GB2628156A

GB2628156A - Manure processing method

Info

Publication number: GB2628156A
Application number: GB2303865.6A
Authority: GB
Inventors: Verinder Sylvie
Original assignee: Tumblebug Ltd
Current assignee: Tumblebug Ltd
Priority date: 2023-03-16
Filing date: 2023-03-16
Publication date: 2024-09-18
Also published as: WO2024189381A1

Abstract

A system 10 for processing manure comprising: a chamber 12 comprising an inlet 16 for receiving manure and an exhaust (32, fig. 2) to allow gas to exit the chamber 12; at least one heater (20, fig. 4) to extract water from manure inside the chamber 12; a fan (22, fig. 2); and a biochar filter (4, fig.2) comprising biochar (66, fig. 2) in fluid communication with the exhaust 32 to filter gas extracted from the chamber 12. There is a method of processing manure comprising removing water from manure by heating the manure in a chamber 12, extracting gas from the chamber 12, and passing the extracted far through a filter (24, fig. 2) comprising biochar (66, fig. 2) to collect water and nutrients removed from the manure. Preferably heating is in the range of 75-90°C for 1-14 hours. In one embodiment the manure is alpaca manure, and the extracted gas comprise one or more of ammonia gas, bacteria, nitrogen and phosphorous. There is also a method of producing fertiliser comprising combining the biochar (66, fig. 2) with the dried manure.

Description

MANURE PROCESSING METHOD

TECHNICAL FIELD

This disclosure relates to a method and system for processing manure, including drying the manure and recapturing nutrients for use in fertilisers.

BACKGROUND

Soil improvers, including organic and inorganic fertilisers, use a range of substances to promote plant growth. Peat has been used for years as a soil improver, for example in horticulture. However, the extraction of peat has harmful effects on the environment, for example through the release of carbon dioxide which contributes to climate change, and so alternative forms of soil improver are desired.

Organic fertilisers can be more beneficial and environmentally friendly than chemical fertilisers. Animal manure is a useful organic fertiliser as it is high in plant nutrients such as nitrogen, phosphorous and potassium.

The use of alpaca manure is particularly environmentally beneficial, since for a number of reasons alpacas have a particularly low environmental impact relative to other farmed animals. For instance, alpacas lack upper incisors, meaning that they cut grass during grazing rather than pulling it up by its roots, as e.g. cows do, and also have pads rather than hooves, minimising damage to their pastures. Moreover, alpacas consume only around 1.5% of their body weight per day, less than most other farmed animals (such as sheep), meaning alpacas can naturally be farmed at a higher density, minimising land use. Alpaca manure also has a particularly high nutrient content, which is advantageous for use as a fertiliser as it enhances growth of plants. Alpaca manure is a plentiful resource, as each adult alpaca produces about 2 kg manure/day, and is easy to collect as alpacas defecate in a communal "toilet" area of their territory/enclosure. In the UK alone, there are around 46,000 alpacas.

However, problems can arise from the storage and use of manure.

Animal manure is typically collected by farmers year-round and stored in large quantities in heaps or slurries until it can be spread on the land. However, this stored manure can be a significant source of unwanted emissions, such as ammonia, and greenhouse gases, such as methane (CH4) and nitrous oxide (N20), which are released as the manure decays. The manure can also leach and produce liquid run-off which leads to high losses of nitrogen, phosphorous, etc. and contamination of -2 -surface water. Manure can also be a source of other harmful/unwanted substances such as pathogens and weed seeds and so measures need to be taken to ensure that the manure does not contaminate, for example, water and crops. Manure can also have a strong unpleasant smell.

Due to these problems with manure, governments can impose regulations on the spreading and storage of manure with which farmers may need to ensure they comply to eliminate the risk of pollution. For example, government regulations may require manure to be stored under specific conditions until a certain time of year when spreading of manure is allowed.

The volatilisation of nitrogen (N) as N20 is also problematic because nitrogen is a useful nutrient for promoting plant growth and therefore losing nitrogen from manure reduces the effectiveness of the manure as a fertiliser.

Drying animal waste for storage, for example in pelletized form, is a known method of manure management. However, dried manure may not be as useful as a fertiliser as wet manure due to the loss of nutrients such as nitrogen in the drying process.

Therefore, there is a need to provide improved manure management solutions.

