KR19980046307A - Method and apparatus for reuse by chemical treatment of regeneration water used for regeneration of NH₄ + saturated zeolite - Google Patents

Abstract

Zeolite is ion-exchanged with the zeolite to remove the ammonia, and then the ammonia attached to the zeolite is removed with zeolite regeneration water, and the ammonia in the zeolite regeneration water is subjected to air stripping to remove ammonia and to return it to the zeolite regeneration water. The regeneration apparatus of is a step of economically enabling zeolite regeneration by reusing the regeneration solution.

Description

Method and apparatus for reuse by chemical treatment of recycled water used for regeneration of zeolite saturated with NH 4 +

[Industrial use]

The present invention relates to a biological wastewater treatment method for removing nitrogen from wastewater, and more particularly, by filtering NH ₄ + in the wastewater with zeolite, and then chemically regenerating and recycling wastewater used for regeneration of saturated zeolite. The present invention relates to a reproduction method and an apparatus thereof. In the present invention, the wastewater is a name collectively referred to as sewage discharged from a general home, wastewater discharged from a factory, and general wastewater generated in a city.

[Private Technology]

When ammonia-containing wastewater is discharged to a river, the nitrifying microorganisms living in the river or lake consume oxygen in the process of nitrifying them, so the dissolved oxygen in the water is insufficient and the water bodies decay. In addition, high concentrations of ammonia are toxic to aquatic life in water bodies, which can destroy ecosystems. Many methods have been developed so far to remove ammonia causing these problems. These methods can be roughly divided into biological and chemical methods. The biological method involves a nitrification step in which ammonia is oxidized to nitric oxide in the aerobic state to NO ₃ −, followed by a denitrification reaction in which the NO ₃ − is converted to nitrogen gas (N ₂ ) in an oxygen free state. In nitrification, NH ₃ is converted into NO ₃ − in two steps by autotrophic Bacteria, which causes nitrification.

Stage 1 :

Step 2:

Total ^{_{reaction: NH 4 + + 2O 2 →}} NO 3 - + 2H + + H 2 O

The nitrate nitrogen produced in this step is blown into the atmosphere in the form of nitrogen gas by a denitrification reaction. At this time, denitrification requires sufficient carbon source, but if the carbon source is insufficient, it must be supplemented from the outside. Materials used as such carbon sources include methanol and acetic acid. However, since these are mostly expensive, this method is less economical.

Physical and chemical methods include breakthrough chlorine injection. This method is a process in which the ammonia nitrogen of waste water is removed to nitrogen through chemical reaction with chlorine. Almost 10 ammonia in this way

Although it can be removed near 0%, the removal effect is negligible if the waste water contains organic nitrogen or nitrate nitrogen. In addition, since the pH of the reaction zone and H + is lowered, the addition of a neutralizer such as lime is essential.

3Cl ₂ + 2 NH ₄ ⁺ N ₂ + 6HCl + 2H ⁺

In addition to these additional drug costs, dechlorination is necessary to remove toxic chlorine from the effluent. Although the ratio of ammonia to chlorine in the above equation is theoretically 7.6: 1, chlorine of 8: 1 or 10: 1 is required because chlorine is consumed by reacting with other substances in the waste water. In other words, 10 mg / L chlorine is required to remove 1 mg / L ammonium nitrogen. This method is necessary to remove low concentrations of ammonia nitrogen. Another method is the removal of ammonia by air stripping. It is a technique used to remove ammonia from wastewater, and the aeration method is modified. Ammonia ions in water are in equilibrium with NH 3 in the following equation.

NH ₃ + H ₂ O↔NH ₄ ++ OH-

Increasing the pH of the sewage shifts the equilibrium to the right, and the NH ₄ ⁺ ions change to NH ₃ . At this time, if the sewage is stirred, NH ₃ will fly into the air. At this time, pH should be maintained at 10.0 ~ 13.5, and adjust using lime. Here lime is precipitated in sludge and then recovered.

