FI73253C - FOERFARANDE FOER AOTERVINNING AV MATERIAL I AVLOPPSVATTEN. - Google Patents

Description

1 73253

This invention relates to the pulp and paper industry, and more particularly to a method for utilizing wastewater residues containing activated sludge biomass, fibers and bark waste.

The invention is applied in pulp and paper mills producing sulphate pulp and having a biological wastewater treatment system.

The pulp and paper industry is one of the largest industries, consuming large amounts of plant raw material (wood) and water during processing. Approximately 50 percent of the raw material becomes waste, liquid, and solid after processing. The amount of wastewater and its degree of contamination depend on the plant's flow chart. In the pulp and paper industry, wastewater can be further subdivided into lye-containing, acidic, malodorous, bark-containing, fibrous and sludge-containing wastewater, depending on the nature of the impurity present. Suspended substances such as fiber, bark, etc. can be removed mechanically, for example in pre-clarification tanks. To treat wastewater from dissolved organic contaminants, the greatest efficiency is in biological treatment. Biological wastewater treatment is based on the consumption of dissolved organic matter by microorganisms, whereby some of the organic matter is oxidized and some is converted to biomass.

30 The biological treatment of waste water allows a high degree of treatment, but it generates significant amounts of activated sludge. The amount of activated waste sludge is 160-210 g / m of treated wastewater. The activated sludge is a substantially amorphous flocculating mass inoculated with 35 2 73253 thick aerobic bacteria and other microorganisms. In terms of mechanical composition, the activated sludge resembles fine suspensions, of which 98% by weight consists of particles smaller than 1 mm in size. Ak-5 sealing slurry is also characterized by a high water content. It is precisely these features that are attributed to the complexity of handling the activated sludge mass, as a large amount of energy is required to remove strongly bound moisture. Moreover, decantation of the slurry by means of filtration methods 10 fails to achieve complete dewatering and leads to clogging of the filter, which in turn entails the need to restore the filtration capacity of the screens periodically. The removal of activated sludge into natural tanks in the form in which they are present in treatment plants is not permitted, as this would lead to the siltation of the tanks and the disturbance of the natural processes taking place in them. As a result, attempts have been made to develop methods for treating activated sludge in a manner that would enhance its usefulness.

20 Wastewater containing fiber and bark is another source that loads wastewater from pulp and paper production with waste. Fiber-containing wastewater is generated when semi-finished products, paper, board and fiberboard are produced. Drainage of fiber-containing sewage by dilution is not permitted, as fiber dispersion results in precipitation of the pool. Sewage containing bark is generated during wet peeling. When the bark is released into natural basins, it can form bottom fines in the water body, which are harmful to the life of the water bodies. As a result, wastewater containing fiber and 30 shells must be treated and residues consisting of shells and fibers must be eliminated.

Numerous methods are known for recovering wastewater residues, after which it is used in the manufacture of products in pulp and paper mills. One of these 35 methods is in the biological treatment of wastewater

II

Use of the slurry lignin formed in 3 73253 as a filler in an amount of 0.6 to 15% by weight, calculated on the absolute dry basis, in the manufacture of packaging material (cf. USSR Inventive Certificate No. 503 967, Int. Cl. ).

According to Soviet Inventor's Certificate No. 440 468 (Int. Cl. D 21H 3/00, published January 31, 1975), up to 20% by weight of activated sludge, calculated on the basis of absolute dryness, is fed to 10 whole paper raw materials for the production of packaging board.

The use of activated raw sludge in the raw material composition results in an increased steam flow rate in the press section of the paper machine due to the need to remove tightly bound moisture in the activated sludge and consequently the use of activated sludge biomass under operating conditions does not exceed 3% and 13 kg / tn products.

According to Soviet Inventor's Certificate No. 536,268 (Int. Cl. D 21 C 1/00, D 21 C 3/02, 20 published March 4, 1977), wood chips are kept in active slurry suspension before cooking. Such treatment results in increased yield of the pulp and its improved mechanical properties. Analogous results are obtained when activated sludge biomass is used directly for cooking instead of 25 parts or all of black liquor (cf. Bukhteev BM, Ishkha-Nov, VA, Grudinin, VB Dergunova, Tv "Ispolzovanie izbytochnogo aktivnogo ila v technologi! , bumaga i karton ", 1979, No. 15 pages 3-4).

