JP2007135491A - Heavy metal removal equipment - Google Patents

Abstract

An apparatus for removing heavy metals from a material containing harmful heavy metals, particularly an apparatus for efficiently removing heavy metals from food and food processing by-products to efficiently obtain food materials.
A harmful heavy metal comprising: means for bringing a material containing harmful heavy metals into contact with an aqueous organic acid or hydrochloric acid; means for heating the resulting mixture; and means for separating the heated mixture into a solid and a liquid That removes heavy metals from materials.
[Selection] Figure 1

Description

  The present invention relates to an apparatus for removing heavy metals from a material containing harmful heavy metals, and more particularly, to an apparatus for providing food materials by removing heavy metals from foods or food processing byproducts containing harmful heavy metals.

  Organic sludge such as food factory sludge, sewage sludge and human waste sludge, soil, bottom mud, livestock manure, fish and shellfish, and animals and plants can be reused as resources if they are purified. However, these materials are often contaminated with harmful heavy metals.

  For example, marine foods and by-products, waste liquids, wastes, etc. generated by processing marine foods include cadmium and other heavy metals that are harmful to the human body. Among them, scallop midgut (uro) and squid viscera (goro) are known to have high cadmium content. These parts have a high water content and are prone to rot and deterioration, causing serious problems such as environmental pollution at processing sites and increased processing costs.

  For this reason, it is necessary to remove harmful heavy metals from these materials in consideration of the environment and food safety and security. Examples of the removal treatment include decomposition of metallothionein by proteolytic enzymes, dissociation of salts by phosphoric acid or sulfuric acid treatment, and precipitation of free metal elements by electrolytic operation.

  However, these methods cannot completely remove heavy metals, and when the residue is used as a fertilizer, there are problems such as remaining heavy metals being mixed from spring water into tap water. Incineration and carbonization processes are also being carried out, but it is difficult to reflect the cost of the product in the price of the product, which puts pressure on production activities and threatens to continue. On the other hand, these marine food processing by-products contain unique aromas and umami ingredients, and it is desired to effectively use and recycle them as food materials.

  The present invention solves the above-mentioned conventional problems, and its object is to remove heavy metals from materials containing harmful heavy metals, particularly from foods and food processing by-products such as seafood. An object of the present invention is to provide an apparatus that efficiently removes heavy metals and efficiently obtains food materials.

The present invention provides a means for contacting a material containing harmful heavy metals with an organic acid aqueous solution or hydrochloric acid;
Means for heating the resulting mixture; and means for separating the heated mixture into a solid and a liquid;
An apparatus for removing heavy metals from a material containing harmful heavy metals is provided.

The present invention also provides means for bringing a food or food processing by-product containing harmful heavy metals into contact with an organic acid aqueous solution or hydrochloric acid;
Means for heating the resulting mixture; and means for separating the heated mixture into a solid and a liquid;
A food material production apparatus from which heavy metals are removed is provided.

The heavy metal removing device or the food material manufacturing device is
Means for removing heavy metals from the separated liquid;
May further be included.

The heavy metal removing means is preferably,
Means for contacting the separated liquid with the chelating resin;
Or means for neutralizing the separated liquid; and means for bringing the neutralized liquid into contact with the chelating resin;
It is.

  According to the apparatus of the present invention, harmful heavy metals can be almost completely removed from various materials by a simple operation. In particular, when foods and food processing by-products are processed by the apparatus of the present invention, the processed foods and the like are rendered harmless and can be reused as they are as food materials.

  The material to be treated by the apparatus of the present invention is a material containing heavy metals harmful to the human body. Such heavy metals include cadmium, chromium, copper, tin, mercury, manganese, molybdenum, nickel, lead, zinc and the like. In addition, the heavy metals referred to in the present invention include heavy metals alone and these compounds.

  Examples of the materials include organic sludges such as food factory sludge, sewage sludge and human waste sludge, soil, bottom mud, livestock manure, fish and shellfish, animals and plants. Preferred materials for processing with the apparatus of the present invention are food and food processing by-products.