SUMMARY

An aspect of the present disclosure provides a method for processing manure, such as animal manure, the method comprising removing water from the manure by heating the manure in a chamber; extracting gas from the chamber; and passing the extracted gas through a filter comprising biochar to collect water and nutrients removed from the manure (and extracted from the chamber along with the gas). The method may further comprise using at least one temperature sensor to measure the temperature (of the manure and/or air) inside the chamber, and/or using at least one moisture sensor to measure the moisture content (of the manure and/or air) inside the chamber.

The method may comprise heating the manure to at least about 75°C, preferably to at least about 80°C, more preferably to at least about 85°C. The method may further comprise heating the manure to at least about 75°C for at least about 1 hour, preferably for at least about 6 hours, more preferably for at least about 12 hours. The method may further comprise heating the manure for a duration in the range of about 1 hour to about 14 hours. The method may further -3 -comprise heating the manure to a temperature in the range of about 75°C to about 90°C for a duration in the range of about 1 hour to about 14 hours.

Removing water from the manure may comprise reducing the water content of the manure to at least about 30% of the total weight of the manure.

The method may comprise reducing the total weight of the manure by at least 40% by removing water from the manure, preferably by at least 50%. The total weight of the manure may be reduced by an amount in the range of about 30% to about 60% by removing water from the manure.

The manure may be alpaca manure.

The method may further comprise using a fan to extract gas from the chamber and direct the gas through the filter.

Extracting gas from the chamber may comprise extracting one or more of ammonia gas, bacteria, nitrogen and phosphorous released by the manure. The biochar may collect one or more of nitrogen, ammonia, phosphorous and bacteria from the extracted gas.

The method may further comprise agitating the manure within the chamber whilst heating the manure and/or extracting gas from the chamber.

Another aspect of the present disclosure provides a method for producing fertiliser, the method comprising: carrying out the preceding method to dry the manure until the water content of the manure has been reduced below a predetermined threshold; combining the biochar with the dried manure to produce fertiliser. The predetermined threshold may be in the range of about 10% to about 30% of the total weight of the manure.

Another aspect of the present disclosure provides a system for processing manure, such as animal manure, comprising: a chamber comprising an inlet for receiving manure and an exhaust to allow gas to exit the chamber; at least one heater for heating the chamber to extract water from manure inside the chamber; a fan in fluid communication with the exhaust for extracting gas from the chamber and discharging gas through the exhaust; and a biochar filter comprising biochar in fluid communication with the exhaust to filter gas extracted from the chamber.

The fan may be arranged downstream of the biochar filter.

At least one additional filter may be arranged in fluid communication with the exhaust upstream of the biochar filter for removing particulate matter from gas passing through the exhaust. -4 -

The system may further comprise a conveyor belt arranged to convey manure up a first incline from a first end to a second end to deliver the manure to the inlet; and a ramp leading up a second incline to the first end of the conveyor.

The at least one heater may be configured to heat the chamber to at least 75°C, preferably to at least 80°C, more preferably to at least 85°C.

The system may further comprise at least one temperature sensor to measure the temperature (of the manure and/or air) inside the chamber, and/or at least one moisture sensor to measure the moisture content (of the manure and/or air) inside the chamber.

BRIEF DESCRIPTION OF DRAWINGS

One or more non-limiting examples will now be described, by way of example only, and with reference to the accompanying figures in which: Figure 1 shows a perspective view of a system for processing manure according to an embodiment of the present disclosure; Figure 2 shows a cross-sectional view of an exhaust and filtration unit of the system of Figure 1; Figure 3 shows a perspective view of the system for processing manure according to an embodiment of the present disclosure; Figure 4 shows a partial cutaway view of the system of Figure 1; Figure 5 shows a cross-sectional view of the system of Figure 1; and Figure 6 shows another cross-sectional view of the system of Figure 1. -5 -

DETAILED DESCRIPTION

In accordance with the present disclosure, a system for processing organic material enables the drying of organic material, for example an organic waste product, and the recapture of nutrients that would otherwise be lost from the organic material in the drying process. The following description uses the example of processing manure, but it will be appreciated that the disclosed system may be suitable for any substance that is to be dried and from which nutrients are desired to be captured in the drying process. For example, the system may also be used for processing food waste or other organic material.

Nitrogen is a component of manure and, along with other nutrients, is useful for promoting plant growth. However, nitrogen can be lost from manure as ammonia gas through volatilisation of nitrogen. Known methods for drying manure, for example by heating the manure for storage, can remove nitrogen and other nutrients from the manure along with the moisture. The nutrient content of the manure is therefore reduced when the manure is dried, and so the dried manure may be of limited use as a soil improver for promoting plant growth. The present disclosure solves this problem by enabling the recapture of nutrients lost from the manure in the drying process.

