CN1579965A - Process for treating chloroform and carbon tetrachloride industrial waste water by catalytic metal reduction-flocculating settling method - Google Patents
Process for treating chloroform and carbon tetrachloride industrial waste water by catalytic metal reduction-flocculating settling method Download PDFInfo
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- CN1579965A CN1579965A CN 03154176 CN03154176A CN1579965A CN 1579965 A CN1579965 A CN 1579965A CN 03154176 CN03154176 CN 03154176 CN 03154176 A CN03154176 A CN 03154176A CN 1579965 A CN1579965 A CN 1579965A
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Abstract
The invention provides a technics using catalyzing metal deoxidization- flocculation precipitation method to process chloroform and carbon tetrachloride industrial wastewater. It follows nether steps: collecting industrial wastewater and adjusting PH value to acidity, adding mineral sulfates as catalyst and iron or iron carbon as reducer to conduct catalytic reduction, introducing reaction mixture into flocculation clarification tank after reaction and adding alkali to neutrality or alkalescence and discharging flocculation after clarification. The technics is under normal temperature and pressure with adopting cheap and available materials, low process cost and excellent effect. It has no secondary pollution and heavy metal pollution.
Description
Technical Field
The invention relates to a water pollution control and treatment technology, in particular to a process for treating chloroform and carbon tetrachloride industrial wastewater by using a catalytic metal reduction and flocculation precipitation method.
Background
Chloroform (CHCl)3) Carbon tetrachloride (CCl)4) The environment-friendly type organic solvent is a common solvent and raw materials in the industries of chemical industry, medicine, pesticide and the like, has large yield and dosage, enters the environment through volatilization, leakage, waste water discharge and other ways, and has large discharge amount to the environment. Chloroform and carbon tetrachloride are important organic compounds which are difficult to degrade and have extreme effect on organismsLarge toxicity, stable chemical property and long-term stable existence in natural environment, thereby possibly causing long-term harm to the ecological environment; and because they have high volatility and lipid solubility, they are easy to be absorbed by skin and mucous membrane, thus causing harm to human body. Chloroform and carbon tetrachloride are the priority environmental pollutants specified by the United states EPA, and have strict environmental quality standards and emission standards in China. So far, the technology which can be applied to the treatment of the industrial wastewater containing chloroform and carbon tetrachloride is not few, and related experimental researches are many, but the technology for treating the wastewater which can lead the chloroform and the carbon tetrachloride to reach the discharge standard is almost blank.
The treatment method of chloroform and carbon tetrachloride waste water can be classified into a physical method, a chemical method and a biological method. The mature treatment processes include gas stripping, activated carbon adsorption, air stripping, aerobic and anaerobic biological treatment, chemical oxidation and chemical reduction.
1. The physical treatment method has the defects that the treatment result is far away from the emission standard or the cost is too high to popularize and apply.
2. The biological method also has a certain treatment effect, particularly in a laboratory, certain microorganisms show stronger degradation capability to chloroform and carbon tetrachloride, but in a wastewater biological treatment facility operated for a long time, the chloroform and the carbon tetrachloride cause the degradation performance of the microorganisms to be reduced, thereby causing the treatment facility to be incapable of operating normally.
3. The chemical method is generally simple and easy to implement, and the chemical oxidation method and the chemical reduction method have good removal effect on chloroform and carbon tetrachloride in the wastewater.
Generally, the heterogeneous photocatalytic oxidation method is used for advanced treatment of organic chlorine wastewater, is an active direction for domestic and foreign research, and is considered as one of the most promising methods, and the method can degrade chloroform and carbon tetrachloride in the wastewater, but has a low reaction rate. Catalyst for chemical oxidationTiO is2Besides being relatively cheap, other catalysts are expensive, and have the problems of complex preparation, difficult recovery and activation and the like, so that the industrial application is in the future.
