LV14789B - A method for wastewater treating from lignin and hemicellulose substances at wood processing plants - Google Patents

Abstract

Invention relates to wastewater purification from lignin and hemicellulose substances. The invention is a method using coagulant composition. The composition contains polyaluminium chloride and aluminium chloride in a ratio 1.5/1 - 1/1. Addition of the coagulant to wastewater should occur at the pH values 6.0 - 7.0. The optimal efficiency of purification occurs in a temperature range from 14 to 40 degrees Celsius.

Description

DESCRIPTION OF THE INVENTION

The present invention relates to the treatment of wastewater from lignin and hemicellulose substances, which are obtained by gentle hydrolysis of wood as well as its further chemical processing, as well as the treatment of natural water.

It is known that aluminum salts - aluminum sulphate, aluminum chloride and polyaluminium chloride - in average doses of 80-400 mg / l are used as coagulants in wastewater treatment of the chemical and mechanical wood processing industry. It has been determined [1] that BSP5 and color reduction of 88-90% in paper waste water require 300-400 mg / l aluminum sulphate. Lowering the wastewater temperature from 22 to 2 ° C increases the optimal dose and optimal flocculation time of aluminum sulphate several times [2]. It has been determined [3] that aluminum chloride at pH 6.0 and 100110 mg / l is able to efficiently separate lignin from wastewater. However, in some cases [4, 5], polyaluminium chloride (PAC) is more effective than sulfuric acid aluminum and aluminum chloride. It is known that the optimum pH for the environment when using PAC is 6.0 [6], but optimum doses vary in the concentration range of 80-110 mg / l (7) .The experiments conducted with a model solution simulating woodworking wastewater show an optimal PAC dose of 100 At the same time, PAC-based coagulants in the formulation more effectively coagulate soluble and colloidal compounds in wastewater, taking full advantage of the individual components and reducing the optimum application dose Polyaluminium chloride is used in various coagulant compositions such as calcium oxide or chloride [9]. ], with iron oxides or halides [10, 11, 12], with natural bisphite [13, 14], with silicic acid and with iron [15] A method of using PAC with a cationic acrylamide and dimethylaminoethyl methacryl copolymer [16], with a cation flocculant is also proposed. based on polyacrylamide [17] There are also some methods of waste water treatment, which includes their step treatment, first with aluminum sulphate followed by polyaluminium chloride [18, 19, 20].

Numerous scientific studies have shown the effectiveness of the ozonation method in the treatment of wastewater of various plants: textile industry [21], wood processing [22, 23, 24, 25, 26, 27]. The use of ozonation allows the reduction of phenolic and other toxic organic substances by their destruction and enhances their biodegradability.

It is known [11] to add iron halide with a metal ion concentration of 1.35 to 4.5 mol / liter to a polyaluminium coagulant solution. Polyaluminium chloride with a basicity of 40-83% is used as the polyaluminium coagulant. The disadvantage of this method is the low efficiency of coagulating impurities in wastewater which have a neutral or acidic pH value.

According to the patent [19], the waste water treatment is carried out sequentially with aluminum sulfate followed by aluminum oxychloride. This technique allows to reduce the consumption of coagulant while maintaining its effectiveness. The disadvantage of this technique is the multistage administration of the coagulant.

A combined ozonation and coagulation method for water purification is known, and in many cases ozonation is performed prior to coagulation [28, 29, 30]. Conversely, initial ozonation with subsequent use of coagulation may adversely affect the deposition of lignin and hemicellulose substances, as ozonation destroys them to low molecular weight fragments which, due to their increased solubility in water, are poorly susceptible to coagulation with chemical reagents. A type of wastewater treatment is known [31], in which ozonation follows the coagulation of wastewater with a composition coagulant based on A1C1 ₃ . However, in order to achieve sufficiently high levels of purification of contaminated water, this technique uses an increased dose of coagulant (> 100 mg / l) and an increased ozonation time (3 hours).

The closest technical solution to the claimed process is the patent [20], which relates to the treatment of wastewater from suspended substances with a mixture of aluminum sulphate and PAC in a weight ratio of (0.3-0.7) / (0.7-0.3) to aluminum. The technique provides cost effective technology at the expense of polyaluminium chloride. At the same time, it does not achieve a high degree of waste water treatment.