Another method is ion exchange. Removed using zeolite to selectively remove ammonium ions (NH ₄ ⁺ ). Zeolites naturally exist in nature and serve as cation exchange resins. Zeolite is ion selective for cationic ^{Cs + Rb + K + NH 4+} Ba + Sr + Na + Ca +2 is a general composition formula _{MO · Al 2 O 3 · mSiO} 2 · nH 2 O (M is an alkaline earth metal) . Natural zeolites are cation exchange resins, and are particularly selective for ammonia. When the wastewater is passed through a reactor containing zeolite, more than 90% of the ammonium ions are removed by ion exchange. This method has little effect of temperature and can be used in stone mills. However, zeolites must be treated once they have been saturated with ammonia. There are two treatment methods, a new zeolite and a regeneration method. In the exchange method, waste zeolites are classified as waste, which is difficult to treat and expensive to replace. The regeneration of zeolite is first separated from the zeolite with NH ₄ ⁺ using ions such as Na ⁺ , and then removed by chemical and biological methods. Thus, the regeneration of the zeolite is divided into biological regeneration and chemical regeneration. The biological method is to nitrate NH ₄ ⁺ to NO ₃ ⁻ using nitrifying bacteria, and then denitrify NO ₃ ⁻ to N ₂ . Since this method requires biological nitrification and denitrification, it is difficult to make Na ⁺ concentration more than 4%, pH is limited, and extra cost is required because denitrification requires an external carbon source. This method has the disadvantage of being time consuming. The chemical method has a fast regeneration time and is not affected by the concentration or pH of Na ⁺ , but various forms of by-products must be produced.

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a wastewater treatment method and apparatus capable of effectively removing ammonia from first wastewater, and secondly to remove ammonia from wastewater. An object of the present invention is to provide a method for effectively reusing a regeneration solution by effectively removing ammonia present in the regeneration solution for regenerating zeolite.

1 is a process diagram schematically showing a biological wastewater treatment process of obtaining and recycling stripping zeolite as an embodiment according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: zeolite reactor 2: zeolite to be regenerated

3: air stripping device 4: ammonia gas removal

5: biological reactor

In order to achieve the object of the present invention as described above, the present invention is to precipitate and / or biologically decompose organic matter in the waste water raw water, and to ammonia from the treated water by ion exchange the treated precipitated or decomposed treated water with zeolite In the biological wastewater treatment method for removing nitrogen, including the step of removing and returning, and removing the ammonia attached to the zeolite with zeolite regeneration water, the ammonia in the zeolite regeneration water by air stripping to remove ammonia And it provides a biological wastewater treatment method for removing nitrogen, characterized in that it is used as zeolite regeneration water again.

In another aspect, the present invention, the biological reaction tank for precipitating and / or biologically decomposing organic matter in the waste water, and the treated water precipitated or decomposed in the biological reaction tank with ionite to remove ammonia from the treated water and then return or discharge In the biological wastewater treatment apparatus for removing nitrogen comprising a zeolite reaction tank for removing ammonia attached to the zeolite with zeolite regeneration water, the ammonia in the zeolite regeneration water is air stripped to remove ammonia and then to the zeolite regeneration water. It provides a biological wastewater treatment apparatus for removing nitrogen, characterized in that it further comprises an air stiffing device to be returned for reuse.

The present invention also removes ammonia by ion-exchanging wastewater with zeolite, and removes ammonia by air stripping the zeolite reaction tank to remove ammonia attached to the zeolite with zeolite regeneration water, and ammonia in the zeolite regeneration water to remove ammonia. Provided is a regeneration apparatus of zeolite, including an air stripping apparatus to be conveyed to be reused with zeolite regeneration water.

In the wastewater treatment method and wastewater treatment apparatus of the present invention, the zeolite regeneration water preferably comprises Na ⁺ ions, the zeolite regeneration water is Na ⁺ concentration of 1 to 5% by weight, pH 10-14, regeneration flow rate 1 It is preferable that it is -20 BV / hr.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

When ammonia in the wastewater introduced from the biological reactor 5 into the zeolite reactor 1 reacts with the zeolite and ammonia adheres to the zeolite, an ammonia saturated zeolite is formed. Such saturated zeolites can be used continuously only after regeneration. After passing the regeneration solution through the zeolite, which is the regeneration target, NH ₄ ⁺ is dropped into the regeneration solution, and the regeneration solution is introduced into the ammonia air stripping apparatus (3), and the regeneration solution can be used again. By reducing the generation of by-products to solve environmental problems. At this time, the regeneration solution has a Na + concentration of 1-5% and maintains a pH of 10-14. The flow rate passes through the zeolite reactor while maintaining 1-20 BV / hr.

