is directly coupled to the outlets 412 of the suction heads 411 and is centrally aligned with respect to the plurality of suction heads 411. The horizontal segment 462 of the air supply line 460 runs parallel to the horizontal segment of the manifold 420 in offset relation thereto. The air intake tubes 468 then enter the suction head 411 through separate openings provided in the head 411. In the configuration shown in Figure 4B, the air intake tubes 468 are formed with an angled section to direct the tube towards the air diffuser 470 which is offset to the supply line 462. In other arrangements, the air intake tube may be provided without the bent or angled portion.

[0113] The plurality of suction head assemblies 410 may be supported for movement over the bottom B of the liquid reservoir by supports which suitably support the suction head assemblies 410 in a substantially horizontal attitude. The supports may comprise skids 480 provided at opposite ends of each suction head assembly 410 as best shown in Figure 4C.

[0114] Referring now to Figure 4E, the operation of the suction head assemblies 410 of the harvesting device 204 shall be described in further detail. [0115] As previously described, in use, the harvesting device 204 is moved across a section of the bottom B of the liquid reservoir having a settled layer of microbial biomass to be harvested. The harvesting device 204 is generally moved across the reservoir by a winch system having a cable coupled directly or indirectly to the harvesting device 204. The winch system is typically positioned on the bank of the reservoir for movement there along, although alternatively the winch system could be mounted on the harvesting device 204 and attached to anchor points, allowing the harvesting device 204 to be moved as required.

[0116] To initiate suction, the air supply (not shown) is turned on so that compressed air or the like flows into the air supply line 460. The air will flow through the supply line 460 and into the air diffuser 470 of each suction head 411. The air exits the air diffusers 470 through apertures 474 as a stream of air bubbles inside each suction head 411.

[0117] The air will then pass upwardly into the manifold 420 which creates a back or suction pressure within each head 411 that serves as an air lift to draw liquid and entrained microbial biomass into the manifold 420. The liquid and entrained microbial biomass then flow along the horizontal segment of the manifold 420 before being drawn up the side discharge pipes 425, 427 and expelled via the discharge ports 424, 426 into the collection tanks 430, 440.

[0118] The suction pressure created in the suction heads 411 will assist in agitating the settled microbial biomass at the bottom of the reservoir. To further assist the agitation, displacing means may also be provided below or adjacent each suction head. In one example, one or more chains (not shown) are disposed beneath each suction head 411, the chains contactable with the bottom B of the liquid reservoir to assist in displacing the settled microbial biomass as the harvesting device 204 is traversed along the bottom B of the reservoir.

[0119] Each suction head 411 may also include skirting which contacts the bottom B of the reservoir when the suction head assembly 410 is being traversed along the bottom. The skirting may assist in preventing air bubbles from escaping from the head 411 to maximize the suction pressure obtained and increase efficiency of the harvesting device 204. The skirt may also ensure that the microbial biomass is contained within the head during collection. [0120] An alternative example of a harvesting device 204 for harvesting the microbial biomass settling at the bottom B of the liquid reservoir will now be described with reference to Figures 12A and 12B.

[0121] In this example, the apparatus again includes a plurality of suction head assemblies 1210, each suction head assembly including a hollow suction head 1211 configured to cause agitation of solids settling in or around the suction head and to draw the solids entrained in a liquid flow into one or more outlets 1212 of the suction head. The apparatus further includes a manifold 1220 including a body having one or more inlets 1222 coupled to the one or more outlets 1212 of each suction head to permit the collected microbial biomass entrained in the liquid flow to pass into the manifold 1220. The manifold further includes one or more discharge ports 1224 configured to expel the collected microbial biomass entrained in the liquid flow from the manifold.

[0122] A pumping arrangement 1230 is provided that draws in liquid and entrained microbial biomass from the suction head assemblies 1210, via the manifold 1220, and discharges the liquid and entrained microbial biomass via a discharge pipe 1233.

[0123] Accordingly, it will be appreciated that in this example, the apparatus includes a similar configuration to that described in the previous example of Figures 4A to 4E, specifically including suction heads in fluid communication with a manifold to allow extraction of microbial biomass via multiple suction head assemblies, whilst using a single pumping arrangement. It will therefore be appreciated that in broad terms operation of the system is similar to that described above.

[0124] However, in contrast to the previous example, the pumping arrangement pumps out liquid and entrained microbial biomass via a discharge pipe, which can extend to shore, allowing the microbial biomass material to be collected on-shore, as opposed to using the above described floating tank arrangement. This can allow for easier removal of microbial biomass, for example allowing the microbial biomass to be pumped into a transportable tanker, either directly or via a settling tank. This also assists in using sealed tanks, which can in turn reduce unwanted odours. [0125] A number of further features will now be described.

[0126] In one example, the apparatus includes a pontoon 1240, with the suction head assemblies being attached to the pontoon, for example by having these suspended from the pontoon 1240 for example using a cable 1231, attached to a winch 1241, allowing the suction head assemblies 1210 to be raised or lowered as required, whilst also allowing for lateral movement by virtue of movement of the pontoon, for example through the use of shore mounted winches.

