KR0128133B1 - Method for treatment of wastewater generated during stainless manuracturing - Google Patents
Method for treatment of wastewater generated during stainless manuracturingInfo
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- KR0128133B1 KR0128133B1 KR1019940038259A KR19940038259A KR0128133B1 KR 0128133 B1 KR0128133 B1 KR 0128133B1 KR 1019940038259 A KR1019940038259 A KR 1019940038259A KR 19940038259 A KR19940038259 A KR 19940038259A KR 0128133 B1 KR0128133 B1 KR 0128133B1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
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Abstract
Description
제1도는 종래방법의 공정도.1 is a process chart of the conventional method.
제2도는 본 발명의 공정도.2 is a process diagram of the present invention.
제3도는 약품투입에 따른 pH변화를 나타낸 그래프이다.3 is a graph showing the pH change according to the drug injection.
본 발명은 스텐레스 제조공정에서 발생하는 폐수의 처리방법에 관한 것이다. 스텐레스 제조공정에서는 표면처리를 위해, 불산, 황산, 질산 등의 강산을 사용하기 때문에 중금속이 많이 함유되어 있고, 폐수가 강산이기 때문에 이를 처리하지 않고 방류하면 수질오염을 일으킨다. 따라서 스텐레스 제조공정에서 발생하는 폐수(이하 스텐레스 폐수라 칭함)를 정화 처리하는 것은 필수적이다.The present invention relates to a method for treating wastewater generated in a stainless steel manufacturing process. The stainless steel manufacturing process uses heavy acids such as hydrofluoric acid, sulfuric acid, and nitric acid for surface treatment, and contains a lot of heavy metals. Since wastewater is a strong acid, discharge of water without treatment causes water pollution. Therefore, it is essential to purify the wastewater generated in the stainless manufacturing process (hereinafter referred to as stainless wastewater).
종래의 스텐레스 폐수처리 방법은 제1도와 같았다. 즉 제1도에서 폐수는 조정조를 거쳐 제1, 2반응조에 들어가게 되는데, 이때 1, 2반응조에서 소석회가 첨가된다. 소석회 첨가에 의해, 스텐레스 폐수는 중화되며, 이때 중금속도 함께 불용성 물질이 된다. 불용성 고형물은 중력 침전조에서 침전분리되며, 침전된 슬러지는 슬러지저장조와 탈수기를 거쳐 외부로 배출된다. 한편 침전조에서 상등액은 제3반응조로 유입되는데, 이때 상등액의 pH가 높기 때문에 염산을 투입하여 중화시키며, 또한 포리머(응집제)를 첨가한다. 부유물질이 포리머에 의해 플록 생성조에서 플록(Floc)이 되면, 이것들을 침전조로 보내어 침전시킨다. 침전조의 상등액은 모래 여과기를 거쳐 방류된다. 이때 모래 여과기의 역세수(혹은 세척수)는 중화조로 다 시들어 간다.The conventional stainless wastewater treatment method is the same as FIG. That is, in FIG. 1, the wastewater enters the first and second reaction tanks through the adjustment tank, in which the lime is added in the first and second reaction tanks. By adding slaked lime, the stainless wastewater is neutralized, with the heavy metals becoming insoluble. Insoluble solids are precipitated in the gravity settling tank, and the sludge is discharged to the outside through the sludge storage tank and dehydrator. On the other hand, the supernatant from the settling tank is introduced into the third reaction tank. At this time, since the pH of the supernatant is high, hydrochloric acid is added and neutralized, and a polymerizer (coagulant) is added. When the suspended solids are floc in the floc generating tank by the polymer, they are sent to the settling tank for precipitation. The supernatant of the settling tank is discharged through a sand filter. At this time, the back washing water (or washing water) of the sand filter goes back to the neutralization tank.
그러나, 종래방법에 의한 경우, 슬러지가 많이 발생하고 폐수중의 불소농도가 법 기준치(15ppm)을 초과하는 문제점이 있었다.However, according to the conventional method, there is a problem that a lot of sludge occurs and the fluorine concentration in the wastewater exceeds the legal standard value (15 ppm).
본 발명의 목적은 종래방법의 결점을 해소하여, 슬러지 발생이 적고 불소농도가 법 기준치 이하로 처리되는 방법을 제공하고자 하는 것이다.An object of the present invention is to solve the drawbacks of the conventional method, to provide a method in which sludge is generated less and the fluorine concentration is treated below the legal standard.
