1. A process for treating pulp black liquor by using viscose waste water is characterized by comprising the following steps:

A. obtaining dilute black liquor by the black liquor through the action of a black liquor pulp extruder twice, introducing the dilute black liquor into a first sedimentation tank, adding an alkaline reagent into the first sedimentation tank, and then precipitating for 1-3 hours;

B. b, introducing the supernatant in the first sedimentation tank in the step A into a desulfurization tower for desulfurization treatment, then introducing the desulfurization waste liquid in the desulfurization tower into a first adjusting tank, adding viscose waste water with the pH value of 1-3 into the first adjusting tank, then introducing the solution in the first adjusting tank into a multi-bucket sedimentation tank, and then adding AlCl into the multi-bucket sedimentation tank₃Precipitating for 1-3 h after mixing with a polyacrylamide solution;

C. b, introducing the sediment in the multi-bucket sedimentation tank in the step B into a sludge collection tank, introducing the supernatant in the multi-bucket sedimentation tank into a second regulating tank, adding fiber wastewater with the pH value of 7-10 into the second regulating tank, and introducing the solution in the second regulating tank into the second sedimentation tank;

D. adding AlCl into the second sedimentation tank in the step C₃Precipitating for 1-3 hours after the polyacrylamide solution is mixed, then introducing the supernatant in the second sedimentation tank into a third sedimentation tank for precipitation for 1-2 hours, and introducing the precipitate in the second sedimentation tank into the sludge collection tank;

E. and D, introducing the supernatant in the third sedimentation tank in the step D into a reactor, then adding hydrogen peroxide and ferrous sulfate into the reactor, then introducing the solution in the reactor into a final sedimentation tank, adding a polyacrylamide solution for 4-8 h, and introducing the precipitate in the final sedimentation tank into a sludge collection tank.

2. The process for treating pulp black liquor by using viscose waste water according to claim 1, wherein in the step A, the alkaline reagent is any one of sodium hydroxide or calcium hydroxide.

3. The process for treating pulp black liquor by using viscose waste water according to claim 1, wherein in the step A, the precipitate in the first sedimentation tank is introduced into the sludge collecting tank.

4. The process for treating pulp black liquor by using viscose wastewater according to claim 1, wherein in the step A, the mass ratio of the weak black liquor to the alkaline reagent is 100: (0.15 to 0.28);

in the step B, the mass ratio of the supernatant liquid to the desulfurization waste liquid in the first sedimentation tank is 10: (6.5-7.3), wherein the mass ratio of the desulfurization waste liquid to the viscose waste water is 10: (3.1-4.6), the AlCl₃The concentration of the polyacrylamide is 2.2-3.2 mol/L, the concentration of the polyacrylamide is 3.1-4.5 mol/L, and the solution and the AlCl in the multi-bucket sedimentation tank₃And polyacrylamide in a mass ratio of 100: (0.4-1.1): (0.3 to 1.5);

in the step C, the mass ratio of the supernatant in the second regulating reservoir to the fiber wastewater is 10: (2-6);

in step D, the AlCl is₃The concentration of the second sedimentation tank is 2.2-3.2 mol/L, the concentration of the polyacrylamide is 3.1-4.5 mol/L, and the solution and the AlCl in the second sedimentation tank₃And polyacrylamide in a mass ratio of 100: (0.8-1.2): (0.2 to 0.6);

in step E, the mass ratio of the supernatant in the third sedimentation tank to the hydrogen peroxide and the ferrous sulfate is 100: (3-7): (0.4-0.8), the concentration of hydrogen peroxide is 2-4 mol/L, the concentration of ferrous sulfate is 1-3 mol/L, the concentration of polyacrylamide solution is 3.1-4.5 mol/L, and the mass ratio of the solution in the reactor to the polyacrylamide solution is 100: (3-12).

5. The process for treating pulp black liquor by using viscose waste water according to claim 1, wherein in the step E, the precipitate in the third sedimentation tank is introduced into a sludge collecting tank.

6. The process for treating pulp black liquor by using viscose waste water according to claim 1, wherein in step C, the treatment for removing bubbles is performed after the fiber waste water is added into the second adjusting tank.

7. The process for treating pulp black liquor by using viscose waste water according to claim 5, wherein the bubble removal treatment is to remove bubbles by using an air blower, and the air pressure generated by the air blower is 1000-3000 Pa.