[0127] In one example, the pumping arrangement can be similar to that described above, involving pumping air directly into the suction heads. However, this is not essential, and in an alternative preferred arrangement, the pumping arrangement includes a suction pump 1230 including an inlet coupled to the manifold discharge port 1224 and an outlet coupled to the discharge pipe 1233. The pump 1230 can be mounted on the pontoon 1240, but more typically is submerged within the liquid reservoir, in particular being attached to the manifold outlet 1224 via connecting pipe 12212, or a direct connection. Providing the pump 1230 close to the manifold increases the effectiveness of the pumping action, in particular increases pressure and/or flow at the suction heads to thereby increases the microbial biomass collection effectiveness, while facilitating pumping direct to shore.

[0128] The pump 1230 can be of any suitable form, but in one example, includes an air operated diaphragm pump 1230, in which case the apparatus further includes an air supply 1242 and an air supply line 1232 connected to the air supply and the suction pump. In general a diaphragm pump 1230 offers a higher degree of pumping action, further facilitating extraction of the solids and transfer to shore. Whilst the air supply 1242 could be shore mounted, more typically this is mounted on the pontoon 1240 to reduce the length of the air supply line 1232.

[0129] The discharge pipe 1233 can extend to the shore based tank arrangement, either directly, or by having the discharge pipe extend to the pontoon, and then from the pontoon to the shore. [0130] The tank arrangement can include a plurality of collection tanks configured to allow progressive clarification of the discharge through settling of the solid material and/or can include a vehicle for collecting the microbial biomass. In either case, the tanks can be enclosed, to thereby reduce the release of odours.

[0131] In one example, the one or more outlets 1212 of each suction head 1210 and the one or more corresponding inlets 1222 of the manifold 1220 comprise spigots to which one or more coupling members 1228 are engaged to thereby interconnect the suction head assemblies to the manifold. In the current example, the coupling members 1228 are shorter than those of the previous example, so that the manifold is closer to the suction head assemblies 1210, and it will be appreciated that these could be removed entirely so that the manifold inlets 1222 are directly connected to the suction head outlets 1212. This reduces the length of the flow path between the suction head and the pump 1230, increasing pump effectiveness.

[0132] The suction head assemblies 1210 are typically arranged side-by-side and supported on skids 1213 to assist the apparatus traverse along the bottom of the liquid reservoir. In the current example, a dual head assembly is shown, with two suction heads mounted in a side- by-side arrangement. Whilst a larger number of heads could be used, this would increase the degree of pumping action required for the apparatus to function effectively, and is not necessarily desirable.

[0133] It will be appreciated that the apparatus could also include further features that assist in collection of microbial biomass. For example, one or more chains can be disposed beneath each suction head, with the chains contacting the bottom of the liquid reservoir to assist in displacing the settled solids as the apparatus is traversed along the bottom of the reservoir. Each suction head can also include an elongated body which has an open lower side defining a mouth and a skirt disposed around the mouth to at least one of improve containment of the collected solids and control release of air bubbles from the air diffuser.

[0134] It will also be appreciated from the above that other arrangements of microbial biomass harvesting equipment could be used and that whilst the above described arrangements are particularly suitable, this should not necessarily exclude the use of other arrangements.

Fluid Flow Control Device

[0135] An example of a fluid flow control device 202 for use in aerating, mixing and circulating liquid in the production pond will now be described with reference to Figures 5A and 5B.

[0136] In this example the fluid flow control device 202 includes a platform 510 that in use is provided on a surface of the pond. The platform 510 is typically at least partially buoyant and may incorporate ballast and/or buoyancy aids in order to provide a desired degree of buoyancy in use.

[0137] The platform 510 includes a mooring connector 511 which can be coupled to a mooring to thereby at least partially restrain movement of the platform in use. Alternatively the mooring connector can be used to interconnect multiple platforms 510, allowing an array of platforms to be provided, as will be described in more detail below. The mooring connector 511 may be of any appropriate form and could include for example an eyelet, cleat, bollard, or the like, which is attached to a mooring line, such as a rope or chain, which can in turn be attached to a shore mounted mooring bollard, an anchor submersed in the pond, another platform, or the like, depending on the preferred implementation. It will therefore be appreciated that any suitable form of mooring mechanism can be used.

[0138] The fluid flow control device 202 further includes a baffle 520 which is attached to the platform so that the baffle is at least partially submerged in the pond at an angle relative to the platform 510 so that the baffle is inclined within the pond. The baffle 520 can be attached to the platform 510 at a fixed angle, but more typically the baffle is pivotally mounted allowing the angle to be adjusted. In this example, the baffle 520 can be held at a desired inclination angle, for example using a locking mechanism, or could be left free over a range of angles, for example depending on currents within the pond. Alternatively, the baffle could include a differential or partial buoyancy, so that a free end of the baffle tends to sink to a defined operating depth. [0139] The baffle 520 can be used in a passive manner to divert flow of liquid within the pond, such as preventing flow across part of the pond, optionally diverting flow towards the pond bed. In this manner, the device 202 can be used to assist in the settling of the microbial biomass when the culture has matured and is ready for harvest. The baffle 520 may also be used to direct flow towards the centre of the pond so that the microbial biomass can settle in this region.

