JP5866708B2 - Phosphorus removal / recovery material, removal / recovery method, and soil conditioner using the same - Google Patents

Description

  The present invention relates to a technique for removing and recovering phosphorus from livestock effluent and the like, and a soil conditioner that effectively uses the technique.

  Currently, phosphorus resources are feared to be exhausted globally, and the price of phosphorus ore has soared more than six times over the past 20 years. Moreover, phosphorus ore is a resource that is rarely produced in Japan, and is currently 100% dependent on foreign imports. On the other hand, in closed water areas, there are problems such as river pollution caused by increased nutrient concentrations such as phosphorus and nitrogen, and fishery damage due to the occurrence of red tides in closed water areas. In addition, air pollution due to bad odor generated from livestock effluent containing phosphoric acid and ammonia, soil pollution due to pollutants in wastewater such as sewage and factory wastewater, and water pollution cannot be ignored. Under such circumstances, a technique for removing and recovering phosphorus and ammonia from various wastes has been devised.

  For example, Japanese Unexamined Patent Application Publication No. 2003-305461 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2003-305462 (Patent Document 2) describe a technique for removing ammonia and phosphorus from waste water using a porous material. Bamboo charcoal and coconut shell charcoal are mentioned as deammonification materials and dephosphorization materials. This technique is only intended for dephosphorization and deammonification by utilizing the simple adsorptivity of these porous materials.

It is well known that phosphate ions react with ammonium ions and magnesium ions to form magnesium ammonium phosphate (MgNH ₄ PO ₄ : 6H ₂ O: MAP) in aqueous solution. Several phosphorus recovery techniques based on the so-called MAP method have been proposed.

  For example, “Kyushu Okinawa Agricultural Center, Research result information, 2009: Removal and recovery technology of phosphorus from pork sewage using porcelain members” (Non-Patent Document 1) includes a ceramic star in a magnesium chloride solution. There is described a technique for removing and recovering phosphorus by injecting swine sewage into a reaction tank in which a shape member is immersed and forming MAP in a porous portion of the member.

  In addition, “Journal of Environmental Biotechnology, Vol.4, No.2, 109-115, 2005: Phosphorus recovery resource system by MAP method” (Non-patent document 2) includes the urine and the coexistence of ammonia and phosphoric acid. A technique is described in which a magnesium agent (magnesium chloride) is added to septic tank sludge to recover nitrogen and phosphorus as MAP.

  Furthermore, in JP 2011-92822 A (Patent Document 3), a phosphorus component and an ammonia component obtained by adsorbing and desorbing a phosphorus component and an ammonia component in water to be treated on an ion adsorbent, respectively, coexist. A method for recovering these components as MAP by adding alkali and magnesium ions to the solution is described.

  However, when removing and recovering phosphorus by the MAP method described above, there are difficulties such as requiring a reaction control operation for adjusting the pH to alkali and a special reaction apparatus in order to advance the MAP reaction. In addition, in the technology for removing and recovering phosphorus based on the conventional MAP method, as understood from the technology described in Non-Patent Document 1, generally, a complicated process for separating the generated MAP is required, or The product cannot be used effectively as it is.

JP 2003-305461 A JP 2003-305462 A JP 2011-92822 A

Kyushu Okinawa Agricultural Center, Research result information, 2009: Removal and recovery technology of phosphorus from piggery sewage using ceramic parts Journal of Environmental Biotechnology, Vol.4, No.2, 109-115, 2005: Phosphorus recovery resource system by MAP method

  An object of the present invention is to provide a new technique that can easily remove and recover phosphorus from waste such as livestock effluent, and that is also useful from the viewpoint of effective use of resources and environmental conservation.

  The present inventor has found that the above object can be achieved by using a plant porous carbide represented by bamboo charcoal and a small amount of magnesium ammonium phosphate supported thereon, and has derived the present invention.

Thus, according to the present invention, there is provided a phosphorus removal / recovery material characterized in that crystals of magnesium ammonium phosphate are supported on a plant porous carbide.
According to the present invention, there is further provided a method for removing and recovering phosphorus from a waste containing phosphoric acid, magnesium and ammonia, wherein the phosphorus removal and recovery material is put into the waste, and the removal and recovery agent A method comprising the step of growing magnesium ammonium phosphate crystals in and on the pores.

  Moreover, according to this invention, it produces | generates by implementing said phosphorus removal collection method, The soil improvement agent characterized by including a vegetable material and magnesium ammonium phosphate is provided.