OBJECTIVE - To develop a wastewater treatment process that achieves the highest levels of lignin and hemicellulose purification, lower residual aluminum concentration and lower wastewater coloration within the temperature range of 14 ° C to 40 ° C, allowing return of consumed water to the technological cycle.

The aim is achieved by a two-stage wastewater treatment process, wherein the first step is the addition of the composition coagulant AICPCAC in a weight ratio of 1.5/1 and 1/1 to the wastewater, and the second step to the filtrate obtained after coagulate containing lignin and hemicellulose. water sedimentation and filtration, ozone treatment.

Methodological part

To solve the task set was used Polyaluminium chloride (PAC) Polypacs 30 (bāziskums- 80% by weight of AI2O3 -35%) and aluminum salts: aluminum chloride AlCl3 * 6H ₂ O and aluminum sulphate A1 ₂ (SO 4) 3 * 16H ₂ O. To prepare the coagulant, the required coagulant weight was taken in dry form and diluted in distilled water. The dose of coagulant added to the composition was varied from 50 to 150 mg / l with a ratio of coagulant in the composition of 0.1 / 1-0.5 / 1 by weight (aluminum chloride / polyaluminium chloride). The coagulant based on aluminum sulphate and polyaluminium chloride was used as a prototype and the ratio of Al ₂ (SO 4) 3 and PAC in the aluminum content ranged from 0.7 / 0.3 to 0.3 / 0.7 respectively. Component ratios for converting aluminum into the weight ratio of the claimed process in the composition coagulant took into account that PAC Polypacs-30 contains approximately 18.5% aluminum and pure aluminum sulfate 15.75% aluminum. The resulting recalculation showed that the mass ratios of the A1 ₂ (SO4) 3 / PAC components in the applied process ranged from 2.7 / 1-0.5 / 1.

Woodworking plant effluent was simulated using a model solution obtained by hydrolysis of birch shavings in 0.01M NaOH solution. The pH of the model solution was changed over a wide range (3.0-10.0 pH units). The weight ratio of chip to liquid phase was 1:50. Processing temperature 90 ° C. The total treatment time was about 6 hours 20 minutes (40-50 minutes to reach temperature, 90 ° C 4 hours, 1.5 hours the system cooled down). The resulting sewage model solution was filtered to remove fine dispersion particles. The obtained model solution was characterized by the following parameters: the total wood contaminant content, which consisted mainly of hemicellulose and lignin substances (HLV) - 1400 mg / l, coloring 746 mg / l Pt, COD - 1285 mgO / l, surface tension - 43.4 mN / m , kinematic viscosity - 3.81 mPa-s. The elemental and functional composition of the solids solids are shown in Table 1.

Table 1. Elemental and functional composition of model solution dry matter

c,% H,% O,% S,% N,% and ₃ ,% CO,% OH _kop % 37.70 4.70 57.16 0.14 0.30 2.29 1.15 10.15

As shown in the component composition study, the model solution consisted of 75-80% of the hemicellulose substances, which were leached with 20% sulfuric acid from the model solution and pre-precipitated with lignin-containing substances [32]. The content of clone lignin in the sediment did not exceed 10%. Low molecular weight lignin and hemicellulose substances, lignin carbohydrate complexes and other extracts were 10-15%.

The volume ratio of model solution to composition coagulant was 1: 1, therefore the level of contamination in the model solution system with coagulant was 2 times lower than in the initial model solution. The experiments were performed at a temperature range of 14 - 40 ° C.

Coagulation of the model solution was performed according to the following procedure. Add 5 Ohms of the coagulant solution to 50 ml of the model solution with continuous stirring at 100 g / min. After 1 minute, add the necessary amount of HCl to the system to reach the desired pH (4.0 - 9.0 pH units). After the pH has been reached, the system is stirred for one minute at 200 rpm and for 2 minutes at 40 rpm. After 120 minutes of treatment, the solution is filtered through a glass fiber filter having a cell size of 16 to 40 µm and the filtrate analyzed for:

- absorbance of the filtrate at 490 nm using a Genesys 10UV spectrophotometer and a 1 cm cuvette to determine the total lignin and hemicellulose content after coagulant treatment of the model solution. After calibration curves the residual concentration of the contaminant was determined;

- absorbance of the filtrate at 280 nm using a Genesys 10UV spectrophotometer and a 1 cm thick cuvette to determine the lignin content using the appropriate calibration curves;

- Color (LVS EN ISO 7887: 1994);

- the concentration of aluminum in the filtrate (EOCT 18165-89);

- chemical oxygen demand (LVS EN ISO 6060: 1989);

- total organic carbon (LVS EN 1484: 2000).