  Examples of the food include at least one selected from marine products such as fish and shellfish, animals and plants, and examples of the food processing by-product include the internal organs of fish and shellfish that have been discarded so far. For example, the midgut line of the scallop shell (uro) and the squid internal organs (goro) are the targets of the treatment method of the present invention. Furthermore, a by-product generated when the food or food processing by-product is further processed as a raw material is also included in the food processing by-product. For example, the device of the present invention is also a residue obtained by boiling the internal organs of seafood, scallop shells, squid shells and the like to extract aroma components and umami components.

  FIG. 1 is a schematic diagram showing a configuration of a food material manufacturing apparatus according to an embodiment of the present invention. This apparatus is provided with a hopper 1, a metering feeder 2, a cutting pump 3, and an acid aqueous solution tank 4 as means for bringing food into contact with acid, and these are connected to a continuous heating device 5.

  The hopper 1 is an entrance for introducing a raw material such as food into the apparatus. Food or the like may be brought into contact with the acid aqueous solution in its original form, but it is preferable to cut or grind it in advance to an appropriate size. By doing so, the raw material moves smoothly in the apparatus, the contact area between the acid and the raw material is increased, and the extraction efficiency of heavy metals is improved. The hopper 1 may include a pulverizer from the above viewpoint. It should be noted that the extraction efficiency of heavy metals is improved when a material rich in oily components such as squid is removed before contacting with an organic acid aqueous solution.

  The raw material is put into the hopper 1, pulverized by a cutter or the like as necessary, and then sent out to the continuous heating device 5 at a predetermined speed by the quantitative feeder 2. If necessary, add water to the hopper. However, the amount of water needs to be determined with care so that the concentration of the acid aqueous solution in contact with the raw material does not depart from the effective range.

  The acid aqueous solution tank 4 has an acid aqueous solution adjusted to a predetermined concentration. A predetermined amount of the acid aqueous solution is supplied from the acid aqueous solution tank 4 to the continuous heating device 5 by a mechanism such as a siphon and a cock, or a quantitative feeder.

  An organic acid or hydrochloric acid is used as the acid. It is preferable to use an organic acid that is harmless to the human body. This is because if the organic acid is harmless to the human body, it is not necessary to remove the treated product when it is reused. Examples of organic acids include acetic acid, citric acid, malic acid, lactic acid, malonic acid, tartaric acid, succinic acid, ascorbic acid and the like. A particularly preferred organic acid is citric acid. These are certified as food additives. In addition, an organic acid may be used independently and may be used in mixture of multiple. For example, a plum extract obtained by boiling plum juice is rich in edible organic acids such as citric acid and can be used as the organic acid referred to in the present invention.

  The concentration of the organic acid aqueous solution is 0.1 to 10% (w / v), preferably 0.1 to 4%, more preferably 1.0 to 4.0%, still more preferably 1.0 to 2.0%. And If the concentration of the organic acid aqueous solution is less than 0.1%, the efficiency of extracting heavy metals from foods and the like is insufficient, and if it exceeds 10%, the efficiency of removing heavy metals from the extract is reduced.

  Hydrochloric acid may be used in place of the organic acid aqueous solution. This is because hydrochloric acid is neutralized with sodium hydroxide to form sodium chloride, which can be easily detoxified without removing it. The concentration of the aqueous hydrochloric acid solution is 0.1 to 14% (w / v), preferably 0.6 to 4.0%, more preferably 1.0 to 3.0%, and still more preferably 1.6 to 2.3. %. If the concentration of the aqueous hydrochloric acid solution is less than 0.6%, the efficiency of extracting heavy metals from foods and the like is insufficient, and if it exceeds 4.0%, the efficiency of removing heavy metals from the extract decreases.

