JP2000015267A - Treatment of wastewater from paper manufacturing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make treated water reusable and lower the load of the wastewater treatment thereafter by using a chelating polymer flocculant of maceration and steam maceration wastewater in paper manufacturing process and adjusting the wastewater neutral or acidic. SOLUTION: After waste paper 6 is macerated by a macerator 1, a chelating polymer flocculant 2 is added to control pH at neutral or lower. In this case, the addition amount is preferably controlled to adjust the pH around 6. After that, the resultant macerated waste paper is washed in a concentrated wastewater washing apparatus (a thickener) 3 and divided to a paper manufacturing substance 4 and washing wastewater 5. By such treatment, COD and BD in the wastewater are significantly lowered and pH adjustment is made unnecessary and the SS and the COD values in the separated water is remarkably decreased and flocculation and precipitation treatment is easily carried out, so that repeat use of the treated water is made possible. Further, dewatering efficiency of cellulose is greatly increased and recovery efficiency is heightened. Furthermore, PVA is made reusable. As the chelating polymer flocculant 2, a mixture of a chlorine type inorganic flocculant and a polyamine type flocculant is especially preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing process and a method for treating wastewater in a papermaking process.

[0002]

2. Description of the Related Art Conventionally, in the process of disintegrating waste paper, cellulose is separated from caustic soda and high-temperature steam or hot water to separate printing ink and coating agent, and the cellulose is recovered by a concentrated wastewater washing device (thickener). Although the method of reuse in the papermaking process has been adopted, the water separated from the thickener is
Since it has a high alkalinity, a pH of 10 or more, a large amount of soluble substances and a high viscosity, a large amount of pouring water (in some cases, hot water) is required for washing. The high-concentration water separated from the thickener contains many soluble substances such as PVA, ink and paste. O. D. , B. O. D. The wastewater has a high numerical value and requires biological treatment, so it takes a long time to process.Unless the biological treatment is performed, the wastewater has a more stable and longer disintegrating drainage property as the standing time is longer. . In addition, these high-concentration waste liquids are treated by a wastewater treatment device. Normally, only precipitation treatment, which is neutralized by pH control, is diluted with general wastewater without dissolving soluble substances, and the untreated numerical value Was discharged as it was. In particular, C.I. O. D. Values are 20-25 p. p. m.
Has been released. Although it is clear by the standard value, the total drainage is extremely large, and the total
It is currently being released into the sea.

[0003]

The inventor of the present invention has conducted various studies in order to solve these conventional drawbacks. As a result, by adding a chelating polymer flocculant to the disintegration and digestion waste liquid to make it neutral or less, The viscosity is reduced and the dissolved substances are extracted, and the dehydration efficiency in the thickener and the cellulose recovery rate are greatly increased.
C. of separation washing wastewater O. D. , B. O. D. In addition, the pigment and the like have been remarkably reduced, and the reuse of the treated water and the like has been made possible, thereby completing a method of greatly reducing the load of the subsequent wastewater treatment.

[0004]

The present invention will be described with reference to the drawings, but the present invention is not limited to the following description. FIG. 1 is a flow sheet for papermaking wastewater treatment using the purification method of the present invention. Conventionally, waste paper collected in a disintegrator is disintegrated by adding steam, caustic soda, and the like, and then sent to a concentrated wastewater cleaning device (thickener). Add coagulant 2 to neutrality or less. In this case, it is desirable to inject an amount to be adjusted around PH6. Thereafter, the concentrated wastewater is washed in a concentrated wastewater washing device (thickener) 3 to be separated into a papermaking product 4 and a washing wastewater 5. O. D. , B. O. D. Etc. decrease significantly, PH adjustment becomes unnecessary, and SS, C.I. O. D. Since the value is greatly reduced and the coagulation-sedimentation treatment is easy, it is possible to reuse the treated water. In addition, the dehydration efficiency of cellulose is greatly increased, and the recovery efficiency is also improved. Further, PVA is conventionally discharged as waste because it is contained in a waste liquid, and newly added during papermaking. However, in the present invention, PVA remains in the paperwork 4, so that PVA can be reused. It is possible to increase efficiency and reduce costs in the papermaking process.

Conventionally, diluted hot water or an inorganic sulfuric acid band has been injected.
O. D. Is known to be difficult to remove. Usually, after adding a pack or the like, since a flocculant is used, the floc surface is cross-linked to obtain a weak adhesion effect. However, the present chelate flocculant (for example, NT floc 0)
5: made by Nippon Solid Co., Ltd.), since coagulation decomposition and cross-linking are performed simultaneously, coagulation is performed inside and outside the floc and acts even inside the floc, so that the removal of soluble substances is excellent.

The chelating polymer flocculant in the present invention comprises:
It may be blended with cationic acrylamide, polyamine, polyimine and the like, which are the same as inorganic (cation). Examples of the inorganic include iron sulfate, aluminum sulfate, iron chloride, and polyaluminum chloride. Furthermore, the mixed polymer is
Polyamine, polyimine, acrylic amide polymer,
Means a mixture of In the present invention, a mixture of a chloride-based inorganic coagulant and a polyamine-based compound is particularly preferable. These include use in concentrated waste liquids and papermaking wastewater treatment.

According to the present invention, the dewatering efficiency and the cellulose recovery rate in the thickener are greatly increased, and the C.I. O. D. , B. O. D. In addition, the pigment and the like are remarkably reduced, the reuse of the treated water and the like is enabled, and the load of the subsequent wastewater treatment is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a flow sheet for papermaking wastewater treatment in the present invention.

[Explanation of symbols]

 1. Disintegrator 2. 2. Chelating polymer flocculant Concentrated wastewater washing device 4. Papermaking 5. Wash liquid 6. used paper

Claims (1)

[Claims] 1. A treatment method characterized by using a chelating polymer flocculant as a disintegration and digestion waste liquid in a papermaking process and adjusting the waste liquid to neutral or lower.