이하 본 발명에 대하여 설명한다.Hereinafter, the present invention will be described.
본 발명의 공정은 제2도에 도시된 바와같다.The process of the present invention is as shown in FIG.
제2도에 의거 본 발명을 설명하면, 조정조를 거쳐 제1반응조에 들어온 폐수에 Mg(OH)2를 100,000-150,000mg/ℓ 투입하고, 제2반응조에서는 Na(OH)를 투입하여 pH를 8.0-9.0이 되도록 조정한다. 이때 스텐레스 폐수는 중화되고 이 과정에서 생성된 불용성 고형물은 중력침전조에서 첨전분리되며, 침전된 슬러지는 슬러지 저장조와 탈수기를 거쳐 외부로 배출된다.Referring to the present invention according to FIG. 2 , 100,000-150,000 mg / l of Mg (OH) 2 is added to the wastewater introduced into the first reactor after the adjustment tank, and Na (OH) is added to the pH of 8.0 in the second reactor. Adjust it to -9.0. At this time, the stainless wastewater is neutralized, and the insoluble solids generated in this process are sedimented and separated in the gravity settling tank, and the precipitated sludge is discharged to the outside through the sludge storage tank and the dehydrator.
한편, 침전조에서 상등액은 제3반응조로 유입되는데, 이에 소석회 500-1000ppm과 알럼(Alum) 300-700ppm을 투입하여 교반한 후, 황산으로 pH를 7.0-7.5로 조정한 후 다시 교반한다. 제4반응조에서는 고분자 응집제(포리머)를 투입, 교반하여, 부유물질이 포리머에 의해 플륵(Floc)생성조에서 플록이되면, 이것들을 침전조에 보내어 침전시킨다. 침전조의 상등액은 모래 여과기를 거쳐 방류된다.On the other hand, the supernatant from the settling tank is introduced into the third reaction tank, 500-1000ppm calcined lime and 300-700ppm of Alum (Alum) was added and stirred, after adjusting the pH to 7.0-7.5 with sulfuric acid and stirred again. In the fourth reaction tank, a polymer flocculant (polymer) is added and stirred, and when the suspended solids are floc in the floc production tank by the polymer, they are sent to the precipitation tank for precipitation. The supernatant of the settling tank is discharged through a sand filter.
본 발명의 방법과 종래방법의 차이점은, 종래방법에 있어서는 제1, 제2반응조에 소석회를 투입하는데 반하여, 본 발명에 있어서는 제1반용조에서 Mg(OH)2를 제2반응조에서 Na(OH)를 투입한다는 점과, 종래방법에 있어서는 제3반용조에서 HCl를 투입함에 반하여, 본 발명에 있어서는 제3반응조에서 소석회, 알럼(Alum) 및 황산을 투입한다는 것이다.The difference between the method of the present invention and the conventional method is that in the conventional method, slaked lime is added to the first and second reaction tanks, whereas in the present invention, Mg (OH) 2 is added to the first reaction tank and Na (OH) is added to the second reaction tank. ), And in the conventional method, while adding HCl in the third semi-bath, in the present invention, slaked lime, alum and sulfuric acid are added.
본 발명에서 제1반응조에 종래 약품인 Ca(OH)2대신에 Mg(OH)2를 사용한 것은 다음과 같은 이유에서 이다. 제3도는 NaOH, Ca(OH)2투입량에 따른 pH변화를 나타낸 것이다. 제3도에 의하면, pH 7.5 이하에서는 NaOH와 Mg(OH)2를 투입한 것이 Ca(OH)2를 투입한 것에 비해 스텐레스 폐수에 대한 중화능력이 큰 것으로 나타났다. 특히 Mg(OH)2가 Ca(OH)2에 비해 중화능력이 큰 것은 분자량이 적기때문이다. 즉 Mg(OH)2는 58.3인데 비해 Ca(OH)2는 74.1로, 같은 양을 투입할 경우 Mg(OH)2는 Ca(OH)2에 비해 약 1.3배의 중화능력이 더 크기 때문이다.In the present invention, the use of Mg (OH) 2 in place of Ca (OH) 2 , which is a conventional medicine, is performed in the first reactor for the following reasons. Figure 3 shows the pH change according to the NaOH, Ca (OH) 2 dose. According to FIG. 3, below pH 7.5, the addition of NaOH and Mg (OH) 2 showed greater neutralization capacity for stainless wastewater than the addition of Ca (OH) 2 . In particular, Mg (OH) 2 has a higher neutralization capacity than Ca (OH) 2 because of its low molecular weight. That is, Mg (OH) 2 is 58.3, while Ca (OH) 2 is 74.1, and Mg (OH) 2 has a neutralization capacity of 1.3 times greater than Ca (OH) 2 when the same amount is added.
