FI127177B

FI127177B - Pet stalls comprising a composting system, as well as a method for recovering heat and / or one or more chemicals from a compost in a pet stall

Info

Publication number: FI127177B
Application number: FI20165999A
Authority: FI
Inventors: Eemeli Piesala; Lasse Piesala
Original assignee: Pasrea Oy
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2017-12-29
Also published as: WO2018115590A1; FI20165999A

Description

A livestock shed comprising a composting system and a method for recovering heat and/or one or more chemical(s) from a compost in a livestock shed

Field of the application

The present application relates to a composting system comprising an aeration floor and utilizing negative aeration. The present application also relates to a method for recovering heat and/or one or more chemical(s) from a compost.

Background

Composting is a natural process which transforms organic materials into decomposed form called compost. The composted material, which is rich in nutrient, may be recycled for example as a fertilizer and soil amendment. It may be used for example in gardens, landscaping, horticulture and agriculture.

On many farms, the basic composting ingredients are animal manure generated on the farm and plant-based bedding. Straw and sawdust are common bedding materials. The composting process is dependent on microorganisms to break down organic matter into compost. There are many types of microorganisms found in active compost, such as bacteria, actinobacteria, fungi, protozoa and rotifers. The composting process generates and releases heat and chemicals. FI962431 discloses a modular composting system intended for composting some compostable materials. The system comprises two or more compartments that have three walls, are arranged next to one another and are fitted with a hanging floor. The material to be composted is placed in these compartments, together with the purifiers for the aerating gas coming from the composting unit. The invention also provides for a fan installation that sucks the aerating gas through the hanging floor construction in the composting compartment and blows the gas into one of the compartments used for filtering it. FR2789989 discloses a method for composting solid material, utilizing improved air circulation and better recovery of ammonia produced as a byproduct, is new. Air is sucked through heaps of solid material being turned into compost by aerobic fermentation. This is done by drawing a slight vacuum in perforated ducts beneath the heaps. Air and gaseous fermentation products are bubbled through an aqueous solution of phosphoric or nitric acid. Ammonia present in the gas reacts with the acid to produce a useful fertilizer. US5160707 discloses an apparatus for scrubbing a stem of process air from a sewage composting facility, wherein the process air has been used to aerate compost for passage the rethrough, the process air including ammonia, sulphides and malodorous organic compounds. US 2007/0111305 A1 discloses a system for generating compost, comprising: an aeration floor comprising a plurality of gas flow apertures positioned on the surface of the aeration floor; and a compost cover sized to cover a compost biomass pile placed on the aeration floor and having a plurality of aeration ports that permit passage of gas and liquid through the compost cover, wherein the plurality of gas flow apertures are connected to at least one gas flow channel installed below grade of the aeration floor.

Summary

It was found out in the present invention how heat and/or chemicals can be recovered from a compost, and how the compost can be controllably implemented, for example in an active livestock shed.

One embodiment provides a livestock shed comprising a composting system comprising an aeration floor for receiving compostable material, the aeration floor comprising -a surface and one or more aperture(s) extending through the surface, wherein the composting system further comprises -an air pump arranged to lead air from the surface through the one or more aperture(s) to provide negative aeration, and -a device arranged to recover heat from the air, and/or -a device arranged to recover one or more chemical(s) from the air.

One embodiment provides a method for recovering heat and/or one or more chemical(s) from a compost in a livestock shed, the method comprising -providing the composting system comprising compostable organic material, -negatively aerating the compost to obtain air from the compostable organic material, -recovering the heat from the air with the device arranged to recover heat from the air, and/or -recovering the one or more chemical(s) from the air with the device arranged to recover one or more chemical(s) from the air.

The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The embodiments recited in dependent claims and in the embodiments are mutually freely combinable unless otherwise explicitly stated.

The aeration floor provides uniform forced air distribution across the compost area. The aeration floor disclosed herein may be easily serviced for example by using machinery but also manually, for example the composted material may be recovered, the facilities may be cleaned and serviced, and a base for a new compost may be created on the aeration floor.

By using forced aeration it is possible to ensure aerobic conditions in the compost and to avoid anaerobic conditions, which could lead to rotting of the compostable material. The forced aeration may be further enhanced by using specific material on the aeration floor providing air ducts and preventing clogging of the system. Also the structure of the aeration floor has an effect on preventing the clogging and for recovering for example liquids obtained from the compostable material.

With the system disclosed herein heat or chemicals may be recovered from the compost and used immediately or at another location. The system also enables controlling and adjusting the composting process.

The composting system may be implemented in a variety of targets, such as general composting locations, which may or may not be covered, buildings, such as animal sheds, or separate containers.

Brief description of the drawings

Figure 1 shows an example of an aeration floor comprising a plurality of apertures on the upper surface.

Figure 2 shows a sectional view of the aeration floor of Figure 1 wherein it is shown how the apertures extend through the surface.

Figure 3 shows a schematic view of a composting system comprising an aeration floor installed into a building and comprising air pump and means for recovering heat and chemicals from the air.

Detailed description

The present disclosure provides a composting system comprising an aeration floor 10 for receiving compostable material, the aeration floor comprising -a surface 14 and one or more aperture(s) 16 extending through the surface, wherein the system further comprises -an air pump 20 arranged to lead air from the surface 14 through the one or more aperture(s) 16 to provide negative aeration, and -a device 23 arranged to recover heat 32 from the air, and/or -a device 28 arranged to recover one or more chemical(s) 30 from the air.

The composting system as used herein refers to an arrangement comprising the aeration floor 10 connected to the devices required to carry out the composting methods described herein. The aeration floor 10 is arranged to receive compostable material 34, which means that compostable material, which comprises compostable organic material and optionally other material, may be placed onto the aeration floor. For example a layer or a pile of the compostable material may be applied onto the floor. The compostable material should be in a form enabling the air to pass through the material, preferably a layer of substantially even thickness. The thickness of the layer may be in the range of 5-200 cm, such as in the range of 10-150 cm, ΙΟΙ 00 cm, for example 10-50 cm or 10-30 cm. If the compostable material contains additional material enhancing the aeration of the compost, the thickness of the layer may be even higher.

