WO2002044107A1

WO2002044107A1 - Method and apparatus for preparing liquid fertilizer using organic industrial wastes

Info

Publication number: WO2002044107A1
Application number: PCT/KR2001/002028
Authority: WO
Inventors: Jae-E Yang; Dong-Kuk Kim; Hae-Nam Hyun
Original assignee: E & A Tech
Priority date: 2000-11-29
Filing date: 2001-11-23
Publication date: 2002-06-06
Also published as: KR20020042013A; AU2002223151A1

Abstract

The present invention relates to a method for the preparation of a liquid fertilizer from organic industrial wastes. The method comprises introducing the organic industrial wastes into a humic substance-extracting apparatus; adding a 0.01 N to 1.00 N alkaline solution to the organic industrial wastes; stirring the resulting mixture at a temperature of 50 to 120 ¡ÆC while extracting a humic substance useful as a fertilizer; and adding to the humic substance, microelements such as iron (Fe), copper (Cu), manganese (Mn), molybdenum (Mn) and boron (B), and plant nutrients such as nitrogen (N), phosphorus (P) and potassium (K). The liquid fertilizer prepared according to the method improves soil quality and increases crop growth.

Description

METHOD AND APPARATUS FOR PREPARING LIQUID FERTILIZER USING

ORGANIC INDUSTRIAL WASTES

Technical Field

The present invention relates generally to a method and apparatus for preparing a liquid fertilizer using organic industrial wastes. More particularly, the present invention relates to a method for preparing a humic liquid fertilizer, which comprises introducing organic industrial wastes such as sewage sludge into a humic substance-extracting apparatus of the present invention, adding an alkaline solution to the sewage sludge, stirring the resulting mixture while extracting a humic substance for a fertilizer from the mixture, and adding plant nutrients and microelements to the humic substance.

Background Art

Korea ranks fourth in the world in fertilizer consumption, and faces with a state where a damage of environmental pollution caused by over-fertilization and therefore a deterioration in soil quality and a decrease in agricultural product quality are serious . To solve this problem, the environment-friendly method is currently promoted in agriculture. In this method, crop cultivation using only compost results in problems in that crop growth is insufficient and also yield of crops is decreased in comparison with the prior cultivation method. This is because the compost mainly serves to improve soil quality and an environment for plant growth, rather than serving as a fertilizer that is important in terms of plant nutrition. On the other hand, compound fertilizers (liquid fertilizers) are mostly marketed as solutions of chemical fertilizers dissolved in specific solvents and thus result in a serious deterioration in soil quality at a protected cultivation area. Also, the compound fertilizers are over-fertilized when considering only the principal ingredients of the fertilizers .

In order to solve these problems, there are required fertilizers that can substitute for chemical fertilizers and pesticides and can improve the soil quality and the growth environment of plants and also is highly valuable in terms of plant nutrition.

Meanwhile, technologies for the treatment of an organic waste stream such as sewage sludge, used in the, practice of the present invention have been subjects in environmental fields for an extended period of time. Although technologies for the reuse of the sewage sludge have been studied and developed, there is not still developed an economical method for the reuse of the sewage sludge. For this reason, the sewage sludge is reused at about 7% and mostly buried, and thus becomes a serious social problem in view of a landfill securing and a causing of secondary environmental pollution.

In Japan and Germany, etc. , there are actively performed studies on the preparation of liquid fertilizer using the organic wastes, so as to solve the environmental pollution problems and achieve a resource curtailment effect. In Korea, however, there has not been carried out a study on the preparation of the liquid fertilizer from a humic substance extracted from the sewage sludge, as disclosed in the present invention.

Disclosure of the Invention

In an attempt to solve the above-mentioned problems occurring in the prior art, the present inventors have extracted only a humic substance highly useful as a fertilizer, from organic industrial waste such as sewage sludge using a humic substance-extracting apparatus of the present invention, and then prepared a liquid fertilizer using the extracted humic substance, thereby achieving the present invention. It is therefore an object of the present invention to provide a method for preparing a liquid fertilizer using organic industrial wastes .

Another object of the present invention is to provide an apparatus for extracting a humic substance from organic industrial wastes used for the preparation of the liquid fertilizer.

