WO2007108286A1

WO2007108286A1 - Process for producing organic fertilizer from leftover resulting from marine product processing

Info

Publication number: WO2007108286A1
Application number: PCT/JP2007/053767
Authority: WO
Inventors: Huifeng Ren; Tetsuhito Hayashi; Ryoji Fukuda
Original assignee: National University Corporation Tokyo University Of Marine Science And Technology; Taisei Nozai Co., Ltd.
Priority date: 2006-03-17
Filing date: 2007-02-28
Publication date: 2007-09-27
Also published as: JPWO2007108286A1; JP5250814B2

Abstract

An aqueous acetic acid solution is added to a product of pulverization of a cadmium-containing leftover resulting from marine product processing. This mixture is heated and the liquid is separated to obtain a residue. This step is conducted repeatedly to reduce the cadmium concentration based on nitrogen to a value not higher than an allowable limit. The final residue having such a reduced cadmium concentration is used as a fertilizer. A liquid fertilizer may be obtained from the liquid separated in this step, by concentrating the liquid under vacuum to obtain a concentrate, adding an aqueous sulfide solution to the concentrate, stirring themixture, subsequently adding a coagulant thereto, and neutralizing the resultant supernatant.

Description

Specification

Production method of organic fertilizer from fishery processing residue

Technical field

[0001] The present invention relates to a method for producing an organic fertilizer using a fishery processing residue containing heavy metals, particularly cadmium.

Background art

[0002] Fish and squid internal organs and midgut glands (internal organs) called the mouth of shellfish are generated in large quantities as remnants with fishery processing. Such fishery residue is an industrial waste that is difficult to dispose of because of heavy accumulation of heavy metals such as cadmium (Cd).

In general, marine processing residue was buried in the ground as it was, and the incinerated ash was solidified with cement and buried in the final disposal site.

However, when landfilled directly in the ground, there will be problems with off-flavors to the surroundings and toxic metal contamination of the soil. Also, when incinerated, air pollution due to vaporized Cd is not negligible. For example, the scallop mouth contains 20 to 80 ppm of Cd, and its effect cannot be ignored.

[0003] On the other hand, aquatic processing residue is rich in peptides that show useful activity for plant growth and nitrogen sources including amino acids, except for the presence of harmful heavy metals. Therefore, if harmful heavy metals can be removed or reduced, it can be effectively used as an excellent fertilizer material.

In view of this, various methods have been proposed for reducing the adverse effects on the environment and reusing them as resources for fishery processing residues containing high concentrations of toxic heavy metals.

[0004] For example, processed seafood residues such as scallop uro are crushed, nitric acid is added thereto, and solids and liquids are separated as acids, and then the liquids and artificial zeolite are brought into contact with each other. In addition, a method for producing liquid fertilizer is known in which heavy metal ions solubilized by acidification are adsorbed on artificial zeolite, and then the artificial zeolite is separated from the liquid material and the liquid material is neutralized with ammonia (Japanese Patent Application Laid-Open (JP-A) 2001_137825).

[0005] Also, scallops are dipped in sulfuric acid or hydrochloric acid, and citrus juice residue is absorbed from the dipping solution. There is also a known method of adsorbing heavy metals, fats and proteins as a dressing and neutralizing the juice of citrus juice after elution of cadmium using high-concentration sulfuric acid to make it a raw material for fertilizer feed (special 2005 — See publication 58951).

However, since these conventional methods use strong acids such as nitric acid and sulfuric acid, not only are the chemicals and equipment that are difficult to handle expensive and expensive, but also the salt concentration after neutralization becomes high. It is difficult to use as fertilizer because protein is oxidized and causes so-called "burn". Disclosure of the invention

[0006] An object of the present invention is to obtain an excellent organic fertilizer by using abandoned processing residue containing heavy metals, particularly cadmium, and to produce a large-scale apparatus, extreme acid such as strong acid, high temperature, etc. It is an object of the present invention to provide a method for producing an organic fertilizer that does not require conditions, can reduce the processing cost, and can prevent the occurrence of pollution such as air pollution.