또한 제3도에서 Mg(OH)2와 Ca(OH)2의 투입에 의한 중화능력이 차이는 pH 4.5-7.5 사이가 가장 큰 것으로 나타났다. 한편 알칼리로 스텐레스 폐수를 중화하면 침전물이 발생되는데, 소석회로 중화시에는, CaF2가 CaSO4가 발생되면 반면, Mg(OH)2로 중화시에는 MgF2만 발생된다. 이것은 중성에서 CaSO4는 KSp가 2.5×10-11dlsep qksgoMgSO4는 가용성(可溶性)이기 때문이다.Also, in FIG. 3, the difference in neutralization capacity by the addition of Mg (OH) 2 and Ca (OH) 2 was found to be the largest between pH 4.5-7.5. On the other hand, neutralization of the stainless wastewater with alkali generates precipitates. In neutralization with calcination, CaF 2 is generated while CaSO 4 is generated, whereas when neutralized with Mg (OH) 2 , only MgF 2 is generated. This is because CaSO 4 in neutral is KSp 2.5 × 10 -11dlsep qksgo MgSO 4 is soluble.
제2반응조에 NaOH를 투입하는 것은 중금속의 완벽한 제거를 위해 pH를 8.5까지 상승시키기 위함이다. 제3도에서 Mg(OH)2투입으로 pH 7.5이상 상승시키는 것이 어려운 것을 알 수 있다.The introduction of NaOH into the second reactor is to raise the pH to 8.5 for complete removal of heavy metals. In FIG. 3, it can be seen that it is difficult to raise the pH above 7.5 by adding Mg (OH) 2 .
제3반응조에서 소석회, 알럼(Alum), 황산등을 투입하는 이유는 제2반응조에서 발생된 폐수중의 불소성분을 제거하기 위함이다. 즉 제 1,2반응조에서 생성된 MgF2는 중성에서 용해도가 87㎎/l정도 이기 때문에, 제3반응조 유입수중의 이론적인 최소 불소농도는 약 53금속 산화물 또는 53ppm정도가 되어 법기준치 15ppm을 상회함으로 소석회와 알럼을 투입하여 제거한다 그리고 황산은 pH조절 역활과 아울러 소석호와 반응하여 CaSO4를 생성하는데, CaSO4는 불소제거 역활도 한다.The reason why slaked lime, alum, sulfuric acid, etc. are added in the third reactor is to remove fluorine in the wastewater generated in the second reactor. That is, the MgF 2 produced in the first and second reactors had a neutral solubility of about 87 mg / l, so the theoretical minimum fluorine concentration in the influent of the third reactor was about 53 metal oxides or 53 ppm, exceeding the legal standard of 15 ppm. As a result, calcined lime and alum are removed to remove sulfuric acid, and sulfuric acid reacts with calcined lake to produce CaSO 4 , and CaSO 4 serves as fluorine removal.
제4반응조는 종래방법의 제3반응조와 유사한 부유물질을 응집하는 작용을 한다. 다만 종래방법의 제3반응조와 다른것은 중화를 위해 염산을 투입하지 않는다는 것과 이로인해 플록생성이 더 양호하다는 것이다. 즉 플록생성은 pH 7.0부근에서 잘 일어나는데, 알칼리 폐수인 스텐레스 폐수에 대해 중화와 응집을 한꺼번에 수행하는 종래방법의 제3반응조에 비해, 이를 따로 수행하는 본 발명에서 더 양호한플록이 생성되었다.The fourth reactor serves to agglomerate suspended solids similar to the third reactor of the conventional method. The difference from the conventional reactor 3 is that no hydrochloric acid is added for neutralization, which results in better floc formation. That is, floc formation occurs well around pH 7.0, and better flocs are produced in the present invention which performs them separately than the third reactor of the conventional method in which neutralization and aggregation of stainless wastewater, which is alkaline wastewater, are performed at once.
이하 실시예에 의거 분발명을 설명한다.The invention will be described based on the following examples.