30 Sulphate cooking is carried out with a strong white liquor mixed with black liquor.

A strong lye is prepared as follows. After cooking, the black liquor waste goes to incineration, during which the organic part of the black liquor is burned off and the mineral part - the sodium-35 salts - forms a melt. The main components of the melt are 4,725,253 sodium carbonate (Na 2 CO 2) and sodium sulfide (NaS).

The melt is then dissolved in a weak white liquor obtained by washing the white slurry, and a solution of the melt in a weak white liquor is called soda liquor. The main component of the soda liquor 5 - sodium carbonate - represents an inactive reagent in the sulphate cooking of wood and consequently the sodium carbonate is converted into an active cooking reagent - sodium hydroxide - i.e. causticization is carried out. The causticization is carried out by adding sufficient lime to the soda liquor, the causticization process leading to the formation of a strong white liquor and a white slurry (CaCO 2). A strong white liquor, which is essentially a mixture of NaOH and Na 2 Sr, is used in cooking.

Thus, when replacing part or all of the black liquor with activated waste sludge, it is not possible to utilize all the sludge accumulated in the treatment plants in the sulphate process.

A method for eliminating wastewater residues is known by driving a previously dehydrated and dried residue to a landfill. Such a method of eliminating wastewater residues involves setting up new waste storage facilities when the existing ones are filled, which in turn requires more land. In addition, the waste storage facilities create 25 conditions in the area that are detrimental to environmental protection. Therefore, it is recommended to use wastewater residue elimination methods that include dewatering, drying, and incineration.

A method is known in the art for the elimination of waste water residues, in particular activated sludge, which comprises coagulating it with ferric chloride solution and lime milk, followed by dewatering in vacuum filters, drying and incineration (cf. Jakovleva, OI, Tkatchenko, WI, "Otchistka stotchnyh", Moscow, 1975, pp. 40-42).

35 The method is carried out as follows. The activated sludge biomass in the slurry packer 5 73253 is mixed in a ratio of 1: 1 or 1: 2 with the residue obtained from the pre-thickening basins, which consists of fiber and bark. To achieve coagulation of the residue, it is treated with ferric chloride and lime-5 milk. The residue is then dewatered in vacuum filters, preferably those with a descending plate of filter cloth. The dehydrated residue is removed from the plate of the vacuum filter with a special knife or blown with compressed air. The residue, dehydrated and having a moisture content of 83-85%, is subjected to heat drying in tumble dryers at a temperature of 500-800 ° C. The dried residue with a moisture content of 20-40% is incinerated. The elimination of wastewater residues by this method involves the construction of heat drying and incineration plants, which consume a lot of energy. In addition, the filtrate, which is decanted upon removal of water from the pre-coagulated residue and has been emptied onto the treatment compositions, contains toxic compounds of iron and calcium which adversely affect the biological wastewater treatment process. The removal of water from the residue in the vacuum filter involves clogging of the filter plate, which impairs its filtering ability. To restore the filter plate, it must be periodically rinsed with inhibited hydrochloric acid.

The present invention relates to a process for the use of activated sludge obtained from the treatment of waste water from the sulphate-25 cellulose industry, which contains activated sludge biomass, fibers and bark.

The present invention is characterized in that the activated sludge is treated with an alkaline solution containing 5-80 g / l Na 2 O at a temperature of 20-70 ° C, whereby part of the activated sludge biomass is hydrolyzed and amino derivatives are formed, that water is removed from the resulting reaction mixture, the early filtrate thus obtained is used to dissolve the melt in the preparation of the alkaline cooking solution, and that a solid product obtained from dewatering is added in an amount of up to 40% by weight to the pulp composition for the production of paperboard and fibreboards.

In a biological wastewater treatment system, the role of bio-10 oxidants is played by a population of microorganisms (biosenosis), which includes bacteria, protozoa, and also aquatic plants, fungi, etc., present in the activated sludge. There is virtually no substance of organic origin that microorganisms would not be able to oxidize.

15 Sewage from pulp and paper production is characterized by a large number of impurities, which explains the diversity of the micro-growth composition of the activated sludge used in the treatment plants of a company. Most of the bacteria that play a role in biosenosis can be up to 10 cells for every gram of dry biomass. During their activity, the microorganisms consume the organic matter in the wastewater, multiply and thus form an activated sludge. The biomass of the activated sludge is characterized by a high protein content (30-50% by weight) which is hydrolyzed by alkali to form amino derivatives which have a beneficial effect on the cooking processes. This makes it possible to use the alkali liquors of the activated sludge biomass during the production of the strong white liquor of the kraft paper process by leading these to melt leaching.