[0007] In order to achieve the above object, the method for producing an organic fertilizer according to the present invention adds an aqueous acetic acid solution to a pulverized product of aquatic processing residue containing heavy metals, particularly cadmium, and then heat-treats the liquid product. The process of separating and obtaining the residue is repeated several times, and the final residue obtained with reduced heavy metals, especially cadmium, is used as fertilizer.

At this time, using cadmium as an index, treatment with an acetic acid aqueous solution may be repeated until the cadmium concentration in the residue is 0.75 ppm or less for a nitrogen content of 1%, and the resulting final residue may be used as fertilizer.

Here, the reason why the cadmium concentration is reduced to 0.75 ppm or less when the nitrogen content is 1% is to satisfy the standard value stipulated in the Fertilizer Control Law. If the number of times the above process is repeated increases, the cadmium concentration gradually decreases, and the lower the cadmium concentration, the better.However, if the fertilizer component decreases, the power or work efficiency also deteriorates. The number of times to minimize loss.

[0008] The fishery processing residue containing cadmium mainly includes, but is not limited to, scallop roe, squid and fish internal organs.

If the concentration of the acetic acid aqueous solution is too high, proteins may be oxidized despite the fact that there is not much difference in the effect of washing out heavy metals.If it is too low, heavy metals cannot be eluted. Is desirable. The liquid material is separated by centrifugation or pressing, but if a simple pressure filtration device equipped with a nylon mesh or a classic pressing bag is used, an expensive device is unnecessary.

[0009] By obtaining liquid organic fertilizer from the separated liquid, in order to use marine resources more efficiently, the separated liquid separated in the above process (which can be combined multiple times) is concentrated by reducing pressure, etc. Then, an aqueous solution of a sulfide salt such as an aqueous solution of sodium sulfide is added to the concentrate and stirred, and heavy metal ions extracted in the separated liquid are analyzed as sulfides with reduced solubility. Aggregate fine precipitates of heavy metal sulfide with an agglomerating precipitant such as aluminum chloride solution, add an aqueous solution of basic substance such as sodium hydroxide to adjust the pH to 6-7, and remove the precipitate. The supernatant obtained after separation may be used as a liquid organic fertilizer.

[0010] Since the method for producing an organic fertilizer of the present invention has the above-described configuration, it is possible to use, as fertilizer, a discarded fishery processing residue containing heavy metal, particularly cadmium, and excessively use inorganic salt. It does not contain, and there is little loss of nitrogen which is an active ingredient of fertilizer.

In addition, large-scale equipment and extreme conditions such as strong acid and high temperature are not required, so the cost can be kept low, and it is possible to manufacture fertilizer relatively easily even for those who do not have specialized technology. .

In addition, acetic acid is used to elute heavy metals, which reduces the price of the product, prevents spoilage until the acetic acid is removed, and the relatively mild chemical properties of acetic acid make the quality of protein burns that occur in sulfuric acid. Decline can be prevented. Also, if this organic fertilizer is sprayed on the leaves without removing acetic acid, for example, in addition to its use as a fertilizer, a disease prevention effect by acetic acid can be expected.

Brief Description of Drawings

FIG. 1 is a graph showing changes in the amount of cadmium as the number of washings increases with respect to the weight of unwashed euro in the examples and comparative examples of the present invention.

FIG. 2 is a graph showing a decrease rate of the cadmium concentration with an increase in the number of washings when the cadmium concentration in the unwashed mouth is used as a reference in the example and the comparative example shown in FIG.

FIG. 3 is a graph showing changes in the amount of nitrogen in the residue as the number of washings increases in the example and the comparative example shown in FIG.

