KR20070066546A - Treatment method of waste water contaminated with fluoride and nitrate - Google Patents

Treatment method of waste water contaminated with fluoride and nitrate Download PDF

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KR20070066546A
KR20070066546A KR1020050127871A KR20050127871A KR20070066546A KR 20070066546 A KR20070066546 A KR 20070066546A KR 1020050127871 A KR1020050127871 A KR 1020050127871A KR 20050127871 A KR20050127871 A KR 20050127871A KR 20070066546 A KR20070066546 A KR 20070066546A
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wastewater
nitric acid
hydrofluoric acid
high concentration
treatment
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KR100733332B1 (en
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윤석민
김태훈
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주식회사 포스코
재단법인 포항산업과학연구원
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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
    • C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
    • C02F1/583—Treatment of water, waste water, or sewage by removing specified dissolved compounds by removing fluoride or fluorine compounds
    • 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
    • C02F1/5209—Regulation methods for flocculation or precipitation
    • 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
    • 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
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/12—Halogens or halogen-containing compounds
    • C02F2101/14—Fluorine or fluorine-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/163—Nitrates
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/06—Controlling or monitoring parameters in water treatment pH
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

A treatment method of wastewater containing high concentration hydrofluoric acid and nitric acid is provided to efficiently purify high concentration hydrofluoric acid and nitric acid contained in wastewater generated after a pickling process in an environmentally friendly and economical manner by a biological treatment process. In a method for treating the wastewater after pickling wastewater containing hydrofluoric acid and nitric acid, a treatment method of wastewater containing high concentration hydrofluoric acid and nitric acid comprises: a first step of treating the wastewater with calcium hydroxide, and purifying settled calcium using a saturated carbonic acid gas solution to which sodium hydroxide is added; and a second step of adjusting a pH of the purified wastewater to a range of 6.5 to 7.0, and flowing the pH adjusted wastewater into a denitrification reactor to purify the wastewater. The first step comprises injecting about 20 to 50 wt.% of the sodium hydroxide into the wastewater. The first step comprises: injecting the carbonic acid gas solution into the wastewater in a amount range from 1.5 to 2.5 times of the consumption amount of the calcium hydroxide, and adjusting a pH of the wastewater to a range from 7 to 14.

Description

고농도 불산 및 질산을 함유하는 폐수처리 방법{TREATMENT METHOD OF WASTE WATER CONTAMINATED WITH FLUORIDE AND NITRATE}Wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid {TREATMENT METHOD OF WASTE WATER CONTAMINATED WITH FLUORIDE AND NITRATE}

도 1은 잔존하는 칼슘이 생물학적 탈질에 미치는 영향을 나타낸 그래프, 1 is a graph showing the effect of remaining calcium on biological denitrification,

도 2는 과량의 칼슘이 존재시에 미생물량에 축적되는 현상을 그래프로 도시한 것이고,2 is a graph showing the phenomenon of accumulation in the microbial amount in the presence of excess calcium,

도 3은 본 발명의 고농도 불산 및 질산을 함유하는 폐수처리 방법의 순서도이다.3 is a flow chart of a wastewater treatment method containing high concentrations of hydrofluoric acid and nitric acid of the present invention.

본 발명은 금속공업에서 발생하는 폐수처리 방법에 관한 것으로, 특히 금속이나 전자산업 등에서 산세공정 후에 발생되는 폐수에 있는 고농도의 불산 및 질산을 환경 친화적이고, 경제적이며 생물학적 처리 공정으로 효율적으로 정화하는 고농도 불산 및 질산을 함유하는 폐수처리 방법에 관한 것이다.The present invention relates to a wastewater treatment method generated in the metal industry, and in particular, high concentration of hydrofluoric acid and nitric acid in the wastewater generated after the pickling process in the metal or electronics industry to efficiently purify by environmentally friendly, economical and biological treatment process A wastewater treatment method containing hydrofluoric acid and nitric acid.

일반적으로 폐수나 오염 물질 등에 있는 질소문제는 가장 광범위하게 대두되 는 환경문제 중의 하나이며 일반 하수에서 이를 제어하기 위해 많은 기술들이 제시되고 있다.In general, the nitrogen problem in waste water and pollutants is one of the most widespread environmental problems, and many techniques have been proposed to control it in general sewage.

