KR20070008262A - Water treatment process using natural zeolites - Google Patents

Abstract

A method for economically treating a contaminated large water resource such as a dam or a lake by using well-known natural zeolites is provided. A method for treating contaminated water of dam and lake using natural zeolites comprises the process of sequentially injecting natural zeolites having different cation exchange capacities into the contaminated water in certain time intervals so that the natural zeolites are reacted with the contaminated water by spraying a first type natural zeolite having a relatively high cation exchange capacity onto the contaminated water such that the first type natural zeolite is naturally subsided into the contaminated water, injecting a second type natural zeolite having a lower cation exchange capacity than the first type natural zeolite into the contaminated water, and additionally injecting poly aluminum chloride for generating bridges between coagulated colloids and reducing coagulation time into the contaminated water such that the poly aluminum chloride is subsided into the contaminated water by gravity. At least one of the first type natural zeolite and the second type zeolite is clinoptilolite.

Description

Water treatment process using natural zeolites

1 is a chemical formula showing the general chemical composition of the zeolite used in the contaminated water treatment method of dams and lakes using the natural zeolite of the present invention.

2 is a chemical formula showing a frame of zeolite.

3 is a chemical formula of clinoptilolite, which is a kind of natural zeolite.

Figure 4 is a frame structure of the clinoptilolite and scanning electron micrograph.

5 is a diagram showing the chemical components of natural zeolites.

6 is a chemical formula explaining the hydrogenation and dehydrogenation of hydroxyl groups by reaction with water on the mineral surface.

7 is an explanatory diagram for explaining particulate matter of soil colloid in turbid water;

8 is an explanatory diagram for explaining repulsion of soil colloid.

9 is an explanatory diagram illustrating the action of zeolite on soil colloid;

10 is an explanatory diagram illustrating a bridge action of zeolites.

11 is a treatment chart for explaining a contaminated water treatment method for dams and lakes using natural zeolites of the present invention.

12 is a specific process chart of FIG. 11.

FIG. 13 is a photograph showing a contaminated water treatment method for dams and lakes using a natural zeolite of the present invention carried out experimentally. FIG.

14 is a photograph showing turbidity compared to raw water and treated water treated according to the present invention.

15 is a chart of raw water versus treated water treated in accordance with the present invention.

16 is a water quality test report performed by an authorized test organization of raw water subject to experimental treatment of the present invention.

17 is a water quality test report of the treated water treated in accordance with the present invention.

The present invention relates to a method for treating contaminated water in dams and lakes using natural zeolite, and more particularly, to a method for economically treating a large amount of contaminated water resources such as dams and lakes.

In Korea, due to industrialization, the outflow of polluted water from factories formed along rivers, etc. is intensifying. Existing crops and livestock wastes are causing serious water pollution on the narrow territory along with living sewage. If the generated eutrophication and green algae arrive at the lakes and dams, and if a typhoon of scale similar to cicada occurs again, the water pollution due to non-point sources such as turbidity including hardly decomposable organic matter, phosphorus and suspended earth is It is a very serious reality.

As an example, the recent Doam Dam in the Namhan River water system, along with the Imha Dam in the Nakdong River water system, called the first East Coast hydroelectric power plant in Korea, costing KRW 122.6 billion by requiring the closure of dams due to pollution, not only by local residents, civil society but also by local governments. Of course, since March 29, 2001, power generation disruption caused by the discontinuation of power generation has caused more than 10 billion won in losses per year. It is a serious case.

The high concentrations of nitrogen and phosphorus, which are the causes of eutrophication, have been pointed out that the effluent from Doam Dam is the major source of pollutants in the Songyang and Donggang waters, including Songcheon. The reason why the water quality of Doam Dam is not improved is Soils mixed with fertilizer and pesticides in highland vegetable complexes are influxing during heavy rains, but it is analyzed that they are not equipped with environmental basic facilities upstream of the dam.