The chemical reduction method includes a single metal reduction method and a double (multi) metal reduction method. The Fe reduction dechlorination technology developed by 1990's provides a feasible way for treating chloroform and carbon tetrachloride in water; the common systems of the multi-metal reduction method are a Pd-Te system, a Pd-Ni system, a Ni/Mo-gamma-Al system and a Pd-Cu system, and a better experimental effect is obtained.
At the end of the last century and in the beginning of this century, the following progress was made in the foreign countries in the research and treatment of chloroform and carbon tetrachloride in wastewater and environmental water bodies:
(1) the electrochemical method comprises the following steps: chloroform is decomposed by adopting a continuous electrochemical method of a carbon fiber electrode with built-in metal, the built-in metal is Ag and Zn, the electrolyte is potassium sulfate, the decomposition rate of the chloroform is close to 100 percent during low-flow treatment, and the main decomposition product is methane.
(2) Non-catalytic chemical reaction method: CuO vs CCl at high temperatures4Is believed to be CCl4Reacts with CuO to produce CuCl2。
(3) The gas-liquid multi-element multi-phase transfer recovery process comprises the following steps: the main mechanism is to transfer chloroform and carbon tetrachloride from the aqueous phase to the gas phase by chemical combination extraction, and then to separate.
(4) Novel catalyst: there is mainly a sulfiding catalyst.
Although chemical reduction has achieved abundant results in the treatment of chloroform and carbon tetrachloride in environmental water and wastewater, there are still many difficulties and difficulties, mainly:
(1) the most effective catalyst Pd at present is too expensive;
(2) the preparation of binary metal or multi-metal catalysts is not yet suitable for the application of industrial wastewater treatment;
(3) the reducing agent or the catalyst belongs to heavy metals, and is easy to cause heavy metal pollution in the process of treating water or wastewater;
(4) the existing multi-metal or multi-phase catalytic system is carried out at higher temperature or pressure, so that the water treatment cost is higher, the facilities are more complex, and the popularization and the application are difficult.
Publication No. CN 1063676a, name: the present invention relates to a process for dechlorinating higher chloromethane by using hydrogen and oxygen in the presence of a catalyst containing noble metals of copper group or platinum group as main components, which is expensive, and partially dechlorinated, and the product is low-grade chlorinated organic matter, and may cause secondary pollution of heavy metals, thus being unsuitable for sewage treatment.
The name of publication No. CN 1183316A is: the invention discloses a catalytic reduction dechlorination technology for quickly catalyzing and dechlorinating polychlorinated organic compounds in water by using zero-valent iron and a palladium catalyst, which uses palladium element as a catalyst and uses a reducing agent as zero-valent iron. Palladium is not only a noble metal but also a heavy metal, and is not effective when treating wastewater, and palladium plating requires a special process, so that the treatment cost is high, and secondary pollution is possibly caused.
Although chemical reduction has achieved abundant results in the treatment of chloroform and carbon tetrachloride in environmental water and wastewater, there are still many difficulties and difficulties, mainly:
(1) the most effective catalyst Pd at present is too expensive;
(2) the preparation of binary metal or multi-metal catalysts is not yet suitable for the application of industrial wastewater treatment;
(3) the reducing agent or the catalyst belongs to heavy metals, and is easy to cause heavy metal pollution in the process of treating water or wastewater;
(4) the existing multi-metal or multi-phase catalytic system is carried out at higher temperature or pressure, so that the water treatment cost is higher, the facilities are more complex, and the popularization and the application are difficult.
Disclosure of Invention
The invention provides a process for treating chloroform and carbon tetrachloride industrial wastewater by using a catalytic metal reduction and flocculation precipitation method, which is carried out at normal temperature and normal pressure, adopts cheap and easily-obtained materials, has low treatment cost and excellent treatment effect, and does not have secondary pollution or heavy metal pollution.