The following coagulant modeling solution of coagulant composition of the composition was used to simulate the conditions of treatment of industrial wastewater at elevated and reduced temperatures.

A model solution at 60 ° C and a composition coagulant solution at 20 ° C were used for coagulation at 40 ° C. The coagulation temperature was 40 (± 1) ° C, which was maintained during the coagulation process by means of a thermostat. Low temperature coagulation was performed by mixing the model solution with a coagulant solution at 14 ° C. The coagulation temperature was maintained at 14 (± 1) ° C with a thermostat which was cooled with tap water.

The efficiency of coagulation was determined by comparing the initial values of the model solution to be treated with the values obtained after filtration of the filtrate using the following formula:

Efficiency,% =

4nod Wed.An

100% where od

A _fil - HLV, lignma, TOC content in filtrate; degree of filtrate coloration and COD value

Anod. ^. - HLV, lignin, TOC content of the model solution; the degree of coloration of the model solution and the COD value

To compare the effluent treatment efficiency after treatment with coagulants, the difference between the HLV and lignin separation values obtained with the claimed composition and the composition coagulant by prototype was determined. To compare the residual aluminum concentration in the system after its treatment with the coagulant, the values obtained by dividing the residual aluminum concentration in the model solution treated with coagulant compositions by prototype with the residual aluminum concentration in the model solution treated with the coagulant were used.

An ozone generator with a production capacity of 5 gO ₃ / h was used for the ozonation process. With the help of this generator ozone was produced by treating dry air with electric charge. The structure of the ozonator used is analogous to that of the ozonator used for wastewater treatment in the prior art [33]. The filtrate obtained after separation of the coagulant, in a volume of 1 liter, was placed in a cylindrical container of a capacity

1.2 1 and ozonated by the bubble method. The ozone-air mixture was fed at 20 1 / min, with an ozone concentration of 0.6 mg / l. The ozonation time varied between 15 and 150 minutes.

The object is achieved by adding to the waste water pH 6-7 a composition coagulant consisting of PAC and A1C1 _{3 in a} weight ratio of 1/1 and 1.5/1, followed by ozonation of the filtrate obtained after separation of the coagulate by settling.

The essence of the invention is based on the results of coagulation efficiency obtained by comparing the coagulant of the composition according to the claimed method with the prototype. The results are summarized in Tables 2-5 and specific examples of coagulation processes.

Table 2 shows the results on the effect on HLV and lignin removal, as well as on the residual aluminum concentration in the model solution at different treatment temperatures obtained by treating the model solution at pH 6.0 with a coagulant composition of the desired composition and prototype with a coagulant dose of 100. mg / l. The analysis of the obtained results shows that the applied composition coagulant compositions AICI3 / PAC, 1/1 and 1.5 / 1 by weight, have a higher degree of purification of the model solution from HLV and lignin substances than the other applied compositions. Comparison of the purification quality of the model solution with these applied coagulant formulations relative to the prototype formulations shows that at T = 14 ° C the HLV separation increases by 8%, the lignin by 7%, and the remaining Al content in the model solution decreases to 2.5 times. At T = 20 ° C, the HLV separation increases to 10%, the lignin increases to 11%, and the remaining Al concentration decreases to 2.0 fold. At T = 40 ° C the HLV separation increases to 18%, the lignin increases to 21%, and the remaining Al content decreases to 2.3 times.

I. Examples showing the effectiveness of the claimed composition coagulant compositions in the purification of a model solution at various temperatures:

Example 1 (Tab. 2)

In a glass containing 50 ml of model solution at room temperature, the composition is coagulated with AlCl3: PAC = 1: 1 in a ratio of 100 mg / l by mixing with a magnetic stirrer at 100 g / min. The model solution is titrated to pH 6.0 with coagulant. The system was agitated for 1 minute at 200 rpm, 2 minutes at 40 rpm. After separating the coagulum formed from the treated water, settling for 120 minutes and filtering, the resulting filtrate was analyzed. The obtained filtrate is characterized by the following parameters: HLV separation - 95.3%, lignin separation - 65.6%, color reduction EN 14789

