KR100770670B1 - Carrier for treatment of organic/inorganic complex contaminants - Google Patents

Abstract

A complex carrier for treating organic/inorganic mixed pollutants is provided to remove simultaneously organic pollutants and inorganic pollutants, by immobilizing synthetic zeolite and powder type activated carbon on Na-alginate. A complex carrier for treating wastewater is formed in a bead shape having a diameter of 1-5 mm. The complex carrier is prepared by mixing Na-alginate, synthetic zeolite, and powder type activated carbon and hardening the mixed materials in a 2-6% of CaCl2 solution. The complex carrier is used to treat simultaneously inorganic pollutants and organic pollutants. A permeable reactive barrier contains the complex carrier as a porous medium body.

Description

Carrier for treatment of organic / inorganic complex contaminants}

1 is a schematic diagram of the installation of a permeable reaction wall at the site scale.

2 is in the form of a ZAC-44 bead.

Figure 3 is a concentration change curve of the water-soluble benzene over time by the adsorption reaction of ZAC-44 bead.

Figure 4 is a concentration change curve of the water-soluble toluene over time by the adsorption reaction of ZAC-44 bead.

5 is a concentration change curve of zinc over time by adsorption reaction of ZAC-44 bead.

The present invention relates to a composite carrier for treating organic / inorganic mixed contaminants, and more particularly, to a composite carrier for wastewater treatment including Na-alginate, synthetic zeolite, and powdered activated carbon.

Research on wastewater treatment techniques has been actively conducted, and various types of adsorbents have been developed and used. For example, divalent heavy metals such as Zn and Cd using hematite (Jeon et al., Water research, Vol 38: 2499-2504), and various heavy metals such as Pb and Cu using gellan gum gel beads (Lazaro et al. , Water research, Vol 37: 2118-2126), Hg and Cd with Ca-alginate (Arica et al., Journal of Hazardous Materials, B109: 191-199), Cd with alginate and silica gel (Rangsayatorn et al. , Environment International, Vol 30: 57-63). On the other hand, the development of adsorbents has been actively studied for organic contaminants, for example, adsorption and removal of phenol using a complex of Ca-alginate and powdered activated carbon (Jorda and Mijangos, Separation science and technology, Vol. 38, No. 8: 1851-1867). , Adsorption characteristics study on complex pollutants (Humic acid, gallic acid, methylene blue, p-Chlorophenol) composed of various organic materials (Lin et al., Journal of Hazardous Materials, Vol 120: 237-241) can do. However, most of the adsorbents to date have been able to remove a single species of contaminants and lack the ability to simultaneously remove organic / inorganic mixed contaminants.

Accordingly, the present inventors have made diligent research efforts to overcome the problems of the prior art, in the case of a composite carrier for wastewater treatment containing Na-alginate, synthetic zeolite and powdered activated carbon, aromatic hydrocarbon The present invention was completed, confirming that it is possible to efficiently remove mixed wastewater composed of inorganic contaminants such as heavy metals as well as organic contaminants as a system compound.

Therefore, the main object of the present invention is to develop a new composite carrier (ZAC-44 bead) which simultaneously removes organic / inorganic contaminants by immobilizing synthetic zeolite and powdered activated carbon in Na-alginate. will be.

The present invention can be regarded as belonging to the field of "wastewater treatment technology" as a technology for developing a carrier that efficiently removes mixed wastewater composed of organic pollutants such as aromatic hydrocarbons as well as inorganic pollutants such as heavy metals.

According to one aspect of the present invention, the present invention provides a composite carrier for wastewater treatment comprising Na-alginate, synthetic zeolite and powdered activated carbon. The composite carrier of the present invention is prepared by mixing synthetic zeolite and powdered activated carbon in Na-alginate dissolved in sterilized distilled water, and the inventor named ZAC-44 bead. When preparing the ZAC-44 bead of the present invention, the content of the powder is preferably 3 to 5 g of activated carbon, 8 to 12 g of Na-alginate powder, 3 to 5 g of synthetic zeolite, and 400 ml of distilled water. More preferably, it has a component content of 4 g of powdered activated carbon, 10 g of Na-alginate powder, 4 g of synthetic zeolite, and 400 ml of distilled water. Within the above component content, ZAC-44 bead exhibited excellent adsorption capacity and highest hardness, and did not break or deform when the carrier was regenerated.

