WO2000026159A1

WO2000026159A1 - Method and system of apparatus for processing dung, especially poultry dung

Info

Publication number: WO2000026159A1
Application number: PCT/NL1999/000672
Authority: WO
Inventors: Hendrikus Johannes Josephus Te Wierik
Original assignee: WIERKO RAALTE BV
Current assignee: WIERKO RAALTE BV
Priority date: 1998-11-02
Filing date: 1999-11-02
Publication date: 2000-05-11
Anticipated expiration: 2001-05-02
Also published as: EP1149062A1; NL1010441C2; AU1189200A

Abstract

The invention relates to a method for processing dung, in particular poultry dung, comprising the following steps of: periodically removing wet dung from an animal accommodation, for instance a poultry house, and causing the dung to dry in predetermined conditions outside the animal accommodation.

Description

METHOD AND SYSTEM OF APPARATUS FOR PROCESSING DUNG, ESPECIALLY POULTRY DUNG

The present invention relates to a method and system of apparatus for processing dung, in particular the processing to compost of cattle, pig, poultry and dung of said animal species in solid and liquid form (slurry) .

Composting is understood to mean the process wherein using micro-organisms one or more organic waste products is degraded and converted into a stable end product such that only slow degradation of humous compounds still takes place therein.

The accumulation of dung is a great problem. The disposal or processing of this dung is very expensive and often even more expensive than keeping the animals themselves . An object of the present invention is to provide a method which provides a solution for the above stated problem.

According to a first aspect of the present invention a method is provided for processing dung, in particular poultry dung, to compost, comprising the following steps of:

- periodically removing wet dung from an animal accommodation, for instance a poultry house, and

- causing the dung to dry in predetermined conditions outside the animal accommodation.

Since in the present invention wet chicken dung is removed from the chicken accommodation before being dried, the problem of ammonia emission, house climate and possible infections is considerably reduced compared with houses in which wet dung is also dried. The present invention further provides the following advantages:

- substantially no investment for drying in the house (belt drying and feed composition) ;

- less disease due to a better climate and less use of medication (assumption) ; - lower feed consumption than in a house with belt drying as a consequence of higher house temperature

(24 °C) - per °C it is necessary to make 1.5 gram/animal/ day extra feed available at a cost price of Nfl. 40.-/100 kg feed;

- substantially no uncertainty in respect of result related to season.

The wet dung is preferably transported to a dung processing area which comprises - one or more composting spaces, and

- dung transporting means.

The method preferably comprises the further steps of

- mixing this dung in a predetermined ratio with a structure-improving agent for increasing the pore volume of the dung for processing, and

- causing this mixture to compost for a predetermined time period under composting conditions in order to obtain compost . Further according to the present invention a usable product is provided, i.e. compost, which provides an economic advantage .

Further features of the present invention can be found in claims 4-12. According to a second aspect of the present invention compost is provided which is obtainable by means of the method according to the present invention.

With the method and system of apparatus a product (dung powder = composted dung) is created which through a further processing (pressing and crumbing) has a determined structure (granules of a determined diameter and length or crumb resulting from breaking of the granule in a crumbing device) and also a more or less fixed composition, as long as the dung is from a particular animal type, (in particular laying hens, broiler chickens or mother animals where poultry is concerned) . Through the addition of for instance nitrogen, phosphate or potassium the product can take the same form with a different fixed composition.

Mixtures of all types of dung in all compositions are possible, wherein however account must be taken of the composition (N:P:P) required in the product by the user and the fact that for diverse reasons particular users absolutely do not want the dung of determined animal species. This is clarified by the legally required name which must be given to such products.

According to a third aspect of the present invention a system of apparatus is provided for performing the method according to the present invention. According to a further aspect of the present invention a chicken farm is provided which comprises such a system of apparatus .

The present invention will be further elucidated with reference to the following description, examples, figures and tables, wherein the tables show inter alia results of analysis of the compost obtained via the present invention.

Figure 1 shows a flow diagram of a system of apparatus according to the present invention.