[0140] Additionally and/or alternatively, the baffle 520 can be used in an active manner to induce movement within the pond. In this example, the baffle 520 includes an inlet 521, a number of outlets 522, and at least one internal channel 523 is provided within the baffle, extending from the inlet 521 to the outlet 522. In use, the inlet 521 is coupled to a fluid supply (not shown) that supplies a fluid, so that this is transferred via the internal channel 523 to the outlets, allowing the fluid to be expelled therefrom, as shown for example by the bubbles 541. The baffle 520 also includes an outer surface 524 that acts with the outlets 522 to at least partially guide the fluid expelled from the outlets 522, so as to induce a flow within the pond, as shown by the arrow 543, and thereby induce flow and hence agitate the liquid in the pond.

[0141] For example, if the fluid is air or another gas, bubbles 541 form as the gas is expelled from the outlets 522, with the bubbles rising guided by the outer surface 524, as shown by the arrow 542. This, along with the angle of the baffle, will draw in surrounding liquid in the pond, inducing flow as shown by arrows 543. However, it will also be appreciated that the outlets 522 can additionally be arranged to direct jets of fluid at least partially parallel to the baffle outer surface 524, to induce or increase the degree of flow.

[0142] Accordingly, the above described fluid flow control device 202 provides a mechanism for inducing flow of liquid within the pond to thereby promote mixing and circulation of the culture ingredients to optimise growth of the microbial biomass. This is performed utilising a baffle 520 having an internal channel 523 allowing a fluid (e.g. gas) to be supplied from an inlet 521, which can be provided above or substantially near a surface of the pond, to an outlet 522 provided at depth within the pond, with the depth being controlled based on an angle of inclination of the baffle 520. Additionally, the baffle 520 can act to provide a guide surface 524 guiding flow of fluids allowing this to be used to introduce directional fluid flow within the pond, which can in turn be used to agitate the liquid in the pond, and in particular, aerate and/or otherwise disturb the liquid in the pond.

[0143] This simple construction avoids the need for a complex arrangement, such as the use of multiple diffusion members for aeration, whilst also allowing flow to be created. This in turn reduces costs and chances of equipment failure. The baffle can be manufactured from fluid and environment tolerant materials, such as plastics, meaning this has a long life and avoids issues of corrosion.

[0144] Additionally, the system can be implemented with a wide range of different fluids and fluid supplies. For example, the system can use a shore mounted pump, attached to the inlet via a connector pipe or tube, allowing a fluid, such as water, air and one or more additives, to be pumped into the inlet 121, without requiring pump or blowing equipment to be installed on the device itself. This separation of the pumping or blowing equipment can help reduce maintenance requirements, and allow the equipment to be interchanged more easily if required.

[0145] The above-described fluid flow control device 202 therefore provides an improved device for mixing and aerating the pond as well as circulating liquid around the pond to promote growth of the microbial biomass and keep it in suspension whilst growing. Once mature, the device can be used to assist in settling of the microbial biomass and may be used to direct the mature microbial biomass towards the middle of the pond for settling and harvest.

[0146] A number of further features will now be described with reference to a specific example including a platform shown in Figures 6A to 6C, a baffle shown in Figures 7A to 7F and a support pillar shown in Figures 8 A and 8B, with the resulting overall device being shown in Figures 9 A to 9C.

[0147] As shown in Figures 6 A to 6C, the platform 510 includes a platform body 611 having a number of ballast tanks 612 mounted thereon. In this example, the platform body 611 is substantially rectangular, with four cuboid ballast tanks 612 provided on an upper surface of the platform body 611, with the platform 611 including an end portion 611.1 extending beyond the ballast tanks 612 at a first end 617 (referred to as a front end for illustration). Multiple ballast tanks can be used to ensure that ballast is evenly distributed over the platform, and in particular to prevent ballast flowing to one corner of the platform in the event that the platform tips over in use, whilst also allowing ballast to be selectively distributed to account for uneven weight distribution on the platform, leading to improved stability.

[0148] It will be appreciated however that this is not essential and in general any shape and arrangement of platform body 611 and tanks 612 could be used. In one example, the platform body 611 and ballast tanks 612 are integrally formed from a suitable polymer, for example through Rotational Moulding, BrE moulding, or the like, although any suitable manufacturing technique could be used. The platforms can also be profiled to allow platforms to be stacked for ease of transport and storage.

[0149] Each ballast tank 612 typically includes an inlet 613 on an upper surface and an outlet 614 provided in a lower part of a side wall, allowing a ballast material, such as water, to be added to and removed from the ballast tank as required. This can be used to adjust the buoyancy of the platform, and in particular selectively control the buoyancy, for example to make a front or rear more or less buoyant, which can be used to help the platform remain substantially level in use. The inlets 613 and outlets 614 are typically sealed using a removable rubber plug or similar in use.