According to the present invention, a weak white liquor can be used to treat wastewater residues containing activated sludge. After such treatment, the weak liquor enriched in the hydrolysis products of the activated sludge biomass is used to produce the melt, which is followed by the treatment of the soda liquor in a conventional manner. The alkali cooking liquor obtained by this process is enriched in the active slurry's potassium hydrolysis products, which makes it possible to produce high-quality cellulose. Treatment of effluent residues with alkali liquors with a Na 2 O concentration of less than 5 g / l is not suitable as it brings with it the increase in temperature and time required for the activated sludge biomass hydrolysis reactions to proceed. The use of alkali liquors with a Na 2 O concentration of more than 80 g / l is also not suitable, as it would lead to an increased degree of hydrolysis of the activated sludge biomass.

10 The alkali mass is added (after dewatering) in an amount of 40% by weight to the board and fibreboard assembly. The alkali mass consists of a fiber and a shell mixed with non-hydrolyzed activated sludge and its alkali hydrolysis products. The addition of more than 15 to 40% by weight of alkali mass to the board production is not suitable, as it would lead to a deterioration of the physico-mechanical factors of the resulting product.

Vegetable fibrous starting material is used in the manufacture of paper, various paperboards and fibreboard 20. The fibrous starting material, in turn, comes from the cooking of cellulose-containing plant sources. The purpose of the soup is to extract lignin from the fibers. Depending on the quality of the products produced in the factory, cellulose with a varying degree of lignin removal is obtained, which affects its physical-mechanical factors. The possibility of replacing part of the defibered material with fiber removed from the effluent makes it possible to reduce the consumption of defibered starting material of plant origin, while the quality of the products obtained is the same or even better.

In addition, the use of the fiber removed from the wastewater in the board and fiberboard assembly makes it possible to solve its utilization problem by returning it to the 35 main production cycles.

e 73253

It is recommended to use white sulphate lye as a chemical reagent for the treatment of waste water residues. There are two types of white sulphate lyes available. Strong white liquor is used to cook plant sources in the power-5 paper process. The weak white liquor obtained in the washing of the white slurry is introduced into the dissolution of the melt during the preparation of the strong white liquor. The white slurry is washed at 60-80 ° C. Therefore, kraft paper mills with a system for regenerating chemicals always have 10 alkali liquors available at a temperature of 60-80 ° C, i.e. a weak white liquor. According to the present invention, waste water residues containing active sludge, fiber and bark in their composition are treated with a weak white liquor before being introduced into the melt.

Thus, a weak white liquor containing hydrolysis products of activated sludge biomass is fed to dissolve the melt. In the use of weak white liquor for the treatment of waste residues, a lye with a temperature of 60-80 ° C and available directly from the factory does not require heating.

The essence of the invention is as follows. Sewage water containing activated sludge biomass is mixed in a ratio of 1: 1 or 1: 2 sewage water containing fiber and bark. The mixture is dewatered, for example in a vacuum filter. The dewatered pulp is treated with an alkali solution having a concentration of 5-80 g / l Na 2 O calculated at a temperature of 20-80 ° C. The treatment is carried out in a mixer into which the anhydrous mass and the alkali liquor are fed. Depending on the temperature and concentration, the treatment takes 30 to 60 minutes. The hydrolysis of the activated sludge biomass, which is carried out by the action of alkali, results in the migration of the alkali hydrolysis products of the activated sludge into solution. The degree of hydrolysis of the activated sludge biomass increases, depending on the temperature and concentration of the alkali liquor, to 50-95.6%.

35 In the next vacuum filtration of the reaction mixture, its 9 73253 is separated into a liquid and a solid phase. The liquid phase, which is in the form of an alkali filtrate containing the alkali hydrolysis products of the activated sludge, is used to melt for dissolution during the preparation of the alkali cooking liquor of the kraft paper process. The solid phase in the form of an alkali mass consisting of a fiber, a shell and a non-hydrolysable active slurry mixed with the hydrolysis products of the activated slurry is added in an amount of up to 40% to an evaporated pulp assembly for the production of paperboard and fibreboard.