In general the compost, or more particularly the composting organisms, require carbon, nitrogen, oxygen and water. The most efficient composting occurs with an optimal carbon:nitrogen ratio of about 10:1 to 20:1. When the organisms degrade the nutrients, water and heat are released. Much of the water is released as vapour and the oxygen will be quickly depleted. The amount of vaporized water from a biomass is very high even in a case of a partial composting. This creates a need to control the process. The air/water ratio has a great effect to the temperature of the compost, and it is desired to maintain high temperature in the compost. Examples of factors slowing down the composting process in general include too much air, too much water, too much carbon, and too little nitrogen. However, in the case of active aeration other factors slowing down the composting may include too little water and too high temperature.

The temperature of the compostable material has a great effect to the efficiency of the composting process, and the temperature may be controlled, such as monitored and adjusted to a selected range, to obtain desired conditions in the compost. In general the temperature of the compost may be in the range of 30-70°C. Some composting may occur at a temperature of 30°C, but in general higher temperatures are desired, such as at least 40°C, or at least 50°C, or preferably at least 60°C or even at least 65°C. However, the temperature should not be too high as most of the microbes will die at temperatures over 70°C, which will slow down the composting process. Useful temperature ranges for the composting process include 40-70°C, 50-70°C, and preferably 60-70°C or 65-70°C. At the high temperatures over 50°C or over 60°C most of the pathogens present in the organic material will die which makes the obtained final composted product free of pathogens and therefore very useful for variety of applications. The temperature of the compost may be controlled by measuring the temperature at one or more locations of the compost and as a feedback carrying out actions to adjust the temperature, for example by providing heat, providing cooling or adjusting the air flow, such as decreasing or increasing the air flow, or adding water, such as heated or cooled water, in the whole aeration floor or separately at one or more locations of the aeration floor, or adjusting other conditions. If water is used for controlling the temperature, either up or down, the adjusting of the temperature and other conditions may be more controllable, for example as water does not contain free oxygen and therefore it does not speed up the composting, as is the case with air.

Heat may be provided by using heated air, which may be applied form the upper part of the compost, by applying water or other aqueous liquid, or by using heating tubes with heated liquid flow. The heat may be heat recovered by a device arranged to recover heat from the air. A temperature controlling system may contain a control unit operatively connected to one or more temperature sensor(s) located in the compostable material or in the aeration floor detecting the temperature(s), wherein the control unit is configured, as a feedback to the detected temperature(s), to maintain the temperature of the compost at a desired range, such as discussed herein, by controlling the air flow and/or by providing heating or cooling to the compostable material, or by controlling any other controllable conditions, such as addition of water into the compostable material. For example the air flow may be controlled in a range of 0-5 times the calculated average need of air. In one example the air flow is in the range of 10-300 m3 of air per hour. The required aeration time may be for example in the range of 1-12 months, or more, for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20 or 24 months, which may be taken into account for example when selecting the efficiency of the air pump.

The moisture content of the compost may have an effect to the composting speed or efficiency. In general the moisture content, especially initial moisture content, may be in the range of 40-60% (w/w) or 45-65%, for example 50-60%, expressed as wet basis gravimetric water contents (mass of water divided by mass of wet compost). Too high moisture content fills pore spaces of the compostable material and leads to anaerobic conditions, which results in rotting. On the other hand too low moisture content will lead to decrease in composting efficiency and to drop of temperature as the water content will become a limiting factor. Too effective aeration may dry the compost, so the moisture content of the compostable material may be monitored and the aeration, such as the speed of the air flow, may be adjusted as a feedback to the detected moisture content. The moisture content may be detected with sensors, for example sensors detecting the conductivity of the compostable material, wherein the conductivity of the material is proportional to the moisture content of the material. If the moisture content is too low, the system may be arranged to provide water to the compost as a feedback to obtain a desired moisture content of the compostable material. The water may be provided for example by spray nozzles and/or tubing located above the compostable material. Such watering system may contain one or more pumps for pumping the water connected to a water source and to a controlling system arranged to detect the moisture content of the compost and as a feedback to provide water to the compost. The water may be water or other aqueous liquid recovered from the composting system, such as liquid flown into the system from the compostable material, which liquid may be recovered and conveyed back to the compost. The water may also be water or other aqueous liquid recovered from a device arranged to recover heat and/or from a device arranged to recover one or more chemical(s).

The compostable material 34 contains organic compostable material, which may contain animal and/or plant based material, and it may be also called biomass or compost biomass. In one example the compostable material contains manure material, such as animal manure, human manure or combinations thereof, more particularly fecal-based material, optionally including urine. In one example the compostable material contains plant based material, such as garden waste, agricultural waste, and the like. In some examples the compostable material contains household bio waste, industrial waste, such as waste from pulp or paper industry, and combinations of the materials described herein. The compostable material may contain manure material and additional plant-based material, such as straws, sawdust, newspaper, chopped cardboard and the like. Such plant-based material may be called as bedding or bedding material. The bedding may help in aeration and absorbing liquids, such as urine, which could otherwise make the compost too dense and prevent aerobic composting reactions. In one example the bedding comprises wood chips having an average diameter in the range of 20-200 mm, or 20-100 mm. Such relatively large chips enhance the aeration if the compostable material.

Each type of manure has its own physical, chemical, and biological characteristics, which may have an effect to the composting process. The process may be controlled by the use of bedding and other aerating material, as well as by controlling the active air flow, for example to enable efficient composting and air flow, or by controlling the temperature or moisture content of the compost. Cattle and horse manures, when mixed with bedding, possess good qualities for composting. Swine manure, which is very wet and usually not mixed with bedding material, may be mixed with straw or the like materials. Poultry manure also may be blended with carbonaceous materials, such as sawdust or straw.