Figure 2 shows a schematic view of a composting tunnel according to the present invention.

Figure 3 shows a flow diagram of the production process according to the present invention.

1. Method

1.1 Composting (see figure 1, table 6 and table 7)

The supplied solid dung is stored in a trench silo (SI) ; the supplied liquid dung is stored in a weighing tank with stirrer (01) ; the sieved structure- improving agent is stored in a trench silo (S7) ; the supplied fresh structure-improving agent is stored in a trench silo (S2) . The mixer (03) is filled by means of a power shovel (A) with a determined quantity of solid dung from trench silo (SI) , a determined quantity of sieved structure-improving agent from trench silo (S7) and fresh structure-improving agent (wood chippings, straw, wood fibre, hemp, plastic shapes) from trench silo (S2) as far as is necessary for filling purposes. Also added are a determined quantity of liquid dung from a tank (01) and a determined quantity of ammonium sulphate solution from a tank (04) . The mixing ratio depends on the structure, the C/N ratio and the dry substance content of the products for processing.

The mixture from the mixer (03) is then deposited by means of a conveyor screw (05) onto a conveyor belt (06) , whereafter it drops onto a mobile conveyor belt (08) above the spreader (09) . On this conveyor belt above spreader (09) an agent for improving the composting process is optionally added to the mixture. This conveyor belt (08) is horizontally movable and fills spreader (09) at the correct level in order to provide a good distribution of the mixture in spreader (09) . This level is reached by applying a back-pressure on the mixture using a counterweight (kg) . From this belt (08) the mixture drops onto the under-chain of spreader (09) with rotating rollers. The mixture is transported by the under-chain into spreader (09) , whereafter it is broken up by the rollers. Due to its flexibility the sheet behind spreader (09) provides a smooth through-flow of the mixture (no accumulation) . Via conveyor belts (06) and (10) the mixture passes to a "walker" (11) (mobile conveyor belt) .

The mixture is then distributed evenly by a distributing disc (12) into one of the composting tunnels (T1-T5) over a width of a maximum of 5 metres (width of the tunnels) . The distributing disc (12) (a profiled round disc, of which the rotation speed, the rotation direction and the length and position of the pins can be adjusted) , lies at the end of the belt (11) , which moves in and out of the tunnels (T1-T5) . The mixture is composted under adjusted conditions (computer- controlled) . Once the mixture has composted sufficiently it is removed from the tunnels with a power shovel (B) and taken to a trench silo (S3-S6) for temporary storage.

1.2 Further drying of powder

The composted mixture (a mixture of dung and structure-improving agent with a dry substance content of between 60 and 70%) is taken out of a trench silo (S3-S6) with a power shovel (B) and tipped into a bunker (13) . From this bunker the composted mixture passes via conveyor screws (14) and an elevator (15) to a drum sieve (16) . The structure-improving agent is separated from the composted dung and drops into a trench silo (S7) . Via an elevator (19) , conveyor belts (18) , a mass conveyor (20) and a walker (21) with a distributing disc (22) the composted dung is carried into the drying bunker (23) for drying. The distributing disc ensures distribution over a width of a maximum of 2.5 m (width of the drying bunker) . After drying the dried composted dung travels via a conveyor belt in drying bunker (23) to a sieve (25) , which sieves therefrom the remnants of structure- improving agent. The further sieved composted dung then travels via an elevator (19) and a mass conveyor (20) to an internal transporting means (e.g. a tractor with tipper) , which can be loaded in dust-free manner using a loading bellows (26) (optionally to the pressing area) .

1.3 Further drying of granules

The further sieved composted dung (powder) can be pressed to granules . These granules are poured into a bunker (28) and pass by means of a conveyor screw (29) and an elevator (30) to a belt dryer (31) where the granules are dried. After drying the granules are loaded in dust-free manner via a mass conveyor (32) , an elevator (33) , a mass conveyor (32) and a loading bellows (34) for delivery (optionally for sacking) . 1 . 4 Airf low

Fresh air is drawn by a fan (36) through the heat exchanger (35) . Heat transfer takes place in heat exchanger (35) whereby the airflow (LI) is heated. This airflow (LI) is transported by fan (36) via an air duct and air valve (37) to the belt dryers (31) , drying bunker (23) and tunnels (T1-T5) .