하지만, 일반 가정하수와는 달리 산업폐수 중의 질소문제는 그 농도 및 독성이 다르며, 이를 고려한 공법의 개발은 필수적이다. 전자산업이나 금속공업의 산세폐수는 불산 및 질산이 고농도로 포함되어 있어 불산의 독성으로 인하여 직접 생물학적인 방법으로 처리하기가 곤란하다고 알려져 있다. 따라서 Ca(OH)2 등의 불산 처리제를 사용하여 불산을 처리한 후 질산을 처리하는 공정이 채택되어왔다. Ca(OH)2 의 경우 소석회형태의 화학약품을 사용하므로 불소처리 후 잔류 칼슘이 다량 발생하여 후단 생물학적 처리설비에 악영향을 나타내는 문제점이 있다. However, unlike general household sewage, the problem of nitrogen in industrial wastewater is different in concentration and toxicity, and it is essential to develop a construction method considering this. Pickling wastewater from the electronics and metals industries is known to contain hydrofluoric acid and nitric acid in high concentrations, which makes it difficult to treat them directly by biological methods. Therefore, a process of treating nitric acid after treating hydrofluoric acid with a hydrofluoric acid treating agent such as Ca (OH) 2 has been adopted. Of Ca (OH) 2 In the case of using the lime-type chemicals, there is a problem in that a large amount of residual calcium is generated after the fluorine treatment, thereby adversely affecting the rear-end biological treatment facility.

한편, 소석회의 경우 광산에서 채굴된 석회를 소성하여 생석회(CaO)를 생성시키고 이를 수화하여 소석회를 제조한다. 소성과정에서 제조방법의 한계로 인해 소석회에는 탄산칼슘형태의 불용성 성분이 상당량 포함되어 있으며 입자도 커서 용해 속도도 상당히 느린 편이다. 따라서 소석회를 사용하는 공정에서는 과량투여 및 이에 따른　 잔존 칼슘도 과량으로 존재하게 된다.Meanwhile, in the case of slaked lime, calcined lime from the mine is calcined to generate quicklime (CaO) and hydrated to prepare slaked lime. Due to the limitations of the manufacturing process during calcining, slaked lime contains a large amount of insoluble components in the form of calcium carbonate, and the particle size is large, so that the dissolution rate is considerably slow. Therefore, in the process using slaked lime, excessive dose and thus remaining calcium are also present.

소석회에 의한 불소처리 후 질소처리나 유기물처리 공정이 연속으로 구성되는 경우 과량의 칼슘은 생물학적 처리설비의 미생물에게 영향을 주게 되는데 대표적인 것이 미생물 반응조에서 미생물과 응집하여 침전물을 형성하는 것이다. When nitrogen treatment or organic matter treatment process is continuously formed after fluorine treatment by slaked lime, the excess calcium affects the microorganisms in the biological treatment facility. A representative example is the aggregation of microorganisms in a microbial reactor to form a precipitate.

또한, 금속표면 처리공업에서 배출되는 주요 폐수는 대부분이 산세과정(pickling process)에서 발생하며 사용되는 산(acid)의 종류 및 농도에 따라 그 성 격이 특징지워진다. 특히 스테인레스 공업 및 반도체 공업의 산세공정에서 사용되는 산세액(acid rinse solution)은 불산(HF)과 질산(HNO3)의 혼합세액으로 구성되어 있으며, 산세공정을 마치고 배출되는 폐수는 고농도의 각종 금속 이온, 질산성질소 이온, 그리고 불소 이온 등을 포함하고 있다. 이러한 폐수를 처리하기 위하여 화학적 처리공정 및 생물학적 처리 공정이 복합적으로 도입되어 운영되고 있다. 폐수처리 공정은 초기 단계에 불소 및 중금속을 물리화학으로 처리하는 공정이 구성되어 있고 후단에는 질산성 질소를 처리하기　 위한 생물학적 처리 공정을 연계하여 처리하는 것이 일반적이다. 이것은 불소가 미생물에게 미치는 영향을 최소화하여 독성에 의한 미생물의 활성저하를 예방하기 위함이다. 불소 및 중금속을 제거하기 위한 물리화학적 처리시에는 약품투입 및 응집반응을 위한 반응기와 침전조로 그리고 각종 약품투입탱크가 주요한 구성요소이다. 현재까지 폐수 속에 포함된 불소 및 중금속 그리고 이로 인한 낮은 pH를 처리하기 위한 각종 약품이 시험되었으며 그 결과 소석회(Ca(OH)2)가 가장 경제적인 처리 약품으로 인식되어 널리 사용되고 있다. 폐수처리 약품으로서의 소석회는 범용성 및 경제성이 가장 큰 장점인 반면 과다한 슬러지의 발생 및 배관에 스케일을 형성하는 문제점이 있다. In addition, most of the major wastewater discharged from the metal surface treatment industry is generated in the pickling process and is characterized by the type and concentration of acid used. In particular, the acid rinse solution used in the pickling process of the stainless industry and the semiconductor industry is composed of a mixed tax solution of hydrofluoric acid (HF) and nitric acid (HNO 3 ). Ions, nitric nitrate ions, and fluorine ions. In order to treat such wastewater, a chemical treatment process and a biological treatment process are introduced and operated in combination. The wastewater treatment process is composed of physicochemical treatment of fluorine and heavy metals in the early stages, and biological treatment for treating nitrate nitrogen is generally performed in the latter stages. This is to minimize the effect of fluorine on the microorganisms to prevent the deactivation of microorganisms due to toxicity. In the physicochemical treatment to remove fluorine and heavy metals, the main components are reactors, settling tanks, and various chemical input tanks for chemical injection and flocculation. To date, various chemicals have been tested to treat fluorine and heavy metals in wastewater and the resulting low pH, and as a result, calcined lime (Ca (OH) 2 ) is widely regarded as the most economical treatment chemical. Slaked lime as a wastewater treatment chemical has the greatest advantages of versatility and economy, but there is a problem of generating excessive sludge and forming scale in the pipe.