Background

During the production process of the pulp, a large amount of black liquor is generated after the cotton linters and the alkali liquor are cooked, the pulp is intercepted to a material washing tank after being treated by a pulp extruder twice, the primary dilute black liquor needs to be circulated in the white water tank and the material washing tank for multiple times to reach more than 35000 COD, the content of sodium carbonate is more than 500g/L, the treatment is difficult, and the development of the industry is restricted. The viscose industry also has the problem of treating acidic wastewater and alkaline wastewater. In the prior art, a large amount of reagents are often required to be added in the treatment process of black liquor, so that the treatment cost of the black liquor is extremely high, a large amount of cost is also required for the treatment of wastewater and fiber wastewater in the viscose industry, the energy conservation and the environmental protection are not facilitated, the treatment cost of an enterprise is reduced while the pollution problem is effectively solved, and the problem becomes the current problem.

Disclosure of Invention

The invention aims to solve the technical problems in the background technology and provides a process for treating pulp black liquor by using viscose waste water to realize treatment of wastes with processes of wastes against one another. Not only can treat pulp black liquor, but also can treat viscose waste water and fiber waste water.

The technical scheme for solving the technical problems is as follows: a process for treating pulp black liquor by using viscose waste water comprises the following steps:

A. obtaining dilute black liquor by the black liquor through the action of a black liquor pulp extruder twice, introducing the dilute black liquor into a first sedimentation tank, adding an alkaline reagent into the first sedimentation tank, and then precipitating for 1-3 hours;

B. b, introducing the supernatant in the first sedimentation tank in the step A into a desulfurization tower for desulfurization treatment, then introducing the desulfurization waste liquid in the desulfurization tower into a first adjusting tank, adding viscose waste water with the pH value of 1-3 into the first adjusting tank, then introducing the solution in the first adjusting tank into a multi-bucket sedimentation tank, and then adding AlCl into the multi-bucket sedimentation tank₃Precipitating for 1-3 h after mixing with a polyacrylamide solution;

C. b, introducing the sediment in the multi-bucket sedimentation tank in the step B into a sludge collection tank, introducing the supernatant in the multi-bucket sedimentation tank into a second regulating tank, adding fiber wastewater with the pH value of 7-10 into the second regulating tank, and introducing the solution in the second regulating tank into the second sedimentation tank;

D. adding AlCl into the second sedimentation tank in the step C₃Precipitating for 1-3 hours after the polyacrylamide solution is mixed, then introducing the supernatant in the second sedimentation tank into a third sedimentation tank for precipitation for 1-2 hours, and introducing the precipitate in the second sedimentation tank into the sludge collection tank;

E. and D, introducing the supernatant in the third sedimentation tank in the step D into a reactor, adding hydrogen peroxide and ferrous sulfate into the reactor, introducing the solution in the reactor into a final sedimentation tank, adding a polyacrylamide solution, precipitating for 4-8 hours, and introducing the precipitate in the final sedimentation tank into a sludge collection tank.

The invention has the beneficial effects that: the black liquor press can adopt a spiral press to extract the black liquor and obtain the thin black liquor with pulp filtered out. The desulfurization tower contains sulfide, and the flue gas can take away about 20% of moisture, so that the dilute black liquor entering the desulfurization tower can produce sulfide salt, and the amount of the dilute black liquor is reduced. The black liquor is squeezed by a black liquor squeezing machine twice, the obtained diluted black liquor reacts with an alkaline reagent to generate calcium carbonate precipitate in a first sedimentation tank, the supernatant enters a desulfurizing tower under the action of a pump through a pipeline, and then partial sulfide salt is generated in the desulfurizing tower. The desulfurization waste liquid enters a first regulating tank under the action of a pump through a pipeline, and is in the regulating tankHemicellulose is separated out through reaction with viscose waste water, and COD is greatly reduced. Realizes the treatment of the weak black liquor by using the viscose waste water and solves the problem of the treatment of the viscose waste water. Then the mixture enters a multi-bucket sedimentation tank, and AlCl is added₃And after the polyacrylamide solution is precipitated, the supernatant of the multi-bucket sedimentation tank enters the second regulating tank through the pipeline under the action of the pump to react with the fiber wastewater, so that the acidic components in the regulating tank are neutralized, and the COD is reduced. Then the mixture is led into a second sedimentation tank, and AlCl is added again₃And polyacrylamide solution is added into a final sedimentation tank, and the final sludge is pumped into a sludge collection tank through a pump after flocculation of the polyacrylamide solution. And the sediment in the sludge collection tank can be sent to a boiler for incineration, so that the secondary pollution of the sediment is eliminated.