The Doam Dam, which lost its self-cleaning capacity, discharges more than a second grade of water, but the sedimentation tank provided by the dam's self-purification facility is only 3 tons per second, which causes worsening water quality. In particular, during the dry season, the Songcheon water system is depleted, which causes ecosystem damage. Almost all dams and lakes in Korea show similar patterns.

Once contaminated lakes and dams are difficult to purify themselves due to the nature of the stagnant water system. In addition to maintaining ecosystems and water quality, such as lakes and dams, nutrients and turbidity are required to maintain the quality of dam discharged water. In the case of the target material in the lake dam, the biological process is followed by many processes for high efficiency purification due to constraints such as the time required for the application of the microorganism lake dam.

The contaminated water treatment method of dams and lakes using the natural zeolite of the present invention has been devised in view of such a problem, and is intended to provide a method for treating the pollution of a large amount of water resources using natural zeolites that are well known.

Hereinafter, the method for treating contaminated water of dams and lakes using the natural zeolite of the present invention together with the accompanying drawings, photographs, and diagrams of FIG. 1 will be described in more detail.

[Zeolite]

The mineral zeolite is defined as a crystalline hydrated aluminosilicate with a solid three-dimensional structure, and the zeolite in the pure sense has a specific gravity of about 2.0 to 2.3 and a refractive index of about 1.44 to 1.52 and a uniform size of about 3 to 20Å. I have a handwork,

About 50 kinds of natural zeolites and 150 kinds of synthetic zeolites for special industrial applications such as industrial catalysts or synthetic detergent enhancers are combined. Currently, about 200 kinds of zeolites having various pore structures are known.

The general chemical formula of the zeolite is shown in Figure 1, and the general chemical composition of the framework is shown in Figure 2. (In the drawing, M is a monovalent cation and D is a divalent cation.)

The basic structure of all zeolites is a (Si, Al) O ₄ skeleton in which each oxygen is shared by two tetrahedra, occupied by relatively large cations and water molecules, surrounded by interconnected cavities (surface pores). It has a structure.

Anion packing of AlO ₄ units is balanced by the presence of exchangeable cations. These ions can easily be replaced with other materials, for example heavy metal or ammonium ions. This phenomenon is called cation exchange, and the cations in zeolites are mainly free of cations such as sodium, potassium, calcium, and some additional cations such as magnesium, barium, strontium, iron, and water in the structure. It has properties such as substitution and reversible-dehydration property. That is, the porous framework of the zeolite enables the molecular sieve reaction for separating the molecular mixture according to the size and shape of the molecular compound.

Clinoptilolite, a type of zeolite with relatively high cation substitution ability, is also known as a powerful adsorbent for toxic gases such as hydrogen sulfide (H ₂ S) and sulfur dioxide (SO ₂ ). .

In particular, in the method of treating contaminated water in dams and lakes using the natural zeolite of the present invention, the domestic natural zeolite using clinoptilolite in Yeongil and Gimpo, Gyeongbuk, which is calculated from the three bases of the Neoplasia, was used as an experimental method. And providing an optimum treatment method as a process.

Clinoptilolite is excellent in terms of stability in domestic scale and quality, and can be said to have the most suitable general purpose industrially among developable species.

The approximate empirical formula of clinoptilolite is shown in FIG. 3, and FIG. 4 shows a typical skeletal structure and a scanning electron microscope photograph of mineral phase. Clinoptilolite is the most representative species among natural zeolites, and is a crystalline chemical or exchangeable cation. In the composition of a large variety of mineral phases.

Clinoptilolites developed in Yeongil and Gampo, Korea, are characterized by Ca-type clinoptilolite, Na-type clinoptilolite, and K-type clinoptil, depending on the nature of the exchange cation and the content ratio of Si / Al. It is divided into low light. In general, Ca-type clinoptilolite is dominant.

In addition to having the best cation exchange capacity among the minerals, zeolites selectively exchange cations and also exhibit selective selectivity with different preferences depending on the species. Small diameter zeolites are mainly used to improve water environment, and C.E.C (Cation Exchange Capacity) value and the type and content of exchangeable cations are important quality standards.