The composting system described herein utilizes active aeration, which is also called as forced aeration, wherein air is actively introduced through the compostable material. Types of active aeration in general include positive aeration and negative aeration. More particularly the present system involves negative aeration wherein air is drawn from the surface of the compost through the compost, i.e. negative pressure or vacuum, such as suction or air intake, is applied from the bottom of the compost. The present system preferably does not use positive aeration, and the devices generally used in positive aeration are not necessary suitable for use in negative aeration. In the present system the compost lies on the aeration floor, which contains apertures for the air flow. More particularly the aeration floor comprises a surface and one or more aperture(s) extending through the surface. The surface of the floor is substantially flat, which enables for example maintenance of the compost by using machinery, such as bulldozer types of machinery, tractors, mini bucket loaders, other tools, such as power tools, for example pressure washer, or manual tools, and the like. There should be no protruding parts, such as nozzles, pipes, tubes or the like, on the surface of the floor which could prevent or hinder the use of the machinery or the tools. The surface refers to the upper surface of the floor, i.e. the surface which is arranged to receive the compostable organic material. In general the oxygen-rich air entering the compost may be called as fresh air and the oxygen-depleted air which has passed the compost may be called as exhaust air or air from the compostable organic material.

There are one or more aperture(s) 16, which may be also called as orifices or holes, on the surface 14 of the floor 10 which extend through the surface, as shown in the examples of Figures 1 and 2. The one or more aperture(s) 16 may be round, elongated or they may have any other shapes. There may be a plurality of the apertures for example arranged as an array, for example a plurality of apertures in a line and several lines in parallel, as shown in Figure 1. The plurality of the apertures may be evenly distributed, for example arranged as a grid. The apertures may have a diameter in the range of 10-50 mm in the case of round or substantially round apertures, and in the case of elongated apertures the width of the aperture may be in the range of 10-50 mm and the length of the aperture may be in the range of 20-5000 mm, or for example in the range of 50-100 mm. Preferably the apertures do not contain any portions protruding to the surface on the aeration floor which is arranged to receive the compostable organic material. The apertures may be also called for example as gas flow apertures or air ducts. The apertures on an aeration floor provide even air flow at all parts of the compost, which is difficult to obtain for example by using perforated tubes.

In one embodiment the aeration floor comprises a body having one or more cavities 12 inside the body connected to the one or more aperture(s) 16. The cavities enable combining the separate air flows from the apertures into a single air flow which may be further lead to the devices arranged to recover heat and/or chemical(s). It is also possible to include one or more of the devices described herein inside the cavity or cavities, for example to enhance recovery of chemicals or heat as the recovery is carried out immediately as the air enters the system. This may also save space and make the system simpler as the devices are not outside the aeration floor, or for example outside a building or container. However, placing one or more of the devices outside will facilitate maintenance and monitoring the system. The cavities may be arranged to be serviced, for example to be washed by using a pressure washer or other tools, by providing removable tubing, manifolds, plugs, seals or the like so that it is possible to enter or reach the cavities or other interior parts of the system to remove contaminants which have entered the system.

The composting system, or more particularly the aeration floor, may include two or more cavities or group of cavities and/or two or more groups of apertures in the aeration floor, which are connected to separate air pumps and/or to separate devices for recovering heat and/or chemicals. The groups of apertures or separate cavities or cavity groups, which may be connected in such way that one group of apertures is connected to one separate cavity or a group of cavities or a group of ducts connected to a cavity, enable controlling separately individual areas of the aeration floor and therefore also individual areas of the compost. These may be called as separately controllable areas, and a composting system may include two or more of such areas, such as two, three, four, five, six, seven, eight or more. The aperture groups may be called also as inlet areas or inlet groups. The two or more separate cavities or cavity groups may be connected into two or more outlet groups, outlet ducts or outlet areas. The conditions may be different at different locations of the compost, so it may be necessary to adjust the conditions separately at different locations, for example to adjust the air flow separately or to adjust the recovery of the heat and/or chemicals separately.

Figure 2 shows an example of the connections 18 between the apertures 16 and the cavities 12 presented as dotted lines. The body may have a thickness for example in the range of 50-300 mm, especially if the body contains cavities. The body 10 may comprise concrete, metal, composite material, such as reinforced concrete, plastic-fiber composite, glass fiber, or the like. In general the body, or the least the surfaces thereof, such as inner and outer surfaces, should be corrosion resistant, as the compostable material and the chemicals released therefrom may be corrosive, especially as the compost generates heat which may accelerate corrosive reactions. The one or more cavities 12 inside the body may be tubular cavities, such as in a case of a hollow core slab, for example as shown in Figure 1, or the cavities may have other shapes, such as a single cavity under the floor, which may have an area corresponding to the area of the floor, or substantially the area of the floor, or more than one cavities having rectangular shapes. The cavity or two or more cavities may be inside the body of the floor, or the cavity or cavities may be under a floor. In one example the floor contains two flat elements connected together with columns or other supporting parts leaving a cavity between the two flat elements. A cavity may be formed between an aeration floor element having the apertures and a floor of a building or a container, other platform, or even a ground. In one example the upper element is a grid element or beam for animal sheds, which is a slotted structure for example made of reinforced concrete, which are available for example having a length in the range of 1000-4000 mm, a height in the range of 140-170 mm and slots with 28-38 mm width.

The cavity or cavities is/are connected to the apertures to allow the flow of air though the apertures into the cavities, i.e. the apertures extend to the cavities from the surface. The cavities and the apertures and/or channels connected to the cavities may be in general called as gas flow channels. An aeration network is provided enabling even air distribution throughout the compost. The aeration network may also include separately controllable areas as described in previous. In such case the air pump is arranged to lead air from the surface through the one or more aperture(s) to the one or more cavities to provide negative aeration. The aeration floor has one or more air outlets which is/are connected to one or more devices as described herein, such as an air pump or a device for recovering heat and/or chemical(s). If there are more than one outlets in the aeration floor they may be connected to a manifold, such as an air suction manifold or an air discard manifold, which will lead the air to the device(s).