In order to accomplish these objects, there is provided a method of preparing a liquid fertilizer using organic industrial wastes, which comprises the steps of introducing the organic industrial wastes into a humic substance-extracting apparatus of the present invention, adding to the organic wastes, a 0.01-1.00 N alkaline solution such as KOH, NaOH and Mg(OH)₂, etc., stirring the resulting mixture at a temperature of 50 to 120 °C while extracting a humic substance useful as a fertilizer, and adding to the humic substance, plant nutrients such as nitrogen (N) , phosphorus (P) and potassium (P) , and microelements such as iron

(Fe) , copper (Cu) , manganese (Mh) , molybdenum (Mo) , zinc (Zn) and boron (B) . Results of test for crop cultivation using the liquid fertilizer prepared according to the method of the present invention indicate that the liquid fertilizer exhibits an excellent crop growth and improves physical conditions of soil . In addition, crops cultivated using the liquid fertilizer prepared according to the method of the present invention exhibit strong resistance against the disease and insect damage in comparison with crops cultivated using other fertilizers.

Brief Description of the Drawings

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows an apparatus for extracting a humic substance from organic industrial wastes according to the present invention;

Fig. 2a shows a change in color of a humic substance according to a concentration of KOH, Fig. 2b shows a change in color of a fulvic acid according to a concentration of KOH,

Fig. 3 is a graph showing contents of nutrients in a humic substance,

Fig. 4 is a graph showing contents of a harmful substance and micronutrients in a humic substance,

Ό

Fig. 5 shows results of crop cultivation using a chemical fertilizer and a humic substance,

Fig. 6a shows results of crop cultivation using commercially available compound fertilizers for foliar application and a humic liquid fertilizer prepared according to the method of the present invention, and

Fig. 6b shows results of crop cultivation using commercially available compound fertilizers for foliar application and a humic liquid fertilizer prepared according to the method of the present inventio .

Best Mode for Carrying Out the Invention

A method of the present invention includes extracting a humic substance from organic wastes using an alkaline solution such as KOH, NaOH and Mg(OH)₂, etc., as an extractant. The extracted humic substance contains a humic acid and a fulvic acid as principal ingredients . In this extraction step, the organic wastes and the alkaline solution are heated to 120 °C in a bath tank. Thus, the organic wastes are decomposed by virtue of the high temperature heating to prevent a toxic substance from being extracted. Next, the preparation of a liquid fertilizer from the extract is carried out. In this step, a solution of nutrients in a solvent is added to the extract in an amount required for crop growth, thereby satisfying requirements of the nutrient content provided in the fertilizer process standard.

In extracting the humic substance from the organic wastes, sludge crushed in a suitable size is preferably used. This is because the use of crushed sludge increases a reaction area between the extractant and the sludge to allow the humic substance to be extracted in a large amount. However, if the extractant is used at . a too high concentration, it mainly • serves to decompose the organic wastes rather than extracting the humic substance, so that the toxic substance can be extracted. For this reason, it is preferred that, as the extractant, the alkaline substance such as KOH, NaOH and Mg(OH)₂, etc. is used at a concentration ranging from 0.01 N to 1.00 N. Preferably, in the extracting step, temperature of the mixture of the organic wastes and the alkaline solution in the bath tank is from room temperature to 120 °C, and a heating time for the mixture in the bath tank is longer than 50 minutes. If the heating time is less than 50 minutes, a reaction time between the sewage sludge and the extractant is insufficient, so that a satisfactory humic substance cannot be obtained.

Moreover, as shown in Fig. 1, the humic substance-extracting apparatus used in the extracting step comprises an extracting container 20 for receiving the alkaline solution 22 and the sewage sludge 23, a stirrer 21 disposed within the extracting container 20 to facilitate a reaction between the alkaline solution 22 and the sewage sludge 23, a bath tank 10 for receiving the extracting container 20, and an indirect heating furnace 30 placed beneath the bath tank 10. The present invention will be described in detail with reference to the following examples and test examples, which should not be construed as limiting the scope of the invention. Example 1 : Extraction of humic substance from organic wastes In order to extract a humic substance from organic wastes, there was used an extracting apparatus of the present invention 5 as shown in Fig. 1. Referring to Fig. 1, the extracting apparatus comprises an extracting container 20 for receiving an alkaline solution 22 and a sewage sludge 23; a stirrer 21 disposed within the extracting container 20 to facilitate a reaction between the alkaline solution 22 and the sewage sludge

10 23; a bath tank 10 for receiving the extracting container 20; and an indirect heating furnace 30 placed beneath the bath tank 10. Using the humic substance-extracting apparatus as described above, the humic substance was extracted by reacting the sewage sludge 23 with the alkaline substance 22 for about 50 minutes or

15 above. In this extraction, the alkaline substance 22 in the extracting container 22 was used at a concentration of 0.01 N to 1.00 N, the volume ratio of the alkaline substance 22 to the sewage sludge 23 was maintained at 25 : 1, temperature of the indirect heating furnace was elevated, and the stirrer 21 was 0 operated at an interval of 10 minutes.