Table 2. Effect of Coagulant Composition Composition on Protective Effect of Model Solution on Hemicellulose and Lignin Substances at Various Temperatures: Treatment pH 6.0, Coagulant Dose 100 mg / L

O 0 © d / gui 'ilBnj B (IOBJULU93U05J EA 0.102 0.234L 0.044 0.089 0.099 0.100 0.089 0.094 suiu§ [q 45.5 40.3 l 64.9 66.2 61.7 61.0 64.3 7— | VT τ · —i tO to CN © © ΛΊΗ tr? r < oo στ VT VT u tO VT 00 00 l> θ ' 00 00 io3 j / gui 'ņjņjļļ. © 00 i-H VT Etc. 04 τ-4 u £ ό rfioBJļU33uoq 09 to © © r — r 04 o σΓ o CO ICC C IV © © © © © θ ' © © O o 03 Lh O Oh o o3 stnuSn ντ 04 to 00 © CN © i-K O Ϊ23 Etc. VT V? O? © οΓ © * © 04 c3 VT ντ to VT VT 'd ^- VT VT I Ό N H © στ στ © Etc. r- T— < Etc. Ί5Ρ ΛΤΗ tr? © tr? to ~ VT © + - » 00 00 CN OJ r- 00 00 eh ' 103 CO I / gui 'ejķilņj r- > »< Etc. στ 04 Etc. © o £ BljOBJļU99UOq QO ov τ-H VT 04 Γ / Τ © , 06 o i-H 04 VO © υ IV CU o © © ; vs © © © © © © ω TT suiugļq H S Etc. oo 3.2 Η-1 H 5.6 © ^ © Tf ^ © CN στ © ^ c <? © r * · ^ VT ur Ό VT VO VT VT VT Ph M τ-l T-M H © στ T-4 στ στ στ ΛΤΗ rf Ph r— ( VO OC rC d οΓ oo r- · CN 00 > · r- —H —H tob bb ob dJ) bb bb tb be £ £ £ £ £ £ £ £ / gui 'Blioisodiuo ^ 27th 67 50 40 30th 20th © T-4 ot get in touch nUBin§BOll - C -H -H ~ Sb bfi bt OD bu bfi bl) 'Sb £ £ £ £ £ £ £ £ στ στ © © © © © o στ VT to 00 © © r ^- ( ντ 04 © '·· VT στ OJ h · ® (SEql09UB d d ^ - ¹ 04 i —— H susbui BUB [n§BOJļ oad) < Ph Ph o PAC, U o < d < d <c SAtJlSBS Sliirejn§12C »[ Ph Ph Ph Ph Ph smoothie oil 'T · o (Z3 cr T- o <Z) cr cr d < CT d cr d m d re d < cr d <

88.0%, organic matter reduction (COD) - 44.4%, aluminum concentration in filtrate 0.061 mg / l.

Example 2 (Tab. 2)

AICI3 / PAC composition coagulant solution (A1C1 ₃ : PAC = 1: 1, 14 (±)) is added to a glass containing 50 ml of the model solution at 13 (± 1 ° C) with magnetic stirrer at 100 rpm. 1 ° C), the composition coagulant dose is 100 mg / l (for the preparation of solutions and the coagulation process at 14 (± 1 ° C), see methodological part above). The model solution is titrated to pH 6.0 with coagulant. The system was stirred for 1 minute at 200 rpm, for 2 minutes at 40 rpm. After separating the resulting coagulum from the treated water, settling for 120 minutes at 14 (± 1 ° C) and filtering, the resulting filtrate was analyzed. The obtained filtrate is characterized by the following parameters: HLV separation - 91.9%, lignin removal - 65.6%, decolorization - 84.4%, organic matter reduction (COD) - 40.6%, aluminum concentration in the filtrate is 0.074 mg / l.

Example 3 (Table 2)

In a glass containing 50 ml of the model solution at 60 ° C was added AICI3 / PAC composition coagulant solution at a ratio of A1C1 ₃ : PAC = 1: 1, at room temperature, at 100 rpm with magnetic stirrer, the dose of composition coagulant was 100. mg / l (for process of solution preparation and coagulation at 40 (± 1 ° C), see methodological part above). The model solution is titrated with the coagulant to pH = 6.0. The system was stirred for 1 minute at 200 rpm, for 2 minutes at 40 rpm. After separating the resulting coagulum from the treated water, settling for 120 minutes at 40 (± 1 ° C) and filtering, the resulting filtrate was analyzed. The obtained filtrate is characterized by the following parameters: HLV separation - 87.6%, lignin removal - 64.9%, decolorization - 75.8%, organic matter reduction (COD) - 36.0%, aluminum concentration in the filtrate is 0.044 mg / l.