Biochar is a carbon material formed from heating organic material in the absence of oxygen which sequesters carbon dioxide and is another option for a peat-free soil improver which locks the carbon dioxide into the soil. Biochar absorbs water and nutrients, so biochar can be activated to add nutrients such as nitrogen before the biochar is added to soil to prevent the biochar adsorbing nutrients from the soil which would be detrimental to plants. For example, to activate biochar, the biochar can be soaked for a few weeks in a solution containing nutrients, such as liquid fertiliser, to allow the biochar to absorb water and nutrients. Biochar can also be inoculated to add beneficial bacteria which can also help to provide nutrients to plants. For example, soaking the biochar in compost mixed with water will allow the biochar to absorb water, nutrients and bacteria and so can activate and inoculate biochar. Activated and inoculated biochar can then be added to soil to improve plant growth. The present disclosure provides a system and method for processing manure which also has the benefit of activating and inoculating biochar for use as a soil improver.

With reference to Figures 1 and 2, a system 10 for processing manure dries and sanitises manure by applying heat to the manure. The system 10 is not limited -6 -to drying and sanitising manure, but may also be used for drying and/or sanitising other types of material. The system 10 comprises a heating chamber 12 and an exhaust and filtration unit 14. The chamber 12 may be contained within a housing 13 and comprises an inlet 16 to allow manure (or other material) to be loaded into the chamber 12, and an outlet 18 to allow dried manure to be unloaded from the chamber 12 once the drying process has been carried out. The heating chamber 12 comprises one or more heaters 20 to heat the manure in order to evaporate liquid contained in the manure. The heating can also sterilise the manure. The exhaust and filtration unit 14 comprises a blower or fan 22, such as a centrifugal fan, to remove gas (i.e., air) from the chamber 12, including moisture removed from the manure by the heating, and one or more filters 24, 26, 28, 30 for filtering the exhaust gas.

In an example, the system 10 may be designed to run a drying cycle on up to about 2000 kg of manure at a time. The maximum amount of manure per drying cycle may depend on the capacity of the chamber 12, and also on the arrangement and efficiency of the heaters 20 and blower 22. Depending on at least these factors, the maximum amount of manure per drying cycle may be in the range of about 100 kg to about 2000 kg.

In an example, the raw, wet manure that is loaded into the chamber 12 for drying may comprise a water content in the range of about 40% to about 60% of the total weight of the wet manure. The drying process may reduce the water content of the manure to about 10% of the total weight of the manure.

Drying the manure, i.e., removing water and sanitising the manure (by killing pathogenic bacteria and weed seeds), provide the advantages of reducing the volume and weight of the manure, and reducing greenhouse gas emissions and potential contaminants for easier, cheaper and more environmentally-friendly storage and transport of the dried manure. These advantages are particularly beneficial for manure to be used as fertiliser, as manure needs to be stored and transported safely for use as fertiliser without the risk of contamination or pollution. Drying manure in accordance with the present disclosure also provides the advantage of reducing odours, which is particularly useful for manure that often has a strong unpleasant smell.

Heating manure inside the chamber 12 releases liquid from the manure into the surrounding air/gas. The blower 22 and an exhaust pipe 32 extract gas from the chamber 12 in order to remove water droplets and water vapour. Heating the manure -7 -to remove moisture also releases nutrients such as nitrogen, for example nutrients dissolved in the water. This can be disadvantageous for manure that is intended to be used as fertiliser, as the amount of nutrients that the dried manure can provide is reduced compared to the 'wet manure. To avoid losing nutrients, a biochar filter 24 is arranged in fluid communication with the exhaust pipe 32 in order to recapture the nutrients that have been removed from the manure along with the moisture.

Manure is delivered to the heating chamber 12 through the inlet 16. Bacteria may also be added to the heating chamber 12, before or with the manure. The bacteria may help to break down the manure to prepare it for use as a fertiliser. For example, thermophilic bacteria may be added to the chamber 12 and undergo a heating process before the manure is added. Mesophilic bacteria may then be added to the chamber 12 with the manure. The added bacteria may be beneficial as a soil improver and can be recaptured by the biochar filter 24 when it is extracted from the manure with the water.