[0150] The platform further includes a number of mooring connectors 615, 616, which in this example are eyelets mounted on upper sides of 612 ballast tanks towards a second end 618 (referred to as a rear end for illustration) of the platform and on the end portion 611.1, allowing the platform 510 to be secured to a mooring at either the front or rear ends 617, 618 of the platform, as well as to allow adjacent platforms in an array to be interconnected at both a front and rear of the platform. When provided in an array, an upper surface of the ballast tanks can be used to define a walkway, in which case additional features such as railings or the like might be incorporated into or attached to the structure as needed, depending on the preferred implementation. [0151] Provision of mooring connectors 651, 616 near a front and rear of the platform can be used to allow a position of the platform within the fluid body to be adjusted. For example if the mooring connectors are coupled via respective mooring lines to separate winches, operation of the winches can be used to move the platform within the pond, including moving the platform, laterally or longitudinally, as well as rotating the platform if required. It will also be appreciated that similar movements could also be performed manually, and reference to winch powered operation is not intended to be restrictive.

[0152] The platform 510 further includes a baffle mounting proximate at a front end 617 of the platform, the baffle mounting being adapted to pivotally support the baffle 520. In this example, the platform mounting is formed from first and second laterally spaced rectangular cut-outs 622 provided in a leading edge of the end portion 611.1, with each cut-out 622 being bridged by a tubular strut 621, which acts to define a pivotal mounting for the baffle 520, as will be described in more detail below. It will be appreciated however that other suitable arrangements could be used.

[0153] The end portion 611.1 can also include a further centrally located cut-out in a leading edge, the cut-out being provided to accommodate a baffle inlet, as will be described in more detail below.

[0154] A rear surface of the rear ballast tanks 612 and a rear edge of the platform body 611, between rear ballast tanks 612, include rectangular cut-outs defining upright laterally spaced side and central pillar channels 631, 632, which in use receive a support pillar. The side pillar channels 631 include a laterally extending tooth 633, whilst a locking pin socket 634 is mounted to a rear surface of the ballast tanks 612, adjacent each laterally spaced channel 631, to assist with locking the support pillar in position.

[0155] As shown in Figures 7A to 7F, the baffle 520 is formed from an at least partially hollow body 710, having a substantially planar upper surface 712 spaced apart from a substantially parallel lower outer surface 711 to define an internal channel 723 extending from an inlet 721, arranged proximate a first (forward) end of the upper surface 712 to a plurality of laterally spaced outlets 722 provided proximate a second (rear) end in the lower outer surface 711. In this example, the baffle 520 has a generally elongate rectangular cuboid shape and can be manufactured from a suitable material, such as a rotationally moulded plastic material, although this is not essential and any suitable arrangement could be used. Again, baffles are typically profiled to allow baffles to be stacked to assist with transport and storage.

[0156] In this example, baffle 520 includes an end wall 713 extending perpendicularly from the lower outer surface 711 proximate the rear end, with the outlets 722 being provided in the end wall 713 so that the outlets face in a direction substantially parallel to the outer surface 711, thereby guiding fluid flow along the outer surface 711.

[0157] The outer surface 711 is typically profiled to define one or more external channels 714 to assist in directing flow of fluid at least part way along a length of the baffle. In this example, the channels 714 are defined by outer downwardly extending side walls 715 and a plurality of spaced apart ridges 716, running substantially along a length of the outer surface 711. It will be appreciated that alternatively other configurations could be used to define the channels, such as a scalloped shaping of the baffle surface 711, or the like. In use the channels assist in guiding the flow of fluid along the underside of the baffle, which can in turn maximise the effectiveness of the flow.

[0158] For example, when used actively for aeration, this can assist in causing merging of bubbles of gaseous fluid, forming larger bubbles, which can more effectively drive movement of the liquid within the pond. Alternatively, when used passively to divert flow, this can be used to ensure incoming flow passes along a length of the baffle surface, guiding this towards the bottom of the pond, and removing more energy than if the flow passes around the baffle. This can therefore be used in assisting settling of the microbial biomass when desired.

[0159] The outlets 722 are typically aligned with the external channels 714, allowing fluid flow from the outlets 722 to be guided along each of the external channels 714, thereby leading to even movement of fluid over substantially the entire outer surface 711 of the baffle 520. This in turn can assist in generating currents of movement within the pond leading to large scale fluid flow.

[0160] The outlets 722 can include simple openings, but more typically include an embedded connector, which can in turn receive a number of different outlet fittings, such as nozzles, or the like. Such a connector could be of any appropriate form, such as an interference or threaded connector. In one example, as shown in Figure 7F, a secondary outlet pipe 724 can be fitted to one or more of the outlets 722 to allow fluid to be emitted remotely from the baffle 520. For example, the secondary outlet pipe 724 can be adapted to extend downwardly from the baffle 720 towards the bottom B of the pond, allowing this to be used to urge fluid directly into or along a line of the bottom, as shown by arrow 725, to assist in agitating the bottom. Additionally, it will be appreciated that gaseous fluids delivered by the secondary outlet pipes 724 will tend to rise and impact on the underside of the baffle, being guided to flow along an underside of the baffle 520, and optionally merge with fluid emitted from the outlets 722.