[FIG. 4] The cadmium concentration of the supernatant liquid in the example, comparative example and other comparative examples shown in FIG. The figure which shows a degree.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The method for producing an organic liquid fertilizer according to the present invention comprises adding an acetic acid aqueous solution to a ground product of aquatic processing residue containing cadmium such as scallop roe, squid and fish internal organs, followed by stirring while heating. , the step of obtaining a residue to separate the liquid substance by centrifugation or pressing force Dominiumu concentration in the residue is the nitrogen content of 1% diary 0. 75 _PP m until below, repeated several times, resulting Leave the final residue as it is or combine it with other fertilizers to make fertilizers. Combine the separated liquids separated in the above repeated steps, and add the aqueous solution of alkali sulfide such as sodium sulfide aqueous solution to the concentrated concentrate. After stirring, the coagulating precipitant is added, neutralized by adding an aqueous solution of a basic substance, solid-liquid separation is performed, and the resulting supernatant is used as a liquid organic fertilizer.

Hereinafter, examples of the present invention will be described.

After crushing scallops with a mixer, add the same amount of 2% aqueous acetic acid solution (100 g) to 100 g, stir at 80 ° C for 10 min, centrifuge at 3000 rpm for 15 min, It was divided into 66 g of residue washing residue (residue) and 134 g of separation liquid.

To the obtained residue (66g), add 2 volumes of 2% acetic acid aqueous solution (132g), stir at 80 ° C for 10 minutes, centrifuge again (3000rpm, 10 minutes), and wash the second time (residue ) Divide into 51g and 47g of separated liquid.

To the obtained residue (51g), add 2 volumes of 2% aqueous acetic acid solution (102g), stir at 80 ° C for 10 minutes, and centrifuge (3000rpm, 10 minutes). ) Divide into 53 g and 100 g of separated liquid.

To the obtained residue (53 g), add 2 volumes of 2% aqueous acetic acid solution (106 g), stir at 80 ° C for 10 minutes, and centrifuge (3000 rpm, 10 minutes). ) Divide into 53g and separated liquid 10 6g.

[0014] In each of the washing steps described above, the separated liquids separated into 4 batches totaled 487 g, and this was concentrated to 100 g under reduced pressure, and then an aqueous sodium sulfide solution was added so that S was 200 mg per kg of untreated fluorocarbon. Stir for an additional 10 minutes to reduce the solubility of heavy metals released from the mouth. Sulfide.

However, since it is suspended as a very fine precipitate as it is, 10% polysalt / aluminum solution is added at a rate of lOOmL per kg of untreated euron, and after aggregation reaction, sodium hydroxide is added. Neutralize to pH 6-7 with an aqueous solution, then perform low-speed centrifugation (3000 rpm, 15 minutes) to obtain a supernatant treatment liquid, which is used as liquid fertilizer or its raw material.

The fourth washing was washed in the same manner to obtain 56 g of the fifth washing (residue).

[0015] The required components of fertilizer vary depending on the intended use, but what is commonly required is the nitrogen content, and generally 6% is the standard value. However, the nitrogen content of the mouth of scallop is about 2.5%, so it is practical to use the obtained slurry-like fertilizer and liquid fertilizer blended with other fertilizers.

In this example, the liquid and the solid were separated by centrifugation. However, since low-speed centrifugation is performed, it is considered that there is not much difference in data even by separation using a classic compression bag or the like.

[0016] For comparison, the same operation was performed using a 2% aqueous citrate solution and hot water (80 ° C) in place of the aqueous acetic acid solution.

Fig. 1 shows the cadmium content of each wash urine (residue) in terms of cadmium content (unit: mg) per unwashed uro lOOg, and Fig. 2 shows the cadmium concentration in the unwashed throat. Indicates the rate of decrease when the standard is used.

As can be seen from Fig. 1 and Fig. 2, the cadmium content in the residue was only slightly decreased in the case of hot water cleaning, but significantly decreased in the case of cleaning with an acetic acid aqueous solution and a citrate aqueous solution. I found out that

[0017] Further, even if heavy metals are reduced by the washing treatment, if the active ingredients of the fertilizer are discharged at the same time, they cannot be used effectively as a fertilizer. Figure 3 shows the change in the amount of nitrogen in the residue as the number of washings increases.