Test example 1: Extraction of humic substance using humic substance-extracting apparatus of the present invention, and verification test for existence of humic substance in extract 5 12 g of sewage sludge was introduced into the humic substance-extracting apparatus of Example 1, and added with 0.01 N KOH, 0.10 N KOH and 1.00 N KOH, respectively, as the alkaline substance. The resulting respective mixtures were heated for one hour to carry out an extraction step. In order to verify weather 0 an extract resulted from the extraction step contains the humic substance or not, a humic acid and a fulvic acid that are representative humic substances were isolated. The humic acid has a characteristic in that it is soluble in an alkali but insoluble in an acid, while the fulvic acid has a characteristic in that it is soluble in both acid and alkali. Using these characteristics, the extract was treated with the acid to lower a pH to 2 or below. As a result, the humic acid was precipitated in the extract, and the resulting- extract was centrifuged to isolate the humic acid and the fulvic acid.

From results of the test, it was found that, as a concentration of KOH that is an alkaline substance increases, the humic substance shows a deep dark-brown color that is a typical color of the humic substance, as shown Figs. 2a and 2b. Also, the treatment of the sewage sludge with 1.00 N KOH has produced the humic acid in an amount larger than that of the treatment with each of 0.01 N KOH and 0.10 N KOH. For this reason, the extractant can be' used at arbitrarily varying concentrations in consideration of an extracting efficiency.

Test example 2 : Analysis for content of nutrients in humic substance

In order to find a plant nutritional value of the humic substance extracted according to Example 1, contents of nitrogen, phosphoric acid and potassium in the humic substance were analyzed using a conventional analysis method. The content of nitrogen (T-N) in the extract was measured using a Kjeldahl distillatory apparatus and agents such as NaOH, H₂S0₄ and boric acid. The content of phosphoric acid in the extract was measured with an absorption photometer (U/V) using agents such as

(NH₄)6Mo₇0₂₄, C₄H₄0₆K(SbO)-l/2H₂0 or NH₄OS0₂NH, etc., according to "a molybdenum blue method using an ascorbic acid" described in a general soil chemical analysis method: Also, the content of potassium was analyzed using an atomic absorption spectrometer

(AAS) . Additionally, Total Organic Carbon (TOC) , that is an important factor in forming conditions suitable for crop growth by improvement of physical conditions of soil and also an increase in activity of microorganism and thus an improvement in soil quality, was analyzed using a total organic carbon analyzer. Test results are shown in Fig. 3. From the test results, it was found that the nutrient content increases as the concentration of the alkaline substance increases from 0.01 N to 0.10 N. Also, the nutrients were extracted at a concentration ranging from about 100 g/ L to about 3,200 mg/L, which shows that the nutrients were extracted at a significantly much amount.

Test example 3: Contents of toxic substances and nutrients in humic substance

In order to find contents of toxic substances in the humic substance extracted according to Example 1, the humic substance was analyzed for contents of cadmium (Cd) , chromium (Cr) , nickel

(Ni) , lead (Pb) and arsenic (As), etc. Also, contents of the micronutrients such as copper (Cu) , iron (Fe) , manganese (Mn) and zinc (Zn) , etc. in the humic substance were analyzed. The content analysis was carried out by inductively coupled plasma (ICP) emission spectrometry. Results are indicated in Fig. 4.

From the test results, it was found that the harmful substances were not detected except for chromium (Cr) and nickel (Ni) that were detected at less than 0.01 mg/L. On the other hand, the micronutrients were extracted at the amount of 0.2 mg/L to 5.0 mg/L.