또한, 종래의 공정에서는 폐수 속에 포함된 각종 이온 성분들(불소 이온을 제외한)과의 복잡한 화학 침전반응으로 말미암아 처리된 폐수의 실제적인 잔류 불소 이온 농도는 용해도를 고려한 이론적 계산 잔류 불소 농도보다 대체적으로 높게 나타나는 문제점이 있으며 배출 기준을 맞추기 위해서 소석회를 과다로 투입하는 경향이 있다. 또한, 생산되는 제품에 따라 사용되는 질산과 불산의 혼합 비율이 수시로 달라지므로 투입되는 소석회 양을 제어하기가 용이하지 않으며 유입 폐수 속의 불소 이온 농도를 측정할 수 있는 적절한 수단이 현실적으로 부재하여 최적의 불소 제거 공정 유지가 어렵다.In addition, in the conventional process, the actual residual fluorine ion concentration of the treated wastewater due to complex chemical precipitation reaction with various ionic components (except fluorine ions) contained in the wastewater is generally larger than the theoretical calculated residual fluorine concentration considering solubility. There is a problem that is high and there is a tendency to add too much lime in order to meet the emission standards. In addition, since the mixing ratio of nitric acid and hydrofluoric acid used varies depending on the product produced, it is not easy to control the amount of added slaked lime, and there is no suitable means for measuring the concentration of fluorine ions in the influent wastewater. It is difficult to maintain the removal process.

도 1은 산업폐수를 소석회로 처리시에 잔존하는 칼슘의 양이 생물학적 탈질에 미치는 영향을 그래프로 표시한 것이고, 도 2는 과량의 칼슘이 존재시에 미생물량에 축적되는 현상을 그래프로 도시한 것이다.1 is a graph showing the effect of the amount of calcium remaining on the biological denitrification in the treatment of industrial wastewater in the calcination process, Figure 2 is a graph showing the phenomenon of accumulation of microorganisms in the presence of excess calcium will be.

도 2에 나타낸 막대 그래프를 참조하면, 불소 폐수처리 후　잔존하는 칼슘은 600mg/L 이상에서는 탈질 미생물의 활성을 저하시키는 것으로 나타났으며 또한 이러한 조건하에서 장기간 탈질 미생물을 배양하면 고형성분의 10%만이 미생물로 구성된 슬러지가 형성되어 반응조에서의 미생물 운영을 매우 불안전하게 하며 매우 쉽게 침강하여 슬러지의 부상이 큰 문제가 된다.Referring to the bar graph shown in Figure 2, after the fluorine wastewater treatment, the residual calcium was found to lower the activity of the denitrification microorganisms at 600 mg / L or more, and in addition, only 10% of the solid components in the long-term denitrification microorganisms under these conditions Sludge composed of microorganisms is formed, which makes the operation of microorganisms in the reactor very unstable and settles very easily, so that sludge injuries become a big problem.