Example 4 (Tab. 2)

According to example 1, characterized in that the weight ratio is AICPAC = 1.5: 1. After the system was coagulated for 120 minutes, the coagulated system was filtered and the filtrate analyzed. The following results were obtained: HLV separation - 91.9%, lignin removal - 57.8%, decolorization - 86.0%, organic matter reduction (COD) - 37.7%, aluminum concentration in filtrate 0.075 mg / l.

Example 5 (Table 2)

As in Example ₂ , wherein the weight ratio is A1C1 ₃ : PAC 1.5: 1. The following results were obtained: HLV separation 86.3%, lignin removal 59.0%, color reduction 83.2%, organic matter reduction (COD) 28.9%, aluminum concentration in filtrate 0.063 mg / l.

Example 6 (Tab. 2)

As in Example 3, which differs in that the weight ratio is AICPAC = 1.5: 1. The following results were obtained: HLV separation - 87.6%, lignin removal - 66.2%, color reduction - 76.1%, organic matter reduction (COD) 32.7%, aluminum concentration in filtrate 0.089 mg / l.

The table below shows the results of purification of the model solution at reduced temperature with the claimed coagulant formulations and prototype coagulant formulations at a dose of 100 mg / l, depending on the pH of the medium. Comparison of the purification quality of the model solution with the applied coagulant compositions relative to the prototype compositions shows that, except for pH = 5.0, the claimed composition coagulant compositions are more effective in purifying the model solution than the prototype coagulant compositions. At pH = 6.0 HLV separation increases by about 20%, lignin by about 12%, but the residual aluminum concentration in the model solution after treatment decreases to 3.0 times. At pH = 7.0, HLV removal increases to 31%, lignin to 14%, and the remaining Al concentration in the model solution decreases to 2-fold after treatment. At pH = 8.0, HLV separation increases to 54%, lignin to 26%, and the remaining Al concentration in the model solution decreases to 4-fold after treatment. At the same time, treatment of the model solution at pH> 8.0 increases the alkalinity of the filtrate and may adversely affect ozonation and the quality of the treated water.

II. The examples illustrate the efficacy of the claimed composition coagulant compositions in the purification of a model solution at various temperatures at defined treatment pH values.

Example 7 (Tab. 3)

As in Example 2, characterized in that the coagulation was performed at a model solution and the coagulant system pH = 6.0. The following results were obtained: HLV separation 91.9%, lignin removal 65.6%, decolorization 84.4%, aluminum concentration in filtrate 0.074 mg / l.

Table 3. Effect of pH on the Effectiveness of Model Solution Removal of Hemicellulose and Lignum Agents Using Applied Composition Coagulants and Coagulants by Prototype at Low Treatment Temperature 14 (± 1 ° C) Coagulant Dose 100 mg / L

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Example 8 (Tab. 3)

As in Example 2, characterized in that the coagulation was carried out at the model solution and the coagulant system pH = 7.0. The following results were obtained: HLV separation - 92.7%, lignin removal - 57.8%, color reduction - 86.0%, aluminum concentration - 0.127 mg / l.

Example 9 (Tab 3)

According to example 5, characterized in that the coagulation was carried out at the model solution and the pH of the coagulant system = 6.0. The following results were obtained: HLV separation - 86.3%, lignin removal - 59.0%, color reduction - 83.2%, aluminum concentration in the filtrate is 0.063 mg / l.

Example 10 (Tab. 3)

As in Example 5, characterized in that the coagulation was performed at a model solution and the coagulant system pH = 7.0. The following results were obtained: HLV separation 83.0%, lignin removal 55.2%, decolorization 75.5%, aluminum concentration in filtrate 0.132 mg / l.

