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CN1755012A - The comprehensive processing method of paper-making sewage black liquor - Google Patents

The comprehensive processing method of paper-making sewage black liquor Download PDF

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Publication number
CN1755012A
CN1755012A CN 02134515 CN02134515A CN1755012A CN 1755012 A CN1755012 A CN 1755012A CN 02134515 CN02134515 CN 02134515 CN 02134515 A CN02134515 A CN 02134515A CN 1755012 A CN1755012 A CN 1755012A
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black liquor
liquor
treatment method
comprehensive treatment
sulfuric acid
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CN 02134515
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Chinese (zh)
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周永康
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Individual
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Abstract

A kind of comprehensive processing method of paper-making sewage black liquor comprises following processing step: 1) the rag paper slurries after the boiling are squeezed the system black liquor by squeezer; 2) in black liquor, add organic polymer flocculation aid polyacrylamide; 3) in black liquor, add the concentrated sulfuric acid and carry out acidifying, make the pH value drop to the pH value gradually between the 4.5-5.0; 4) the lignin particulate in the black liquor reclaims and obtains lignin through assembling, clarify, dewater, separating, and makes the Sandy aqueous solution simultaneously; 5) the Sandy aqueous solution is passed through activated carbon filtration, decolouring, remove organic matter, make the dilute sulfuric acid sodium solution.6) in described dilute sulfuric acid sodium solution, add quick lime and carry out metathesis reaction, further remove biological oxygen demand and COD, make sig water.7) sig water that makes is carried out the concentrated alkali lye of evaporation and concentration after half and add cooking process boiling next time.Also the described dilute sulfuric acid sodium solution that makes can be added and do the water recycling in the white liquid of papermaking wastewater together.