위에서 언급한 바와 같이 종래의 기술은 소석회(Ca(OH)2)를 사용하여 불소를 침전 처리한 후 질소처리를 위한 탈질공정을 거쳤다. 그러나 소석회의 투입량이 과다하게 사용되어 과량의 칼슘성분으로 탈질 효율 저하 및 미생물 반응기내 과량의 칼슘 슬러지가 축적되는 문제가 있다.As mentioned above, the prior art has been subjected to the denitrification process for nitrogen treatment after precipitation of fluorine using slaked lime (Ca (OH) 2 ). However, there is a problem in that the input amount of slaked lime is excessively used to reduce the denitrification efficiency and the excess calcium sludge accumulates in the microbial reactor.

질산성 질소를 제거하는 탈질기술의 경우 일반적으로는 부유식 방법을 사용하고 있으나 처리 효율이 낮은 관계로 광대한 부지 및 설비비가 상당히 높기 때문에 금속표면처리공업에서 발생하는 고농도의 질산성질소(약 1,000mg/L 수준 )의 처 리에는 부적합하다. 이를 해결하기 위한 방법으로 미생물을 고정화하여 처리할 수 있는 충전형 반응기를 도입함으로써 좁은 공간에서도 설치 용이하며 고안된 반응기는 반응기안의 미생물 활성부분을 극대화함으로써 부유식에 비해 20배 이상 탈질 효율을 향상시킴으로써 경제적 측면에서도 상당히 유리하다.In the case of the denitrification technology to remove nitrate nitrogen, the floating method is generally used, but due to the low processing efficiency, the vast site and equipment costs are very high, so the high concentration of nitrate nitrogen generated in the metal surface treatment industry (about 1,000 mg / L levels) are not suitable for treatment. In order to solve this problem, it is easy to install in a narrow space by introducing a packed reactor that can fix and treat microorganisms. The designed reactor is economical by improving the denitrification efficiency more than 20 times compared to the floating type by maximizing the microorganism active part in the reactor. It is also quite advantageous from the side.

반면, 고농도의 칼슘을 포함하는 폐수를 이러한 담체를 사용하여 생물학적으로 처리하고자 할 경우에는 위에서 언급한 폐해로 말미암아 고농도로 유지되는 미생물반응기를 적용하지 못할 수준에 도달하게 되므로 이의 보완 기술의 개발이 필수적이다.On the other hand, when biologically treating wastewater containing a high concentration of calcium using such a carrier, it is necessary to develop a complementary technology because the above mentioned waste may not be able to apply a microorganism reactor maintained at a high concentration. to be.

본 발명은 금속공업이나 전자산업 등에서 세정된 후 배출되는 산업폐수에 있는 오염물질인 불산 및 질산을 보다 환경 친화적이며 경제적이며 생물학적 공정처리를 적용하여 전체 질불산 폐수처리 공정의 효율을 증가시키는 고농도 불산 및 질산을 함유하는 폐수처리 방법을 제공하는 것을 목적으로 한다.The present invention is more environmentally friendly, economical and biological processing of hydrofluoric acid and nitric acid, which are pollutants in industrial wastewater discharged after being cleaned in the metal industry or the electronics industry, to increase the efficiency of the entire hydrofluoric acid wastewater treatment process. And a wastewater treatment method containing nitric acid.

또한, 본 발명은 산업폐수의 처리에 있어서, 잔존 칼슘의 발생을 감소시키며, 이를 위해 불소 폐수에 소석회를 투입하여 불소를 침전시켜 처리하고, 잔존하는 과량의 칼슘은 탄산가스가 포함된 가성소다를 사용하여 탄산칼슘의 형태로 침전시키고, 잔존 칼슘이 처리된 폐수는 탈질설비로 유입되어 원활한 탈질이 일어나도록 하여 효율적이고 경제적으로 산업폐수를 처리하는 고농도 불산 및 질산을 함유하는 폐수처리 방법을 제공하는 것을 목적으로 한다.In addition, the present invention, in the treatment of industrial wastewater, the generation of residual calcium is reduced, for this purpose, by adding hydrated lime to fluorine wastewater to precipitate the fluorine, the excess calcium remaining is caustic soda containing carbon dioxide gas It is used to precipitate in the form of calcium carbonate, and the remaining calcium treated wastewater flows into the denitrification equipment to provide smooth denitrification, thereby providing a wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid, which efficiently and economically treats industrial wastewater. For the purpose of