The airflow (L2) from the drying bunker (23) passes through an air valve (38) and then through a filter (39) , where dust is removed from the airflow. The airflow (L3) from the belt dryers goes through an air valve (38) and is merged with the airflow (L2) . This mixed airflow (L2-L3) is then supplied to the composting tunnels (T1-T5) through an air valve (41) . Composting tunnels (T1-T5) are provided in each case with a fan (45) for aerating the mixture in the tunnels with an airflow (LI or L2-L3) through perforated air ducts (46) in the floor of the tunnels (T1-T5) . Composting tunnels (T1-T5) have in each case an outlet (47) through which the airflow (L4) comes out onto an air duct. The remainder of the airflow (L2-L3) which is not taken up in the tunnels goes through an overpressure-relief valve (40) and is merged with the airflow (L4) . The mixed airflow (L2-L3- L4) , which contains the ammonia, is drawn in by a fan (48) and subsequently transported via an air duct through the heat exchanger (35) , the chemical washer (49) and the cooling block (50) to the biobeds (B1-B12)

In the heat exchanger (35) heat-exchange takes place between the airflow from the tunnels (L2-L3-L4) and the supplied fresh air (LI) . 1 . 5 Water flow

Washing water (Wl)

Washing water is a solution of mains water (55) and sulphuric acid in the chemical washer (49) . The mixed airflow (L2-L3-L4) is cleaned in chemical washer (49). The sulphuric acid binds to the ammonia from the airflow (L2-L3-L4), thus creating ammonium sulphate. The acidity and the specific gravity of the washing water hereby changes.

By once again adding the thus created solution of ammonium sulphate to the mixture (see 3.2) and causing the composting to take place in a closed space there is substantially no loss of N₂. The acidity of the washing water is kept up to level by pH measurement (54) and acid dosing (56) . The specific gravity and therefore the quality of the washing water is kept to level by a preadjusted sluice (57) (replacement of washing water) . The sluice water is transported via the sluice control washing water (57) via a conduit to the tank with ammonium sulphate solution (04) . So as to have a large buffer of this washing water with limited fluctuations in the composition, a buffer tank of washing water (58) is connected to the supply of washing water in the chemical washer (49) .

Condensation water (W2)

Condensation water results from warm airflow (L2-L3-L4) with a high relative humidity passing through a cooling block (50), whereby the water vapour condenses. This water is collected and runs to a tank (59) in a lower position.

Percolation water (W3) Percolation water results from relatively warm airflow (L2-L3-L4) with a high relative humidity cooling in the biofilters (B1-B12) , whereby the water vapour condenses. This water is collected and runs to the tank (59) in a lower position.

Condensation and percolation water (W2-3) This is a mixture of condensation and percolation water, which is made suitable as cooling water by means of additives and aeration. The water from the tank (59) is pumped by means of a pomp (60) to the tanks (62) for purification. During the pumping an agent for biological purification is added in the tanks (62) by means of a dosing device (61) . Aeration of the water takes place here by means of a blower (69) . The water remains there for 24 hours, whereafter it is used as cooling water. It is transported by means of a pump (68) to the supply tank of the cooling tower (64) to supplement the supply of cooling water caused by evaporation through the cooling tower.

Rainwater (W4) Rainwater is collected and runs via a sieving bend (66) to a tank (67) .

Mains water (W5)

When the water in the tank (67) falls below a determined level the supply is supplemented with mains water (W5) to a minimal supply, for instance for 24 hours .

Rainwater and Mains water (W4-5) This is a mixture of rainwater and mains water, which is made suitable as cooling water by means of additives and aeration. When the water in the tank (62) falls below a determined level, the supply is supplemented with rainwater and mains water (W4-5) by means of a pomp (63) . Cooling water (W6)

This is biologically purified condensation and percolation water (W3-4) and/or the mixture of rainwater and mains water (W4-5) .