Description

Comprehensive treatment method for black liquor of papermaking sewage
Technical Field
The present invention relates to papermaking sewage treating technology, and is especially the treatment of black liquid from papermaking effluent.
Background
The fiber raw materials used in the pulping and papermaking industry, whether wood or grass, are chemically pulped. In domestic small and medium-sized enterprises, most of the small and medium-sized enterprises adopt a process of preparing paper pulp by mixing caustic soda and sodium sulfide, and then carry out the procedures of rinsing, bleaching and finding paper. The content of the pulping wastewater is complex, the main component is cellulose, the content is generally not more than 50%, the other components are lignin, hemicellulose, inorganic matters, extractable polysaccharide and the like, and settleable floating matters, non-settleable matters and organic substances which are easy to biodegrade are formed, and toxic organic matters, namely abietic acid, unsaturated fatty acid and the like are also formed. Most of these substances are present in black liquor, which is the product of the pulping process. In the pulping process, caustic soda, sodium sulfide and fiber raw materials are mixed according to a certain proportion, and proper water is added for cooking to obtain coarse pulp and black liquor.
The yield of the pulping and papermaking industry in China is third in the world, but the treatment of wastewater is behind that of developed countries. The treatment of waste water of paper mill, black liquor and white liquor, especially black liquor, is difficult, and it is a great pollution source for water body pollution. The treatment processes currently used in paper mills are mostly distillation processes. Although the distillation technology is mature, common small and medium-sized enterprises are difficult to accept in investment due to large investment of distillation processing equipment. However, when other technologies such as chemical treatment and biological treatment are applied, medium and small-sized enterprises directly discharge sewage and seriously pollute a water system due to immature chemical treatment technology, unreliable biological treatment and the like.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a comprehensive treatment method for the black liquor of the papermaking sewage, which has simple equipment and low investment, can comprehensively treat the black liquor of the wastewater to prevent the black liquor from polluting a water system and can recover a large amount of alkali liquor and lignin through a series of experimental researches.
The technical scheme for realizing the purpose is as follows: a comprehensive treatment method of papermaking sewage black liquor comprises the following process steps:
1) squeezing the boiled crude paper pulp liquid through a squeezer to obtain thick black liquid;
2) adding organic polymer coagulant aid polyacrylamide into the black liquor;
3) adding concentrated sulfuric acid into the black liquor for acidification, and gradually reducing the pH value to 4.5-5.0;
4) collecting, clarifying, dehydrating and separating lignin fine particles in the black liquor, recovering to obtain lignin, and preparing a light brown aqueous solution;
5) filtering and decoloring the light brown water solution by active carbon, and removing organic matters to prepare a dilute sodium sulfate solution.
Adding quicklime into the dilute sodium sulfate solution to carry out double decomposition reaction, and further removing biological oxygen demand and chemical oxygen demand to prepare dilutealkali liquor.
And (4) evaporating and concentrating the dilute alkali liquor.
Adding the alkali liquor after evaporation and concentration into the next cooking procedure for cooking.
And adding the concentrated alkali liquor obtained after the obtained diluted alkali liquor is evaporated and concentrated by a half into the next cooking procedure for cooking.
Adding the prepared dilute sodium sulfate solution into white liquor of papermaking sewage, performing coagulative precipitation by using a chemical coagulant, namely polyaluminium chloride, and simultaneously adding a small amount of bleaching solution for disinfection, clarification and filtration, and respectively recovering fine paper pulp and water for recycling.
The addition amount of the organic polymer coagulant aid polyacrylamide in the black liquor is as follows: 100-300 g/cubic meter.
The adding amount of the concentrated sulfuric acid in the black liquor is as follows: 4-16 kg/cubic meter.
The adding amount of the polyaluminium chloride in the white liquid is as follows: 10-15 g/cubic meter.
Adopt above-mentioned technical scheme, the utility model discloses profitable technological effect lies in: 1) the treatment process of the black liquor of the papermaking sewage is simple, the equipment investment is very little, the defect of large investment of distillation treatment equipment is overcome, and the common medium and small enterprises can accept the investment. 2) The treatment of the sewage black liquor is scientific and ingenious. The comprehensive treatment can avoid polluting water system and recover a large amount of alkali liquor and lignin. 3) The invention has good treatment effect on the black liquid of the sewage and obvious economic benefit through experiments and experimental operation.
Detailed Description
The first embodiment is as follows: a comprehensive treatment method for black liquor in papermaking sewage takes a paper mill as an example, which produces 5.4 tons of paper pulp in wheat straw per day, produces 7 tons of writing paper and produces 81 cubic meters of black liquor sewage, and the sewage treatment comprises the following process steps:
1) and squeezing the steamed wheat straw coarse paper pulp liquid through a squeezer to prepare black liquor.
2) 250g of organic polymer coagulant aid polyacrylamide is added into each cubic meter of black liquor.
3) Adding 10kg of concentrated sulfuric acid into each cubic meter of black liquor for acidification, and gradually reducing the pH value to 4.5-5.0.
4) The fine lignin particles in the black liquor are collected, clarified, dehydrated and separated, and 18.7kg of lignin is obtained by recovery and is used as a raw material for manufacturing active carbon and the like. At the same time, a light brown aqueous solution was prepared.
In the process, the pressing speed is high, the treatment aqueous solution is kept at a certain temperature, the lignin precipitation is helped to a certain extent, the structure of the lignin is compact, and the separation is convenient.
5) And filtering and decoloring the light brown water solution by using activated carbon, and removing organic matters to prepare a dilute sodium sulfate solution.
6) Adding 10kg of quicklime into the dilute sodium sulfate solution, carrying out double decomposition reaction, and removing precipitates toobtain dilute alkali liquor.
The reaction equation for obtaining caustic soda by carrying out double decomposition reaction on dilute sodium sulfate solution by using lime is as follows:
through the steps, the black liquor is treated by concentrated sulfuric acid and lime water, so that the chemical oxygen consumption and the biological oxygen consumption in the black liquor can be completely removed.
6) Evaporating and concentrating the dilute alkali liquor. When the dilute alkali liquor is evaporated and concentrated, complete concentration is not necessary, and the dilute alkali liquor is only concentrated by half of the volume (if complete concentration is performed, 10kg of caustic soda can be prepared). The concentrated dilute alkali liquor can be added into the next cooking procedure for cooking, so that the water addition amount can be reduced, only alkali needs to be supplemented, the energy required by concentration is reduced, and the operation cost is reduced.