[0161] The internal channel 723 within the baffle 520 can be of any appropriate shape, and could extend between the upper and lower surfaces 711, 712 and/or extend along the side walls 715. The internal chamber can also include internal features, such as tortuosities, baffles or the like, to assist with internal mixing. For example, in the event that two fluids are supplied to the inlet, the internal features can assist with mixing of the fluids, thereby ensuring these are sufficiently mixed prior to delivery to the outlets 722.

[0162] The baffle 520 includes laterally spaced platform mountings 733 provided proximate the front end of the upper surface 712, allowing the baffle to be pivotally mounted to the platform 510, so that an inclination of the baffle 520 within the fluid body can be adjusted. Adjusting the inclination of the baffle 520 can assist in controlling fluid flow within the pond. For example, this can be used to adjust whether flow is largely confined to a surface of the pond, or extends to deep within the pond, drawing fluid up from the bottom. [0163] In this example, the platform mountings 733 include spaced apart arms defining a lateral opening that can clip onto the tubular strut 621, although it will be appreciated that other arrangements for pivotally mounting the baffle 520 to the platform 510 could be used.

[0164] The baffle 520 can also include laterally spaced mooring connectors 734, such as eyelets, cleats, or the like, mounted proximate the front end of the upper surface 712, to assist with attaching the device to a mooring or to other baffles in an array.

[0165] The baffle 520 includes baffle connectors 731, extending from rear corners of the baffle body, allowing a secondary baffle to be supported from the lower end of the baffle, as shown in Figure 9C. The secondary baffle can be used to support a secondary outlet pipe 724, and or the assist in guiding formation of currents within the pond.

[0166] In one example, the device includes a locking mechanism to lock the baffle 520 at a selected angle relative to the platform 510. The locking mechanism could be associated with the pivotal mounting, for example restricting movement of the pivotal mounting to thereby lock the baffle 520 in position. More typically, however the locking mechanism includes an adjustable support pillar extending between the baffle 520 and the platform 510, with the support pillar being pivotally attached to the baffle 520 and able to selectively engage the platform 510 to thereby allow the angle of the baffle 520 relative to the platform 510 to be adjusted.

[0167] To achieve this, in one example, the baffle 520 includes laterally spaced support pillar mountings 732 provided on the upper surface 712 part way in from the rear edge of the baffle body, allowing a support pillar to be pivotally mounted thereto.

[0168] An example support pillar will now be described with reference to Figures 8A and 8B.

[0169] In this example, the support pillar 810 includes a central elongate support beam 812 and first and second laterally spaced elongate side support beams 811 spaced apart from the central support beam and attached to the central support beam via lateral ribs 812, to form a grid-like structure. The central and side support beams 812, 811 are spaced apart to align with the side and central pillar channels 631, 632 of the platform, as will be described in more detail below. The pillar can be manufactured from a plastic material, for example using rotational moulding, and is generally configured to be stackable to assist with storage and transport. The pillar can also be hollow to reduce weight, and in one example can include openings (not shown) allowing the pillar to fill with fluid upon submersion in the pond, thereby avoiding the pillar adversely affecting the overall buoyancy of the device.

[0170] The central and side beams 812, 811 are generally curved to define an arcuate shape, as shown in Figure 8B, to facilitate engagement with the platform through a range of different baffle angles. A plurality of pillar teeth 815 are provided extending along part of an inner face of the side support beams 811, with a plurality of lateral fastener openings 814 extending through the side beams, being spaced apart along part of the length of the side beams 811, which are used to secure the support pillar to the platform 510. Finally, a baffle mounting, including a baffle fastener opening 816 is provided in a lower end of the side beams 811, allowing the support pillar to be attached to the baffle 520.

[0171] An alternative example apparatus will now be described with reference to Figures 13 A and 13B.

[0172] In this example, the apparatus includes a baffle 520 generally similar to the baffle described above with respect to Figures 5 A and 5B, and features of this will not therefore be described in further detail.

[0173] In this example, instead of being attached to a platform, the baffle can be secured in the fluid body using a securing member, such as a mooring rope 1361, which is coupled to a mooring to thereby at least partially restrain movement of the baffle in use. In this example, the mooring rope 1361 passes through the mooring connectors 734 although other suitable connections could be used.

[0174] In this example, the baffle can have a negative buoyancy so that the baffle is at least partially submerged in the fluid reservoir. The negative buoyancy can result from the construction of the baffle, for example by manufacturing the baffle from a negatively buoyant material, or may arise through the use of ballast, either contained internally within the baffle, or connected to the baffle, for example as part of secondary baffles 1370, or connected to external baffle connectors 731. Such ballast could include sand, gravel, concrete, metal, or the like.

[0175] The baffle can be provided at any orientation within the fluid body, and could be provided vertically, to thereby act as an under fluid retaining fence structure, to thereby constrain movement of fluid and/or other contents within the fluid body. Alternatively, the baffle could be angled, for example by attaching ballast offset from a centre of the baffle, so that differential buoyancy maintains a desired angle.

[0176] Additionally and/or alternatively, a first end of the baffle is attached to a first mooring connector 1361 and a second end of the baffle is suspended from a surface body 1362, such as a float or second mooring connector, for example using a rope, chain or other securing member 1363 attached to the support pillar mountings 732, allowing an angle of the baffle to be adjusted based on a length of the securing member.