2. System of apparatus

2.1 Composting 0 no . apparatus function

1. Tank Storage of liquid dung

2. Pomp with dosing device Dosing of liquid dung

3. Mixer (weighing) Mixing of dung, structure- improving agent and 5 ammonium sulphate

4. Tank Storage of ammonium sulphate solution

5. Conveyor screw Transporting of mixture

6. Conveyor belt (fixed) Transporting of mixture 0 7. Tank with dosing device Storage and dosing of composting-improving products

8. Conveyor belt Transport of mixture (mobile) 25 9. Spreader (with under Breaking-up of mixture chain, rollers, sheet and overflow belt) 10. Conveyor belt Transporting of mixture (displaceable) 30 11. Walker (conveyor belt Transport and distribution mobile) of mixture 12. Distributing disc Distribution of mixture in tunnel 2.2. Further drying of powder (composted dung) (see also figure 2)

no . apparatus function 13. Filling bunker Feeding composted mixture back into system

14. Conveyor screw Transport of composted mixture

15. Elevator Transport of composted mixture

16. Drum sieve Sieving composted dung out of composted mixture

17. Conveyor belt Transport sieved-out structure-improving agent (reuse)

18. Conveyor belt Transport of composted dung

19. Elevator Transport of composted dung

20. Mass conveyor Transport of composted dung 21. Walker Transport and distribution of composted dung

22. Distributing disc Distribution of composted dung in drying bunker

23. Drying bunker with Storage and drying of comconveyor belt posted dung and transport

24. Conveyor screw Transport of dried composted dung

25. Sieve Further sieving of dried composted dung 26. Loading bellows Dust-free loading of a transporting means with further sieved dried composted dung

27. Conveyor belt Transport of materials sieved out of the dried composted dung 2.3 Further drying of granules

no . apparatus function

28. Filling bunker Carrying granules (pressed composted dung) into the system

29. Conveyor screw Transporting of the granules

30. Elevator Transporting of the granules

31. Belt dryer Drying of the dung granules on a perforated conveyor belt

32. Mass conveyor Transporting of the dried granules

33. Elevator Transporting of the dried granules

34. Loading bellows Dust-free loading of a transporting means with dried granules

2.4 Airflow

no . apparatus function 35. Heat exchanger Transfer of heat from process air to fresh air

36. Fan Transport of air from the heat exchanger to the belt dryer and the drying bunker 37. Air valve Closing valve air supply

38. Air valve Closing valve air discharge

39. Filter Removing dust from air

40. Air valve Valve which opens when the air pressure becomes too high for the valve

41. Air valve Controls the supply of air from belt dryer and drying bunker to tunnel 42 . Air valve Controls the supply of air from heat exchanger to tunnel

43 . Air valve Controls the supply of fresh air to tunnel

4 . Air valve Controls the recirculation of air from the tunnel

45 . Fan Transport of air through the mixture in the tunnel 46. Perforated air duct Air distribution system in the tunnel floor

47. Air valve outlet Controls the discharge of process air

48. Fan (washer) Transport of process air 49. Chemical washer Removal of ammonia from process air

50. Cooling block Transfer of heat from process air to cooling water 51. Tank with dosing device Storage and dosing of products for treatment of the process air from the bio- filters

2.5 Water flow

no . apparatus function

52. Tank sulphuric acid Storage of sulphuric acid

53. Acid-dosing device Dosing of sulphuric acid to the washing water

54. pH-measurement/control Control of the dosing device for sulphuric acid

55. Volume control washing Maintaining level of the water quantity of washing water in the chemical washer by means of a float 56 . Recirculation pump Circulation of washing water in the chemical washer and buffer tank and discharge of sluice water 57. Sluice control Control of the quantity washing water for sluicing