In the composite carrier for wastewater treatment of the present invention, the composite carrier is preferably a composite carrier, characterized in that beads having a diameter of 1 to 5 mm are formed using 2.0 to 6.0% of CaCl ₂ solution. . When the concentration of CaCl ₂ solution is less than 2.0%, it is difficult to maintain a bead form in the formation of the carrier. When the concentration of the CaCl ₂ solution is more than 6.0%, the surface of the carrier is not formed smoothly, and the powder activated carbon is rough on the surface of the carrier. In addition, when the diameter of the carrier was larger than 5 mm, the gap between the carriers was large, so that the adsorption treatment efficiency was low. More preferably, 4.0% CaCl ₂ solution is used to form a carrier having a diameter of 4 mm. The CaCl ₂ solution was found to have the highest hardness when the concentration was 4.0%. The surface of the carrier was also smoothly formed. When the diameter was 4 mm, the adsorption capacity and hardness of the composite carrier were the most appropriate. In the present invention, by mixing the synthetic zeolite and powdered activated carbon in the Na- alginate solution, the adsorbents of the powder state in the form of a carrier to maintain a certain level of hardness, it is characterized in that it is easy to reuse or regeneration after absorption do.

In the preparation of the composite carrier, a difference occurs in the hardness of the carrier depending on the Na-alginate powder content. In the present invention, 10 g of Na-alginate powder was dissolved in 400 ml of distilled water (DI water), and 20 g of CaCl ₂ powder was dissolved in 500 ml of distilled water. If the ratio of Na-alginate to distilled water is lower than this, it takes a long time to harden and it is easy to be destroyed after hardening. At higher ratios, on the other hand, the viscosity becomes larger and does not fall into the CaCl ₂ solution in the burette and is not produced spherically.

According to another aspect of the present invention, the present invention provides a wastewater treatment method characterized by simultaneously treating the inorganic and organic contaminants using the composite carrier. Preferably, the present invention provides a wastewater treatment method for simultaneously treating inorganic pollutants including heavy metals and aromatic hydrocarbon-based organic pollutants such as benzene and toluene using the composite carrier. In the composite carrier of the present invention including synthetic zeolite, it is possible to simultaneously process organic / inorganic complex contaminants by mixing synthetic zeolite with excellent heavy metal adsorption capacity and powdered activated carbon having excellent adsorption capacity with aromatic hydrocarbon organic pollutants such as benzene and toluene. Proved.

According to another aspect of the present invention, the present invention is to expand the applicability of the composite carrier (ZAC-44 bead) to toluene and zinc (Zn) using a one-dimensional column reactor (heavy metal and BTEX (Benzene, It can be used for the treatment of complex industrial wastewater containing Toluene, Ethylbenzene, m, p-Xylene, o-Xylene). In addition, after the permeable reactive barrier (PRB) is installed in the free-surface aquifer in a two-dimensional model or on a site scale, it can be used as a content for adsorption removal, that is, a carrier (Fig. 1). ). In the present invention, the permeation reaction wall is a free surface aquifer, when the groundwater polluted cloud moves by the groundwater flow, the porous medium having high permeability and adsorption is installed in the direction perpendicular to the flow direction, and then guides the polluted cloud to pass through the adsorption or biodegradation. By other mechanisms, such as refers to walls that reduce the concentration of polluted clouds. Preferably, the water-permeable reaction wall of the present invention includes two types of continuous walls (Continuous PRBs) and a funnel & gate system, and the funnel & gate system is illustrated in FIG. 1. Funnel & Gate system is equipped with a guide barrier to guide the flow of contaminants into the ground. Such a system is economical by greatly reducing the area of the reactants, while increasing the contact speed of the reactants of the contaminants, thereby increasing the wall thickness so that sufficient contact can occur. Funnels include slurry walls such as soil-bentonite slurry walls, cement-bentonite slurry walls, diaphragm walls, steel sheets, geosynthetic sheets, Sheet piles such as wood sheet piles are used.

According to another aspect of the present invention, the present invention comprises the steps of dissolving Na-alginate in sterile distilled water to prepare a Na-alginate solution; Mixing the synthetic zeolite and powdered activated carbon with the prepared Na-alginate solution; And dropping a Na-alginate solution mixed with synthetic zeolite and powdered activated carbon into a CaCl ₂ solution to form beads.