According to the present invention, phosphorus can be recovered by simply introducing the phosphorus removal / recovery material of the present invention into the waste without requiring any reaction control operation such as pH adjustment or any special reaction apparatus.
In addition, the product obtained by carrying out the method for removing and recovering phosphorus according to the present invention can be effectively used as it is as a soil conditioner (organic fertilizer) without requiring a complicated separation step of MAP.

The phosphorus removal / recovery material of the present invention, which is made of modified bamboo charcoal prepared from bamboo waste material, is fired and then crushed to a small size, and then immersed in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions. A later photo is shown. SEM photograph after firing of the phosphorus removal and recovery material of the present invention comprising modified bamboo charcoal prepared from bamboo waste (1200 times), and SEM photograph after immersion in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions (1200) Times). It is a SEM photograph which shows that the crystal | crystallization of MAP is growing when the phosphorus removal collection material of this invention which consists of modified bamboo charcoal prepared from bamboo waste material is applied to pig manure. The SEM photograph of the phosphorus removal collection material of this invention prepared by carrying | supporting the MAP crystal | crystallization on commercially available bamboo charcoal is shown. The SEM photograph after immersing the phosphorus removal collection material of the present invention prepared by carrying MAP crystals on commercially available bamboo charcoal in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions is shown.

  According to the present invention, phosphorus can be recovered from waste as magnesium ammonium phosphate, and the waste targeted by the present invention includes a phosphorus component (phosphate ion), a magnesium component (magnesium ion), and an ammonia component. (Ammonium ion) is contained. Animal excreta (human waste) contains a magnesium component in addition to a phosphorus component and an ammonia component. Therefore, particularly suitable wastes targeted by the present invention include livestock drainage (livestock manure), human waste from toilets, and septic tank sludge.

  Preferable examples of the plant porous carbide used for constituting the phosphorus removal / recovery material of the present invention include wood-based carbides such as bamboo charcoal, charcoal, palm (coconut) shell charcoal, and as will be described later, Preferred is bamboo charcoal. Plant porous carbides such as rice husks and rice bran other than wood-based carbides can also be used.

  When plant porous carbide is obtained as a powder or granule, it can be used as a plate, rod, or sphere having an appropriate size (for example, a length or diameter of about 0.5 cm to 1 m). Hardened and used for removal recovery according to the present invention.

Compared to other plant porous carbides such as charcoal, there are many fine pores, the pores and surface area are large, and from the viewpoint of effective utilization of resources and environmental conservation described below, it is particularly preferable. , Bamboo charcoal. Bamboo charcoal generally has a pore diameter of about 10 to 30 nm and many surface areas of about 10 to 500 m ² / g.

  The phosphorus removal / recovery material according to the present invention is configured by supporting magnesium ammonium phosphate (MAP) crystals on the above-described plant porous carbide. The amount of MAP supported on the plant porous carbide is not limited, and an amount existing as a seed crystal (seed crystal) is sufficient, and when it is put into waste later, Due to the seed crystal, a MAP crystal grows. The amount of MAP supported on a vegetable porous carbide such as bamboo charcoal is, for example, 1 to 3% by weight with respect to the carbide, but is not limited thereto. Further, the MAP to be used does not have to be high in purity as marketed by a chemical / chemical manufacturer. For example, MAP may be used because it is readily obtained by reacting potassium dihydrogen phosphate, magnesium chloride and ammonium chloride in an aqueous solution. Alternatively, MAP having a low purity such as that obtained by the phosphorus recovery technique by the MAP method described above can also be used.

  According to a preferred embodiment of the present invention, when bamboo charcoal is used as the plant porous carbide, magnesium ammonium phosphate crystals may be supported on those manufactured or sold as bamboo charcoal, which will be described below. In this way, it is also possible to prepare a phosphorus removal / recovery material in which bamboo charcoal crystals of magnesium ammonium phosphate are supported on the bamboo material itself.

  When adjusting the phosphorus removal / recovery material in which MAP crystals are supported on bamboo charcoal from bamboo, the MAP penetrates into the surface and pores of the bamboo by immersing the raw bamboo into an aqueous solution of MAP. After being attached, the bamboo is taken out and dried, and then placed in a closed reactor (electric furnace or charcoal kiln) and fired. The higher the calcination temperature is, the larger the resulting bamboo charcoal pores are. However, if the calcination temperature is too high, the MAP crystals decompose and evaporate, so the calcination should be carried out at a temperature below 600 ° C. That is, when the phosphorus removal / recovery material of the present invention is prepared, the firing temperature of the bamboo material to which MAP is attached is 200 ° C. to less than 600 ° C., preferably 400 ° C. to less than 600 ° C. In contrast, it is generally said that good quality bamboo charcoal is said to be obtained by firing at 800 to 1000 ° C.