A process for treating chloroform and carbon tetrachloride industrial wastewater by a catalytic metal reduction-flocculation precipitation method comprises the following steps: collecting industrial wastewater, adjusting the pH value to acidity, inputting the industrial wastewater into a reaction tower, adding inorganic sulfate serving as a catalyst, iron or iron-carbon alloy serving as a reducing agent to perform catalytic reduction reaction, introducing a reaction mixture into a flocculation clarification tank after the reaction is finished, adding alkali to neutralize the reaction mixture to be neutral to alkalescence, and discharging the reaction mixture after flocculation clarification.
The catalyst is sodium sulfate or ammonium sulfate, and the dosage of the catalyst is 0.2-2 kg per ton of wastewater.
The reducing agent is one of metal iron powder, cast iron powder and carbon steel powder, and the dosage of the reducing agentis 1-5 kg per ton of wastewater.
The reaction mechanism of the invention is as follows:
1. mechanism of metal reductive dechlorination
(1) Direct electron transfer from metal surface:
(2) fe generated by corrosion of metals2+Reduction:
(3) reduction by the original ecology H generated during the corrosion:
the principle of the original ecological hydrogen reduction can be further illustrated as follows:
in acidic solutions, the native H and organic chloride produced by metal corrosion first adsorb on the metal surface and form a transition complex. H attacks the transition complex, hydrogenation reaction occurs, and chlorine is reduced.
2. Mechanism of catalytic reaction
In the process of metal reductive dechlorination, the chemical reaction of the metal surface is a rate control step. Inorganic sulfates, such as sodium sulfate, catalyze dechlorination by accelerating the electron transfer on the metal surface and accelerating the generation rate of reduced metal ions.
3. Principle of flocculant produced in reduction process
During the reductive dechlorination of chloroform and carbon tetrachloride, metals are oxidized into metal ions. Solutions containing large amounts of such metal ions, after adjusting the pH of the solution, form metal hydroxide colloids, which have a flocculating effect.
The invention has the following effects:
1. reducing agent
The powdery metallic iron or iron-carbon alloy reducing agent is cheap and easily available, contains components which are not in pollutants listed in Integrated wastewater discharge Standard (GB8978-1996), does not introduce secondary pollution or heavy metal pollution, and has no adverse effect on subsequent treatment (such as biochemical treatment and coagulation treatment) of wastewater.
2. Catalyst and process for preparing same
(1) The catalyst is water-soluble inorganic salt, has low price, is easy to purchase from the market, contains components which are not in pollutants listed in Integrated wastewater discharge Standard (GB8978-1996), namely does not introduce secondary pollution;
(2) the catalyst replaces the prior expensive or secondary pollution-prone heavy metal and noble metal catalysts, such as Pd, Pt, Cu and the like;
(3) the catalyst has no adverse effect on the subsequent treatment of the wastewater;
(4) the catalysis mode is homogeneous, the catalyst does not need to be recovered or activated, and the solid waste of the catalyst is not generated.
3. Process conditions
(1) The process is operated at room temperature and under the atmospheric pressure condition, and does not need heating and pressurizing.
(2) In the wastewater treatment project, the processes of mixing, reacting, separating and the like of wastewater, a reducing agent and a catalyst are carried out in the same unit, and the batch operation and the continuous operation can be carried out, so that the design and the construction of the wastewater treatment project are relatively simple, and the improvement of theoperation stability is facilitated.
(3) Although the catalytic reduction is preferably carried out under oxygen-free conditions, industrial applications require special equipment if oxygen-free conditions are to be achieved, which leads to increased investment costs and complicated operation, for which the process can be operated without air isolation, and a high removal rate of carbon tetrachloride and chloroform is substantially maintained.
4. Application of the invention
(1) Is suitable for treating industrial wastewater containing carbon tetrachloride and chloroform;
(2) the removal rate of carbon tetrachloride is more than 95 percent, and the removal rate of chloroform is more than 85 percent;
(3) the cost is low, and the cost of treatment per ton of water is generally less than 2.5 yuan;
(4) the device is simple, easy to operate and stable to operate.