본 발명은 고농도의 불산과 질산이 함유된 산업폐수에 소석회 사용한 후에 발생되는 잔존 칼슘의 처리를 위해 탄산가스가 포함된 가성소다(NaOH)를 주입하여 소석회를 사용 후에 잔존하는 칼슘을 탄산칼슘형태로 침전시키고, 탈질설비에서 원활한 탈질이 일어나도록 처리하므로, 효율적이고 경제적으로 산업폐수를 처리하는 고농도 불산 및 질산을 함유하는 폐수처리 방법을 제공하는 것을 그 목적으로 한다.The present invention injects caustic soda (NaOH) containing carbon dioxide to treat the residual calcium generated after the use of hydrated lime in industrial wastewater containing high concentration of hydrofluoric acid and nitric acid in the form of calcium carbonate It is an object of the present invention to provide a wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid, which is precipitated and treated so that smooth denitrification occurs in the denitrification equipment.

본 발명의 탄산가스는 알칼리 용액에서의 용해도가 매우 높으므로 20% 이상의 가성소다를 사용하여 탄산가스를 포집하면 충분히 높은 농도의 포화된 용액을 제조할 수 있으며 이를 활용하여 효율적으로 칼슘제거에 적용할 수 있는 고농도 불산 및 질산을 함유하는 폐수처리 방법을 제공하는 것을 그 목적으로 한다.Since the carbon dioxide gas of the present invention has a very high solubility in alkaline solution, it is possible to prepare a saturated solution having a sufficiently high concentration by capturing carbon dioxide gas using 20% or more of caustic soda, which can be efficiently applied to calcium removal. It is an object of the present invention to provide a wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid.

또한, 본 발명의 탄산가스가 포화된 가성소다의 농도는 20 - 50%로서 탄산가스는 상용화 된 제품 이외에도 공장굴뚝에서 발생하는 배기가스를 적용할 수 있으며, 탄산가스의 주입농도는 소석회 대비 1.5 ~ 2.5배 수준으로 pH 범위는 7 ~ 14의 범위로 적용하여 효율적이고 경제적이며 친환경적으로 산업폐수를 처리하는 고농도 불산 및 질산을 함유하는 폐수처리 방법을 제공하는 것을 그 목적으로 한다.In addition, the concentration of caustic soda saturated with carbon dioxide gas of the present invention is 20 to 50%, carbon dioxide gas can be applied to the exhaust gas generated from the factory chimney in addition to the commercialized products, the injection concentration of carbon dioxide gas is 1.5 ~ The purpose of the present invention is to provide a wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid, which treats industrial wastewater efficiently and economically by applying a pH range of 7 to 14 at 2.5 times.

언급한 목적을 달성하기 위한 본 발명의 고농도 불산 및 질산을 함유하는 폐수처리 장치 및 방법은, 불소 및 질산을 함유하는 산세공정 후의 폐수처리에 있어서, 소석회 처리 후에 가성소다를 첨가한 포화된 탄산가스 용액을 이용하여 침전된 칼슘을 정화시키는 1단계와, 정화시킨 폐수의 pH를 6.5-7.0으로 조절한 후 탈질반응기로 유입시켜 정화시키는 2단계를 포함하는 것을 특징으로 한다.The wastewater treatment apparatus and method containing high concentration of hydrofluoric acid and nitric acid of the present invention for achieving the above-mentioned object is, in the wastewater treatment after the pickling process containing fluorine and nitric acid, saturated carbon dioxide gas added with caustic soda after the treatment with lime It characterized in that it comprises a first step of purifying the precipitated calcium by using a solution, and after adjusting the pH of the purified wastewater to 6.5-7.0 and introduced into the denitrification reactor to purify.

또한, 본 발명은 언급한 1단계에서 가성소다의 농도는 20 - 50% 정도를 투입하여 구비되고, 탄산가스 용액은 소석회 사용량의 1.5~2.5배의 범위에서 조절되어 투입되고 pH 범위는 7 ~ 14의 범위인 것을 특징으로 하며, 탄산가스는 공장굴뚝에서 발생하는 배기가스를 적용 가능한 것을 특징으로 한다.In addition, the present invention is equipped with a concentration of caustic soda 20 to 50% in the first step mentioned above, the carbon dioxide gas solution is adjusted in the range of 1.5 to 2.5 times the amount of calcined lime used and the pH range is 7 to 14 Characterized in that the range, the carbon dioxide is characterized in that the exhaust gas generated from the factory chimney can be applied.