As can be seen from Fig. 3, the amount of nitrogen hardly changes when washed with hot water, but the amount of nitrogen decreases as the number of washings increases when washed with aqueous acetic acid and citrate. . However, when washed with a citrate aqueous solution, the phenomenon is significantly reduced to less than half, whereas when washed with an acetic acid aqueous solution, the amount of nitrogen in the unwashed mouth is reduced. 2. About 2/3 of the remaining 3% remains, which is more advantageous than a citrate aqueous solution and can be expected to be useful as a fertilizer.

[0018] Furthermore, in order to verify the effectiveness of the concentration of the acetic acid aqueous solution, the transition of the cadmium concentration of the residue (washing uro) when the scallop uro was similarly washed with 1% acetic acid aqueous solution, Table 1 shows the results compared to the case of using 2% aqueous acetic acid.

In Table 1, the analytical value of the Cd content of the residue (cleaning iron) is shown as it is.

[0019] [Table 1]

[0020] As can be seen from Table 1 and Fig. 3, the nitrogen content in the residue is 1.77% and the cadmium concentration is 3.57ppm at the stage of washing with 2% acetic acid aqueous solution three times. When the nitrogen content was 1.7%, the cadmium concentration was 1.32 ppm or less from the fertilizer regulations, but this standard value was not met.

On the other hand, the final residue obtained after washing 4 times had a nitrogen content of 1.52% and a cadmium concentration of 0.98 ppm, meeting the standard values.

By the way, the nitrogen content in the residue after the 5th washing is 1.31%, and the cadmium concentration is 0.26 ppm, 7 pieces.

[0021] As is clear from Table 1, the 1% aqueous acetic acid solution has poor cadmium extraction efficiency. A 2% aqueous acetic acid solution can be processed at a satisfactory level. However, if the acetic acid concentration is too high, it will be a cost or work burden when considering the subsequent treatment, so it is practical to use a 2% aqueous acetic acid solution.

[0022] The concentration of cadmium remaining in the supernatant after treatment with sodium sulfide (Na S) and polysalt aluminum (PAC) and the squeezed solution (Na S Figure 4 shows the cadmium concentration in the concentrated separation liquid before treatment with PAC.

As can be seen from Fig. 4, when the squeezed solution at the mouth is 18.8 ppm and cenoic acid is used The concentration of cadmium in the treatment solution is 1.41 ppm, compared to 0.45 ppm when acetic acid is used, which is much lower than that of citrate. From the standpoint of coagulation and removal of cadmium from the separated solution, Is more advantageous than citrate.

In other words, from the transition of the cadmium concentration and nitrogen amount in the washing port and the degree of removal of cadmium from the separated liquid, washing with acetic acid reduces the loss of nitrogen, and the washed residue and separated liquid are used as fertilizer. Is advantageous in some cases.

Claims

The scope of the claims

[1] After heat treatment by adding acetic acid aqueous solution to crushed fishery processing residue containing heavy metals

The method for producing an organic fertilizer, in which the step of separating the liquid substance to obtain a residue is repeated a plurality of times, and the resulting final residue is used as a fertilizer.

[2] After adding the sulfide brine solution to the vacuum concentrate obtained by concentrating the separated liquid separated in the above step under reduced pressure, the mixture is stirred, and then agglomerated precipitant is added, and the resulting supernatant is neutralized to obtain a liquid. The method for producing an organic fertilizer according to claim 1, wherein the fertilizer is used as a fertilizer.

[3] The organic material according to claim 1, wherein the heavy metal is cadmium (Cd), and the treatment with the acetic acid aqueous solution is repeated until the cadmium concentration in the final residue is 0.75 ppm or less at a nitrogen content of 1%. Fertilizer manufacturing method.

[4] The method for producing organic fertilizer according to claim 1, wherein the fishery processing residue is scallop roe.