[0177] Accordingly, the above described arrangement provides a simple apparatus that can be used actively for aeration and/or to meet other requirements for generating flow. It will also be appreciated that the apparatus can also or alternatively be used passively to provide a barrier to divert, deflect, control and/or reduce flow as required, which can assist in settling of solids within the fluid body.

[0178] In one example, the system includes a three piece construction, which can be easily assembled simply by attaching the baffle and platform, attaching the support pillar to the baffle and then the platform, once the baffle has been provided in a desired orientation. This is feasible largely due to the simple one piece construction of the baffle, including the integrated internal channel to deliver fluid from an inlet to multiple outlets that are positioned within the fluid body by virtue of the inclination of the baffle relative to the platform.

[0179] As each of the components, and in particular the platform, baffle and support pillar, can be constructed from lightweight moulded plastic materials, this makes it feasible for these to be manipulated by a single person, meaning the apparatus can be assembled and deployed by a single person. Furthermore, the plastic construction makes the apparatus extremely durable, enabling this to be used in adverse environments, and with a wide range of different fluids, without risk of corrosion.

[0180] In another example, the baffle can be used without the platform and support pillar, with the baffle being held in position using a mooring rope or other securing member, and the orientation of the baffle being controlled through one or more of negative buoyancy, positive buoyancy, suspension from a mooring rope or float, or the like.

[0181] It will also be appreciated from the above that other arrangements of fluid flow equipment could be used and that whilst the above described arrangements are particularly suitable, this should not necessarily exclude the use of other arrangements. For example, alternative arrangements could include wastewater diffuser systems, paddlewheels, or the like.

[0182] An example of the device in a constructed operational state will now be described with reference to Figures 9 A to 9C.

[0183] In this example, the baffle 520 is coupled to the platform 510, by having the arms of the platform mountings 733 clip into engagement with the tubular struts 621 so that front ends of the platform 510 and baffle 520 are pivotally connected. In this configuration, the inlet 721 sits within the central cut-out 623, allowing a fluid supply tube (not shown) to be attached to the inlet 721.

[0184] The support pillar 810 is then coupled to the baffle 520, by having a fastener, such as a bolt or pin extend through the baffle fastener opening 816 and the spaced support pillar mountings 332, thereby pivotally mounting the support pillar 810 to the baffle 520.

[0185] The side and central beams 811, 812 of the support pillar are then positioned in the side and central channels 631, 632 of the platform 510, so that the pillar teeth 815 engage the tooth 633 within the side pillar channels 631, thereby positioning the support pillar 810, so that the baffle 520 is provided at a desired angle relative to the 510. A locking pin 902 can then be inserted through the locking pin socket 634 and one of the fastener openings 814 to thereby secure the support pillar 810 to the platform 510. [0186] Accordingly, it will be appreciated that this allows the baffle 520 to be connected to the platform 510 at a desired angle, and held in position using the support pillar 810, as shown for example in Figures 9B and 9C. Additionally secondary baffles 910 can be provided mounted to the baffle connectors 731, allowing additional control over the flow of liquid in the pond. In particular, the secondary baffles can be used to provide a curtain for assisting diverting currents. The secondary baffles can be made of one or more of a woven or unwoven fabric, plastic, netting, rubber, a permeable or semi permeable membrane, plastic or the like. The secondary baffle can also be used to provide support to a secondary outlet pipe 724.

[0187] Once configured, the device can be deployed by placing this in the pond, and attaching one or more mooring lines to the mooring connectors, to move the device to and then hold the device in a desired position, and with ballast being added to the ballast tanks 612 as required. In this regard, the ballast requirements will depend on factors such as the nature and pressure of the fluid being delivered, the angle of the baffle 520 or the like. For example, if the fluid is air, this will mean the baffle is substantially air filled in use, and hence will be very buoyant, meaning the ballast tanks 612 may need to be full and/or nearly full of ballast, whereas if the second fluid is water, minimal ballast may be required. Additionally, if the fluid is delivered under high pressure, this will cause a downward jetting force as fluid is emitted from the outlets 722, meaning a reduced level of ballast may be required.

[0188] Multiple platforms 510 can be interconnected via the mooring lines, allowing an array of platforms 510 and baffles 520 to be created. Such an array can use multiple baffles provided at the same of different angles of inclination, in order to create desired flow within the pond.

[0189] Once positioned, fluid can be delivered from a supply to the inlet 721 via a supply tube. The nature of the fluid will vary depending on the particular circumstances. For example, this could include water if the primary purpose is mere agitation of the pond, but could include air if greater aeration is required. Additionally, further additives can be included, such as flocculants and the like, which can be used to assist in settling of the microbial biomass within the pond.

[0190] Accordingly, the above described arrangement provides a simple device that can be used actively for aeration and/or to meet other requirements for generating lateral and/or vertical flow. It will also be appreciated that the device can also or alternatively be used passively to provide a barrier to divert, deflect, control and/or reduce flow as required, which can assist in settling of the microbial biomass within the pond when required.

