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Title:
METHOD FOR PREPARING NITROGENOUS FERTILIZER AND SOIL CONDITIONER FROM LIQUID MANURE AND/OR MANURE
Document Type and Number:
WIPO Patent Application WO/2020/201636
Kind Code:
A1
Abstract:
A method for preparing nitrogenous fertilizer and soil conditioner from liquid manure and/or manure. The method comprises the following steps: - separating liquid manure and/or manure into a solid fraction and a liquid fraction, - subjecting the liquid fraction to ammonia stripping, thereby obtaining a liquid fraction with a low nitrogen content and a gas phase containing ammonia, - performing nitrogen recovery from the gas phase into a liquid solution containing acid, thereby obtaining an ammonium salt solution (ammonium nitrogen), - treating the solid fraction with pyrolysis, wherein charcoal, pyrolysis liquid and pyrolysis gas are formed, - charging the ammonium salt solution obtained from the nitrogen recovery step into the charcoal formed in the pyrolysis process, whereby nitrogenous fertilizer and soil conditioner is obtained as the end product.

Inventors:
TAKALA JUHA (FI)
Application Number:
FI2020/050219
Publication Date:
October 08, 2020
Filing Date:
April 03, 2020
Export Citation:
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Assignee:
PELLON GROUP OY (FI)
International Classes:
C05F3/00; A01C3/00; C01C1/02; C02F1/20; C02F1/58; C05C3/00; C05G3/80; C10B53/02
Foreign References:
US9919976B12018-03-20
US8361186B12013-01-29
EP2279153A12011-02-02
US20170210677A12017-07-27
EP0351922A11990-01-24
Attorney, Agent or Firm:
LEITZINGER OY (FI)
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Claims:
Claims

1. A method for preparing nitrogenous fertilizer and soil conditioner from liq uid manure and/or manure, which method comprises the following steps: - separating liquid manure and/or manure into a solid fraction and a liquid fraction,

- subjecting the liquid fraction to an aerobic biological treatment,

- subjecting the pretreated liquid fraction to ammonia stripping, thereby ob¬ taining a liquid fraction with a low nitrogen content and a gas phase contain- ing ammonia,

- performing nitrogen recovery from the gas phase into a liquid solution con taining acid, thereby obtaining an ammonium salt solution (ammonium nitro gen),

- treating the solid fraction with pyrolysis, wherein charcoal, pyrolysis liquid and pyrolysis gas are formed,

- charging the ammonium salt solution obtained from the nitrogen recovery step into the charcoal formed in the pyrolysis process, whereby nitrogenous fertilizer and soil conditioner is obtained as the end product. 2. The method according to claim 1, characterized in that the acid in the liquid solution is sulfuric acid (H2SO4), in which case the ammonium salt solu¬ tion is ammonium sulfate ((NH^SCM).

3. The method according to claim 1 or 2, characterized in that the amount of phosphorus contained in the charcoal is analyzed and the amount of nitro¬ gen to be charged into the charcoal is adjusted in order to adjust the ratios of the amounts of nitrogen and phosphorus to correspond to the cultivation plan. 4. The method according to any one of claims 1 to 3, characterized in that the charcoal obtained from the pyrolysis is ground or crushed and the ammonium salt solution is charged into the ground or crushed charcoal by spraying.

5. The method according to claim 4, characterized in that the ground or crushed charcoal is fed as a continuous stream through a weighing appa¬ ratus and the feed volume of the ammonium salt solution is controlled based on the weight recorded.

6. An NPK fertilizer impregnated into charcoal, prepared according to the method according to any one of claims 1 to 5.

Description:
Method for preparing nitrogenous fertilizer and soil conditioner from liquid manure and/or manure

The object of the invention is a method for preparing nitrogenous fertilizer and soil conditioner from liquid manure and/or manure, which method com ¬ prises the following steps:

- separating liquid manure and/or manure into a solid fraction and a liquid fraction,

- subjecting the liquid fraction to ammonia stripping, thereby obtaining a liq- uid fraction with a low nitrogen content and a gas phase containing ammo ¬ nia,

- performing nitrogen recovery from the gas phase into a liquid solution con taining acid, thereby obtaining an ammonium salt solution (ammonium nitro gen),

- treating the solid fraction with pyrolysis, wherein carbon, pyrolysis liquid and pyrolysis gas are formed.

The above-mentioned process steps are known per se. However, all of the steps have not been carried out as sub-steps of one method.

It is known to separate and recover nitrogen from a manure-based liquid by concentrating nitrogen into its own fraction by stripping and washing the am monia gas formed with a receiving solution, typically with sulfuric acid, thereby obtaining ammonium sulfate (NH^SCM. The ammonium ions of the ammonium sulfate act as nitrogenous fertilizer and the sulfate ions lower the pH of soil. Patent application EP 2279153 B1 filed by the applicant discloses a method in which, prior to ammonia stripping, the liquid fraction is subjected to an aerobic microbiological treatment, thereby reducing the need for chem ¬ icals during the step of concentrating nitrogen.

It is also known to use biochar produced from manure by means of pyrolysis as soil conditioner and fertilizer. Charcoal retains water and prevents nutrients, particularly phosphorus and nitrogen, from being washed into wa ¬ terways. Further, charcoal obtained from solid manure or the solid fraction of the method according to the invention contains a significant amount of phos ¬ phorus.