58. Buffer tank washing water Supplementary store of washing water

59. Tank Storage condensation and percolation water

60. Water pump Transport of condensation and percolation water

61. Dosing device Dosing of products for treatment of the condensation and percolation water

62. Tank Storage with aeration for purifying condensation and percolation water with additives to form cooling water

63. Water pump Transport of rainwater and mains water

64. Cooling tower Cooling of cooling water 65. Recirculation pump Circulation of cooling water between cooling tower and cooling block

66. Sieve bend Sieving out coarse parts from collected rainwater 67. Tank Storage with aeration and purification of rainwater and mains water to form cooling water

68. Water pump Transport of cooling water 69. Blower Aeration of water in tanks 2 . 6 Other

no . apparatus function B1-B12: biofilter Biological cleaning of process air

SI : trench silo Storage solid dung S2 : trench silo Storage fresh structure- improving agent

S3-S6: trench silo Storage of the composted mixture

S7: trench silo Storage sieved-out structure-improving agent

T1-T5: tunnel Composting of the mixture Power shovel A Means for transporting solid dung and the structure-improving agent to mixer

Power shovel B Transport of the composted mixture from the tunnel to the trench silo

3. Production process (see figure 3)

3.1 Supply Fresh poultry dung of laying hens (A) (25-30%

DS) is supplied (flow 1) . A structure-improving agent (B) (60-70% DS) is also supplied (flow 2) .

3.2 Mixing Fresh poultry dung of laying hens (A) with a dry substance content of 25-30% (flow 3) , structure- improving agent (B) with a dry substance content of 60- 70% (flow 4) , sieved-out structure-improving agent (J) with a dry substance content of 60-70% (flow 12) , composted mixture with a dry substance content of 60-70% and the solution of ammonium sulphate with a specific gravity of 1.1 (flow 5) is carried into the mixer (E) in a predetermined ratio. The mixing ratio of the mixture (38-42% DS) is dung: structure-improving agent: composted material: ammonium sulphate solution = 1:2:0.1. The ratio depends on the structure, C/N ratio and the dry substance content of the products for processing.

3.3 Filling

Before the mixture (38-42% DS) (flow 6) is carried into a tunnel (G) , it can first be sprayed (flow 7) with biological products so as to improve the composting process. The mixture (flow 7) is subsequently broken up (F) for a correct product distribution in the tunnel and a better oxygen through-flow to then obtain an aerobe bacteriological activity (oxygen consumption) . This mixture is then transported to a tunnel (flow 8) and distributed (G) . The tunnel is now filled with 400 m³ of mixture at a filling height of 3.5 tot 4.0 m. The control program for this tunnel is now at stage 1.1 "filling" (for settings see annex) .

3.4 Composting process

When the tunnel has been completely filled with a mixture (38-42% DS) , the control program is then set to stage 1.2 "heating", whereafter the mixture heats up in 8 hours (set time) from 20 °C to 70 °C. When the temperature of 70 °C has been reached and the set time has elapsed, the control program switches to stage 2.1 "pasteurizing" where the mixture is subsequently held for 8 hours (set time) at 70 °C. When this time has passed the control program switches to stage 3.1 "cooling before conditioning" where the mixture is cooled for 12 hours (set time) from 70 °C back to 65 °C.

When the temperature of 65 °C is reached, the control program switches to stage 4.1 "conditioning". In this stage the starting temperature of the mixture is 65 °C. This temperature is decreased over a period of 124 hours from 65 °C to 61 °C. During this stage the air supply (mixture of outside and tunnel air) is adjusted to 55 °C. The air supply is increased gradually over a period of 124 hours from 55 °C to 55.5 °C. During this stage oxygen minimum (14%) and maximum (22%) are set in order to cause optional response of the air valve which ensures that sufficient oxygen is supplied. Aerobe micro-organisms use oxygen to degrade organic matter. In order to supply this oxygen and to keep the temperature of the mixture as homogeneous as possible an airflow is adjusted of 6000 m³/hour, which is maintained by a (continuously regulated) fan. An airflow of 1000-2000 m³/hour leaves the tunnel at a temperature of 65 °C. The airflow (outside air) with a temperature of 16 °C and an RH of 70% which enters the tunnel will contain little water relative to the airflow (return air) with a temperature of 65 °C and an RH of 100% leaving the tunnel; water evaporation will therefore take place. Over a period of 124 hours 50,000 litres of water are evaporated (average 400 litres/hour) .