The chemical composition of the natural zeolite used as the treatment agent is shown in the diagram of FIG. 5 and consists mainly of silicic acid, aluminum oxide, iron oxide, magnesium oxide, sodium oxide, potassium oxide, and various values of CEC by chemical or mechanical processing. It can be configured to have a Cation Exchange Capacity (Cation Exchange Capacity) value, such techniques are well known in the art.

[Reaction Mechanism of Zeolite]

Adsorption or ion exchange of cations and anions plays a major role in the surface charge of minerals. Permanent charges generated by homomorphic substitution generally occur when atoms with small charges replace atoms with large charges in the lattice.

(Eg Al ₃ ⁺ Si ₄ ⁺ , Mg ₂ ⁺ Al ₃ ⁺ ) It has a negative value. This charge is electrically neutralized by alkali metal ions or alkaline earth metal ions in the structure. Oxides in contact with water (MgO, Al ₂ O ₃ , Fe ₂ O ₃ , SiO _2, etc.) have a hydroxide surface.

When the cracked surface reacts with water, the mineral surface has a negative or positive charge through the following reaction. This charge is determined by the hydrogenation or dehydrogenation of the hydroxyl groups on the surface as shown in FIG. 6 and is therefore sensitive to pH.

If the pH is lower than the point of zero charge (PZC), which is the pH at which the total charge on the surface of the mineral is zero, the negative ions can be adsorbed with a positive charge. Can adsorb a cation cation

The cations present in the lattice to neutralize the permanent charge of the zeolite can be exchanged for other ions by CEC in aqueous solution. In general, CEC is related to the adsorption pattern and volume in the zeolite, the type of cation being ion exchanged, the radius of the ion and the charge of the ion in the solution, and the selectivity of the cation exchange is determined by the Si / Al ratio and pore for each zeolite. It depends on the size and shape.

As shown in Fig. 7, the properties of turbid water particles, such as dams and lakes, exhibit anionic properties with molecules of various components constituting the soil colloidal particles. Looking at the water treatment reactor using a natural zeolite for turbid water treatment, as shown in Figure 8, it can be seen that the soil colloid has anion repulsive force.

The cation-substituted natural zeolite has a reaction structure that aggregates soil colloidal particles using (+) ions on a surface having a (-) charge, as shown in FIG. 9, and can be represented as shown in FIG. 10. Once the particles are aggregated by forming a bridge between the particle aggregates, the turbidity is reduced through reaggregation even if re-aggregation occurs. Therefore, it can be seen that it is desirable to create an environment so that this bridge is easily caused.

Experimental Example

On May 19, 2005, 18:00 to 21:00, the Doam Dam Settlement Site (one of 1,200ton × 2) was used for the treatment of contaminated water from dams and lakes using natural zeolite.

The material precipitated at the bottom of one of the two settlements (1,200ton) was subjected to aeration & overturn (turbidity 977NTU: field measurement) and compared with water treatment.

[Method of treating polluted water in dams and lakes using natural zeolite]

Specific processing methods are the same as those in the processing diagram of FIG. 11 and the process diagram of FIG.

Looking at the turbidity treatment process through ion substitution of the natural zeolite, which is the main part of the present invention, first, the natural zeolite TYPE I is sprayed with 100 ppm of natural zeolite TYPE I (100) and then settled for 110 minutes (110) for 60 minutes.

7 ppm injection (120) of natural zeolite TYPE II. At this time, in order to generate a bridge well and shorten the aggregation time, 12.5ppm P.A.C (Poly Aluminum Chloride), which was tested for stability in water treatment of a general water treatment plant, was injected (130) and then gravity settled (140).

Above, C.E.C., a kind of zeolite mineral group of tertiary tuff beds of neoplasia, which is relatively large in the east coast of Korea. Zeolite TYPE I, which has a high unit ion substitution ability of 200 or more, is processed in a natural state in which no chemicals are added to clinoptilolite,

C.E.C. selected from one of zeolites such as clinoptilolite. Selected zeolites having an ion-exchange capacity of 150 or more were used as zeolite TYPE II (Mg-IWAMILITE & IWAMILITE), and zeolite TYPE II was selected from C.E.C. If it has an ion substitution ability of 150 or more, it may be selected from the combined zeolites of the above-described elemental configuration, regardless of which component is provided.