Publication US 9919976 B1 discloses a method in which soil conditioner con taining biochar is produced by means of pyrolysis from manure or by anaero ¬ bic digestion from the solid matter fraction of processed manure. The nutri ¬ ent content of biochar produced by means of pyrolysis is improved by adding thereto nutrients separated from the liquid fraction obtained from the diges ¬ tion process. The separation of the solid fraction and the liquid fraction is performed only after the digestion process. The solid matter obtained from the digestion process is not particularly suitable for pyrolysis, as the majority of charcoal has exited with the biogases. Separating nutrients from the liquid fraction of the digestion process requires hygienization and the nitrogen ob tained is in the form of ammonia dissolved into liquid, wherein the ammonia is a volatile, smelly gas.

The purpose of the invention is to further develop the above-mentioned known methods so that their advantages can be combined in a method with which a new type of fertilizer can be prepared from fresh manure without a digestion process, which fertilizer acts as both nitrogenous fertilizer and soil conditioner. This purpose is achieved according to the accompanying claim 1 in such a way that in addition to the process steps mentioned hereinbefore, ammo ¬ nium salt solution obtained from the nitrogen recovery step is charged into the charcoal formed during the pyrolysis process, whereby nitrogenous ferti ¬ lizer and soil conditioner is obtained as the end product.

Preferred embodiments of the invention are presented in the dependent claims. Next, the invention is described with reference to the accompanying drawing, in which Figure 1 shows a process chart of the method according to the invention. The process description of Figure 1 :

1. Manure and/or liquid manure is provided as starting material, which may also contain other fractions, such as washing water. Any manure of animal origin can be used as the manure and/or liquid manure. The manure and/or liquid manure is fed into the separation of solid matter.

2. The liquid manure and/or manure is separated into a solid fraction and a liquid fraction. A separator, wire sieve or precipitation can be used as equip ment. A polymer binding to the solid matter can be added to the precipita ¬ tion tank and the precipitate sinks to the bottom, wherefrom the solid matter can be removed with a scraper. Another separation method, such as a centri fuge, can be used for separating the solid matter. The aim is to essentially separate the solid and liquid fractions of the manure and/or liquid manure.

3. The separated liquid fraction can be subjected to a biological pretreatment before the concentration of nitrogen. The pretreatment is an aerobic micro ¬ bial treatment as described e.g. in patent publication EP 2279153 B1 by the applicant. With the biological pretreatment, and if necessary, with chemicals, the pH of the liquid fraction can be increased to a desired level to facilitate the concentration of nitrogen.

4. In order to concentrate the nitrogen, the liquid fraction is subjected to am- monia stripping, thereby obtaining a liquid fraction with a low nitrogen con tent and a gas phase containing ammonia. From the gas phase, the nitrogen is recovered into a liquid solution containing acid (a so-called receiving solution), whereby an ammonium salt solution (ammonium nitrogen) is ob tained. Diluted sulfuric acid (H2SO4) is primarily used as the liquid solution, in which case the ammonium salt solution is ammonium sulfate ((NH^SC ). The receiving solution used in the gas phase washer may also comprise an acid other than sulfuric acid or it may consist of a mixture of different acids. In addition, a dilute liquid fraction with a significantly lowered nitrogen con ¬ tent is obtained from the ammonia stripping step. This dilute liquid fraction can be used as nitrogenous fertilizer that can be spread directly on a field or it can be transferred as such to a wastewater treatment plant. Alternatively, nitrogen and organic matter can be removed from the dilute liquid fraction using membrane technology, whereby the purified liquid fraction can be re ¬ leased straight into nature.

5. The solid fraction obtained from separating the solid matter is treated with pyrolysis, wherein charcoal, pyrolysis liquid and pyrolysis gas are formed. In pyrolysis, organic matter is decomposed in anoxic or low oxygen conditions. In general, the pyrolysis process is carried out as slow pyrolysis. Before py ¬ rolysis, the solid fraction can be pre-dried and/or heated. Another solid frac ¬ tion essentially containing charcoal or solid manure that does not need to be passed through the solid matter separation step can be added to the pyroly ¬ sis. The biochar formed as the pyrolysis product contains significants amount of phosphorus (P) and potassium (K) as well as other nutrients important to plants. The charcoal can be ground or crushed to granules of a suitable size for further use and treatment. The pyrolysis gas and the pyrolysis liquid can be utilized as energy or for other purposes of use.

6. In order to obtain the end product according to the invention, the ammo ¬ nium salt solution obtained from the nitrogen recovery step is charged into the charcoal formed in the pyrolysis process, whereby nitrogenous fertilizer and soil conditioner is obtained as the end product. The ammonium salt solu ¬ tion can be charged into the ground or crushed charcoal by spraying, for ex ¬ ample. The ammonium salt solution is typically ammonium sulfate (NH^SCM. Other nutrients and/or trace elements can also be charged into the charcoal according to cultivation needs.

7. The desired nutrient content to be charged into the charcoal is adjusted using flow measurement based on weight. Ground or crushed charcoal is fed as a continuous stream through a weighing apparatus and the feed volume of the ammonium salt solution is controlled based on the weight recorded. The ratios of the amounts of nitrogen and phosphorus are adjusted accord ¬ ing to the cultivation plan. For adjustment, the amount of phosphorus con- tained in the charcoal is first analyzed, and the amount of nitrogen to be charged into the charcoal is adjusted accordingly. The amount of nitrogen and phosphorus per cultivation area has been provided for in directives and national decrees. The end product is an NPK fertilizer impregnated in charcoal, further acting as soil conditioner owing to its charcoal content.

The above-described process steps may comprise heating and/or cooling processes.




 
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