Actual industrial wastewater can often exist in the form of mixed pollutants of heavy metals and organic pollutants. In this case, it is necessary to develop an adsorbent that simultaneously removes organic and inorganic pollutants. However, most of the researches on the development of adsorbents conducted so far have been limited to the removal of inorganic contaminants such as heavy metals or organic contaminants such as benzene and phenol. Therefore, in the present invention, a new composite carrier (ZAC-44 bead) is developed by immobilizing synthetic zeolite and powdered activated carbon on Na-alginate to remove organic / inorganic contaminants at the same time. .

Hereinafter, the present invention will be described in more detail with reference to Examples. Since these examples are only for illustrating the present invention, the scope of the present invention is not to be construed as being limited by these examples.

Experimental Materials and Equipment

Na-alginate powder (Sigma-aldrich, Korea), powdered activated carbon (Sigma-aldrich, Korea), synthetic zeolite (Jishim tech, Korea) and CaCl ₂ powder used in the present invention are those that can be commonly obtained in Korea Used. HPLC (Young-Lin Instruments co., Korea) was used for the adsorption capacity for toluene, and ICP (Perkin elmer inc., USA) was used to measure the liquid phase concentration of zinc. Air shaker (Daehan Scientific co., Korea) was used for the material reaction.

Example  One. Complex  ( ZAC -44 bead Manufacturing

1) Dissolve 10g of powdered Na-alginate in 400 mL of sterile distilled water to make Na-alginate solution.

2) Inject 4 g of synthetic zeolite and powdered activated carbon into the prepared 400 mL Na-alginate solution and mix homogeneously for about 20 hours.

3) Na-alginate solution mixed with synthetic zeolite and powdered activated carbon was dropped into a 500 mL solution of 0.5% CaCl ₂ using a burette to form a dark gray 4 mm diameter beads (ZAC-44 bead). 2a and b).

Example  2. Adsorption test of benzene, toluene and zinc

Adsorption tests on zinc, benzene and toluene were carried out using ZAC-44 bead as a composite carrier, and the test procedure was as follows.

1) Add 8 g of ZAC-44 bead to a 250 mL flask, and inject 250 mL of benzene or toluene solution at an initial concentration of about 600 mg / L, and seal the flask inlet in a short time using a Teflon stopper.

2) Take an aqueous sample at regular intervals while stirring in a sealed flask air shaker and measure the liquid concentration by HPLC (High performance liquid chromatography).

3) The adsorption test is carried out in the same way as in 1) -3) for zinc, but the reaction is performed by adding 20 g of ZAC-44 bead to 80 mL of the initial concentration of 1000 mg / L zinc solution. Measure the concentration.

Experimental Results 1. Adsorption Removal Effect of Benzene or Toluene

1) The decrease in the concentration of water-soluble benzene or toluene with time is shown in Figures 3 and 4, the initial concentration of about 600 mg / L after the reaction 5 hours after the reaction of benzene about 42% of the initial concentration, toluene initial About 50% of the concentration was removed and after 3 days benzene was about 45%. Toluene was removed about 60%.

2) The toluene removal rate of ZAC-44 bead is about 11.25 mg / g, which is very high.

Experimental Results 2. Adsorption Removal Effect of Zinc

1) The decrease in concentration of zinc solution with time is shown in Figure 5, and after 6 hours of reaction, about 70% of the initial concentration was removed, showing a gentle decrease in concentration after 1 day. It can be seen that 80% of zinc has been adsorbed and removed.

2) The zinc removal rate of ZAC-44 bead is about 3.2 mg / g, which is relatively lower than that of toluene, but it indicates the possibility of adsorption on heavy metals.

As described above, according to the present invention, a new composite carrier is developed by immobilizing synthetic zeolite and powdered activated carbon on Na-alginate to remove organic / inorganic contaminants at the same time. In addition, on-site scale is expected to be utilized as a carrier for adsorption removal to be introduced into the permeable reaction wall in the free surface aquifer.

Claims (5)

Na-alginate, synthetic zeolite and powdered activated carbon were mixed and cured in 2-6% CaCl ₂ solution to form beads of diameter 1-5 mm. Complex carrier for wastewater treatment. delete Wastewater treatment method comprising the simultaneous treatment of inorganic and organic contaminants using the composite carrier of claim 1. Permeable reactive barrier comprising the composite carrier of claim 1 as a porous medium. Dissolving Na-alginate in sterile distilled water to prepare a Na-alginate solution; Mixing the synthetic zeolite and powdered activated carbon with the prepared Na-alginate solution; And dropping a Na-alginate solution mixed with a synthetic zeolite and powdered activated carbon into a CaCl ₂ solution to form beads.

Images