When the set time of 124 hours has elapsed and the adjusted final temperature of 61 °C has been reached, the control program switches to stage 5.1 "cooling before emptying". During this stage the mixture is cooled in a preset time (16 hours) from 61 °C to 20 °C. Air is used which has been heated by a heat exchanger. This air has a great cooling and drying effect. During this cooling a further 5000 litres of water is evaporated (average 300 litres/hour) . When the set time of 16 hours has elapsed and the adjusted final temperature of 20 °C has been reached, the control program switches to stage 5.2 "ready for emptying" .

3.5 Emptying

In stage 5.2 the control program for this tunnel stands at "ready for emptying" . The composted mixture is driven using a power shovel to a post- treatment storage (H) (flow 9) . After composting the mixture has acquired a dry substance content of 60-70%. 3 . 6 Sieving

The composted mixture with a dry substance content of 60-70% (composted dung and structure-improving agent) is then sieved (I) , wherein the composted dung is separated from the structure-improving agent. The structure-improving agent goes to a store (J) (flow 11) for subsequent reuse .

3.7 Further drying of powder The composted dung (powder) with a dry substance content of 60-70% is carried into a drying bunker (K) (flow 13) and then dried for 16 hours. During this drying process an airflow, heated by the heat exchanger, of 10,000-25,000 m³/hour at a temperature of 55 °C and an RH of 5% is blown through the composted dung, whereby water is evaporated. The composted dung is concentrated to a dry substance content of between 70 and 80%. After drying the powder is sieved for a second time (L) (flow 14) , wherein the remaining structure-improving agent is sieved out and transported (flow 15) to a storage (J) for reuse. The material is ready for bulk delivery (flow 16) or for pressing to granules (flow 17) .

3.8 Further drying of granules Granules (pressed composted dung) with a dry substance content of 75-85% are supplied (flow 20) which are dried for 16 hours by means of a belt dryer (P) . During this drying process an airflow, heated by the heat exchanger, of 10,000-25,000 m³/hour at a temperature of 55 °C and an RH of 5% is blown through the granules, whereby water is evaporated. The granules are concentrated to a dry substance content of a minimum of 90%. The dried granules are then ready for bulk delivery (flow 21) or for packaging (flow 22) . Compost obtained with the method according to the present invention as well as the preceding fresh dung were tested at the Bedrijfslaboratorium voor Grond- en Gewasonderzoek (Soil and Crop Research Laboratory) in Oosterbeek. The results of these tests are shown in the tables below.

Table 1

Table 2

Table 3

Table 4

Sample data Dung type : Dry compost Sampling : own Date of sampling: 14-10-1996

Table 5 Analysis results

Table 6 Parts list production process (see figure 3]

A. Supply dung B. Supply structure-improving agent

C . Storage dung

D. Storage structure-improving agent

E . Mixing

F. Breaking-up G. Composting

H . Emptying

I . Sieving

J. Storage structure-improving agent (sieved)

K. Drying L. Further sieving

M. Storage powder

N. Pressing

0. Storage granule

P . Drying Q. Storage granule

R. Crumbing

S . Storage crumb

T. Packaging

Table 7 Parts list method

Table 8

Sample : Batch specification product : Dung sample no. 9933

Sample taken by : Third Parties

Date of sampling

Date of receipt : 16-09-99

Result Parameter Result Unit

Q Chloride 5.7 g Cl/kg dry substance

Q pH-H₂0 7.6 -log[H+]

Q Acid binding constituents 11.1 % ABC d.s. expressed as CaO

Q Boron mg B/kg dry substance

Q Cadmium 60.5 mg Cd/kg dry substance

Q Chromium 0.23 mg Cr/kg dry substance

Q Copper 4.3 mg Cu/kg dry substance

Q Nickel 49 mg Ni/kg dry substance

Q Lead <4.5 mg Pb/kg dry substance

Q Zinc 9.8 mg Zn/kg dry substance

Q Mercury 330 mg Hg/kg dry substance

Q Arsenic 0.05 mg As/kg dry substance

Q Iron 0.86 mg Fe/kgdry substance

Q Manganese 1770 mg Mn/kg dry substance 480

Q = measurement accredited by STERLAB . The conversion of the contents per kg d.s. to the contents per kg fresh material can take place using the formula below.