The following table shows the results of purification of the model solution at reduced temperature with the applied coagulant formulations and the coagulant formulations by prototype depending on the dose of coagulants. Analysis of the obtained results shows that the claimed composition coagulant formulations AICI3 / PAC, 1/1 and 1.5 / 1 by weight at 75125 mg / l in the pH range 6.0-7.0 at a coagulation temperature of 14 ° C, exhibit a higher degree of purification of the model solution from HLV and lignin substances compared to the prototype compositions. Purification of the model solution with the claimed formulations under the specified conditions compared to the coagulant by prototype shows that at a dose of 75 mg / l HLV, the separation from the model solution increases to 72%, the lignin removal to 36% and the remaining Al concentration in the model solution decreases to 7.0. At a dose of 100 mg / L HLV, the removal increases to 31%, the lignin increases by 14%, and the remaining Al concentration in the model solution after treatment decreases to 3.4 times. With an addition dose of 125 mg / L HLV, the removal increases to 21%, lignin to 13%, and the remaining Al concentration in the model solution after treatment decreases to 4-fold. At the same time, treatment of the model solution with the claimed coagulant formulations at a dose greater than 125 mg / l does not lead to a significant increase in the separation of hemicellulose and lignin substances.

Table 4. Effect of Coagulant Dose Composition on Effectiveness of Model Solution Removal of Hemicellulose and Lignin Substances Using Applied Composition Coagulants and Coagulants by Prototype at pH 6.0-7.0 and Treatment Temperature 14 (± 1 ° C)

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III. Examples showing the effectiveness of the claimed composition coagulant formulations in the use of model solution purification at the claimed doses and the applied processing pH values:

Example 11 (Tab. 4)

According to Example 2, characterized in that the composition coagulant dose was 75 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 91.4%, lignin removal - 63.6%, color reduction - 82.2%, aluminum concentration in the filtrate is 0.092 mg / l.

Example 12 (Table 4)

According to Example 2, characterized in that the composition coagulant dose was 100 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 91.9%, lignin removal - 65.6%, decolorization - 84.4%, aluminum concentration in filtrate 0.074 mg / l.

Example 13 (Tab. 4)

According to Example 2, characterized in that the composition coagulant dose was 125 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 89.3%, lignin removal - 59.7%, decolorization - 90.6%, aluminum concentration in filtrate 0.039 mg / l.

Example 14 (Table 4)

According to Example 8, characterized in that the composition coagulant dose was 100 mg / l, the pH of the model solution and coagulant system = 7.0. The following results were obtained: HLV separation - 92.7%, lignin removal - 57.8%, decolorization - 86.0%, aluminum concentration in filtrate 0.127 mg / l.

Example 15. (Tab. 4)

According to Example 8, characterized in that the composition coagulant dose was 125 mg / l, the pH of the model solution and coagulant system = 7.0. The following results were obtained: HLV separation - 87.9%, lignin removal - 55.8%, color reduction -76.7%, aluminum concentration 0.019 mg / l.

Example 16. (Tab. 4)

According to Example 5, characterized in that the composition coagulant dose was 75 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 82.4%, lignin removal - 57.1%, decolorization - 81.4%, aluminum concentration in the filtrate is 0.103 mg / l.

Example 17 (Table 4)

According to Example 5, characterized in that the composition coagulant dose was 100 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 86.3%, lignin removal - 59.0%, color reduction - 83.2%, aluminum concentration in filtrate 0.063 mg / l

Example 18 (Table 4)

According to Example 5, characterized in that the composition coagulant dose was 125 mg / l, the pH of the model solution and coagulant system = 6.0. The following results were obtained: HLV separation - 91.0%, lignin removal - 63.6%, decolorization - 90.2%, aluminum concentration of filtrate 0.024 mg / l.

Example 19. (Tab. 4)

According to Example 10, characterized in that the composition coagulant dose was 100 mg / l, the pH of the model solution and coagulant system = 7.0. The following results were obtained: HLV separation - 83.0%, lignin removal - 55.2%, decolorization - 75.5%, aluminum concentration in the filtrate is 0.132 mg / l.

Example 20. (Tab. 4)

According to Example 10, characterized in that the composition coagulant dose was 125 mg / l, the pH of the model solution and coagulant system = 7.0. The following results were obtained: HLV separation - 85.6%, lignin removal - 55.2%, decolorization - 78.0%, aluminum concentration in filtrate 0.056 mg / l.