On the basis of the technical scheme, the invention can be further improved as follows.

Further, in the step a, the alkaline agent is any one of sodium hydroxide or calcium hydroxide.

The further scheme has the beneficial effects that the sodium hydroxide or the calcium hydroxide has low cost and good effect, and can react with the dilute black liquor rapidly to generate calcium carbonate precipitate in a large amount.

Further, in the step A, the sediment in the first sedimentation tank is introduced into the sludge collecting tank.

The beneficial effect of adopting the further scheme is that the secondary pollution of the sediment in the first sedimentation tank is eliminated.

Further, in the step A, the mass ratio of the weak black liquor to the alkaline reagent is 100: (0.15 to 0.28);

in the step B, the mass ratio of the supernatant liquid to the desulfurization waste liquid in the first sedimentation tank is 10: (6.5 to 7.3), the step of removingThe mass ratio of the sulfur waste liquid to the viscose waste water is 10: (3.1-4.6), the AlCl₃The concentration of the polyacrylamide is 2.2-3.2 mol/L, the concentration of the polyacrylamide is 3.1-4.5 mol/L, and the solution and the AlCl in the multi-bucket sedimentation tank₃And polyacrylamide in a mass ratio of 100: (0.4-1.1): (0.3 to 1.5);

in the step C, the mass ratio of the supernatant in the second regulating reservoir to the fiber wastewater is 10: (2-6);

in step D, the AlCl is₃The concentration of the second sedimentation tank is 2.2-3.2 mol/L, the concentration of the polyacrylamide is 3.1-4.5 mol/L, and the solution and the AlCl in the second sedimentation tank₃And polyacrylamide in a mass ratio of 100: (0.8-1.2): (0.2 to 0.6);

in step E, the mass ratio of the supernatant in the third sedimentation tank to the hydrogen peroxide and the ferrous sulfate is 100: (3-7): (0.4-0.8), the concentration of hydrogen peroxide is 2-4 mol/L, the concentration of ferrous sulfate is 1-3 mol/L, the concentration of polyacrylamide solution is 3.1-4.5 mol/L, and the mass ratio of the solution in the reactor to the polyacrylamide solution is 100: (3-12).

The further scheme has the beneficial effect that the determined reaction conditions can ensure the normal operation of the process. Improving the effect of reducing COD of the black liquor, protecting the environment and realizing the treatment of waste by waste.

Further, in step E, the sediment in the third sedimentation tank is introduced into a sludge collection tank.

The beneficial effect of adopting the further scheme is that the secondary pollution of the sediment in the third sedimentation tank is eliminated.

Further, in the step C, the fiber wastewater is added into the second adjusting tank and then is subjected to bubble removal treatment.

The beneficial effect of adopting above-mentioned further scheme is that, in the second equalizing basin, owing to separate out the cellulose, so can produce a large amount of bubbles, adopts and gets rid of the bubble, can avoid the interference of foreign matter to this technology.

Further, the bubble removing treatment is to remove bubbles by adopting an air blower, and the air pressure generated by the air blower is 1000-3000 Pa.

Adopt above-mentioned further scheme's beneficial effect to be, the air pressure of air-blower can guarantee that more than 95% bubble breaks, reaches the effect of getting rid of the bubble, and with low costs, and the safety risk is low.