(dry substance/lOOO) x content in the d.s. = content in fresh material Table 9

Table 10

* Test preformed by Analytic Agrifood B.V. Aw-value 0.61 (method IAV)

It is concluded from the tests that with the present further composting tunnels (21 x 5 x 4 m) a capacity is available for the processing of the dung of 120,000 animals. From 1 ton of dung is created 325 kg compost. The energy consumption amounts to about 25 kWh/ton processed dung.

This compost satisfies the requirements laid down by the Decree on Quality and Use of Residual Organic Dungs (BOOM), published on 20 November 1991. The present invention is not limited to the above description; the rights sought are defined by the following claims.

Claims

1. Method for processing dung, in particular poultry dung, comprising the following steps of:

- periodically removing wet dung from an animal accommodation, for instance a poultry house, and - causing the dung to dry in predetermined conditions outside the animal accommodation.

2. Method as claimed in claim 1, wherein the wet dung is transported to a dung processing area, which area comprises: - one or more composting spaces, and

- dung transporting means.

3. Method as claimed in claim 1 or 2, comprising the further steps of:

- causing this mixture to compost for a predetermined time period under composting conditions in the composting spaces in order to obtain compost.

4. Method as claimed in claim 3, wherein a predetermined quantity of this compost is fed back into the process .

5. Method as claimed in claim 3 or 4, wherein the added structure-improving agent is separated from the compost.

6. Method as claimed in claim 5, wherein this structure- improving agent separated from the compost and/or a predetermined part of the compost and/or wet dung is fed back into the process.

7. Method as claimed in any of the foregoing claims 3-6, wherein the structure-improving agent comprises wood-chippings .

8. Method as claimed in any of the foregoing claims, wherein composting-enhancing agent, for instance bacteria, is added.

9. Method as claimed in any of the foregoing claims 3-8, wherein the mixture is left undisturbed for a maximum of about 20 hours before being fed back into the process.

10. Method as claimed in claim 9, wherein the mixture is permitted to compost for a maximum of about 10 days, preferably about 5 days and most preferably about 3 days in a separate composting space.

11. Method as claimed in claim 10, wherein the compost has a dry substance content of at least 25%, preferably at least 40%, preferably at least 50% and most preferably at least 80%.

12. Method as claimed in any of the foregoing claims, wherein the composting is performed at a temperature of less than about 70 °C, preferably less than about 60 °C and most preferably at a temperature of about 52°C.

13. Compost obtainable with the method as claimed in any of the foregoing claims .

14. Poultry compost as claimed in claim 13, comprising at least 50% dry substance and preferably at least 60% dry substance and most preferably at least 80%, for instance 90% dry substance.

15. Compost, in particular poultry compost, comprising at least 50% dry substance and preferably at least 60% dry substance and most preferably at least 80%, for instance 90% dry substance.

16. Compost as claimed in claim 14 or 15 with a dry substance content of at least 80%, preferably at least 90%, for instance 90% and an AW value of less than 0.8%, preferably less than 0.7%.

17. System of apparatus for performing the method as claimed in any of the foregoing claims, comprising: - mixing means for mixing wet dung and dung structure-improving agents,

- a composting space for composting this mixture , - and transport means for transporting the mixture from the mixer to this composting space.

18. System as claimed in claim 17, wherein the transport means and/or the mixing means comprise one or more conveyor belts and/or one or more rotating screw devices.

19. Chicken farm comprising the system of apparatus as claimed in claim 17 of 18.