이하, 본 발명의 실시 예를 첨부된 도면을 참조하여 상세히 설명한다.Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도 3은 본 발명의 고농도 불산 및 질산을 함유하는 폐수처리 방법의 순서도이다.3 is a flow chart of a wastewater treatment method containing high concentrations of hydrofluoric acid and nitric acid of the present invention.

본 발명은 금속공업이나 전자산업 등의 산세공정 후에 발생되는 폐수처리에 관한 것으로, 폐수에 있는 고농도의 불산 및 질산을 환경 친화적이고, 경제적이며 생물학적 처리 공정으로 효율적으로 처리한다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of wastewater generated after pickling processes in the metal industry or the electronics industry, and efficiently treats high concentrations of hydrofluoric acid and nitric acid in wastewater in an environmentally friendly, economical and biological treatment process.

본 발명은 고농도의 불산과 질산이 함유된 산업폐수에 소석회 사용한 후에 발생되는 잔존 칼슘의 처리를 위해 탄산가스가 포함된 가성소다(NaOH)를 주입하여 잔존하는 칼슘을 탄산칼슘 형태로 침전시키고, 탈질설비에서 원활한 탈질이 일어나도록 처리한다.The present invention injects caustic soda (NaOH) containing carbon dioxide to treat the residual calcium generated after the use of slaked lime in industrial wastewater containing high concentrations of hydrofluoric acid and nitric acid to precipitate the remaining calcium in the form of calcium carbonate, and denitrification. Treat the equipment so that smooth denitration occurs

잔존 칼슘의 처리를 위해 공급되는 탄산가스는 알칼리 용액에서의 용해도가 매우 높으므로 20% 이상의 가성소다를 사용하여 탄산가스를 포집하면 충분히 높은 농도의 포화된 용액을 제조할 수 있으며, 가성소다의 농도는 20 - 50%로서 탄산가스는 상용화된 제품 이외에도 공장굴뚝에서 발생하는 배기가스를 적용할 수 있으 며, 탄산가스의 주입농도는 소석회 대비 1.5 ~ 2.5배 수준으로 pH 범위는 7 ~ 14의 범위로 적용하여 효율적이고 경제적이며 친환경적으로 산업폐수를 정화한다.The carbon dioxide gas supplied for the treatment of the remaining calcium has a very high solubility in an alkaline solution. Thus, when a carbon dioxide gas is collected using 20% or more caustic soda, a saturated solution having a sufficiently high concentration can be produced. In addition to commercialized products, carbon dioxide gas can be applied to exhaust gas from factory chimneys, and the concentration of carbon dioxide gas is 1.5 to 2.5 times that of slaked lime and the pH range is 7 to 14. Purifies industrial wastewater efficiently, economically and environmentally

도 3은 본 발명의 산업 폐수를 처리하는 순서도로, 먼저, 산업폐수에 소석회를 투입하여 불소 및 중금속을 제거하고 pH를 상승시키는 화학적 처리 과정을 거친다.Figure 3 is a flow chart of the treatment of the industrial wastewater of the present invention, first, by applying the lime to the industrial wastewater is subjected to a chemical treatment process to remove fluorine and heavy metals and raise the pH.

우선 산세후 폐수수집조(Buffer tank)에 수집된 폐수는 1차 처리조에 유입되어 소석회에 의한 불소처리, 중금속 처리 및 pH 상승이 동반된다. 이때 반응조의 pH는 충분한 중금속제거 및 불소제거를 위해 pH 9까지 상승하도록 충분량의 소석회를 투입한다. 사용되는 소석회는 분말제품을 물에 녹인 30% 용액을 사용한다(S81~S83).First, after the pickling, the wastewater collected in the buffer tank is introduced into the primary treatment tank, which is accompanied by fluorine treatment, heavy metal treatment and pH rise by slaked lime. At this time, a sufficient amount of slaked lime is added to raise the pH of the reactor to pH 9 for sufficient heavy metal removal and fluorine removal. The slaked lime used is a 30% solution of powdered product dissolved in water (S81 ~ S83).

언급한 바와 같이, 소석회를 투입하여 불소 및 중금속을 제거하고 pH를 상승시키는 화학적 처리 과정을 마친후, 다음으로 탄산가스가 포함된 가성소다를 주입하는 화학적 처리 과정을 거친다.As mentioned, after the addition of slaked lime to remove the fluorine and heavy metals and to raise the pH, the chemical treatment is followed by the injection of caustic soda containing carbon dioxide.