The drying process occurs inside the chamber 12. The inlet 16 may be located at the top of the chamber 12, and a hopper or funnel 34 may be provided at the inlet 16 to facilitate loading manure into the chamber 12.

With reference to Figure 3, an inclined conveyor belt 36 may be provided for conveying manure to the inlet 16 from a first end 40 at a lower elevation to a second end 41 at a higher elevation, for example if the inlet 16 is located at the top of the chamber 12. A ramp 38 may be provided at the lower end 40 of the conveyor belt 36 to assist delivery of manure to the conveyor belt 36, for example to allow a wheelbarrow to be wheeled up the ramp 38 from ground level.

With reference to Figures 4 and 5, the chamber 12 is provided with one or more heaters 20 for heating the contents of the chamber 12. In Figure 4, the front wall of the housing 13 has been removed to show the chamber 12 and heaters 20. Figure 5 is a side cross-sectional view through the housing 13, chamber 12 and hopper 34 of Figure 1. The chamber 12 may be provided inside a tank 42 with heating elements 44 positioned on the outer surface 46 of the tank 42. For example, the one or more heaters 20 may comprise an insulated heating jacket 20 fitted around the tank 42.

Preferably, the one or more heaters 20 heat the manure within the chamber 12 to at least a temperature sufficient to sterilize the manure, for example to kill pathogens and weed seeds that may be present in manure. This is beneficial to reduce or eliminate the risk of contamination of foodstuffs or water supplies by -8 -pathogens that may otherwise be present in the dried material. Killing weed seeds is beneficial to avoid spreading weeds to areas in which the dried manure is stored or used as a fertiliser, for example.

It has been found that heating the manure to at least about 75°C allows the benefits of efficiently drying the manure and sufficiently sterilizing the manure to be achieved. In some embodiments, the manure is heated in the chamber 12 to at least about 80°C, and more preferably at least about 85°C. For example, the manure is heated to a temperature between about 75°C and about 90°C. Preferably, the manure is heated for at least an hour, preferably at least about 6 hours, and more preferably at least about 12 hours. For example, the manure is heated for a duration between about 1 hour and about 14 hours. These temperatures and durations have been found to provide sufficient drying and sanitisation of manure. The temperature and duration required may depend on the type of manure, the amount of liquid contained in the manure at the start of the process, and the intended use or destination of the dried manure. Other suitable types of heaters, temperatures and durations for heating, drying and sterilising the manure will be apparent to the skilled person.

Figure 6 shows a front cross-sectional view through the housing 13 and chamber 12 as shown in Figure 1. The system 10 may comprise one or more temperature sensors 48 to measure the temperature inside the chamber 12. This allows the temperature to be monitored as the contents of chamber 12 are heated to determine that the desired temperature has been reached and ensure the temperature stays at the desired level.

The one or more temperature sensors 48 may be in communication with a control system 50 coupled to the chamber 12 for controlling and/or monitoring the operation of the system 10, including the temperature of the chamber 12. The control system 50 may comprise a control panel 52 and/or display 54 for controlling and/or monitoring the operation of the system 10 at the chamber itself, and/or the control system 50 may be in communication with a remote secondary control system (not shown) for controlling and/or monitoring the operation of the system 10 remotely.

The control system 50 may comprise a timer for monitoring the duration of the drying process. The control system 50 may be programmed to automatically switch the heaters off when a specified heating duration has ended. -9 -

When manure is heated in the chamber 12, at least some of the liquid contained in the manure is evaporated. The moisture content (i.e., humidity) of the air inside the chamber 12 therefore increases as the manure is heated.

In order to remove the moist air from the chamber 12, the exhaust pipe 32 fluidly connects the chamber 12 to the blower or centrifugal fan 22 that operates to remove gas from the chamber 12. The skilled person would be able to determine appropriate air flow rates for the blower 22 that would be suitable for extracting gas from the chamber, for example at least based on the number and types of filter arranged upstream of the blower 22.

Preferably, the extraction of air from the chamber 12 only occurs once the temperature of the contents of the chamber 12 has reached a predetermined level (for example, a temperature between about 75°C and about 90°C) and, optionally, has been at the predetermined level for a predetermined amount of time. This helps to ensure that most, if not all, of the harmful bacteria in the manure has been killed before air is extracted from the chamber 12.