The adding amount of polyacrylamide and concentrated sulfuric acid is determined according to the lignin content, and the higher the lignin content is, the adding amount of polyacrylamide and concentrated sulfuric acid is increased simultaneously.
If alkali liquor after black liquor treatment is not required to be recycled, dilute sodium sulfate solution obtained after active carbon filtration is gradually added into white liquor of papermaking sewage, and the pH value after white liquor treatment can also be kept between 6 and 8 to be recycled together with the white liquor.
The white liquor treatment process comprises the following steps: the white liquor contains fine paper pulp, talcum powder and the like, and is subjected to coagulating sedimentation by using a chemical coagulant, namely polyaluminium chloride, wherein the adding amount of the polyaluminium chloride is preferably 10-15 g per cubic meter. Meanwhile, a small amount of bleaching solution is added for disinfection, clarification and filtration, a cylinder paper machine is adopted for filtration to recover 250g of fine paper pulp per cubic meter of white liquor, and the water after filtration and recovery meets the industrial water standard GB 12941-91.
The paper making sewage treatment economic analysis of the embodiment: the daily production of 7 cubic meters of paper can recover 1512 kilograms of lignin, and the price of each cubic meter of lignin is 2000 yuan, and the daily recovery value is 3024 yuan; 810 kg of alkali is recovered, and the recovery value is 1296 yuan; recycling paper pulp, wherein 3400 cubic meter of white water is produced daily, 250g of paper pulp in each cubic meter of white water is recycled daily, 850 kg of paper pulp is recycled daily, 2000 yuan of paper pulp is recycled per cubic meter, and the recycling value is 1750 yuan/day; the total recovery value is 6070 yuan, and the total processing cost is about 2312 yuan. The recovery income minus the treatment cost is in profit of 3758 yuan, and the recovery value exceeds the operation cost. Not only does not increase the burden of enterprises, but also creates obvious income. Environmental protection and economic benefit are achieved at the same time, and the method is feasible.
Example two: a comprehensive treatment method for black liquor in papermaking sewage takes a paper mill as an example, wherein 5.4 tons of paper pulp are produced by wood pulp per day, 7 tons of writing paper are produced, and 81 cubic meters of black liquor sewage is produced, and the sewage treatment comprises the following process steps:
1) and squeezing the steamed wheat straw coarse paper pulp liquid through a squeezer to prepare black liquor.
2) 100g of organic polymer coagulant aid polyacrylamide is added into each cubic meter of black liquor.
3) Adding 4kg of concentrated sulfuric acid into each cubic meter of black liquor for acidification, and gradually reducing the pH value to 4.5-5.0.
4) The lignin fine particles in the black liquor are collected, clarified, dehydrated and separated, and 13.7kg of lignin is obtained by recovery and is used as a raw material for manufacturing active carbon and the like. At the same time, a light brown aqueous solution was prepared.
In the process, the pressing speed is high, the treatment aqueous solution is kept at a certain temperature, the lignin precipitation is helped to a certain extent, the structure of the lignin is compact, and the separation is convenient.
5) And filtering and decoloring the light brown water solution by using activated carbon, and removing organic matters to prepare a dilute sodium sulfate solution.
6) 3kg of quicklime is added into the dilute sodium sulfate solution for double decomposition reaction, and precipitates are removed to prepare dilute alkali solution.
The reaction equation for obtaining caustic soda by carrying out double decomposition reaction on dilute sodium sulfate solution by using lime is as follows:
through the steps, the black liquor is treated by concentrated sulfuric acid and lime water, so that the chemical oxygen consumption and the biological oxygen consumption in the black liquor can be completely removed.
7) Evaporating and concentrating the dilute alkali liquor. When the dilute alkali liquor is evaporated and concentrated, complete concentration is not needed, and only half of the volume of the dilute alkali liquor is required to be concentrated (if complete concentration is adopted, caustic soda 2.8 kg. can be prepared, when the concentrated dilute alkali liquor can be added into the next cooking procedure for cooking, the water addition amount can be reduced, and only alkali needs to be supplemented, so that the energy required by concentration is reduced, and the operation cost is reduced.
If alkali liquor after black liquor treatment is not required to be recycled, dilute sodium sulfate solution obtained after active carbon filtration is gradually added into white liquor of papermaking sewage, and the pH value after white liquor treatment can also be kept between 6 and 8 to be recycled together with the white liquor. The process is the same as the first embodiment.
Example three: a comprehensive treatment method for black liquor in papermaking sewage takes grass as raw material, produces 5.4 tons of pulp per day, produces 7 tons of writing paper, and produces 81 cubic meters of black liquor sewage as an example, and the sewage treatment comprises the following process steps:
1) and squeezing the steamed wheat straw coarse paper pulp liquid through a squeezer to prepare black liquor.
2) 300g of organic polymer coagulant aid polyacrylamide is added into each cubic meter of black liquor.
3) Adding16kg of concentrated sulfuric acid into each cubic meter of black liquor for acidification, and gradually reducing the pH value to 4.5-5.0.
4) The lignin fine particles in each cubic meter of black liquor are aggregated, clarified, dehydrated and separated, and recovered to obtain 31kg of lignin which is used as a raw material for manufacturing active carbon and the like. At the same time, a light brown aqueous solution was prepared. In the process, the pressing speed is high, the treatment aqueous solution is kept at a certain temperature, the lignin precipitation is helped to a certain extent, the structure of the lignin is compact, and the separation is convenient.
5) And filtering and decoloring the light brown water solution by using activated carbon, and removing organic matters to prepare a dilute sodium sulfate solution.
6) And adding 12kg of quicklime into the dilute sodium sulfate solution, carrying out double decomposition reaction, and removing precipitates to obtain dilute alkali liquor.
The reaction equation for obtaining caustic soda by carrying out double decomposition reaction on dilute sodium sulfate solution by using lime is as follows:
through the steps, the black liquor is treated by concentrated sulfuric acid and lime water, so that the chemical oxygen consumption and the biological oxygen consumption in the black liquor can be completely removed.
7) Evaporating and concentrating the dilute alkali liquor. When the dilute alkali liquor is evaporated and concentrated, complete concentration isnot needed, and only half of the volume of the dilute alkali liquor is required to be concentrated (if complete concentration is required, caustic soda 13 kg. can be prepared, when the concentrated dilute alkali liquor can be added into the next cooking procedure for cooking, the water addition amount can be reduced, and only alkali needs to be supplemented, so that the energy required by concentration is reduced, and the operation cost is reduced.
If alkali liquor after black liquor treatment is not required to be recycled, dilute sodium sulfate solution obtained after active carbon filtration is gradually added into white liquor of papermaking sewage, and the pH value after white liquor treatment can also be kept between 6 and 8 to be recycled together with the white liquor. The process is the same as the first embodiment.