Detailed Description
Storing the industrial wastewater containing chloroform and carbon tetrachloride in a water collecting tank, determining whether water quality adjustment or other pretreatment is needed according to the water quality, and adjusting the pH value of the wastewater to be acidic; and (3) accounting the dosage of the reducing agent and the catalyst, wherein the dosage of the reducing agent is 1-5 kg per ton of wastewater, and the dosage of the catalyst is 0.2-2 kg per ton of wastewater. The wastewater enters a catalytic reduction reaction tower, the operation temperature is room temperature, and the operation pressure is atmospheric pressure. After reductive dechlorination, if the concentration of chloroform and carbon tetrachloride is too high, two (or more) stages of reaction towers can be considered. The wastewater treated by the catalytic reduction reaction is discharged into a flocculation clarification tank. In the flocculation clarification tank, chemical agents (such as caustic alkali, carbide slag and lime) are adopted to adjust the pH value of the wastewater to be neutral to alkalescent, so that the metal compounds generated by catalytic reduction can be fully utilized to generate flocculation, and carbon tetrachloride and chloroform in the wastewater are further removed.
The specific implementation scheme for realizing the invention content is as follows:
example 1
Reducing agent: the dosage of the metallic iron powder is 1-5 kg per ton of wastewater;
catalyst: the dosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH5.2; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: carbide slag;
flocculation clarification operating conditions: pH8.2; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Example 2
Reducing agent: the dosage of the metallic iron powder is 1-5 kg per ton of wastewater
Catalyst: the dosage of the ammonium sulfate is 0.2-2 kg per ton of wastewater
Catalytic reduction operating conditions: pH4.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: lime milk;
flocculation clarification operating conditions: pH7.0; HRT for 1-3h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Example 3
Reducing agent: the dosage of the metallic iron powder is 1-5 kg per ton of wastewater;
catalyst: the dosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH3.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: a caustic alkali;
flocculation clarification operating conditions: pH7.8; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Example 4
Reducing agent: 1-5 kg of cast iron powder per ton of wastewater;
catalyst: the dosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH5.7; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: carbide slag;
flocculation clarification operating conditions: pH9.0; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 97 percent.
Example 5
Reducing agent: 1-5 kg of cast iron powder per ton of wastewater;
catalyst: thedosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH4.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: lime milk;
flocculation clarification operating conditions: pH7.5; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 97 percent.
Example 6
Reducing agent: 1-5 kg of cast iron powder per ton of wastewater;
catalyst: the dosage of the ammonium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH4.5; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: a caustic alkali;
flocculation clarification operating conditions: pH8.5; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 97 percent.
Example 7
Reducing agent: 1-5 kg of carbon steel powder is used per ton of wastewater;
catalyst: the dosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH3.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: carbide slag;
flocculation clarification operating conditions: pH7.5; HRT for 1-3 h; and(4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Example 8
Reducing agent: 1-5 kg of carbon steel powder is used per ton of wastewater;
catalyst: the dosage of the sodium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH5.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: lime milk;
flocculation clarification operating conditions: pH7.0; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Example 9
Reducing agent: 1-5 kg of carbon steel powder is used per ton of wastewater;
catalyst: the dosage of the ammonium sulfate is 0.2-2 kg per ton of wastewater;
catalytic reduction operating conditions: pH5.0; the temperature is room temperature; the pressure is atmospheric pressure;
flocculating agent: caustic soda;
flocculation clarification operating conditions: pH9.0; HRT for 1-3 h; and (4) stirring.
The treatment effect is as follows: the chloroform removal rate is more than 90 percent; the removal rate of carbon tetrachloride is more than 95 percent.
Claims (5)
1. A process for treating chloroform and carbon tetrachloride industrial wastewater by a catalytic metal reduction-flocculation precipitation method comprises the following steps: after industrial wastewater is collected, adjusting the pH value to acidity, inputting the industrial wastewater into a reaction tower, adding inorganic sulfate serving as a catalyst, adding iron or iron-carbon alloy serving as a reducing agent, and carrying out catalytic reduction reaction; after the reaction is finished, the reaction mixture is led into a flocculation clarification tank, alkali is added for neutralization until the reaction mixture is neutral to alkalescent, and the reaction mixture is discharged after flocculation clarification.