Referring to Figure 1, there is shown a modification of a plant flow chart to implement the proposed method for recovering wastewater residues.

From the basin 1, the activated waste sludge is led to a mixer 15 2, to which sewage containing fiber and bark is also fed. The ratio of wastewater is 1: 1. The mixture is then dewatered in a vacuum filter, preferably one with a descending plate. The filtrate decanted from the vacuum filter 3 is passed to a cellulose wash or discharged to purification-20 assemblies. The anhydrous layer of the residue is fed to a mixer 4, to which an alkaline solution with a concentration of 5-80 g / l, calculated as Na 2 O, is supplied. The mixer 4 is essentially a tank provided with a mixer device and openings: at the top for feeding the dehydrated residue and the alkali solution; in the bottom for removal of the alkaline reaction suspension. In mixer 4, alkali hydrolysis of the activated sludge biomass takes place. The suspension thus obtained, consisting of an alkali solution containing the alkali hydrolysis products of the active slurry (liquid phase) 30 and a solid phase in the form of a fiber, a shell and a part of the non-hydrolysed slurry, is separated by a vacuum filter 5.

The alkali filtrate decanted from the vacuum filter 5 is used to dissolve the melt during the preparation of the alkali cooking liquor of the kraft paper process, and the anhydrous alkali mucilage is added to the fibrous pulp when making paperboard and fibreboard.

_______ - Τ '10 73253

During the production of the fibrous pulp for making paperboard, an adhesive as well as a precipitating agent are added to it to attach it to the fiberized ingredient, after which the paperboard sheet is created, followed by dewatering and drying.

When making a fibreboard, the paraffin emulsion is added to the prepared fibrous pulp. The mass thus prepared is then formed into a sheet, followed by compression and heating.

Thus, the proposed invention enables its low-waste mill flow chart in pulp and paper mills by utilizing wastewater residues in the main production process and at the same time reducing raw water consumption per tonne of products obtained.

In the manufacture of paperboard and fibreboard, the proposed invention helps to reduce the consumption of vegetable fiberized starting material and at the same time increase production. Elimination of thermal drying and incineration processes of residues results in reduced energy costs.

The commercial application of the invention makes it possible to cope without the use of non-regenerable and toxic reagents which have hitherto been used to coagulate residues.

Example 1 The activated sludge removed from pool 1 was mixed in a 1: 1 ratio in a mixer with a residue obtained from 2 primary pools consisting of fiber and shell. Immediately after stirring, the mixture was fed to a vacuum filter 3. In a vacuum filter, the mixture was dewatered to a humidity of 95%. The anhydrous residue containing 43% by weight of activated sludge and 57% by weight of fiber and bark was treated in a mixer with 4 alkali solutions having a total alkali content of 20 g / l calculated as Na2O. The treatment was performed at 70 ° C for 20 minutes.

35 The degree of hydrolysis of activated sludge biomass to this state was 95.6% (see Table 1). The mixture thus treated 11 73253 was dewatered in a vacuum filter to a moisture content of 5 to 80%. The decanted filtrate with a total alkali content of 15.5 g / l calculated as Na 2 was passed to dissolve the melt. The 5 alkali masses removed from the plate of the vacuum filter 5 were used in the manufacture of paperboard and fibreboard.

Example 2 Wastewater residues were prepared for treatment with an alkali solution in the same manner as in Example 1. The alkali-10 treatment conditions were as follows:

total alkali content of white liquor 10 g / l Namina temperature 70 ° C

duration 40 min.

Under these treatment conditions, the degree of hydrolysis of the activated sludge was 76.4%. The products obtained by removing water from the alkaline reaction mixture were used as in Example 1.

The analytical results obtained in Examples 1 and 2 are shown in Table 1.

Example 3 Wastewater residues were prepared to be treated with an alkaline solution in Saimaa as in Example 1. The conditions of the alkali treatment were as follows:

sodium hydroxide (NaOH) concentration 5 g / l Namina 25 temperature 20 ° C

duration 60 min.

Under said conditions, the degree of hydrolysis of the activated sludge was 50%. The products obtained by removing water from the alkaline reaction mixture were used as in Example 1.

