Treatment method of papermaking black liquor

A technology for papermaking black liquor and treatment methods, applied in chemical instruments and methods, methods based on microorganisms, multi-stage water/sewage treatment, etc., can solve the problems of unreachable pollution control, limited application, low lignin content, etc. Achieve the effect of reducing treatment cost, reducing dosage and improving treatment efficiency

Active Publication Date: 2012-08-15
CENT SOUTH UNIV
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Problems solved by technology

At present, there is no good treatment process for the black liquor of alkaline pulping and papermaking. Alkali recovery method is the most mature treatment method for papermaking black liquor at this stage, but it is more suitable for wood pulp and papermaking, not suitable for the treatment of wheat straw pulp black liquor The reasons are: 1. Due to the high viscosity and short fibers, it is difficult to extract the black liquor, resulting in low black liquor recovery rate and high alkali recovery cost. 2. Due to the high viscosity, it is difficult to spray the black liquor in the furnace, and the black liquor The dispersion of the liquid is poor, and the lignin content in the solid matter of the black liquor is low, which brings difficulties to the combustion of the black liquor
Therefore, most papermaking enterprises discharge the cooking black liquor without treatment or incomplete treatment, resulting in serious environmental pollution and becoming a major problem restricting the development of the papermaking industry.
[0003] Traditional papermaking black liquor treatment technologies mainly include chemical methods, physical chemical methods and biological methods, or a

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Experimental program
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Embodiment 1

[0037] Embodiment 1: the biological identification of bacterial strain

[0038] 1. Morphological characteristics of the strain

[0039] (1) Morphological characteristics of the colony: more regular round, larger and denser, with rough surface and jagged edges; the front of the colony is white when it is born; the colony gradually turns red from the center in the middle stage of growth; the colony in the late growth stage is concentric circles, with It is off-white, the outer circle is pink, the outermost circle is white, and the opposite side of the colony is yellowish brown. See figure 1 .

[0040] (2) Morphological characteristics of the bacteria: the aerial mycelium is in the shape of a long tube, with a transverse septum, and the top of the mycelium expands into spherical vesicles, and clusters of conidia are radially formed on the surface of the vesicles; and scanning electron microscopy Observe the bacterial strain, the scanning electron microscope photos of the bacte...

Embodiment 2

[0043] Embodiment 2. Taking a pulp and paper mill with an annual output of 10,000 tons as an example, with reeds as production raw materials, it can produce 400 tons of black liquor and 25 tons of pulp per day. The initial COD of the black liquor is about 83,000mg / l, the pH is 13.1-13.6, and the chromaticity is 225,000CU.

[0044] Such as image 3 As shown, the whole treatment process of the present invention is as follows: the papermaking black liquor enters the sedimentation tank first, and impurities such as silt and fiber mud in the black liquor are removed. After the black liquor is treated in the sedimentation tank, it is transported to the storage tank by the lifting pump, and a certain chemical agent is added. The wastewater is mixed with the chemical agent in the storage tank. After filtration, it is treated in the biochemical treatment tank, and the effluent is settled in the secondary sedimentation tank and then mixed with the middle papermaking wastewater. After ...

Embodiment 4

[0058] Embodiment 4. Taking the pulp and paper mill with an annual output of 10,000 tons as an example, using Asparagus as a production raw material, the daily output of black liquor is 350 tons, and the pulp is 22 tons. The initial COD of the black liquor is about 130,000mg / l, the pH is 13.2-13.6, and the chromaticity is 320,000CU.

[0059] The entire treatment process of the present invention is as follows: the papermaking black liquor first enters the sedimentation tank, and is mixed with part of the middle papermaking wastewater to reduce the COD of the black liquor to about 70,000, and simultaneously remove impurities such as silt and fiber mud in the black liquor. After the black liquor is treated in the sedimentation tank, it is transported to the storage tank by the lifting pump, and a certain chemical agent is added. The wastewater is mixed with the chemical agent in the storage tank. After filtration, it is treated in the biochemical treatment tank, and the effluent ...

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Abstract

The invention relates to a treatment method which is suitable for papermaking black liquor (in particular to alkaline pulping papermaking black liquor which takes wheat straw hood as raw material). The treatment method comprises the following steps of: firstly performing standing treatment on the fresh black liquor, adding a high-efficient alkaline separation agent into the black liquor after treatment, separating out lignin, and further performing biological strengthening technical treatment on filtrate. According to the process disclosed by the invention, after the combined treatment of thestanding treatment, an alkaline separation method and a biological strengthening system is performed on the black liquor with initial COD (chemical oxygen demand) of 83,000mg/l, pH of 13.1 and chromaticity of 225,000CU, the COD and chromaticity of outlet water are respectively reduced to below 15% and 7% of the original black liquor (namely the COD total removal rate and chromaticity total removal rate of the whole system are about 85% and 93% respectively), the outlet water can be mixed with a quite large quantity of middle-stage wastewater in a papermaking factory, and the treatment can be performed according to the existing comparatively mature middle-stage wastewater treatment method. The process has the characteristics of low investment and operation cost and capability of recycling the lignin, and is suitable for wheat straw pulp papermaking factories above 5000 tons.

Description

technical field [0001] The invention relates to a treatment method suitable for papermaking black liquor (especially alkaline pulping and papermaking black liquor with wheat straw as raw material). Background technique [0002] Paper industry wastewater accounts for about 10% of the total industrial wastewater in the country, and the pollution to my country's water resources and environment is becoming more and more serious. The papermaking black liquor produced in the pulping process is an important source of pollution in the papermaking industry. At present, there is no good treatment process for the black liquor of alkaline pulping and papermaking. Alkali recovery method is the most mature treatment method for papermaking black liquor at this stage, but it is more suitable for wood pulp and papermaking, not suitable for the treatment of wheat straw pulp black liquor The reasons are: 1. Due to the high viscosity and short fibers, it is difficult to extract the black liquo...

Claims

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Application Information

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IPC IPC(8): C02F9/14C12N1/14C12N1/20C12R1/66C12R1/01
Inventor 柴立元郑玉闵小波杨志辉王庆伟陈跃辉张欢
Owner CENT SOUTH UNIV
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