Liquid may enter to the cavities or it may be condensed in the cavities, such as water or other aqueous liquid from the composting system. The cavity or cavities may be designed to include flow channels or slopes which make the liquid flow towards a drain, a sump or other outlet, preferably to the direction of the air flow, for removing and/or recovering the liquid. The liquid may be conveyed to a target, such as a tank, a sump or other container, and it may be transferred to another target or it may be also treated, for example chemicals and/or water may be recovered from the liquid. Especially liquid condensing before the air pump may be collected in this way. Liquid condensing after a pump may end up in a device for recovering chemicals, and further to the aqueous liquid containing the chemical(s), such as ammonia.

In one embodiment the aeration floor comprises one or more hollow core slab(s), such as shown in Figure 1, preferably one or more concrete hollow core slab(s). Hollow core slabs, such as concrete hollow core slabs, may be provided as ready-made elements, which may be easily installed to construct the aeration floor. Concrete hollow core slabs, preferably enforced concrete hollow core slabs, or other hollow core slabs made of solid, stiff and durable material enable the use of heavy machinery on the floor or using the floor as a floor of a livestock shed.

Figure 3 shows an example of the composting system in a building or in a container 24. An outlet of the aeration floor 10 is connected to an inlet of an air pump 20 arranged to lead fresh air 26 from the surface through the one or more aperture(s) 18 to the one or more cavities 12 in the aeration floor to provide negative aeration. The “air pump” as used herein refers to a device, which may be also called an air distributor or air handling means, arranged to provide air flow, for example air intake, from the surface through the one or more aperture(s) to the one or more cavities. The air pump is preferably located at the exhaust air side of the compostable material, for example in the aeration floor or after the aeration floor, so that a suction of air is provided to the compost. The air pump contains an inlet for the incoming air, and an outlet for outgoing air. The device may provide negative pressure to the compost or to the cavities. The system may comprise one or more air pumps. More than one air pumps may enable even distribution of the air flow and/or accurate control of the aeration for example in cases wherein the conditions are different at the different locations of the air floor and/or the compost. Such a device may comprise for example an air compressor, a fan, or other arrangements to provide air flow or negative pressure. The air pump may be connected to a control unit configured to control the air pump, for example to adjust the speed of the air flow, or to switch the air pump on and off, or in case of more than one air pumps to control the individual air pumps separately, for example to obtain a desired air flow at a desired location of the compost. The air led from the surface through the one or more aperture(s) to the one or more cavities is further lead to one or more device(s) to recover heat 22 and/or chemical(s) 28 from the air. The device(s) may be located in the floor structure, or they may be located outside the floor structure, as shown in Figure 3, for example in a separate device unit or more than one device units 22, 28. The devices may be chained with each other, as shown in Figure 3. Flowever, one or more device(s) may also branch from the arrangement. The devices may be connected to the aeration floor via tubing, which may be insulated. The order of the devices may be as shown in Figure 3, or it may be different. In general an outlet of a device is connected to an inlet of a next device in the chain, preferably inlets and outlets for air. Finally the air which has passed through the devices arranged to recover heat and/or chemical(s) is outputted from an output 30, which is generally in the last device in the chain. The outputted air is cooled and/or it has lowered chemical content, and it may be further utilized. For example it may have a lowered odour content or a content of corrosive chemicals compared to the air outputted from the compost. The connections in and between the aeration floor, the devices, the tubing or any other parts or components of the system are sealably and preferably removably connected to each other. The used materials should tolerate ammonia. For example the tubes may be plastic or metal tubes, and the metal parts may be steel, such as stainless, corrosion-resisting or coated steel.

In one embodiment the composting system comprises a device arranged to recover heat from the air, wherefrom the air is arranged to be conducted into a device arranged to recover one or more chemical(s) from the air. In one embodiment the composting system comprises a device arranged to recover heat from the air, wherefrom the air is arranged to be conducted into a device arranged to recover ammonia from the air. Therefore the air is first cooled before it is conducted to a device arranged to recover one or more chemical(s) from the air. The recovery of the chemicals, such as ammonia, may be more efficient at lower temperatures compared to higher temperatures, so this arrangement may enhance the chemical recovery from the air. Further, the cooled air will cool also the system, such as the cavities, body of the floor, tubing, the devices attached to the system and the like, and this will decrease the risk of corrosion of the system or the parts of the system. For example if the device arranged to recover heat from the air is located at the cavities or tubing connected to device arranged to recover heat from the air are integrated into the body of the aeration floor, a larger part of the system is cooled compared to a situation wherein the device arranged to recover heat from the air is located apart from the aeration floor.

In one embodiment the device arranged to recover heat 22 from the air comprises one or more heat exchanger(s) 23, preferably air-to-liquid heat exchanger, for example air-to-water heat exchanger. The device arranged to recover heat contains an inlet for the incoming air, and an outlet for outgoing air, and preferably an outlet for condensed water, as most probably at least some of the water vapour will be condensed into water in the device. A heat exchanger refers to a device which maybe used to transfer heat between one or more fluids. The fluids may refer to phases of matter including gas and liquid. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. One example of a heat exchanger is a shell and tube heat exchanger, which contains a series of tubes. Another example of a heat exchanger is a plate heat exchanger. These exchangers comprise many thin, slightly separated plates that have very large surface areas and small fluid flow passages for heat transfer. The heat exchanger may be located in the cavity or it may be outside the aeration floor. The heat is outputted from the device 22 from an heat outlet 32, for example in liquid or in gas, such as air. The heat may be transferred to and utilized in a target.

The amount of the water vapour which is formed in the composting process is very high. One type of heat exchanger utilizes water vapour in a device wherein the incoming air is subjected to pressure in a pressure container. The vapour will be condensed into liquid and it releases heat in the phase transition. This may be carried out in a pressure container having heat conducting structure, such as a metal container with metal walls, and wherein the pressure container has a heat exchanger on the outer surface for receiving the released heat. Such as device includes means for producing pressure to the container, such as a compressor.