Example 4 Wastewater residues were prepared for treatment with an alkali solution in the same manner as in Example 1. The conditions for the alkali treatment were as follows: 12 73253

sodium hydroxide concentration 20 g / l Na 2 Orna temperature 20 ° C

duration 20 min.

Under these conditions, the degree of hydrolysis of the activated slurry was 62.3%. The products obtained in the alkali treatment were used as in Example 1.

Example 5 Wastewater residues were prepared for treatment with an alkaline solution in the same manner as in Example 1.

The alkali treatment conditions were as follows: concentration of sodium hydroxide in 20 g / l Na 2 O

temperature 60 ° C

duration 5 min.

The degree of hydrolysis of the activated sludge was 84.4%.

The products obtained by dewatering the alkaline reaction mixture were used as in Example 1.

Example 6 Wastewater residues were prepared for treatment with an alkali solution as in Example 1. The conditions of the alkali treatment were as follows: concentration of sodium hydroxide as 20 g / l Na 2 O

temperature 60 ° C

duration 20 min.

Under these treatment conditions, the degree of hydrolysis of the activated sludge was 87.6%. The products obtained by dewatering the alkaline reaction mass were used as in Example 1.

Example 7 Wastewater residues were prepared to be treated with an alkali solution in the same manner as in Example 1. The alkali treatment conditions were as follows: sodium hydroxide concentration 20 g / l Na 2 O

temperature 70 C

duration 20 min.

35 The degree of hydrolysis under these conditions was 93.4%.

n 73253

The products obtained by removing water from the alkaline reaction mixture were used as in Example 1.

Example 8 Wastewater residues were prepared for treatment with 5 alkaline solutions in the same manner as in Example 1. The treatment conditions were as follows: sodium hydroxide concentration 40 g / l Na 2 O

temperature 20 ° C

duration 20 min.

Under these conditions, the degree of hydrolysis of the activated sludge was 74.6%. The products obtained by removing water from the alkaline reaction product were used as in Example 1.

Example 9 Wastewater residues were prepared for treatment with an alkaline solution in the same manner as in Example 1. The alkali treatment conditions were as follows: sodium hydroxide concentration 80 g / l Na 2 <3

temperature 70 ° C

20 duration 5 min.

The degree of hydrolysis in said treatment was 80.2%. The products obtained by removing water from the alkaline reaction mixture were used as in Example 1.

The analytical results obtained in Examples 3-9 are shown in Table 2.

table 1

Pre-Alkali content Heat treatment Activated sludge mark in solution space duration biomass hydro No. g / 1 Na 0 as degree of lysis, C% 30 ------— 1 20 70 20 95.6 2 10 70 40 76.4 14 73253

Table 2

Pre-Alkali content Heat treatment Activated sludge mark in solution, state duration Biomass hyd. No. g / 1 as Na 2 O Degree of oolysis,% 5 —'— 1— ~ —————-------- - - 1 2 3 4 5 35 70 60 50.0 4 20 20 20 62.3 5 20 60 5 84.4 10 6 20 60 20 87.6 7 20 70 20 93.4 8 40 20 20 74.6 9 80 70 5 80.2 15 Example 10

An alkali filtrate containing hydrolysis extracts of the activated sludge, which is used during the preparation of strong white liquors, was obtained as follows.

From basin 1, the activated sludge was fed to a mixer 20 2, to which was also fed the residue from the primary basin, which consisted of fiber and shell. The ratio of activated waste sludge to the residue obtained from the primary pool was 1: 1. Immediately after stirring, the mixture was passed to a vacuum filter 3 for dewatering. The residue, dewatered to 85% moisture and containing 43% by weight of activated sludge and 57% by weight of fiber and bark, was treated with 4 white liquors in a mixer. The total alkali content of the white liquor was 20 g / l calculated as Na 2 O 2. The treatment temperature was 70 ° C and the duration was 20 minutes. At these conditions, the degree of hydrolysis of the activated sludge biomass was 95.6%. The alkaline reaction mixture obtained in the treatment was dewatered in a vacuum filter to 80% humidity. The alkali filtrate decanted in the dewatering contained the products of alkali hydrolysis of the activated sludge. Kokonaisalkalipi-

II

The content of is 73253 was 15.5 g / l calculated as Na 2 O 2. The melt was dissolved in alkali filtrate. The resulting soda liquor having a total alkali content of 125.2 g / l calculated as Na 2 O, an active alkali content of 42.9 g / l and a sulfidation of 28.2% was causticized. The causticization conditions were as follows:

temperature 95 ° C

duration 2 h

The causticization rate with this procedure was 80.6%.