EXAMPLE

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only preferred embodiments of the present invention to aid in understanding the present invention, and the present invention is not limited to the following examples.

Table 1 shows the regeneration efficiency according to the concentration of NaOH. The use of NaOH increases the pH and increases the regeneration efficiency because Na ⁺ required during regeneration is entered. It is possible to use NaCl to further increase the concentration of Na ⁺ .

TABLE 1

Regeneration Efficiency of Zeolite According to NaOH Concentration

NH ₄ ⁺ desorbed into the regeneration solution enters the ammonia air stripping apparatus to degas the NH ₄ ⁺ . The degassing principle is to raise the pH to transform NH ₄ ⁺ into NH ₃ as described in Equation-1 below, and then discharge the liquid NH ₃ to the gas phase by air stripping.

NH ₄ ⁺ → NH ₃ + H ⁺ (Equation-1)

When degassing, the concentration of NaOH (or pH) is very important. The degassing efficiency according to NaOH concentration is shown in Table 2. This experiment measures the degassing efficiency by batch test when the initial ammonia concentration is 100 mg NH ₄ ⁺ -N / 1.

TABLE 2

Ammonia Degassing Ash Test According to NaOH Concentration

Another important factor is the flow rate during regeneration.

Table 3 shows the regeneration efficiency of removing NH ₄ ⁺ from the zeolite into the regeneration liquid phase and the degassing efficiency of NH ₃ in consideration of the flow rate during regeneration and NaOH concentration. According to this table, the regeneration efficiencies were 95%, 108% and 92% with NaOH concentrations of 0.3, 0.6 and 0.8N and the regeneration flow rates of 16.7, 8.3 and 6.25 BV / hr, respectively. %, 96%.

TABLE 3

Regeneration efficiency and degassing efficiency according to NaOH concentration and regeneration flow rate

The stripping tank has an acid period with fine holes, which continuously blows out the air for stripping. NH₄ ⁺The regeneration solution from which was removed was used to regenerate saturated zeolite again. NH for air stripping₃ Gas is generated. This gas is a source of odor and is restricted by the Air Pollution Control Act. This is NH₃Remove with a protective device.

The present invention passes the regeneration solution through the zeolite to be regenerated to allow NH ₄ ⁺ to fall into the regeneration solution, and then introduces the regeneration solution into the ammonia air stripping apparatus, thereby allowing the regeneration solution to be used again. Nitrogen removal is a solution to environmental problems that can be removed and easily removed ammonia.

Claims (7)

Precipitating and / or biologically degrading organics in the wastewater source water; The treated precipitated or decomposed treated water is ion exchanged with zeolite to remove ammonia from the treated water and then returned or discharged; Ammonia attached to the zeolite is removed with zeolite regeneration water; In the biological wastewater treatment apparatus for removing nitrogen comprising a process, And biological ammonia in the zeolite regeneration water to remove ammonia and use the same as zeolite regeneration water. The wastewater treatment method according to claim 1, wherein the zeolite regeneration water comprises Na + ions. The method of claim 2, wherein the zeolite regeneration water is Na ⁺ concentration of 1 to 5% by weight, pH 10-14, regeneration flow rate 1 ~ 15 BV / hr wastewater treatment method. A biological reactor for sedimenting and / or biologically degrading organic matter in the wastewater raw water; A zeolite reaction tank in which the treated water precipitated or decomposed in the biological reactor is ion exchanged with zeolite to remove ammonia from the treated water and then returned or discharged, and the ammonia attached to the zeolite is removed with zeolite regeneration water; In the biological wastewater treatment apparatus for removing nitrogen containing, And biologically stripping the ammonia in the zeolite regeneration water to remove the ammonia and return the same to be reused as the zeolite regeneration water. The wastewater treatment apparatus of claim 4, wherein the zeolite regeneration water comprises Na ⁺ ions. The wastewater treatment apparatus according to claim 5, wherein the zeolite regeneration water is Na ⁺ concentration of 1 to 5% by weight, pH 10 to 14, and regeneration flow rate of 1 to 20 BV / hr. A zeolite reactor for ion-exchanging wastewater with zeolite to remove ammonia and then removing ammonia attached to the zeolite with zeolite regeneration water; An air stripping apparatus for air stripping the ammonia in the zeolite regeneration water to remove the ammonia and to return the ammonia to reuse the zeolite regeneration water; Zeolite regeneration device comprising.