[0191] In one example, the device includes a three piece construction, which can be easily assembled simply by attaching the baffle and platform, attaching the support pillar to the baffle and then the platform, once the baffle has been provided in a desired orientation. This is feasible largely due to the simple one piece construction of the baffle, including the integrated internal channel to deliver fluid from an inlet to multiple outlets that are positioned within the pond by virtue of the inclination of the baffle relative to the platform.

[0192] As each of the components, and in particular the platform, baffle and support pillar, can be constructed from lightweight moulded plastic materials, this makes it feasible for these to be manipulated by a single person, meaning the device can be assembled and deployed by a single person. Furthermore, the plastic construction makes the device extremely durable, enabling this to be used in adverse environments, and with a wide range of different fluids, without risk of corrosion.

[0193] Referring now to Figures 10 and 11, an example process flow for a feed and harvest cycle will be described.

[0194] With respect to the feed cycle, at step 1000 the pond is fed with culture ingredients for the production of the microbial biomass as previous described. One of more fluid flow control devices are then operated in order to respectively mix the pond water at step 1010, aerate the pond water at step 1020 and optionally promote circulation of the water around the pond at step 1030. These actions to agitate the pond water and culture ingredients to promote growth of the microbial biomass typically occur continuously while the pond is in production. At step 1040, a plant operator will determine the time since the last feed and at step 1050 determine if the time is equal to or greater than the designated feed cycle frequency for the particular production plant. If it is, then the process repeats and further feed ingredients are dispersed into the pond to ensure continuous production is achieved. If not, no action occurs and the process of mixing, aerating and circulation continues. Rather than a plant operator determining when the next feed cycle should occur, this process may be automated so that culture ingredients are automatically mixed in the agitation tank and dispersed to the pond at the appropriate time.

[0195] Referring now to Figure 11, the harvesting cycle begins at step 1100 whereby the harvesting device is traversed along the bottom of the pond. At step 1110, the settled microbial biomass is collected by the suction head assemblies and sucked up into the on board collection tanks. At step 1120, the collected microbial biomass is transferred to the on shore settling tanks or silos and then passed through a high-speed centrifuge at step 1130 in order to dewater the collected microbial biomass. The dewatered microbial biomass is then transferred to a drying system at step 1140 and at step 1150 a dried microbial biomass is obtained suitable for packaging and use in or as an aquaculture feed.

[0196] At step 1160, a plant operator determines the time since last harvest and at step 1170 determines if the time is equal to or greater than the designated harvest cycle frequency for the particular production plant. If yes, then the harvesting cycle begins again and the harvesting device is deployed back into the pond to collect further settled microbial biomass. If no, the operator will wait until the elapsed time between harvests reaches the harvest cycle frequency before initiating a further harvest. The feed and harvest cycles are depicted separately in these flow charts and it will be appreciated that they typically operate independently in that feeding may occur in between harvest cycles or during harvest or a combination thereof.

[0197] Accordingly, it will be appreciated that in at least one example, the above-described production process enables the continuous or semi-continuous production of a microbial biomass. This ensures that a steady supply of microbial biomass is produced and harvested which increases efficiency and utilisation of the liquid reservoir enabling large-scale commercial production to be realised. The use of the novel plant equipment described facilitates this continuous production which is an important step forward in the evolution of sustainable aquaculture. The problems associated with batch culture production are alleviated by enabling harvest to occur in-situ in the reservoir without requiring the reservoir to be drained thereby assisting to retain water-borne nutrients and reducing the environmental impact of the process.

[0198] Throughout this specification and claims which follow, unless the context requires otherwise, the word“comprise”, and variations such as“comprises” or“comprising”, will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

[0199] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1) A process for the production of a microbial biomass, the process including:

a) culturing the microbial biomass in a liquid reservoir, at least some of the microbial biomass settling at the bottom of the liquid reservoir for harvesting;

b) harvesting the settled microbial biomass from the bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir, the harvesting including:

i) traversing a harvesting device along the bottom of the reservoir;

ii) collecting the settled microbial biomass using the harvesting device; and, iii) transferring the collected microbial biomass from the harvesting device to one or more settling tanks;

c) dewatering the collected microbial biomass in the one or more settling tanks; and, d) drying the dewatered microbial biomass.

2) The process according to claim 1, further including feeding the liquid reservoir by transferring a mixture of culture ingredients to the liquid reservoir.

3) The process according to claim 2, wherein the feeding occurs periodically without draining the liquid reservoir at least one of:

a) before a harvest;

b) during a harvest; and,

c) after a harvest.

4) The process according to claim 3, wherein an initial feed is added to the liquid reservoir to begin the culturing and a further periodic feed is added whilst at least a portion of the microbial biomass is still being cultured.

5) The process according to any one of claims 2 to 4, wherein the culture ingredients are combined in a mixing or agitation tank and at least one of:

a) pumped to the liquid reservoir via a pipeline; and,

b) delivered to the liquid reservoir via a tanker truck.

6) The process according to any one of the preceding claims, wherein the step of culturing the microbial biomass in the liquid reservoir includes agitating the liquid in the reservoir by at least one of:

a) aeration; b) circulation; and,

c) mixing.