The strong white liquor obtained in the causticization process had the following properties: total alkali content 102.2 g / l Na 2 Oina active alkali content 98.7 g / l Na 2 O 3 sulphidity 27.9% Example 11

An alkali filtrate containing the hydrolysis products of activated sludge biomass was prepared in the same manner as in Example 10.

The alkali filtrate and white liquor with a total alkali-20 lip content of 1.5 g / l were fed in a 1: 1 ratio to dissolve the melt. Soda liquor with a total alkali content of 125.2 g / l calculated as Na 2 O and a sulfidity of 27.7% was causticized. The causticization conditions were maintained as in Example 10. The causticization efficiency was 80.3% and the 25 strong white liquors had the following properties: total alkali content 101.8 g / l as Na 2 O active alkali content 98.5 g / l Namina sulphidity 27.4%

Example 12 (Comparative) A weak white liquor with a total alkali content of 15.5 g / l calculated as Na 2 O was used to dissolve the melt. The resulting soda liquor having an active alkali content of 41.2 g / l calculated as Na 2 O and a sulfidity of 28.0% was causticized. The causticization conditions were maintained as in Example 10. The causticization efficiency at this ie 73253 Γ

The procedure had 81.2% and the white liquor contained 10.2 g / l of Na 2 O in total alkali, 98.8 g / l of Na 2 O of active alkali and a sulphidity of 27.8%.

The properties of the soda and white liquors obtained in Examples 10-12 are shown in Table 3.

The results in Table 3 show that the use of an alkali filtrate enriched in the hydrolysis products of activated sludge to produce strong white liquors makes it possible to produce lyes of better quality than any conventionally obtained lyes.

Table 3

Eg Properties of soda liquor Kausti_ Strong white liquor No. Total-Active Sulphinisation- P ^: i-Suut- 15 Alkali-alkali content useful- Total-Active- Sulphide content other% ratio alkaline substance g / 1 g / 1 content-caliph%

NaJOjna Na 0 in the mouth g / l

Na_0: na g / l

Namina 20 10 125.2 42.9 28.2 80.6 102.2 98.7 27.9 11 125.2 43.4 27.7 80.3 101.8 98.5 27.4 12 125.2 41.2 28.0 81.2 102.1 98.8 27.8 25

Example 13

To the fiberized pulp assembly for making paperboard, alkali pulp was added, which was obtained as follows.

From the basin 1, the activated waste slurry was fed to a mixer 2, in which a 1: 1 residue from the primary basin, consisting of fiber and shell, was mixed with it. Immediately after stirring, the mixture was passed through a vacuum filter 35 for dewatering. The residue, dehydrated to 85% moisture and consisting of 43% by weight of 17 7325 3 activated sludge and 57% by weight of fiber and bark, was treated with white liquor in mixer 4. The total alkali content of the white liquor was 20 g / l Na 2 O. calculated. The treatment was carried out for 20 minutes at a temperature of 70 ° C. After the alkali treatment, the reaction mixture was dewatered in a vacuum filter to 80% moisture. From the alkali pulp thus obtained and unbleached sulphate cellulose, a defibered pulp was made for the manufacture of paperboard. The composition of the fiberized pulp in 10% by weight was as follows: unbleached sulphate cellulose 75 alkali pulp 25

The fibrous pulp was ground to a degree of grinding of 76 ° ST (Schopper-Riegler scale), followed by the addition of an adhesive, e.g. resin adhesive, in an amount of 6 kg / ton and a precipitant, e.g. aluminum sulphate in an amount of 70 kg per ton. From the fibrous pulp thus prepared, paperboard having a basis weight of 2,200 g / m 2 was made and the following mechanical values were determined: absorbency, refractory strength, puncture resistance and ring crushing strength.

The produced board had the following properties: 2 absorbency 18 g / m refractive index 167 2 25 puncture resistance 5.3 kp / cm ring crushing strength 31 kp

Example 14

An alkali pulp was prepared in the same manner as in Example 13. An alkali pulp and unbleached sulfate-30 distillate were prepared as a defibered pulp having the following composition in weight percent: unbleached sulfate cellulose 7 0 alkali pulp 30 35 The defibered pulp was then treated as in Example 13 7 3 2 5 3 was 200 g / m 2. The mechanical properties of the produced board were determined. They were as follows: 2 absorbency 15 g / m refractive index 143 2 5 puncture resistance 5.0 kp / cm ring crushing strength 31 kp

Example 15

Alkali mass was obtained as described in Example 13.