Claims (9)

1. A comprehensive treatment method of papermaking sewage black liquor is characterized by comprising the following process steps:
1) squeezing the boiled crude paper pulp liquid through a squeezer to obtain thick black liquid;
2) adding organic polymer coagulant aid polyacrylamide into the black liquor;
3) adding concentrated sulfuric acid into the black liquor for acidification, and gradually reducing the pH value to 4.5-5.0;
4) collecting, clarifying, dehydrating and separating lignin fine particles in the black liquor, recovering to obtain lignin, and preparing a light brown aqueous solution;
5) filtering and decoloring the light brown aqueous solution by active carbon, and removing organic matters to prepare a dilute sodium sulfate solution.
2. The comprehensive treatment method of black liquor in papermaking sewage according to claim 1, characterized in that: adding quicklime into the dilute sodium sulfate solution to carry out double decomposition reaction, and further removing biological oxygen demand and chemical oxygen demand to prepare dilute alkali liquor.
3. The comprehensive treatment method of black liquor in papermaking sewage according to claim 2, characterized in that: and (4) evaporating and concentrating the dilute alkali liquor.
4. The comprehensive treatment method of black liquor in papermaking sewage according to claim 3, characterized in that: adding the alkali liquor after evaporation and concentration into the next cooking procedure for cooking.
5. The comprehensive treatment method of black liquor in papermaking sewage according to claim 3, characterized in that: and adding the concentrated alkali liquor obtained after the obtained diluted alkali liquor is evaporated and concentrated by a half into the next cooking procedure for cooking.
6. The comprehensive treatment method of black liquor in papermaking sewage according to claim 1, characterized in that: and adding the dilute sodium sulfate solution into the white liquid of the papermaking sewage, performing coagulating sedimentation by using a chemical coagulant, namely polyaluminium chloride, and simultaneously adding a small amount of bleaching solution for disinfection, clarification and filtration, and respectively recovering fine paper pulp and water for recycling.
7. The comprehensive treatment method of black liquor in papermaking sewageaccording to claim 1, characterized in that: the adding amount of the organic polymer coagulant aid polyacrylamide in the black liquor is 100-300 g/cubic meter.
8. The comprehensive treatment method of black liquor in papermaking sewage according to claim 1, characterized in that the addition amount of concentrated sulfuric acid in the black liquor is: 4-16 Kg/cubic meter.
9. The method for comprehensively treating black liquor in papermaking sewage according to claim 6, characterized by comprising the following steps: the adding amount of the polyaluminium chloride in the white liquid is 10-15 g/cubic meter.
CN 02134515 2002-08-06 2002-08-06 The comprehensive processing method of paper-making sewage black liquor Pending CN1755012A (en)

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Application Number Priority Date Filing Date Title
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102050951A (en) * 2010-11-10 2011-05-11 山东龙力生物科技股份有限公司 Cleaner production method of functional lignin
CN102561085A (en) * 2012-01-19 2012-07-11 河南省科学院化学研究所有限公司 Technology for removing water insoluble matter in pulping black liquor
US20140357847A1 (en) * 2011-06-28 2014-12-04 Henrik Wallmo Method for lignin separation from black liquor having removal of sulphur compounds from formed water effluent

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102050951A (en) * 2010-11-10 2011-05-11 山东龙力生物科技股份有限公司 Cleaner production method of functional lignin
US20140357847A1 (en) * 2011-06-28 2014-12-04 Henrik Wallmo Method for lignin separation from black liquor having removal of sulphur compounds from formed water effluent
US9475833B2 (en) * 2011-06-28 2016-10-25 Valmet Power Ab Method for lignin separation from black liquor comprising removal of sulfur compounds from formed water effluent
CN102561085A (en) * 2012-01-19 2012-07-11 河南省科学院化学研究所有限公司 Technology for removing water insoluble matter in pulping black liquor

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