The total amount of zeolite 20ppm is sufficient, but for the convenience of the field, 22ppm was sprayed in consideration of the loss caused by wind by direct spraying.

The photographs of FIG. 13 show the process of the field experiment.

Experimental Results and Analysis

Field experiments were carried out on Doam Dam Settlement Sites according to the method for treating contaminated water in dams and lakes using natural zeolites of the present invention.

During the pilot test, the experiment was conducted by measuring pH, turbidity, and TDS using a simple water quality measurement device in the field. The raw water for analysis was collected before the pilot test and used as a control of the treated water. The turbidity of the settlement during the experiment showed 977 NTU characteristics as a result of field measurement, but after 72 hours, it settled naturally and showed 720 NTU at the time of requesting the test. 14). Natural zeolite TYPE I, TYPE II 22 mg / l and PAC 12.5 mg / l were added to these settlements, and 12 hours of gravity settling was carried out to analyze the treated water. The collected hours were analyzed by Korea ENC, a national test laboratory other than the Institute. Dissolved oxygen content was analyzed by Wingkler method, turbidity was analyzed by turbidimeter (model 2100P, Hach), ABS, Cr6 +, T-N, T-P, etc. were analyzed by spectrophotometer (UV120, Shimatzu).

This increase in turbidity is due to C.E.C. It is considered that the use of different zeolites in combination increases the bridge between the soil colloids and the bridge of the composite strength increases the mutual adsorption.

The analysis results are shown in a diagram in FIG. 15, and the water quality analysis results in the water quality test report of raw water of FIG. 16 and the water quality test report of the treated water of FIG. 17 show that the drinking water standard is 10 ppm or less of nitrate nitrogen. In the case of organic phosphorus, it is much more stable than total-phosphorus regulation item, and COD shows 1.2ppm of treated water at 18.9ppm of raw water.

Of course, no heavy metal such as hexavalent chromium or cyan was detected, and no anionic surfactant was detected. In the case of turbidity, which was a problem in the first place, 0.57 NTU based on raw water 720 NTU treated water was able to show a sufficient turbidity removal effect.

The contaminated water treatment method of dams and lakes using the natural zeolite of the present invention as described above is applied to large-capacity lakes and dams in a difficult situation in water treatment other than turbidity, in which river water containing phosphorus and nitrogen is introduced, thereby using inexpensive natural zeolites. It is a useful invention that can significantly improve the physical properties of contaminated water.

Claims (3)

In the method of treating the contaminated water using zeolite, The treatment method is spontaneous sedimentation by sprinkling a natural zeolite of TYPE I having a relatively high ion exchange capacity (CEC), and then a natural zeolite TYPE II having a relatively low ion exchange capacity (CEC) compared to the natural zeolite of the TYPE I After additional injection, gravity infiltration by additional injection of PAC (Poly Aluminum Chloride) for the formation of bridges between aggregated colloids and shortening of the aggregation time is achieved. Method for treating contaminated water of dams and lakes using natural zeolite, comprising the step of injection reaction. The method of claim 1, At least one of the natural zeolites of the TYPE I and TYPE II is clinoptilolite, characterized in that the treatment of contaminated water of dams and lakes using natural zeolite. The method of claim 1, The natural zeolite TYPE I is C.E.C. After spraying 15 ppm adjacent value and spontaneously settling for 60 minutes having an ion-substitution ability of 200 or more, the natural zeolite TYPE II was obtained by C.E.C. A method of treating polluted water of dams and lakes using natural zeolite, wherein the P.A.C (Poly Aluminum Chloride) is injected with 12.5 ppm of adjacent values to inject a value of at least 150 ppm of ionic substitution.

Images