From the alkali pulp and unbleached sulphate cellulose, a defibered pulp having the following composition in weight percent was prepared: unbleached sulphate cellulose 60 alkali pulp 40 The fibrous pulp was then treated as in Example 13 and paperboard with a basis weight of 2 was 200 g / m 2. The obtained board had the following mechanical properties: 2 absorbency 16 g / m 20 folding resistance 161 2 puncture resistance 4.7 kp / cm ring crushing strength 32 kp

The quality characteristics of cartons made according to the processes described in Examples 13-15 are shown in Table 4.

The results given in Table 4 show that the alkali pulp separated from the wastewater residues is suitable for use in the assembly of fibrous pulp for the production of packaging, construction and shoe board.

Example 16

The alkali mass was prepared according to the process described in Example 13. A fibrous mixture was prepared from alkali pulp and wood pulp, having the following composition in 35% by weight: wood pulp 90 alkali pulp 10 19 73253

The resulting mass was neutralized with sulfuric acid, the paraffin emulsion was added in an amount of 0.8% by weight, and then a fiberized sheet was formed, which was further compressed for 7 minutes at a pressure of 30 kp / cm 2 and a temperature of 180 ° C.

5 The obtained fibreboard had the following properties: density 870 kg / m3 moisture 8% water absorption in 24 h 16% thickness expansion in 24 h 12%

O

10 bending strength 530 kp / cm

Table 4

Fibrous pulp Mechanical properties composition_

Pre- Bleached- Alkali- Density Absorbency Folding- Puncture-Fengas- markless sulphate pulp g / m ^ g / m ^ resistance strength crushed no. Cellulose, weight% seasonal weight% lu cheese ___pcs 13 75 25 200 18 167 5.3 31 20 14 70 30 200 15 143 5.0 31 15 60 40 200 16 161 4.7 32

Example 17

The alkali mass was obtained in the same manner as in Example 25. 13. A fibreboard was prepared as follows. Paraffin emulsion was added to the wood pulp (90% by weight) in an amount of 0.8% by weight, and then the base of the board was formed, after which an alkali-neutralized alkali mass was previously applied in an amount of 10% by weight to the inner layer. The compression conditions were as follows: pressure 30 kp / cm, temperature 180 ° C, duration 7 min.

20 7 3 2 5 3

The obtained fibreboard had the following properties: density 870 kg / m3 moisture 8% 5 moisture absorption in 24 h 16% thickness in 24 h 12% bending strength 500 kp / cm

Example 18 (Comparative) 10 Wood pulp alone was used to make wood pulp. The plate was prepared according to the process of Example 16. The quality characteristics of the board were as follows: density 870 kg / m3 moisture 8% 15 water absorption in 24 h 22% swelling in 24 h 15% 2 flexural strength 350 kp / cm 20 Table 5 below shows the quality characteristics of the wood fiber board obtained in Examples 16-18.

Table 5

Quality characteristics Example No. 16 17 18 2 5 ______

Density, kg / m3 870 870 870

Humidity,% 888

Water absorption in 24 h,% 16 18 22 30 Thickness expansion in 24 h,% 12 13 15

Flexural strength, kp / cm ^ 530 500 350

The experimental results show that the recovery of wastewater residues, followed by their utilization in the main production-35 process, makes it possible to obtain high-quality products.

Claims (2)

21 73253 A method of using activated sludge from the treatment of effluents from the sulphate cellulose industry, comprising biomass, fibers and bark of an activated sludge, characterized in that the activated sludge is treated with an alkaline solution containing 5-80 g / l Na 2 O at a temperature of 20-70 ° C, the activated sludge biomass is hydrolyzed to form amino derivatives, the resulting reaction mixture is dewatered, the alkaline filtrate thus obtained is used to dissolve the melt in the preparation of alkaline cooking solution, and the solid dewatering solid product is added up to 40% by weight. Process according to Claim 1, characterized in that the white liquor of the sulphate soup is used as the alkaline solution for treating the active solution.