In one embodiment the aeration floor body comprises separate tubing for liquid circulation for recovering heat, such as tubing integrated into the body or tubing installed into the cavities. The tubing may be inside the body, but not in the cavities, for example in case of concrete slabs, the tubing may be at least partly moulded in the concrete. Tubing integrated to the material of the body enables good transfer of heat from the compost to the liquid circulating in the tubing and therefore efficient cooling is obtained already in the body of the floor. In another example the tubing is installed inside the cavities, such as inside the tube-shaped cavities of a hollow core slab, for example attached to a surface of a cavity. Such construction facilitates the maintenance of the system. The tubing may be a part of a heat exchanger. The tubing may be made of metal to enhance the transfer of heat, such as copper, steel, aluminium or the like. The tubing may also contain plastic tubes, which are inexpensive and easy to install, and the limited heat transfer capacity thereof is compensated by using slower liquid flow speed and/or by using a larger amount of tubes. The liquid circulating in the tubing may be aqueous liquid, such as water, or it may be or contain organic liquid, such as methanol, ethanol, glycol or the like. The tubing is connected to a device for recovering heat, such as a heat exchanger, thereby forming a heat recover circuit. In the circulating systems described herein there may be one or more separate pump(s) for providing a flow of the liquid in the system, more particularly in the tubing, which pump(s) may be controllable, for example the speed of the flow may be adjusted as a response to measurements from the system, such as temperature in one or more locations in the tubing and/or in the body of the floor.

The air which is lead through the compost contains a variety of chemicals released from the composting process. The chemicals originate mainly from aerobic reactions, but also anaerobic reactions may occur. These chemicals include ammonia, methane, volatile organic compounds (VOC), such as alcohols, ketones, terpenes and aldehydes. In one embodiment the composting system comprises one or more device(s) 28 arranged to recover one or more chemical(s) from the air. The device arranged to recover one or more chemical(s) contains an inlet for the incoming air, and an outlet 32 for outgoing air. The device also contains one or more outlet(s) 30 for the one or more recovered chemical(s). The chemicals may be transferred to and/or utilized in a target.

Ammonia recovery is beneficial for many reasons. The nitrogen present in the ammonia is a very valuable nutrient which may be used in the agriculture. It is advantageous to recover this nitrogen as ammonia, wherefrom it is easily available for plants. On the contrary the nitrogen present in the manure will be released usually at the wrong time when applied to the fields of the like targets as such, and therefore most of such nitrogen is not available to the plants. The recovered and concentrated ammonia from the composting system is in a form which can be stored, transported and applied to the target easily. In general manure may contain about 2-4.5% by dry weight of total nitrogen. The fresh compostable organic material may contain about 15 kg of ammonia per 1000 kg of the organic material.

In one embodiment the device arranged to recover one or more chemical(s) from the air comprises one or more device(s) arranged to recover ammonia from the air. The ammonia recovery may be implemented in several ways. The ammonia may be also recovered from condensed water, such as water condensed in the device arranged to recover heat, such as a heat exchanger, or from water condensed elsewhere in the system. In general condensed water from one or more locations or outlets of the composting system or the devices may be conveyed to one location, combined and recovered. In one example the device arranged to recover one or more chemical(s) from the air comprises one or more device(s) arranged to recover ammonia from the water condensed in the system, such as from the water condensed in a device arranged to recover heat. The water may be further controllably conveyed to the compostable material.

In one embodiment the device arranged to recover ammonia from the air comprises a device arranged to extract the ammonia to water and/or to acid. In one example this alkaline gas component is separated by means of a chemical scrubbing process with acid, such as sulphuric acid, to obtain a liquid, such as aqueous ammonia. Also organic acids may be used, such as formic acid or acetic acid. Aqueous ammonia, which is also known as ammonium hydroxide, ammonia water, ammonical liquor, ammonia liquor, aqua ammonia, ammonia solution, or simply ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Ammonia has water solubility of 33.1% at 20°C, and in general ammonia may have a concentration of up to about 26-30% (w/w) in water at ambient conditions, in practice liquid having ammonia content for example in the range of 5-25% (w/w), or 10-25% (w/w), or 10-20% (w/w) may be obtained. The solubility of ammonia in water increases as the temperature lowers, so it is advantageous to cool the air or the liquid when recovering the ammonia. In one example the temperature of the water or other aqueous liquid used for recovering the ammonia is below 20°C, or below 10°C, or even below 0°C as the freezing point of aqueous ammonia lower when the ammonia content rises. It may be possible to use temperatures even about -10°C, for example temperatures in the range of-10-15°C, -10-10°C, -10-0°C, -5-15°C, -5-10°C, or -5-5°C, 0-15°C, 0-10°C, or 0-5°C. In one example the temperature of the compost is adjusted to a such temperature range, for example by using outside air, for example when a compost is run during wintertime wherein the outside temperature may be below 0°C.

If air is conveyed to sulphate-saturated solution containing an amount of sulphuric acid, such as 2-4%, the ammonia will be crystallized as ammonium sulphate and precipitated on the bottom of a container, and can be therefore recovered as solid. As the sulphate is consumed, more sulphuric acid may be added to the solution.

Ammonia may be stripped from gases with steam. Stripping with steam enables concentrating the gases in a subsequent distillation column. This process is energy intensive but operates without residuals. The economically usable end product is ammonia water, which typically contains about 20% NH3. With air stripping, the ammonia-containing gases can be discharged either by combustion or by absorption with an acid scrubbing process. In the scrubber stage ammonia is absorbed by sulfuric acid. The end product is a concentrated salt solution which is may be used as liquid fertilizer.