  As described above, when preparing a phosphorus removal and recovery material made of bamboo charcoal on which MAP crystals are supported, it is preferable to use bamboo waste material as a bamboo material. In recent years, there have been many damages to farmland and forests due to abnormal breeding of abandoned bamboo forests in satoyama. In addition, the disposal of the thinned bamboo waste generated during the construction of the bamboo forest is an issue. The use of bamboo waste material for the phosphorus removal and recovery material of the present invention provides a useful technique from the viewpoint of reducing the damage to the bamboo forest, preserving the environment and effectively utilizing resources.

  The phosphorus removal and recovery material of the present invention can also be directly prepared from those manufactured or sold as bamboo charcoal. In that case, the bamboo charcoal is immersed in an aqueous solution of MAP to attach crystals of MAP to the surface and pores of the bamboo charcoal, and then dried for use.

  Even when plant porous carbides other than bamboo charcoal such as charcoal, coconut shell charcoal, rice husk, rice bran, etc. are used, the plant porous carbide with an appropriate size and shape is immersed in an aqueous solution of MAP and then dried. Thus, the phosphorus removal / recovery material of the present invention in which MAP crystals are supported on these plant porous carbides can be obtained.

  The phosphorus removal / recovery material of the present invention obtained as described above is simply put in a suitable holding tool (for example, a washing net) and put into a liquid waste (such as livestock wastewater). The phosphorus contained in the waste can be removed and recovered as crystals of magnesium ammonium phosphate (MAP). That is, using ammonium ammonium phosphate previously supported on the phosphorus removal and recovery material as a seed crystal (seed crystal), crystals of magnesium ammonium phosphate grow in the pores and on the surface of the removal and recovery material. At this time, there is no need for pH adjustment or reaction control operation for generating MAP as in the case of phosphorus recovery by the conventional MAP generation method.

  The product containing the vegetable carbon carbide and magnesium ammonium phosphate (MAP) obtained by the phosphorus removal and recovery method of the present invention as described above can be used as it is as a soil conditioner or organic fertilizer. That is, after carrying out the method for removing and recovering phosphorus according to the present invention, the plant porous carbide on which the MAP crystals have grown is taken out of the holder (washing net or the like) (after drying if necessary), and is appropriately sized. It can be used as a soil conditioner (organic fertilizer) just by crushing it into corn and does not require a complicated separation process of the produced MAP.

  Bamboo charcoal and charcoal have been conventionally used as soil conditioners, and it is known that when mixed with soil, the air permeability and water permeability of the soil are improved. The plant material represented by bamboo charcoal constituting the phosphorus removal and recovery material of the present invention contains potassium. Therefore, the soil conditioner (organic fertilizer) obtained by carrying out the method for recovering phosphorus according to the present invention contains nutrients such as magnesium in addition to the three elements of phosphorus, nitrogen and potassium fertilizers. Compared to the conventional method of improving soil by spreading bamboo charcoal or the like in the soil itself, the effect of promoting the plant can be enhanced. Moreover, such a soil improvement effect cannot be achieved by a method using pottery or the like as seen in the conventional phosphorus recovery technology based on MAP generation.

EXAMPLES Hereinafter, although this invention is demonstrated along an Example, this invention is not restrict | limited by these Examples.
Example 1: Preparation and verification of phosphorus removal / recovery material from bamboo waste material 1% by weight aqueous solution of MAP (MgNH ₄ PO ₄ .6H ₂ O: manufactured by Wako Pure Chemical Industries, Ltd.) was put in a trash box (inner volume 45 L). Then, the bamboo waste material that was produced when the village forest was maintained was immersed for 24 hours.
The bamboo waste was removed from the trash can, dried at room temperature, and then fired in an electric furnace. The temperature was raised from room temperature, and it was confirmed that the temperature in the furnace was 500 ° C. to 550 ° C., and the bamboo waste material was fired to prepare a phosphorus removal and recovery material made of bamboo charcoal modified from the bamboo waste material.

  The phosphorus removal / recovery material composed of the modified bamboo charcoal obtained as described above is cut to a size of approximately 5 cm to 40 cm, and 5000 mL of an aqueous solution containing phosphate ions, magnesium ions, and ammonia containing um ions (that is, phosphorus It was immersed for 24 hours in an aqueous solution of 0.0728 mol of potassium dihydrogen acid, magnesium chloride, and ammonium chloride in 1000 mL of water, and the effect on a laboratory scale was verified.