2. The process according to claim 1, characterized in that: the dosage of the catalyst is 0.2-2 kg per ton of wastewater.
3. The process according to claim 1 or 2, characterized in that: the catalyst is sodium sulfate or ammonium sulfate.
4. The process according to claim 1, characterized in that: the dosage of the reducing agent is 1-5 kg per ton of wastewater.
5. The process according to claim 1 or 4, characterized in that: the reducing agent is one of metal iron powder, cast iron powder and carbon steel powder.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 03154176 CN1242939C (en) | 2003-08-15 | 2003-08-15 | Process for treating chloroform and carbon tetrachloride industrial waste water by catalytic metal reduction-flocculating settling method |
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| CN 03154176 CN1242939C (en) | 2003-08-15 | 2003-08-15 | Process for treating chloroform and carbon tetrachloride industrial waste water by catalytic metal reduction-flocculating settling method |
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| CN1579965A true CN1579965A (en) | 2005-02-16 |
| CN1242939C CN1242939C (en) | 2006-02-22 |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100398468C (en) * | 2006-04-18 | 2008-07-02 | 浙江大学 | Process for dechlorination of organic chloride through metal reduction assisted and strengthened by ultrasonic wave |
| CN100429158C (en) * | 2006-01-23 | 2008-10-29 | 浙江大学 | Method and equipment for removing organic chloride from wastewater |
| CN102295375A (en) * | 2011-08-01 | 2011-12-28 | 浙江环耀环境建设有限公司 | Recovery and treatment process of methyl chloride waste water by coagulative precipitation-heating stripping technology |
| CN102627360A (en) * | 2012-03-16 | 2012-08-08 | 同济大学 | Method for pretreatment on industrial wastewater by nascent state ferrous iron reduction |
| CN105776714A (en) * | 2016-05-13 | 2016-07-20 | 徐州市城区水资源管理处 | Device for processing carbon tetrachloride in underground water by catalyst heating method and working method thereof |
| CN114195298A (en) * | 2021-12-17 | 2022-03-18 | 广州一博环保科技有限公司 | Sewage catalytic reduction treatment process and system |
-
2003
- 2003-08-15 CN CN 03154176 patent/CN1242939C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100429158C (en) * | 2006-01-23 | 2008-10-29 | 浙江大学 | Method and equipment for removing organic chloride from wastewater |
| CN100398468C (en) * | 2006-04-18 | 2008-07-02 | 浙江大学 | Process for dechlorination of organic chloride through metal reduction assisted and strengthened by ultrasonic wave |
| CN102295375A (en) * | 2011-08-01 | 2011-12-28 | 浙江环耀环境建设有限公司 | Recovery and treatment process of methyl chloride waste water by coagulative precipitation-heating stripping technology |
| CN102295375B (en) * | 2011-08-01 | 2013-11-20 | 浙江环耀环境建设有限公司 | Recovery and treatment process of methyl chloride waste water by coagulative precipitation-heating stripping technology |
| CN102627360A (en) * | 2012-03-16 | 2012-08-08 | 同济大学 | Method for pretreatment on industrial wastewater by nascent state ferrous iron reduction |
| CN102627360B (en) * | 2012-03-16 | 2013-12-25 | 同济大学 | Method for pretreatment on industrial wastewater by nascent state ferrous iron reduction |
| CN105776714A (en) * | 2016-05-13 | 2016-07-20 | 徐州市城区水资源管理处 | Device for processing carbon tetrachloride in underground water by catalyst heating method and working method thereof |
| CN114195298A (en) * | 2021-12-17 | 2022-03-18 | 广州一博环保科技有限公司 | Sewage catalytic reduction treatment process and system |
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| CN1242939C (en) | 2006-02-22 |
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