  The continuous heating device 5 may have any structure as long as the mixed raw material and acid can be heated and held for a predetermined time. For example, a tank equipped with a heating and stirring device may be used. For example, the heating device has a configuration in which a space is provided in the outer peripheral portion of the tank and the heat medium S is circulated. When the solid content concentration is high, it is preferable to use a screw extrusion mechanism for the stirring device.

  The heating temperature is 60 to 110 ° C, preferably 70 to 90 ° C, more preferably 75 to 85 ° C. The heating temperature is appropriately determined within this range depending on the type of food to be treated. In general, when the heating temperature is less than 60 ° C., the metal extraction efficiency decreases or the treatment takes a long time. When the heating temperature exceeds 110 ° C., coloring of the processed food material becomes remarkable.

  The heating time is 1 to 120 minutes, preferably 3 to 60 minutes, more preferably about 5 to 20 minutes. The heating time is appropriately determined within this range depending on the type of food to be treated. Generally, when the heating time is less than 1 minute, the metal extraction efficiency decreases. Even if heating is performed for more than 120 minutes, an advantageous effect cannot be obtained.

  The apparatus of FIG. 1 has a drum screen 6, a screw press type dehydrator 7, an inclined screen 10, a centrifuge 11, and a filtration filter 12 as means for separating the heated mixture into solid and liquid. The solid-liquid separation means may be either a drum screen or a screw press type dehydrator depending on the type of food to be processed, and the order of use may be reversed. In addition to these, a suitable type of solid-liquid separation means such as a filter press may be used. As the drum screen and the inclined screen, for example, those commercially available from Toyo Screen Industry may be used.

  The heated mixture is washed with water on a solid-liquid separation screen. The solid remaining on the screen is collected in the container 15. You may remove a solid water | moisture content more completely using a belt press apparatus etc.

  You may perform a solid-liquid separation process in multiple times. At that time, the solid collected in the container is again passed through the drum screen and washed and dehydrated. A multi-stage solid-liquid separation mechanism provided with a plurality of drum screens, screw press dehydrators and the like may be used.

  The heavy metals contained in the untreated food and the like almost completely move to the aqueous solution and do not remain in the solid residue. Therefore, when an organic acid certified as a food additive is used for processing, the solid residue can be reused as a food material as it is. On the other hand, when hydrochloric acid is used for the treatment, the solid residue can be reused as a food material after neutralization by adding sodium hydroxide.

  The food material referred to in this specification broadly includes solids and liquids whose components may be ingested by the human body in the future. That is, raw materials for processed foods, livestock feed, fertilizers for agricultural products and the like are highly likely to be ingested by the human body in the future, and are included in the food material referred to in the present invention.

  In the case where the liquid separated from the solid is processed and reused as a food material, the apparatus of the present invention may further have a configuration described below.

  The apparatus of FIG. 1 has a neutralization tank 8 and an alkaline aqueous solution tank 9 as means for neutralizing the separated liquid. The aqueous solution that has passed through the screen is collected in the neutralization tank 8. This aqueous solution contains added acid, heavy metals extracted from untreated food, etc., aroma components and umami components. The extract is neutralized to pH 3.0 to 5.5 by adding an alkali as necessary. If neutralization is not performed so that the pH is 3.0 or more, the removal efficiency of heavy metals may be lowered. Further, when the pH is neutralized to 5.5 or more, precipitation occurs and most of the cadmium is contained in the precipitate.

  The alkaline aqueous solution tank 9 contains an alkaline aqueous solution adjusted to a predetermined concentration. A predetermined amount of the alkaline aqueous solution is supplied from the alkaline aqueous solution tank 9 to the neutralization tank 8 by a mechanism such as a siphon and a valve or a quantitative supply pump. When hydrochloric acid is used for the extraction treatment, sodium hydroxide is preferably used as the neutralizing alkali.

  The apparatus shown in FIG. 1 has a chelate resin column 13 as means for bringing the neutralized extract into contact with the chelate resin. The extract neutralized in the neutralization tank may be purified before being introduced into the chelate resin column to further remove fine solids.