1차 처리조를 거친 폐수는 1차 침전조로 유입되어 소석회에 의한 불소 및 중금속 입자들을 중력 침강시킨다. 1차 침전조를 거친 상등수는 2차 처리조로 이송되어 폐수에 함유된 잔여량의 칼슘을 제거하게 된다. 2차 처리조에 유입되는 폐수에는 과량의 소석회 사용으로 인한 잔류 칼슘의 농도가 1500mg/L - 3000mg/L 수준에 도달하게 되며 이를 처리하여 600mg/L 이하로 유지시키는 것이 2차 처리조의 목적이다. Wastewater from the primary treatment tank flows into the primary sedimentation tank to gravity sediment the fluorine and heavy metal particles by slaked lime. The supernatant from the primary sedimentation tank is sent to a secondary treatment tank to remove residual calcium in the wastewater. Wastewater flowing into the secondary treatment tank reaches a concentration of 1500 mg / L-3000 mg / L due to the use of excess lime, and the purpose of the secondary treatment tank is to maintain the concentration below 600 mg / L.

2차 처리조에 사용되는 약품은 가성소다와 탄산가스로서 별도로 마련된 약품 탱크에서 혼합하여 사용한다. 탄산가스의 경우 상용화된 제품을 사용해도 되지만 경제적인 타당성이 부족하므로 공장굴뚝에서 발생하는 탄산가스가 포함된 배기가스를 사용하는 것이 보다 유리하다. 탄산가스는 용액에 매우 잘 녹기 때문에 쉽게 포화되며 알칼리 용액에는 용해도가 매우 높기 때문에 가성소다의 경우 최대 포화농도까지 쉽게 포화될 수 있다. 탄산가스가 포화된 용액이 주입되는 양은 소석회 사용량의 1.5 - 2.5배의 범위에서 조절한다(S85).The chemicals used in the secondary treatment tank are mixed with caustic soda and carbon dioxide in a chemical tank provided separately. In the case of carbon dioxide gas, although a commercially available product may be used, it is more advantageous to use an exhaust gas containing carbon dioxide gas generated from a factory chimney because it lacks economic feasibility. Carbon dioxide is easily saturated because it dissolves very well in the solution, and because of its high solubility in alkaline solutions, caustic soda can easily be saturated to its maximum saturation concentration. The amount of carbon dioxide gas saturated solution is adjusted in the range of 1.5 to 2.5 times the amount of slaked lime used (S85).

언급한 바와 같이, 탄산가스가 포함된 가성소다를 주입하는 화학적 처리 과정을 거쳐서 잔여량의 칼슘을 제거한 후에는 다음 과정으로 최종 pH조정 과정을 거친다(S87).As mentioned, after removing the residual amount of calcium through a chemical treatment of injecting caustic soda containing carbonic acid gas is subjected to the final pH adjustment process to the next step (S87).

최종 pH조정 과정은 생물학적 탈질 시스템에서 처리하는 것으로, 생물학적 처리시스템에는 유량조정조, 탈질조, 폭기조 및 침전조 그리고 탄소원으로서 사용하는 메탄올 공급용 저장조 등으로 구성되어 있으며 유량조정조에서 pH를 6.5-7.0으로 조절한 후 탈질반응기로 유입한다. The final pH adjustment process takes place in a biological denitrification system, which consists of a flow control tank, a denitrification tank, an aeration tank and a settling tank, and a storage tank for methanol supply as a carbon source. The pH control tank adjusts the pH to 6.5-7.0. After entering the denitrification reactor.

본 발명은 고농도의 불산과 질산이 함유된 산업폐수에 소석회를 사용하여 불산처리 후 잔존하는 고농도의 칼슘을 탄산가스가 포함된 가성소다 용액으로 처리함으로써 칼슘의 수준을 400 mg/L 이하로 유지할 수 있었으며 이를 통해 생물학적 탈질 공정이 칼슘에 의한 저해를 받지 않고 효율적으로 질산성 질소를 처리할 수 있었다.According to the present invention, the calcium level can be maintained at 400 mg / L or less by treating the high concentration of calcium remaining after hydrofluoric acid with a caustic soda solution containing carbon dioxide by using slaked lime in industrial wastewater containing high concentration of hydrofluoric acid and nitric acid. This allows the biological denitrification process to efficiently process nitrate nitrogen without being inhibited by calcium.