The system 10 may comprise one or more moisture sensors 56 to measure the moisture content of the air inside the chamber 12. Monitoring the moisture content throughout the drying process can indicate by how much the manure has been dried. This can help to determine when the manure has been sufficiently dried and the dried manure can be unloaded from the chamber 12. Preferably, the chamber 12 comprises at least two moisture sensors 56 and at least two temperature sensors 48 to provide redundancy in case the operation of one of the moisture sensors 56 and/or one of the temperature sensors 48 is impaired, for example due to a build-up of manure on a sensor.

The one or more moisture sensors 56 may be in communication with the control system 50. The control system 50 may be programmed to automatically switch the heaters off when a specified moisture content has been reached.

The moisture sensor readings may be used in addition to, or instead of, a predetermined heating duration to determine when to end the drying process. The amount of drying required may depend on various factors such as the type of manure, the amount of liquid contained in the manure at the start of the process, and the intended use or destination of the dried manure. For example, the manure can be heated in the chamber until the one or more moisture sensors 56 measure a moisture content of the air (or the manure) inside the chamber 12 that is at least a predetermined amount lower than the moisture content at the beginning of the drying process, or until the one or more moisture sensors 56 measure a moisture content of the air (or the manure) inside the chamber 12 below a predetermined threshold, which may depend on the temperature inside the chamber 12. For example, if the system 10 is used for drying manure to store for later use as a fertiliser, it may be advantageous to reduce the moisture content of the manure to or below a threshold in the range of about 10% to about 30% of the total weight of the manure. Reducing the moisture content to below about 30% of the total weight has been found to be advantageous when drying manure, particularly alpaca manure, to reduce weight and volume for storage and transport, and also for deodorising the manure. In some examples, drying the manure in this way may reduce the total weight of the manure by an amount in the range of about 30% to about 60%. Preferably, the total weight of the manure is reduced by at least about 40% or at least about 50% by the drying process.

Once the manure has been sufficiently dried, which may be determined by the heating duration and/or the moisture content, it can be unloaded from the chamber 12 through the outlet 18, which may be positioned in a side of the chamber 12. For example, a screw conveyor may be used to convey the dried manure from the chamber 12 to a storage location or container.

The drying process may be assisted by agitating the contents of the chamber 12. For this purpose, an agitator 58 may be provided for mixing the contents of the chamber 12, as shown in Figures 5 and 6. The agitator 58 may be used to mix the contents of the chamber 12 whilst heat is being applied in order to help achieve a more even application of heat throughout the contents. Agitation of the contents can also promote air circulation in the chamber 12 and through the contents of the chamber 12 which can help the evaporation of liquid from the manure and thus speed up the drying process.

The agitator 58 may comprise a shaft 60 extending through the chamber 12, with one or more paddles 62 extending from the shaft 60. The system 10 may comprise a motor 64 for rotating the shaft 60. Operation of the motor 64 to rotate the shaft 60 causes the paddles 62 to rotate around the chamber 12 so as to agitate/mix the contents of the chamber 12. For example, the agitator 58 may be rotated by the motor 64 at a speed in the range of 1 to 5 rpm, preferably 2 to 3 rpm. Operation of the agitator 58 may be controlled by the control system 50, separately or in combination with controlling the temperature of the chamber 12.

In other embodiments, the agitator 58 may comprise a rotating drum with the chamber 12 provided within the drum. The skilled person would be able to determine a suitable rotational speed for the agitator 58 and suitable dimensions for the paddles 62 for different applications, for example particular types or amounts of manure and chamber size/shape.

Figure 2 shows a cross-sectional view of the exhaust and filtration unit 14 which comprises one or more filters 24, 26, 28, 30 arranged in series in fluid communication with the exhaust pipe 32 so that gas drawn out of the chamber 12 by the blower 22 passes through the one or more filters 24, 26, 28, 30. The one or more filters 24, 26, 28, 30 are preferably arranged upstream of the blower 22 to minimise particulate build up on the blower 22.