  The chelate resin is not particularly limited as long as it is a resin having an iminodiacetic acid group or an iminodipropionic acid group and can be chelate-bonded to heavy metal ions at the carboxyl group. For example, a chelating resin such as a resin obtained by binding an iminodiacetic acid group or an iminodipropionic acid group to a porous crosslinked polystyrene substrate, a styrene / divinylbenzene copolymer, a carbamic acid resin, or the like is preferable.

  Specific examples of the chelating resin having an iminodiacetic acid group include “Diaion CR11” manufactured by Mitsubishi Chemical Corporation, “Amberlite IRC748” manufactured by Rohm & Haas, “Eporus MX-10” manufactured by Miyoshi Oil & Fats Co., Ltd., and Purolite International. Specific examples of “Purolite S930” manufactured by Co., Ltd. and chelating resins having iminodipropionic acid groups include “Eporus MX-8,8C” manufactured by Moritex Co., Ltd., “Sumichel” manufactured by Sumika Chemtex Co., Ltd., Asahi Glass Engineering Co., Ltd. Examples include “Aclean Z” manufactured by company, “Uniselec UR-10S” manufactured by Unitika Category, and “Purolite, Levacit” manufactured by Urano.

  Such chelate resins are heavy metal ions> alkaline earth metal ions> alkali metal ions in terms of metal ion scavenging ability, and have high selectivity for heavy metal ions. Thereby, even if an organic acid or ions derived from sodium chloride are contained in the extract, heavy metal ions can be selectively captured, and an extract from which harmful heavy metals are removed can be obtained.

  The liquid passing through the chelate resin column 13 is collected in the container 14. The liquid passing through the column does not contain a component harmful to the human body and can be used as it is as a food material extract.

  The food material extract refers to the liquid food material. However, semisolids and solids obtained by concentrating or drying food material extracts are also included in the scope of the present invention as food materials. Examples of the concentration method and the drying method include a vacuum concentration method using an evaporator and a global concentrator, a freeze drying method, a spray drying method, and the like.

  In the present specification, the treatment of food and the like has been specifically described, but organic sludge, soil, bottom mud, livestock excrement, fish and shellfish, animals and plants are treated in the same manner using the apparatus of the present invention. Can do.

  The following examples further illustrate the present invention, but the present invention is not limited thereto.

  An apparatus having the configuration shown in FIG. 1 was assembled. As the chelating resin, “Purolite S930” manufactured by Mitsubishi Chemical Corporation “Purolite International Co., Ltd.” was used.

  The acid aqueous solution tank was filled with 35% (W / V) hydrochloric acid, and the flow rate of hydrochloric acid was adjusted to 35 liters / hour. The alkaline aqueous solution tank was filled with 48% sodium hydroxide aqueous solution, and the outflow amount of the sodium hydroxide aqueous solution was adjusted to 35 liters / hour.

  The temperature of the continuous heating device was adjusted to 85 ° C., and the feed rate of the metering feed pump was adjusted so that the heating time of the raw material was 10 minutes in consideration of the length and flow rate in the continuous heating device. The flow rate of the clean water line was adjusted so that the washing water for the screen was about 6 to 10 liters / minute for the drum screen.

  We prepared scallops from Kushiro. The scallop shell contains about 100-120 ppm of cadmium by weight of dry matter. 500 kg of this scallop shell was put into a hopper, and the operation of the apparatus was started.

  The collected solid residue was dehydrated, dried and weighed. The cadmium content of the dried solid residue was measured by ICP method (vs dry matter weight). The cadmium content of the column passage liquid collected in the liquid recovery container was measured by ICP method (vs dry matter weight). These results are shown in Table 1.