In one embodiment the device arranged to recover ammonia from the air comprises a device arranged to increase pressure and lower temperature to condense the ammonia from the air. In one example the air is pumped to a heat-insulated pressure container, wherein the air may be pressurized, for example to at least 5 bar, such as to about 10 bar, to condense the water vapour and gaseous ammonia present in the air into liquid. The volume of the container may be for in the range of 0.5-1 m3 for example when the air flow is about 60 m3 per hour. The condensing releases energy, which may be detected as temperature rise of the air. Further, the pumping of the air also rises the temperature of the pressurised air. A heat exchanger connected to the pressure container, for example in a casing of the container or inside the container, is arranged to transfer the heat to circulating liquid, which may be conveyed to another location and recovered there. The temperature of the pressure container will lower to a desired range, such as into a range of 5-20°C, or to another range disclosed in previous. A liquid fraction will be formed in the container containing water and ammonia. The gas phase contains for example N2 and CO2, but not much oxygen as the oxygen has been consumed in the composting process. The aqueous ammonia may be released from the container via an outlet and recovered, for example is may be conveyed into a storage tank. After the liquid has been removed, also the cooled air may be released. This process may be carried out as a batch process. The container contains an inlet for the air, and an outlet for the liquid and optionally an outlet for the air, and a device for recovering heat, such as the heat exchanger, and actuators for operating the inlets and outlets, as well as means for adjusting the pressure, such as a pump or the like. The container may also contain one or more sensor(s) for detecting temperature, pressure, and the like, connected to a controlling means arranged to monitor the detected quantities and arranged to carry out adjusting means for maintaining desired values, said adjusting means including operating the actuators and the pump and any other required means for controlling and/or adjusting the system.

In one embodiment composting system further comprises one or more sensor(s) located in the aeration floor or in the tubing, at one or more locations, arranged to monitor one or more of temperature, humidity, oxygen content, pH, flow speed of air, flow speed of liquid, and chemical content, such as ammonia content, which sensor(s) is/are connected to a device for receiving the monitored data and arranged to control the aeration, the recovery of the heat, or the recovery of one or more chemical(s) as a response to the monitored data. Such device may be called as a control device or a control unit. The control device may contain one or more control unit(s) arranged to monitor the sensed data and to carry out any controlling actions in a predetermined manner, for example as programmed. A control unit may include one or more processors, memory, user interface, display, keyboard, power connection, one or more physical connectors for connecting to external computerized devices, and/or optionally network connection, such as wired or wireless connection. The control unit contains a software configured to carry out the controlling actions, such as to control the devices connected to the control device. The control device may be connected to means for controlling the aeration, such as the air pump(s), to the device(s) arranged to recover the heat, the device(s) arranged to recover one or more chemical(s), or to any other actuators, valves, pumps or the like, and arranged to control one or more of these devices to control the aeration, the recovery of the heat, or the recovery of one or more chemical(s) or combinations thereof, or any other parameter which may be controlled by the system. The control device may be arranged to control the devices as a feedback to one or more detected and measured value(s) to maintain the temperature, humidity, oxygen content, pH, flow speed of air, flow speed of liquid, or chemical content at a desired level, such as at a predetermined range. The control unit(s), device(s), sensor(s) and other electronic components are connected by wiring or they may be wirelessly connected. The system is connected to a power source, such as a to power network, to provide power for the electronics, actuators, pumps or the like devices and components.

In one embodiment the composting system comprises compostable organic material 34 on the aeration floor 10, i.e. a compost. The compostable organic material may be applied onto the aeration floor and/or it may be formed onto it for example in a case wherein livestock are present on the floor, i.e. the aeration floor is a floor of a livestock shed, house, accommodation or the like building. It may be also a similar building, such as a house or shed, without the animals.

The composting system may be installed in a building or in a container or a vessel, in general to a closed or covered place, as shown in an example of Figure 3. The building or the container may contain one or more walls around the compost, and it may be fully or partly insulated to maintain the heat inside the building or the container. However, even if the building or the container forms a closed room, it should not be air-sealed because the active aeration requires fresh air entering the system. Therefore the building or the container contains usually at least one opening or air conduit to the outside air, such as a valve or open window, door, opening or even an open wall, for example as in a livestock shed. In one example the composting system is installed onto a transport platform, which enables easily transportable system. The area of the aeration floor may be in the range of 4-20 m2 when a container or a transport platform area used. However, in other types of composting systems, such as ones in a building or at open area, the area of the aeration floor may be in the range of 40-1000 m2 or even more.

One embodiment provides a livestock shed comprising the composting system described herein. The livestock shed 24 comprises one or more walls and preferably a roof. The livestock shed may contain a floor below the aeration floor 10, or the aeration floor 10 may be installed onto ground. In case of livestock shed, which may be also called as cattle shed, cowshed, animal shed or the like, the animals may live in the shed, continuously or part-timely. The animals or the cattle may include cows, sheeps, horses, pigs, poultry and the like. As the animals live and saunter on the aeration floor, it is important that the floor is solid. For example hollow core slabs, such as concrete hollow core slabs, are suitable for livestock shed. The animals produce manure, more particularly feces, continuously onto the floor, so it is important that the floor may be maintained from time to time, such as at least once a year, for example the manure-containing composted organic material is recovered, preferably by using machinery, even heavy machinery. Also for this reason it is important that the aeration floor carrying the compostable material, the animals and the maintenance machinery is solid and durable. Further, as the machinery is used to grab or push the organic material on or from the aeration floor, for example by using bucker charger, bulldozer blade or the like, it is also important that the upper surface of the floor is flat and planar and does not contain any protruding parts, such as tubes, nozzles, vent pipes or the like. The composting system in a livestock shed or the like place wherein living animals live on the compostable material, is very challenging as the animals tamp the material into a compact form, and thereby the air permeability decreases. The active aeration and the air permeable material under the compostable material help maintaining the aerobic conditions in such environment. For this reason it is also important that the compostable material can be easily recovered from the floor.

