Alkaline method for treating black liquor from straw pulp paper-making

Abstract

The present invention relates to an equipment and method for processing black liquor of straw pulp papermaking by alkaline method, which comprises the following two steps in turn: 1. Black liquor treatment: black liquor and flocculant are mixed with dilute acid in a static mixer, and the overflow of the tank is precipitated by flocculation. into the inclined mesh filter for filtration. When the inorganic acid acidifying agent is added, the pH value of the mixture is reduced to 3.5-1.5, and the lignin in the black liquor forms a brown floc which is easy to filter. The filtrate and floc can be separated quickly and well in the inclined screen filter. 2. Filtrate treatment: After 1-3 days of storage and hydrolysis, the filtrate is neutralized by adding white mud or lime, the waste produced by the papermaking alkali recovery method, so that the pH value reaches 6.5-7.2, and enters anaerobic after sedimentation in the sedimentation tank. Pool biochemical treatment. After treatment, enter the middle stage water treatment system for aerobic treatment and then reuse or discharge. The invention has simple equipment process and low investment, and after the filtrate is hydrolyzed, neutralized and anaerobic biochemically treated, it can ensure that the filtrate is discharged up to the standard without affecting the treatment effect of the subsequent middle stage after being mixed into the middle stage water.

Description

(1) Technical field [0001] The invention relates to the technical field of alkaline papermaking sewage treatment, in particular to a method for treating black liquor of alkaline straw pulp papermaking. (2) Background technology [0002] The environmental pollution of straw pulp papermaking wastewater has always troubled papermaking enterprises, and has now affected the survival of enterprises, especially the alkaline cooking liquor in the papermaking process is difficult to deal with, and its COD is as high as 80,000-120,000 mg / L, which is the main source of pollution. [0003] In the application number 00113922 titled "in the comprehensive treatment method of alkaline papermaking sewage", a kind of local materials are disclosed, and the aluminum sulfate solution in the production process is selected to carry out the black liquor neutralization acidification and the method of flocculation filtration, but the aluminum sulfate addition is relatively large. More, the follow-up ...

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Problems solved by technology

[0003] In the application number 00113922 titled "in the comprehensive treatment method of alkaline papermaking sewage", a kind of local materials are disclosed, and the aluminum sulfate solution in the production process is selected to carry out the black liquor neutralization acidification and the method of flocculation filtration, but the aluminum sulfate addition is relatively large. More, the follow-up pH adjustment is worth adding caustic soda with a higher price, which increases the treatment cost, and the acidification treatment of yellow residue increases the complexity of the process

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