Example 2: Preparation of humic liquid fertilizer from extracted humic substance This example shows the preparation of a liquid fertilizer for foliar application using the humic substance extracted according to Example 1. 1,000 ml of the extracted humic substance was mixed with 215 g of urea, 200 g of calcium double superphosphate and 100 g of potassium chloride, thereby preparing a liquid fertilizer containing fertilizer components of nitrogen (N) , phosphorus (P) and potassium (K) . However, the respective fertilizer components may also be obtained from urea, ammonium sulfate, ammonium nitrate, lime nitrogen, ammonia water, triple superphosphate, superphosphate, phosphoric acid solution, ammonium phosphate, fused phosphate, calcined phosphate, potassium chloride, potassium sulfate, potassium dihydrogen phosphate, potassium monohydrogen phosphate, sodium dihydrogen phosphate and sodium monohydrogen phosphate, etc. The prepared liquid fertilizer maintains agricultural productivity at the present level while minimizing an environmental hazard.

Test ^■ example 4 : Tests for crop cultivation using liquid fertilizer prepared according to the present invention and conventional chemical fertilizer

Tests for crop cultivation using the liquid fertilizer prepared according to Example 2 were carried out. For the tests, seven kinds of cultivated crops of cucumbers, pumpkins, lettuces, young radishes, radishes, Chinese cabbages and kales were used.

Also, the cultivated crops were divided into three group of a humic substance-treated group, a chemical fertilizer-treated group and a control group. Test results are indicated in Fig. 5.

From the test results, it was found that the humic substance- treated- group is higher than the chemical fertilizer-treated group in green weight.

Test example 5: Tests for crop cultivation using liquid fertilizer prepared according to the present invention and conventional compound fertilizers for foliar application

Tests for crop cultivation were performed using the liquid fertilizer prepared according to Example 2 (F) , Korea-made three compound fertilizers for foliar application (A, B, C) , one Japan- made fertilizer (D) and one Germany-made fertilizer (E) as indicated in Table 1. In the tests, six kinds of cultivated crops of kales, crown daisies, spinaches, radishes, Chinese cabbages and lettuces were used.

Table 1

Group Maker Product name

A Greenwell, Inc. Blue NaRapho (11-4-7)

B Yuil, Inc. Golden Top (4-4-3)

C Korean synthetic amino Amino Green (4-4-4) acid fertilizer, Inc.

D Korean trading company HYPONeXΘ (5-10-5)

(Korean agency)

E ARCTECH, Inc. Actosol (15-3-5)

F - Example 2 of the present invention

G - . Control group

Test results are indicated in Figs. 6a and 6b. The test results indicate that the liquid fertilizer according to Example 2 has exhibited an excellent or similar effect in growth of kales, crown daisies and spinaches, in comparison with other products. Also, in growth of radishes, Chinese cabbages and lettuces, the German-made product has exhibited a somewhat superior effect, and the next excellent effect was obtained by the liquid fertilizer according to Example 2 of the present invention.

Industrial Applicability

As apparent from the foregoing, the present invention provides the method of preparing the liquid fertilizer for foliar application from organic industrial wastes such as sewage sludge, which comprises extracting the humic substance from the organic industrial wastes using the alkaline substance such as KOH, NaOH and Mg(OH)₂ in an easy manner, and then adding the microelements and the plant nutrients to the extracted humic substance. The liquid fertilizer prepared according to the present invention exhibits excellent effects of improving the soil quality and increasing the crop growth, in comparison with the prior chemical fertilizers that are currently used in protected cultivation. Therefore, the present invention is highly useful in the fertilizer industry.

Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A method of preparing a liquid fertilizer from organic industrial wastes, which comprises the steps of: introducing the organic industrial wastes into a humic substance-extracting apparatus; adding an alkaline solution to the organic industrial wastes; stirring the resulting mixture at a temperature of 50 °C to

120 °C while extracting a humic substance; and adding microelements and plant nutrients to the humic substance.

2. The method of Claim 1, in which the alkaline solution is selected from KOH, NaOH and Mg(OH)₂

3. The method of Claim 2, in which the alkaline solution is used at a concentration of 0.01 N to 1.00 N.

4. The method of Claim 1, in which the microelements and the plant nutrients are selected from the group consisting of nitrogen, phosphorus, potassium, iron, copper, manganese, molybdenum, zinc and boron.

5. An apparatus for extracting a humic substance useful as a fertilizer from organic industrial wastes, which comprises: an extracting container for receiving an alkaline solution and the organic industrial wastes, a stirrer disposed within the extracting container to facilitate a reaction between the alkaline solution and the organic industrial wastes, a bath tank for receiving the extracting container, and an indirect heating furnace placed beneath the bath tank.

. A liquid fertilizer prepared according to the method of Claim 1.