The one or more filters 24, 26, 28, 30 comprise a biochar filter 24. The biochar filter 24 comprises biochar 66 retained within a housing 68 to allow gas removed from the chamber 12 to pass over the biochar 66. In some embodiments, one or more additional filters 26, 28, 30, such as dust/particulate filters, are arranged upstream of the biochar filter 24 to filter out particulates from the manure that have been carried through the exhaust pipe 32 along with the gas. This helps to protect the biochar filter 24 from particulate build-up, which may reduce the absorption of water, nutrients and bacteria by the biochar 66. The upstream particulate filters are particularly advantageous when the system 10 is used for drying manure, which has been found to produce a large amount of suspended solids in the air extracted by the blower 22. For example, three particulate filters 26, 28, 30 with varying mesh sizes may be arranged consecutively in the exhaust pipe 32. The first, most upstream filter 26 that is furthest from the biochar filter 24 may have the largest mesh size, whilst the third, most downstream filter 30 of the additional filters 26, 28, 30 that is closest to the biochar filter 24 may have the smallest mesh size. The second, middle filter 28 may have a mesh size between the mesh sizes of the first and third filters 26, 30. The particulate filters 26, 28, 30 capture the majority of suspended solids in the moist air extracted from the chamber 12 by the blower 22. The one or more particulate filters 26, 28, 30 may comprise hydrophobic material to maximise the filtration efficacy in the high moisture environment of the exhaust pipe 32. The particulate filters 26, 28, 30 are preferably removable to allow them to be cleaned as particulates build up on the filters.

Due to the heating of the manure in the chamber 12, the exhaust gases removed from the chamber 12 by the blower 22 comprise water droplets/vapour and -12 -nutrients such as nitrogen and phosphorous that may be dissolved in the water. Beneficial bacteria from the manure may also be carried out of the chamber 12 with the water.

The inlet 16 may comprise a door 68 that can be sealed shut during the drying process to prevent loss of water and nutrients through the inlet 16 and thus maximise the nutrients that are removed through the exhaust pipe 32 for adsorption by the biochar filter 24.

When first installed, the biochar 66 in the biochar filter 24 has not yet been activated or inoculated, so it will readily absorb water and adsorb nutrients and bacteria carried by the extracted gas as the gas passes over the biochar 66. Water carried by the extracted gas may comprise dissolved nutrients, such as nitrogen, phosphorous, ammonia, potassium, calcium, sulphur and magnesium. The water may also comprise trace elements such as iron, copper, zinc and manganese. The biochar 66 can collect these nutrients/elements that are removed from the manure in the drying process.

The amount of biochar 66 used in the biochar filter 24 may be chosen depending on a number of factors, such as the maximum amount of manure used per cycle, the diameter of the exhaust pipe 32, the speed of the blower 22 and the rate of air extraction from the chamber 12. In some examples, the biochar filter 24 may be designed to hold about 120 kg of biochar 66.

In some embodiments, a water collection device 70 may be arranged beneath the biochar filter 24 to collect condensate as the biochar 66 becomes saturated with water. The water collection device 70 may comprise a controllable valve and/or a drip tray to allow for easy removal of excess water from the biochar filter 24.

Due to the sterilisation of the manure by the heat in the chamber and the filtration by the biochar filter 24, and by additional filters 26, 28, 30, if present, the water collected in the water collection device 70 has been cleaned and sterilise. The collected water can therefore be reused rather than needing to be disposed of, which reduces water wastage, and so the burden of having to safely dispose of contaminated water is eliminated. The water collection device 70 may be connected to a fluid conduit and/or a tap for convenient removal and collection of water. Conventionally, the drying of manure can have the problem of where to drain or store the extracted water. For example, the extraction of water from manure may require the water to be drained to a foul sewer. However, access to a foul sewer could be a problem and may require additional equipment and/or infrastructure to provide the necessary drainage. The present disclosure mitigates this problem by recapturing the water in the biochar 66 and collecting clean water via the water collection device 70 for subsequent use.

Due to the removal of odours, bacteria and potential pollutants, such as nitrogen, from the exhaust gas by the biochar filter 24, the gas that has passed through the biochar filter 24 has been cleaned and sterilised and can be vented to atmosphere via the blower 22.

The biochar 66 in the biochar filter 24 can be removed when saturated, and/or when sufficiently activated and inoculated, and replaced with fresh biochar 66. The activated and inoculated biochar 66 removed from the filter 24 has collected nutrients from the manure and so can be used as a soil improver. For example, the biochar 66 can be combined with the dried manure to produce a fertiliser. The combination of the dried manure and the activated and inoculated biochar 66 provides an improved fertiliser compared to just the dried manure on its own due to the nutrients and bacteria that have been recaptured in the biochar 66. Furthermore, capturing nutrients in the biochar 66 makes the nutrients more concentrated compared to in the wet manure, which can be more beneficial for promoting plant growth.