One example provides a container comprising the composting system described herein. The container may be for example a freight container or a shipping container type of container, or the like portable container, which may be transferred to a desired location and operated there. In some examples a container has dimensions of about 2.0 x 2.0 x 1.9 meters, about 2.4 x 2.2 x 2.3 meters, about 6.0 x 2.0 x 1.5 meters, about 6.0 x 2.5 x 2.5 meters, or about 12.0 x 2.5 x 2.5 meters, or the size of a container may be expressed as feet, such as 6’, 8’, 10’, 15’, 20’ or 40’. The volume of a container may be for example in the range of 2-100 m3, such as 8-75 m3, 8-40 m3 or 10-20 m3. For example the container may be moved to a location wherein the recovered heat and/or chemicals are needed, for example near a building needing heat or near an agricultural location needing the required chemical(s) or wherein the compostable material is available. The container may contain the required devices inside the container or the devices may be outside the container. The container may be equipped with an electrical inlet connector for connecting to electric power network. The aeration floor is inside the container, for example above or on the actual floor of the container. The container may contain one or more aeration floors, for example two or more aeration floors on top of each other and at a distance from each other, wherein the compostable material is applied on each floor surface. This enables utilizing the whole volume of the container while keeping the thickness of the compostable material on each floor at reasonable range to enable unrestricted air flow through the organic material. For example the two or more aeration floors may be at a distance in the range of 30-100 cm from each other. The one or more floors may be movable, for example they may be placed on rails in the container to enable maintenance, such as application of the organic material and removal of the composted material. The one or more floors may be made of metal, composite material, plastic, or combinations thereof.

In one embodiment the composting system comprises a layer of aeration material 36 on the surface of the aeration floor 10 and below the compostable organic material 34, as shown in the example of Figure 3. The layer of aeration material 36 should be material which enables the air to pass though the material, such as wood chips, charcoal, porous lime-containing granules or stones, for example limestones, or ground concrete. The aeration material may be organic or inorganic or a combination thereof. This would enhance the aeration by reducing the possibility of the compostable organic material blocking or plugging the one or more aperture(s) extending through the surface. The aeration material also prevent particulate matter entering the apertures and the cavities. Preferably the aeration material is such material which has a large particle size or is present as agglomerates, such as particles or agglomerates having an mean average diameter for example in the range of 1-20 cm, or 1-10 cm, for example 2-20 cm, 2-10 cm, 5-15 cm or 5-20 cm. The aeration material is also preferably such material which may be applied together with the composted material to further use or target, such as to fields, wherein the aeration material may act as a soil conditioner or at least does not have an adverse effect to the use of the composted material. The thickness of the layer of the aeration material in the compost may be for example in the range of 5-30 cm, such as 10-30 cm, 10-20 cm, 5-20 cm, 5-15 cm or 5-10 cm. The aeration material may be also compostable, such as plant-based material, which is advantageous for example in cases the material from the aeration floor is transferred to a field, garden, tree nursery or other agricultural target. The aeration material as described herein may be different from the bedding material described in previous, but in some cases it may contain same or similar material. Flowever, preferably the aeration material is different from the bedding material. Unlike the bedding material, the aeration material is not mixed with the compostable organic material. The aeration material may be material which absorbs liquid, for example urine, the therefore prevents blocking of the compost or even prevents the liquid entering the cavities. The aeration material may be porous material, such as porous rock or mineral material, porous concrete pieces or the like.

The composting system described herein may be used in methods wherein the heat and/or chemicals are recovered from the composting process and further transferred or lead to suitable target(s) or applications.

One embodiment provides a method for recovering heat from a compost, the method comprising -providing compostable organic material -providing the composting system comprising the compostable organic material, -negatively aerating the compost to obtain air from the compostable organic material, and -recovering heat from the air with the device arranged to recover heat from the air.

One embodiment provides a method for recovering one or more chemical(s) from a compost, the method comprising -providing compostable organic material -providing the composting system comprising the compostable organic material, -negatively aerating the compost to obtain air from the compostable organic material, and -recovering one or more chemical(s) from the air with the device arranged to recover one or more chemical(s) from the air.

One embodiment provides a method for recovering heat and/or one or more chemical(s) from a compost, the method comprising -providing compostable organic material -providing the composting system comprising the compostable organic material, -negatively aerating the compost to obtain air from the compostable organic material, -recovering heat from the air with the device arranged to recover heat from the air, and/or -recovering one or more chemical(s) from the air with the device arranged to recover one or more chemical(s) from the air.

The compostable organic material of the embodiments may be any material described herein. In general the compostable organic material is provided onto the aeration floor of the composting system.

In one embodiment the method comprises recovering heat and one or more chemical(s) from the air. In one embodiment the method comprises first recovering heat from the air with the device arranged to recover heat from the air and then recovering one or more chemical(s) from the air with the device arranged to recover one or more chemical(s) from the air. In one embodiment the method comprises first recovering heat from the air with the device arranged to recover heat from the air and then recovering ammonia from the air with the device arranged to recover ammonia from the air. In one example the method comprises first recovering one or more chemical(s) from the air with the device arranged to recover one or more chemical(s) from the air and then recovering heat from the air with the device arranged to recover heat from the air.

In some embodiments said methods comprise leading the recovered heat to a heating system of a building, such as the animal shed wherein the composting system in installed, or to other suitable target, such as other heating system. In one example the heat is used for adjusting the temperature of the compost to a desired range, such as to 30-70°C. 40-70°C, 50-70°C, 60-70°C or 65-70°C, as an action of controlling the compost.

The recovered one or more chemical(s) may be stored, for example in a storage tank or a container, such as a container for transportation. In some embodiments said methods comprise leading the recovered one or more chemical(s), such as ammonia, for example from a container or directly from the composting system, to agricultural land, to garden or the like. The chemical(s) may be provided as an aqueous solution to the target, for example in the case of ammonia it may be provided as aqueous ammonia. The chemicals may be also absorbed to a solid material, for example to the obtained compost product or to another material.