The second purification step is the ozonation of the filtrate obtained after coagulation and filtration of the treated model solution by bubbling. 5. The following table gives the results obtained by ozonating the filtrates of the treated model solution after coagulation with the claimed coagulant formulations AlCl2 / PAC, 1/1 and 1.5/1 by weight at pH = 6.0, coagulant doses of 100 mg / L at reduced and room temperature . The ozonation time was 60 min, which was selected based on the dependence of the decrease in filtrate coloration on the ozonation time. The analysis of the obtained results shows that the ozonation of filtrates of the model solutions treated with the applied coagulant compositions at reduced temperatures allows to increase the HLV removal by up to 10%, lignin by up to 35% and decrease the color by up to 13%. By ozonizing filtrates obtained by coagulation at room temperature, HLV removal increases to 7.6%, lignin to 36%, and decolorization to 10.8%.

IV. Examples showing the efficiency of ozonation by ozonating the filtrate obtained after treatment of a model solution with the claimed coagulant formulations at the claimed dose and pH with further coagulation and filtration of the treated solution:

Example 21 (Tab. 5)

According to example 1, characterized in that the filtrate was subjected to ozonation in a bubbling reactor for 60 minutes after coagulation, the ozone concentration was 0.6 mg / l. After ozonation, the filtrate was characterized by the following: HLV separation - 99.4%, lignin removal - 94.2%, chromaticity reduction - 96.8%, TOC reduction - 92.1%.

Example 22. (Tab. 5)

According to Example 4, characterized in that the filtrate was subjected to ozonation in a bubbling reactor for 60 minutes after the coagulate removal, the ozone concentration was 0.6 mg / l. After ozonation the filtrate was characterized by the following: HLV separation - 99.5%, lignin removal - 93.5%, chromaticity reduction - 96.4%, TOC reduction - 91.1%.

Example 23 (Table 5)

According to Example 2, characterized in that the filtrate was subjected to ozonation in a bubbling reactor for 60 minutes after coagulation, the ozone concentration was 0.6 mg / l. After ozonation the filtrate was characterized by the following values: HLV separation - 97.9%, lignin removal - 96.1%, color reduction - 96.8%, TOC reduction - 92.4%.

Example 24. (Tab. 5)

According to Example 5, characterized in that the filtrate was subjected to ozonization in a bubbling reactor for 60 minutes after coagulation, the ozone concentration was 0.6 mg / l. After ozonation the filtrate was characterized by the following values: HLV separation - 95.7%, lignin removal - 93.5%, color reduction - 96.4%, TOC reduction - -90.3%.

The increase in coagulation capacity of the novel composition coagulant by the claimed method for the coagulant by prototype is due to the predominant formation of multi-core Al-complexes having a polymer and a high molecular weight structure in AICI3 / PAC. This is evidenced by the comparative study of coagulants of the composition using Ferron's method and ion mass spectroscopy. The first method is based on the reaction kinetics of the monomeric, polymeric, and high molecular weight aluminum forms with Ferron's reagent [34]. The interaction of aluminum salts with the reagent results in colored complexes having an optical density

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at 370 nm is measured in time. The monomeric aluminum forms (Ali) react with Ferron's reagent within 1 minute, the polymeric aluminum forms (A1 ₂ A1 _{] O} ) react with the Ferron's reagent within 120 minutes, while the high molecular forms and the amorphous aluminum phase (AlnAbi, A1 (OH) ₃ ) react slowly or not reacting at all [35]. According to the results shown in Table 6, the content of Al-polynuclear complexes in the claimed composition coagulant exceeds their content in the original PAC as well as in the Al / SCLfi / PAC system, PAC and its compositions with A1 ₂ (SO ₄ ) ₃ .

Table 6

Content of PAC, A1 ₂ (SO ₄ ) ₃ / PAC and AlCfi / PAC hydrolysis product forms

Coagulant Hook, % Al _b ,% Al _c ,% PAC 16.6 66.6 16.8 A1 ₂ (SO ₄ ) ₃ / PAC (1/1 by weight) 16.4 67.2 16.4 A1C1 ₃ / PAC (1/1 by weight) 10.3 72.6 17.1 Al _a - Aluminum monomeric forms, Alf aluminum po imeu forms, Al _c - aluminum

macromolecular forms and amorphous phase

The second comparison method is based on the analysis of the quality of the coagulant hydrolysis products of the composition by ion mass spectroscopy on a GCMSQP2010 instrument (Shimadzu, Japan). To obtain ions from the solution in gaseous form, ionization was performed by spraying on an electric field with a potential of 3500 V and a Taylor cone voltage of 70 V [36]. The analysis of aluminum shapes was performed using characteristic signals of not less than 20% intensity. The obtained PAC and composition coagulant spectral data are shown in Figure 1.