In some examples, the biochar 66 may be replaced after one or two drying cycles. The frequency with which the biochar 66 should be replaced can depend on a number of factors, including, but not limited to, the amount of biochar used, the amount of manure that is dried in each drying cycle (i.e., the chamber capacity), the water content of the wet manure, the rate of exhaustion by the blower 22, and the amount of water removed from the manure in each drying cycle.

Tests may be carried out on the biochar filter 24 to analyse the filtration efficiency across one or more drying cycles to determine an optimal biochar replacement schedule. In some examples, the biochar 66 may be sufficiently activated and inoculated by the filtration process to be used as a soil improver before it becomes fully saturated, and so in some cases the biochar 66 may be removed and replaced before nearing saturation levels.

Claims

CLAIMS1. A method for processing manure, the method comprising: removing water from manure by heating the manure in a chamber (12); extracting gas from the chamber (12); and passing the extracted gas through a filter (24) comprising biochar (66) to collect water and nutrients removed from the manure.
2. The method of claim 1, further comprising heating the manure to at least about 75°C, preferably to at least about 80°C, more preferably to at least about 85°C.
3. The method of claim 1 or 2, further comprising heating the manure to at least about 75°C for at least about 1 hour, preferably for at least about 6 hours, more preferably for at least about 12 hours.
4. The method of claim 1, 2, or 3, comprising heating the manure for a duration in the range of about 1 hour to about 14 hours.
5. The method of any preceding claim, comprising heating the manure to a temperature in the range of about 75°C to about 90°C for a duration in the range of about 1 hour to about 14 hours.
6. The method of any preceding claim, wherein removing water from the manure comprises reducing the water content of the manure to at least about 30% of the total weight of the manure.
The method of any preceding claim, wherein the manure is alpaca manure.
8. The method of any preceding claim, further comprising using a fan (22) to extract gas from the chamber (12) and direct the gas through the filter (24).
9. The method of any preceding claim, wherein extracting gas from the chamber (12) comprises extracting one or more of ammonia gas, bacteria, nitrogen and phosphorous released by the manure.
10. The method of any preceding claim, wherein the biochar (66) collects one or more of nitrogen, ammonia, phosphorous and bacteria from the extracted gas.
11. The method of any preceding claim, wherein the total weight of the manure is reduced by at least 40% by removing water from the manure, and is preferably reduced by at least 50%.
12. The method of any preceding claim, wherein the total weight of the manure is reduced by an amount in the range of about 30% to about 60% by removing water from the manure.
13. The method of any preceding claim, further comprising agitating the manure within the chamber (12) whilst heating the manure and/or extracting gas from the chamber (12).
14. A method for producing fertiliser, the method comprising: carrying out the method of any preceding claim to dry the manure until the water content of the manure has been reduced below a predetermined threshold; and combining the biochar (66) with the dried manure to produce fertiliser.
15. The method of claim 14, wherein the predetermined threshold is in the range of about 10% to about 30% of the total weight of the manure. 25
16. A system (10) for processing manure, comprising: a chamber (12) comprising an inlet (16) for receiving manure and an exhaust (32) to allow gas to exit the chamber (12); at least one heater (20) for heating the chamber (12) to extract water from manure inside the chamber (12); a fan (22) in fluid communication with the exhaust (32) for extracting gas from the chamber (12) and discharging gas through the exhaust (32); and a biochar filter (24) comprising biochar (66) in fluid communication with the exhaust (32) to filter gas extracted from the chamber (12).
17. The system of claim 16, wherein the fan (22) is arranged downstream of the biochar filter (24).
18. The system of claim 16 or 17, wherein at least one additional filter (26, 28, 30) is arranged in fluid communication with the exhaust (32) upstream of the biochar filter (24) for removing particulate matter from gas passing through the exhaust (32).
19. The system of claim 16, 17 or 18, further comprising: a conveyor belt (36) arranged to convey manure up a first incline from a first end (40) to a second end (41) to deliver manure to the inlet (16); and a ramp (38) leading up a second incline to the first end (40) of the conveyor belt (36).
20. The system of any of claims 16 to 19, wherein the at least one heater (20) is configured to heat the chamber to at least 75°C, preferably to at least 80°C, more preferably to at least 85°C.
21. The system of any of claims 16 to 20, further comprising at least one temperature sensor (48) for measuring a temperature inside the chamber (12).
22. The system of any of claims 16 to 21, further comprising using at least one moisture sensor (56) to measure a moisture content inside the chamber (12).