In one example a composting system for a container or for a transport platform is constructed by first heat insulating the container or platform and building an aeration floor with perforated upper elements which tolerated the weight of the intended biomass. A water-circulating heat recovery system is built under the floor and slopes for recovering liquid are arranged to a lower floor or to a platform under the perforated floor element. Suction air tubes are installed leading outside the container or the platform and connected to a device unit containing first a heat exchanger and then an air pump, or alternatively vice versa. The aeration speed depends on the size and power of the composting system, on the amount of the biomass, on composting speed and on operating efficiency. In an optimal case the amount of air used is about 1200 m3 per ton of biomass after all the biomass has been composted. When using a 12 m2 container containing up to 12 tons on biomass the required air intake may be about 10 m3 per hour, i.e. about 166 I/ min, but to enable the system to be controlled, there should be in general a range of variation of 2-30 m3 per hour. The air obtained from the system is conveyed to ammonia recovery by an aqueous solution containing sulphate, acid or both. In a solution saturated enough the ammonia is recovered. Cold water is introduced to the heat exchanger, wherein the water is heated.

In one example a composting system is built into an animal shed. A foundation bed is prepared onto ground by sand and gravel and by preparing underdrains. Concrete hollow slabs are placed onto the foundation and punched to obtain aeration apertures. A surface concrete layer is poured onto the slabs and perforated. The shed or the like building is built to cover the aeration floor, and the walls are heat insulated. Also the ground below the floor may be insulated if necessary. Any tubes, devices and other related parts outside the floor or the shed or building are insulated, and the devices may be placed into a separate insulated closet or cabinet located outside the building.

Water-circulating 22 mm plastic tubes are installed into the cavities of the hollow slabs, which tubes are connected to one or more heat exchangers outside the shed or directly to a heating system of the shed or another building. An air pump creates a vacuum into the cavities sucking air evenly through the biomass via the apertures in the floor. The air obtained from the system is conveyed by 100 mm heat-insulated tubes to one or more heat exchangers and to recovery of ammonia in a solution. A layer of coarse wood chips of about 10 cm is applied onto the aeration floor. On this layer an initial manure layer or a layer of other organic material, such as bedding, may be applied, and the layer(s) is/are dried for the animals. The animals are brought into the shed. After there is enough biomass so that the composting begins, the air pump is started. The composting may take from one month to one year, for example. The optimal aeration depends on the composition of the biomass and the desired objectives. The composting of each biomass ton requires about 1200 m3 of air. If the initial amount of the compostable material on the area is about 1 meter, the required total aeration air amount grows in relation to the area and inversely to the processing time. For example with a composting area of 1000 m2 about 60 m3 of air per hour would be needed.

Claims

A livestock enclosure comprising a composting system comprising an aeration floor (10) for receiving compostable material (34), the aeration floor being a livestock enclosure floor comprising: - a flat surface (14) and one or more openings (16) extending therethrough, wherein the composting system further comprises an air pump (20) arranged to conduct air from the surface (14) through said one or more openings (16) to provide negative aeration, and - a device (22) arranged to recover heat from the air (32), and / or - a device (28) arranged to recover one or more chemicals (30) from the air.

The livestock shelter according to claim 1, wherein the aeration floor comprises a body, wherein within the body (10) is one or more cavities (12) connected to said one or more openings.

The livestock shelter according to claim 2, wherein the aeration floor comprises one or more hollow core slabs, preferably one or more concrete hollow core slabs.

The livestock shelter according to any one of the preceding claims, wherein the composting system comprises a device (22) arranged to recover heat from the air and from which the air is arranged to be fed to a device (28) arranged to recover one or more chemicals (30). .

The livestock shelter according to any one of the preceding claims, wherein the device (22) for recovering heat from the air comprises one or more heat exchangers (23).

The livestock shelter according to any one of the preceding claims, wherein the aeration floor frame comprises a separate fluid circulation conduit for heat recovery, such as a conduit integrated into the housing or cavity mounted conduit.

The livestock shelter of any one of the preceding claims, wherein the device (28) for recovering one or more chemicals (30) from the air comprises one or more devices arranged to recover ammonia from the air.

The livestock shelter of claim 7, wherein the device for recovering ammonia from the air comprises a device arranged to extract the ammonia into water or an acid.

The livestock shelter of claim 7, wherein the device for recovering ammonia from the air comprises a device arranged to increase the pressure and lower the temperature to liquefy the ammonia from the air.

The livestock shelter according to any one of the preceding claims, comprising: - one or more sensors disposed on the aeration floor and arranged to monitor one or more of: temperature, air humidity, oxygen content, pH, air flow rate, liquid flow rate and ammonia concentration, and connected to a control data receiving device arranged to control aeration, heat recovery, and / or one or more chemicals in response to the control data.

The livestock shelter according to any one of the preceding claims, wherein the aeration floor has compostable organic material (34).

The livestock shelter according to any one of the preceding claims, wherein the aeration floor (10) and below the compostable organic material (34) is a layer of aeration material (36), such as chips, charcoal, porous lime granules or rocks, or ground concrete, e.g. n floor.

A method of recovering heat and / or one or more chemicals from compost in a livestock shelter, comprising: - providing an livestock shelter comprising a composting system according to any one of claims 1 to 12 comprising organic compostable material; manure as compostable organic material (34), - degreasing the compost thus formed to obtain air from the compostable organic material, - recovering heat from the air by means of a device (22) arranged to recover heat from the air (32), and / or a plurality of chemicals by means of a device (28) arranged to recover one or more chemicals (30) from the air.

The method of claim 13, wherein first heat is recovered from the air by means of a device arranged to recover heat from the air, and then one or more chemicals are recovered from the air by a device arranged to recover one or more chemicals, preferably ammonia.

The method of any one of claims 13 to 14, wherein said recovered heat is introduced into a building heating system and / or said one or more recovered chemicals, such as ammonia, are applied to the cultivated land.