실시예 1Example 1
pH 2.01이며 블소농도 16,000-17,000ppm의 스텐레스 페수에 소석회를 투입하여 불소정화처리를 수회 반복 실시하여 그 결과를 표 1에 나타내었다.Slurry was added to stainless wastewater having a pH of 2.01 and a fluorine concentration of 16,000-17,000 ppm, and the fluorine purification treatment was repeated several times. The results are shown in Table 1.
[표 1] TABLE 1
상기 표 1에서 알수 있듯이, 200,000ppm의 소석회를 투입한 경우에 있어서도 잔류불소 또는 법기준인 15ppm 이하로 낮추어지지 않는다.As can be seen from Table 1, even when 200,000 ppm of lime is added, the residual fluorine does not fall below 15 ppm, which is a legal standard.
실시예 2Example 2
스텐레스 폐수에 종래방법(소석회투입)과 본 발명의 방법(수산화 마그네슘과 가성소다 투입)을 각각 사용하여 pH 8.5까지 중화시켰으며, 이에 발생되는 슬러지량을 조사하여 그 결과를 표 2에 나타내었다.The stainless wastewater was neutralized to pH 8.5 using the conventional method (calcined lime injection) and the method of the present invention (magnesium hydroxide and caustic soda), respectively, and the amount of sludge produced therein was investigated and the results are shown in Table 2.
[표 2] TABLE 2
표 2에서 보듯이, 본 발명을 사용하는 경우, 종래방법을 사용하는 것보다 슬러지량이 25.6% 줄어들었다.As shown in Table 2, in the case of using the present invention, the sludge amount was reduced by 25.6% compared with the conventional method.
실시예 3Example 3
스텐레스 폐수에 수산화 마그네슘 100,000에서 150,000mg/l를 투입한 후 가성소다로 pH를 8.0에서 9.0으로 조정할때, 스텐레스 폐수의 잔류 불소이온 농도는 60.5-151.2ppm이었다. 이렇게 처리된 폐수의 상등액을 원수로 하여, 소석회 500-1000ppm과 알럼(Alum) 300-700ppm을 투입하여 교반한 후, 황산으로 pH를 7.0-7.5로 조정한 후, 다시 교반하고, 이 용액에 고분자 응집제를 투입한다. 교반후 침전물을 분리하고 상등액의 불소농도를 측정한 결과, 이용액의 불소농도는 3-10ppm이었다.When the pH was adjusted from 8.0 to 9.0 with caustic soda after adding 100,000 to 150,000 mg / l of magnesium hydroxide to the stainless wastewater, the residual fluorine ion concentration of the stainless wastewater was 60.5-151.2 ppm. Using the supernatant of the wastewater treated as raw water, 500-1000 ppm of hydrated lime and 300-700 ppm of alum were added and stirred, the pH was adjusted to 7.0-7.5 with sulfuric acid, and then stirred again. Add flocculant. After stirring, the precipitate was separated and the fluorine concentration of the supernatant was measured. The fluorine concentration of the used solution was 3-10 ppm.
종래방법에 있어서는, 실시예 1에서 보았듯이 폐수의 잔류 불소농도는 54-92ppm으로 법기준치(15ppm)을 훨씬 상화하였지만, 실시예 3에서 보듯이, 본 발명의 공정을 모두 거친 경우에는 폐수의 잔류 불소농다가 3-10ppm으로 법기준치(15ppm)를 만족시켰다.In the conventional method, as shown in Example 1, the residual fluorine concentration in the wastewater was 54-92 ppm, which far exceeded the legal standard value (15 ppm). However, as shown in Example 3, the waste water remained in the case where all the processes of the present invention were passed. Fluoride concentration was 3-10ppm, which satisfies the legal standard (15ppm).
이와같이 본 발명은 스텐레스 폐수처리 공정에서 문제가 되고 있는 유해폐기물의 발생량을 크게 감소시키고 또 수질오염물질인 폐수중 잔류불소 농도를 대폭 감소시킬 수 있는 매우 유용한 것이라 하겠다.As such, the present invention is said to be very useful to greatly reduce the amount of hazardous wastes that are a problem in the stainless wastewater treatment process and to significantly reduce the residual fluorine concentration in the wastewater, which is a water pollutant.
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KR100741529B1 (en) * | 2006-02-01 | 2007-07-20 | 코스모화학 주식회사 | Method for treating acidic wastewater |
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