The PAC spectrum (Fig. 1a) is characterized by monomeric forms of aluminum at 78.8 and 98.9 m / z, tetramer forms [Al ₃ 0 ₄ (H ₂ 0) o-5] ⁺ at 145.1, 162.2, 181.2 m / z. In contrast, the intense signals at 231.1 and 337.0 m / z correspond to the high molecular forms of [Ali ₃ O ₁₈ (H ₂ O) ₀ - _2A T and [Al ₁₃ O ₁₈ (OH) (H ₂ O) ₀ 4] ^{2+, respectively} .

The composition coagulant A1 ₂ (SO ₄ ) ₃ / PAC (Figure 1b) has characteristic monomeric aluminum form signals [Al (OH) ₂ (H ₂ O) i ₂ ] ⁺ - 97.0 m / z, dimers [Al ₂ O ₂ (OH) ( H2O) 0-4] ⁺ - 103.0, 157.1 m / z tetramer [AL30 ₄ (H ₂ 0) o-5] ⁺ - 145.8, 163.1 m / z tetramer [Α1 ₄ Ο5 (ΟΗ) (Η ₂ Ο) ι.5] ⁺ - 188.0, 205.1, 222.8 m / z and pentomeric aluminum form [ΑΚΟγ] * - 246.9 m / z. A less intense signal at 327.6 m / z indicates the presence of the high molecular weight aluminum form [Ali ₃ O ₈ (OH) (H ₂ O) ₀ 4] ²⁺ .

Figure 1. ESI-MS spectra of PAC (a), A1 ₂ (SO ₄ ) ₃ / PAC (b) and AlCl ₃ / PAC (c)

In contrast, the claimed composition coagulant A1C1 ₃ / PAC (Figure 1c), in addition to the specified aluminum monomers and polymeric forms, expresses high molecular weight types [A1i ₂ O] 7] ²⁺ - 297.6 m / z, [A1i3Oi8 (OH)]. ) (H20) o.4] ²⁺ - 327.6 m / z [A1i4O ₂₀ (H ₂ O) ₀ s] ²⁺ - 348.9 m / z presence of the observed composition coagulant A1 ₂ (SO _{4) 3} / PAC . Signals were observed in the 400-550 m / z range typical for high molecular weight aluminum forms with 9, 10 and 16 aluminum atoms in the structure [37].

According to the obtained results, the claimed composition coagulant A1C1 ₃ / PAC characterized by a high molecular weight form of the [AI12O17] ^{2 1,} [Al] 3Oi8 (OH) (H20) o-4] ^2+, [A1i40 ₂ q (H ₂ 0 ) oi] ²⁺ quantity and diversity compared to the original PAC and AbCSOrta / PAC system. Similarly, unlike PAC and Ah / SCbT / PAC, the claimed AICI3 / PAC observes the presence of high molecular weight aluminum forms with 16 aluminum nuclei in non-Al-containing coagulants.

The results obtained on the purification efficiency of wastewater from gentle hydrolysis of wood show that the application of the claimed technique in comparison with the prototype allows, at the same doses of the composition coagulant, to significantly increase the purification rate of the wastewater, , allows the purified water to be returned to the technological cycle.

Sources of information taken into account in writing the application:

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Claims (5)

Claims 1. The process for treating wastewater from wood processing plants from lignin and hemicellulose substances, which includes coagulation of the effluent with a composite coagulant containing polyaluminium chloride (PAC), with the use of aluminum chloride (A1C1 ₃ ) as the second component in the weight ratio A / 1 - 1/1 and further ozonation of the filtrate after separation of the coagulum from the treated waste water by settling and filtration. 2. The process according to claim 1, wherein the coagulation occurs at a temperature in the range of 14 ° C to 40 ° C. 3. The process according to claim 1, wherein the coagulation occurs in a pH range of 6.0-7.0. 4. The method of claim 1, wherein 75 to 125 mg / l of coagulant is added to the coagulation process. 5. A process according to claim 1, wherein the filtrate obtained after separation of the coagulate from the treated wastewater by settling and filtration is subjected to ozonation in a bubbling reactor for 60 minutes at an ozone concentration of 0.6 mg / l.