  The photograph (a) of the modified bamboo charcoal after being crushed into small sizes after firing in FIG. 1 and the photograph (b) of the modified bamboo charcoal after being immersed in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions Indicates. Further, FIG. 2 shows an SEM photograph (a) of the modified bamboo charcoal after firing and crushing it to the same size, and the modified bamboo charcoal after immersion in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions. An SEM photograph (b) is shown.

  In the modified bamboo charcoal obtained by the above firing, a white portion considered to be a seed crystal of MAP is recognized, but as a whole, it is black as shown in FIG. 2), and it is understood from FIG. 2 (a) that it is porous. After immersing this in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions, as shown in FIG. 1 (b), the whole is white, and when observed with SEM, phosphoric acid is formed on the surface of the modified bamboo charcoal. It can be understood from FIG. 2B that magnesium ammonium crystals are growing. Thus, it was confirmed by experiments that the phosphate ion concentration and the ammonium ion concentration in the solution can be simultaneously reduced by using the phosphorus removal and recovery material made of the modified bamboo charcoal of the present invention.

Next, by applying the phosphorus removal and recovery material comprising the modified bamboo charcoal of the present invention to human waste discharged from a pig farm in Miyazaki Prefecture, the practical effect was verified. Seven aeration tanks are connected in series, and 8 m ³ / day of human waste is continuously circulated and processed in the first aeration tank (with an internal volume of 250 m ³ ) of the human waste treatment apparatus. 2 kg of phosphorus removal / recovery material made of modified bamboo charcoal was put into a laundry net, and charged and immersed. After the introduction, 5 kg and 10 days later, 1 kg each was pulled out of the aeration tank, taken out from the washing net and dried for observation.

  As in the case of the laboratory-scale detection described above, the phosphorus removal / recovery material composed of modified bamboo charcoal, which was initially black as a whole, became white when dried after immersion. The SEM photograph is shown in FIG. It was observed that the crystals of magnesium ammonium phosphate (MAP) were sufficiently grown in both cases after 5 days and 10 days, and it was confirmed that phosphorus in the drainage could be recovered as MAP crystals.

Example 2: Preparation and verification of phosphorus removal and recovery material from bamboo charcoal Commercial bamboo charcoal (manufactured by Tachibana Bamboo Co., Ltd., trade name: Yumetake charcoal) in 0, 1, 2 and 3 wt% MAP aqueous solution for 24 hours After immersion, the material for removing and collecting phosphorus was prepared by drying at room temperature. FIG. 4 shows SEM photographs of the obtained phosphorus removal and recovery materials for each concentration of MAP aqueous solution. As the concentration of the MAP aqueous solution increases, the white portion that becomes the seed crystal of MAP tends to increase, but it was confirmed that all retained the porous material derived from bamboo charcoal.

The obtained phosphorus removal / recovery material was immersed in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions for 10 days in the same manner as in Example 1. The initial phosphorus concentration was 100 ppm and the pH was 8.4. The removal rate (recovery rate) of phosphorus at concentrations of 0, 1, 2 and 3% by weight of the MAP aqueous solution used for the preparation of the removal and recovery material was 31%, 46%, 50% and 51%, respectively. As the removal rate increased, the pH decreased, and in the case of the phosphorus removal and recovery material prepared at a MAP concentration of 3% by weight (recovery rate of 51%), the pH was changed from the initial 8.4 to 7.5. FIG. 5 shows an SEM photograph of the phosphorus removal and recovery material after immersion in an aqueous solution containing phosphate ions / magnesium ions / ammonium ions. According to the removal rate of phosphorus described above, MAP crystal growth is observed, and even when MAP is directly supported on bamboo charcoal, phosphate ions and ammonium ions in the solution can be removed and recovered as MAP crystals. confirmed.

Claims (4)

  A method for producing a phosphorus removal and recovery material using bamboo as a raw material for plant porous carbide, wherein the bamboo is immersed in an aqueous solution of magnesium ammonium phosphate and then fired at a temperature of 200 ° C. to less than 600 ° C. A method for producing a phosphorus removal and recovery material, characterized in that bamboo charcoal in a state where crystals of magnesium ammonium oxide are supported is obtained.   A method for removing and recovering phosphorus from a waste containing phosphoric acid, magnesium and ammonia, wherein the phosphorus removal and recovery material produced by the production method according to claim 1 is introduced into the waste, and the phosphorus is removed. A method for removing and recovering phosphorus, comprising a step of growing magnesium ammonium phosphate crystals in the pores and on the surface of the recovery material without adjusting the pH to alkali.   The method for removing and recovering phosphorus according to claim 2, wherein the waste is livestock drainage.   A method for producing a soil improver, characterized in that bamboo charcoal carrying crystals grown with magnesium ammonium phosphate is obtained by carrying out the method according to claim 2 or 3.