본 발명은 산업폐수에 소석회를 사용한 후, 잔존 칼슘의 처리를 탄산가스가 포함된 가성소다(NaOH)를 주입하여 칼슘을 탄산칼슘 형태로 침전시키고, 탈질설비에서 원활한 탈질이 일어나므로, 효율적이고 경제적이며, 친환경적으로 산업폐수를 정화한다.According to the present invention, after the use of slaked lime in industrial wastewater, the treatment of residual calcium is injected into caustic soda (NaOH) containing carbon dioxide to precipitate calcium in the form of calcium carbonate, and smooth denitrification occurs in the denitrification equipment. It cleans industrial wastewater in an eco-friendly way.

Claims (4)

불소 및 질산을 함유하는 산세공정 후의 폐수처리에 있어서, In the wastewater treatment after the pickling process containing fluorine and nitric acid, 소석회 처리 후에 가성소다를 첨가한 포화된 탄산가스 용액을 이용하여 침전된 칼슘을 정화시키는 1단계와;A step 1 of purifying precipitated calcium using a saturated carbon dioxide solution to which caustic soda is added after the treatment of slaked lime; 정화시킨 폐수의 pH를 6.5-7.0으로 조절한 후 탈질반응기로 유입시켜 정화시키는 2단계를 포함하는 것을 특징으로 하는 고농도 불산 및 질산을 함유하는 폐수처리 방법.A method for treating wastewater containing high concentration of hydrofluoric acid and nitric acid, comprising two steps of adjusting the pH of the purified wastewater to 6.5-7.0 and then introducing the purified wastewater into a denitrification reactor. 제 1항에 있어서,The method of claim 1, 상기 1단계에서 In step 1 above 상기 가성소다의 농도는 20 - 50% 정도를 투입하여 구비되는 것을 특징으로 하는 고농도 불산 및 질산을 함유하는 폐수처리 방법.The concentration of caustic soda is a waste water treatment method containing high concentration of hydrofluoric acid and nitric acid, characterized in that is provided by adding about 20-50%. 제 1항에 있어서,The method of claim 1, 상기 1단계에서 In step 1 above 상기 탄산가스 용액은 소석회 사용량의 1.5 - 2.5배의 범위에서 조절되어 투입되고 pH 범위는 7 ~ 14의 범위인 것을 특징으로 하는 고농도 불산 및 질산을 함 유하는 폐수처리 방법.The carbon dioxide gas solution is adjusted in the range of 1.5 to 2.5 times the amount of hydrated lime and the pH is in the range of 7 to 14 wastewater treatment method containing high concentration hydrofluoric acid and nitric acid. 제 1항에 있어서,The method of claim 1, 상기 1단계에서 In step 1 above 상기 탄산가스는 공장굴뚝에서 발생하는 배기가스를 적용 가능한 것을 특징으로 하는 고농도 불산 및 질산을 함유하는 폐수처리 방법.The carbon dioxide gas is a wastewater treatment method containing high concentration of hydrofluoric acid and nitric acid, characterized in that the exhaust gas generated in the factory chimney can be applied.
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KR100921688B1 (en) * 2007-12-26 2009-10-15 한전원자력연료 주식회사 Method for acidic wasten in iron industry
CN115254865A (en) * 2022-08-25 2022-11-01 中原环保股份有限公司 Method for treating denitrogenated gas in denitrification filter

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KR19990027070A (en) * 1997-09-27 1999-04-15 김영남 Biological denitrification of wastewater and simultaneous treatment of high concentration hydrofluoric acid, lead and nitric acid
KR19990053036A (en) * 1997-12-23 1999-07-15 양인모 Method and apparatus for treating wastewater containing hydrofluoric acid
KR100448629B1 (en) * 2000-12-19 2004-09-13 주식회사 포스코 A denitrification method of wastewater containing high concentration fluoride and nitrate
KR20030053266A (en) * 2001-12-22 2003-06-28 주식회사 포스코 Treatment method of waste water contaminated with fluoride and nitrate
JP4368249B2 (en) * 2004-06-01 2009-11-18 三洋電機株式会社 Treatment apparatus and treatment method of water to be treated using the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100921688B1 (en) * 2007-12-26 2009-10-15 한전원자력연료 주식회사 Method for acidic wasten in iron industry
CN115254865A (en) * 2022-08-25 2022-11-01 中原环保股份有限公司 Method for treating denitrogenated gas in denitrification filter

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