Detailed Description

The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Examples 1,

A process for treating pulp black liquor by using viscose waste water comprises the following steps:

A. obtaining 800kg of dilute black liquor by the action of 2000kg of black liquor through two black liquor press machines, introducing the dilute black liquor into a first sedimentation tank, adding 12kg of sodium hydroxide into the first sedimentation tank, and then precipitating for 3 hours;

B. b, introducing 620kg of supernatant in the first sedimentation tank in the step A into a desulfurization tower for desulfurization treatment, then introducing 403kg of desulfurization waste liquid in the desulfurization tower into a first regulating tank, adding 125kg of viscose waste water with the pH value of 2 into the first regulating tank, then introducing the solution in the first regulating tank into a multi-bucket sedimentation tank, and then adding 4.5kg of AlCl into the multi-bucket sedimentation tank₃Precipitating for 2 hours after adding 4.8kg of polyacrylamide solution;

C. b, introducing the sediment in the multi-bucket sedimentation tank in the step B into a sludge collection tank, then introducing the supernatant in the multi-bucket sedimentation tank into a second regulating tank, then adding 105kg of fiber wastewater with the pH value of 10 into the second regulating tank, and then introducing the solution in the second regulating tank into a second sedimentation tank;

D. adding 7kg of AlCl into the second sedimentation tank in the step C₃Precipitating for 3 hours after 7.2kg of polyacrylamide solution is added, then introducing 320kg of supernatant in the second sedimentation tank into a third sedimentation tank for precipitation for 2 hours, and introducing precipitates in the second sedimentation tank into the sludge collection tank;

E. and D, introducing 160kg of supernatant in the third sedimentation tank in the step D into a reactor, then adding 8kg of hydrogen peroxide and 1kg of ferrous sulfate into the reactor, then introducing the solution in the reactor into a final sedimentation tank, adding 4.8kg of polyacrylamide solution, then precipitating for 5 hours, and introducing the precipitate in the final sedimentation tank into a sludge collection tank.

Through detection, the COD of the weak black liquor in the step A is 37504mg/L, the COD of the desulfurization waste liquor in the step B is 19525mg/L, the COD of the supernatant in the second sedimentation tank in the step C is 1865mg/L, and the COD of the supernatant in the third sedimentation tank in the step E is 89mg/L, which is greatly lower than the national first-class A standard (according to GB 18918-2002). Realizes the treatment of wastes with processes of wastes against one another, reduces waste and solves the pollution problem.

Examples 2,

A process for treating pulp black liquor by using viscose waste water comprises the following steps:

A. obtaining 420kg of dilute black liquor by passing 1000kg of black liquor through two black liquor press machines, introducing the dilute black liquor into a first sedimentation tank, adding 7kg of sodium hydroxide into the first sedimentation tank, and then precipitating for 3 hours;

B. b, introducing 310kg of supernatant in the first sedimentation tank in the step A into a desulfurization tower for desulfurization treatment, then introducing 210kg of desulfurization waste liquid in the desulfurization tower into a first regulating tank, adding 61kg of viscose waste water with the pH value of 2 into the first regulating tank, then introducing the solution in the first regulating tank into a multi-bucket sedimentation tank, and then adding 2.1kg of AlCl into the multi-bucket sedimentation tank₃Precipitating for 2 hours after adding 2.3kg of polyacrylamide solution;

C. b, introducing the sediment in the multi-bucket sedimentation tank in the step B into a sludge collection tank, then introducing the supernatant in the multi-bucket sedimentation tank into a second regulating tank, then adding 56kg of fiber wastewater with the pH value of 10 into the second regulating tank, and then introducing the solution in the second regulating tank into a second sedimentation tank;

D. adding 4kg of AlCl into the second sedimentation tank in the step C₃Precipitating for 3h with 4.1kg of polyacrylamide solution, then introducing 146kg of supernatant in the second sedimentation tank into a third sedimentation tank for precipitation for 2h, and precipitating the precipitate in the second sedimentation tankIntroducing the sludge into the sludge collecting pool;

E. and D, introducing 87kg of supernatant in the third sedimentation tank in the step D into a reactor, adding 4kg of hydrogen peroxide and 0.6kg of ferrous sulfate into the reactor, introducing the solution in the reactor into a final sedimentation tank, adding 2.5kg of polyacrylamide solution, precipitating for 5 hours, and introducing the precipitate in the final sedimentation tank into a sludge collection tank.

Through detection, the COD of the weak black liquor in the step A is 39504mg/L, the COD of the desulfurization waste liquor in the step B is 17631mg/L, the COD of the supernatant in the second sedimentation tank in the step C is 1954mg/L, and the COD of the supernatant in the third sedimentation tank in the step E is 95mg/L, which is greatly lower than the national first-class A standard (according to GB 18918-2002). Realizes the treatment of wastes with processes of wastes against one another, reduces waste and solves the pollution problem.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.