  The solid residue and column passage liquid that had been subjected to demetalization treatment with the apparatus of the present invention contained almost no cadmium. Moreover, as a result of analyzing the components of the flow-through liquid, it was confirmed that a large amount of inosinic acid and glutamic acid, which are the main roles of umami, and taurine, glycine and alanine, which are the supporting roles of umami, were also included.

  Prepared squid goro from Wakayama Prefecture. Squid goro contains about 100-130 ppm cadmium by weight of dry matter. A solid residue and a column passage liquid were obtained in the same manner as in Example 1 except that 500 kg of the squid goro was used instead of scallop shell. Next, the solid residue was dried and weighed, and the cadmium content of the solid residue and the column passing solution was measured. These results are shown in Table 1. Moreover, as a result of analyzing the components of the flow-through liquid, it was confirmed that a large amount of inosinic acid and glutamic acid, which are the main roles of umami, and taurine, glycine and alanine, which are the supporting roles of umami, were also included.

  The acid aqueous solution tank of the apparatus used in Example 1 was filled with 20% (W / V) citric acid aqueous solution, and the outflow amount of the citric acid aqueous solution was adjusted to 50 to 100 liters / hour. The alkaline aqueous solution tank was filled with 48% aqueous sodium hydroxide solution, and the outflow rate was adjusted to 20 to 40 liters / hour.

  1000 kg of scallop shells from Kushiro, the same as in Example 1, were charged into the hopper, and the apparatus was operated in the same manner to obtain a solid residue and a column passing solution. Next, the solid residue was dried and weighed, and the cadmium content of the solid residue and the column passing solution was measured. These results are shown in Table 1.

  The acid aqueous solution tank of the apparatus used in Example 1 was filled with 50% (W / V) plum extract aqueous solution, and the outflow amount of the plum extract aqueous solution was adjusted to 100 to 200 liters / hour. The alkaline aqueous solution tank was filled with 48% aqueous sodium hydroxide solution, and the outflow rate was adjusted to 20 to 40 liters / hour.

  500 kg of scallop shells from Kushiro, the same as in Example 1, were charged into the hopper, and the apparatus was operated in the same manner to obtain a solid residue and a column passing solution. Next, the solid residue was dried and weighed, and the cadmium content of the solid residue and the column passing solution was measured. These results are shown in Table 1.

[Table 1]

It is a schematic diagram which shows the structure of the foodstuff raw material manufacturing apparatus which is one embodiment of this invention.

Explanation of symbols

1 ... Hopper,
2 ... Quantity feeder,
3. Cutting pump,
4 ... acid aqueous solution tank,
5 ... Continuous heating device,
6 ... drum screen,
7 ... Screw press dehydrator,
8 ... neutralization tank,
9 ... Alkaline aqueous solution tank,
10 ... inclined screen,
11 ... centrifuge,
12 ... filtration filter,
13 ... Chelate resin column,

Claims (7)

Means for contacting a material containing harmful heavy metals with an organic acid aqueous solution or hydrochloric acid;
Means for heating the resulting mixture; and means for separating the heated mixture into a solid and a liquid;
An apparatus for removing heavy metals from a material containing harmful heavy metals. Means for contacting foods or food processing by-products containing harmful heavy metals with aqueous organic acid or hydrochloric acid;
Means for heating the resulting mixture; and means for separating the heated mixture into a solid and a liquid;
A food material manufacturing apparatus from which heavy metals are removed. Means for removing heavy metals from the separated liquid;
The apparatus according to claim 1, further comprising: Means for removing the heavy metals,
Means for contacting the separated liquid with the chelating resin;
The apparatus of claim 3, wherein Means for removing the heavy metals,
Means for neutralizing the separated liquid; and means for contacting the neutralized liquid with the chelating resin;
The apparatus of claim 3, wherein   The food material manufacturing apparatus according to any one of claims 1 to 5, wherein the heavy metal is cadmium, zinc, copper, lead or mercury. The food material manufacturing apparatus according to any one of claims 2 to 6, wherein the food or food processing by-product is scallop shell or squid shell.

Images