7) The process according to claim 6, wherein the agitation occurs at least one of:

a) periodically,

b) semi-continuously; and,

c) continuously.

8) The process according to claim 6 or claim 7, wherein the agitation of the liquid in the reservoir is caused by deploying at least one fluid flow control device in the reservoir.

9) The process according to claim 8, wherein the fluid flow control device includes a baffle at least partially submerged in the fluid body, the baffle including:

a) an inlet that in use is coupled to a fluid supply adapted to supply a second fluid;

b) at least one outlet;

c) at least one internal channel extending from the inlet to the at least one outlet to thereby allow second fluid to be expelled from the at least one outlet; and,

d) an outer surface which acts with the at least one outlet to at least partially guide second fluid expelled from the outlet to induce flow within the fluid body and thereby agitate the fluid body.

10) The process according to claim 9, wherein the fluid flow control device includes a platform that in use is provided on a surface of the fluid body, the platform including at least one mooring connector that in use is coupled to a mooring to thereby at least partially restrain movement of the platform in use, and wherein the baffle is attached to the platform.

11)The process according to any one of the claims 8 to 10, wherein a plurality of fluid flow control devices are positioned around the reservoir and configured to cause agitation that achieves optimum rates of culture growth.

12) The process according to any one of the claims 8 to 11, wherein the agitation at least partially causes matured microbial biomass to settle to the bottom of the reservoir for harvesting.

13)The process according to claim 12, wherein the agitation assists in directing movement of the matured microbial biomass towards the middle of the reservoir for settling and harvest. 14) The process according to any one of the preceding claims, wherein the harvesting device includes:

a) a plurality of suction head assemblies, each suction head assembly including a hollow suction head configured to cause agitation of solids settling in or around the suction head and to draw the solids entrained in a liquid flow into one or more outlets of the suction head;

b) a manifold including a body having:

i) one or more inlets coupled to the one or more outlets of each suction head to permit the collected solids entrained in the liquid flow to pass into the manifold; ii) one or more discharge ports configured to expel the collected solids entrained in the liquid flow from the manifold; and,

c) a pumping arrangement that draws in liquid and entrained solids from the suction head assemblies via the manifold and discharges the liquid and entrained solids via a discharge pipe.

15)The process according to any one of the claims 1 to 14, wherein the harvesting device includes:

a) a plurality of suction head assemblies, each suction head assembly including a hollow suction head configured to cause agitation of microbial biomass settling in or around the suction head and to draw the microbial biomass entrained in a liquid flow into one or more outlets of the suction head;

b) a manifold including a body having:

i) one or more inlets coupled to the one or more outlets of each suction head to permit the collected microbial biomass entrained in the liquid flow to pass into the manifold; and,

ii) one or more discharge ports configured to expel the collected microbial biomass entrained in the liquid flow from the manifold; and,

c) a plurality of buoyant collection tanks positioned to receive the collected microbial biomass entrained in the liquid flow from the one or more discharge ports of the manifold. 16) The process according to claim 14 or claim 15, wherein the collected microbial biomass is pumped from the collection tanks onboard the harvesting device to the one or more settling tanks.

17)The process according to claim 16, wherein the collected microbial biomass is transferred from the one or more settling tanks to a centrifuge.

18) The process according to claim 17, wherein the collected microbial biomass is passed through the centrifuge in order to dewater the collected microbial biomass.

19)The process according to claim 18, wherein the dewatered microbial biomass is transferred to a drying system including at least one of:

a) a belt dryer; and,

b) a rotary drum dryer.

20) The process according to claim 19, wherein a dried microbial biomass is produced and stored for subsequent use.

21)The process according to any one of the claims 1 to 20, wherein the microbial biomass is for use in or as at least one of aquaculture feed and agriculture feed.

22) A continuous process for the production of a microbial biomass for use in or as an aquaculture or agriculture feed, the process including:

a) feeding a liquid reservoir a mixture of culture ingredients;

b) culturing the microbial biomass in the liquid reservoir, the step of culturing including agitating the liquid reservoir using a fluid flow control device;

c) adding further feed to the liquid reservoir whilst at least a portion of the microbial biomass is still growing;

d) harvesting a mature portion of the microbial biomass that has settled on the bottom of the liquid reservoir, the harvesting including:

i) traversing a harvesting device along the bottom of the reservoir;

ii) collecting the mature microbial biomass that has settled using the harvesting device; and,

iii) moving the collected microbial biomass from the harvesting device to one or more settling tanks;

e) dewatering the collected microbial biomass in the one or more settling tanks; and, f) drying the dewatered microbial biomass to thereby make it suitable for use as or in the aquaculture or agriculture feed.

23) Apparatus for the production of a microbial biomass cultured within a liquid reservoir, the apparatus including:

a) a harvesting device that harvests settled microbial biomass from a bottom of the liquid reservoir whilst at least some of the microbial biomass is still growing and remains in suspension in the liquid reservoir by:

i) traversing the bottom of the reservoir; and,

ii) collecting the settled microbial biomass;

b) dewatering apparatus that dewaters the collected microbial biomass in the one or more settling tanks; and,

c) a drying arrangement for drying the dewatered microbial biomass.