WO2015120661A1

WO2015120661A1 - Circulation engineering for achieving near-zero discharge of tanning waste water

Info

Publication number: WO2015120661A1
Application number: PCT/CN2014/075331
Authority: WO
Inventors: 张壮斗
Original assignee: 张壮斗
Priority date: 2014-02-15
Filing date: 2014-04-14
Publication date: 2015-08-20
Also published as: CN104843807A

Abstract

Provided is circulation engineering for achieving near-zero discharge of tanning waste water, characterized by stepwise and independently recycling waste water from the processes of pre-soaking, main-soaking, liming, reliming, deliming and softening, pickling and chrome tanning, retanning, neutralizing and dyeing. The recycling of all the waste water from the above-mentioned processes is realized. This technique has been practised and verified in practical mass production in a tanning workshop of Biosk (Shangqiu) Chemical Co., Ltd. The present invention achieves the recycling of waste water from pre-soaking to dyeing, greatly reduces polluted water discharge, completely solves the difficult problem of tanning pollution, and at the same time can ensure the quality of finished leather, effectively reduce the loose grain rate of the finished leather, improve the compactness and fullness of the finished leather, and can achieve the saving of 15-55% of chemical materials, for instance, saving 35-65% of chromium powder, in which some chemical materials can be saved by not less than 90%, and individual chemical materials, such as table salt, can be saved by 100%.

Description

A circular engineering project to achieve near zero discharge of tannery wastewater

The invention relates to the field of recycling and recycling of wastewater in the tanning industry.

Background technique

In the tanning process, a large amount of chemical raw materials such as acids, alkalis, salts, sulfides, limes, chrome tanning agents, fatliquors, dyes, etc. are used, and a considerable part of them enter the waste water. Tannery wastewater is mainly from preparation, tanning and other wet processing sections. The amount of sewage discharged from the pre-soaked water to the dyeing production process accounts for more than 90% of the total sewage discharge during the whole tanning process. The water quality is characterized by a large amount of complex and toxic and harmful substances. It contains a lot of lime, salt, oil, ammonia nitrogen compounds, proteins, sulfides, chromium salts, dyes, hair, pomace, sediment, etc., and COD, BOD is very high. It has a wide variety of pollutants, a large coefficient of variation in water quality and quantity, and a foul smell, which is an industrial wastewater that is difficult to treat.

With the development of environmentally-friendly technology equipment, the current tannery wastewater has formed a relatively mature treatment process (see table below). However, its operation process is often costly, inefficient, and poorly effective, and cannot achieve the true purpose of pollution control.

Process name Technical advantage Technical defect

The traditional activated sludge method has a high removal rate of BOD ₅ in 90 pairs, and requires high water quality.

More than %, COD is 60%~ not suitable for impact load, need high 80%, chroma 50%~90 power and infrastructure costs; between area %, S is between 85% and 98%. It is also large, and it is difficult for general enterprises to bear; at the same time, the effect of ammonia nitrogen treatment in wastewater is not good. Biological contact oxidation method for organic matter removal rate BOD ₅ is prone to blockage, maintenance is also compared

About 95%, COD is difficult at 92%. Once there is a problem, the system is around, and S is around 98%. You have to stop running to be able to maintain it.

The removal rate of BOD _{5 by} oxidation ditch is 95%, and the treatment effect is unstable. It is more suitable, S is 99%~100%, in the south with higher temperature, about 75% for northern suspended matter. Fang, there may be problems with winter operation. The double-layer biofilter has a suspension removal rate of 95%, and it is necessary to determine a suitable reflux ratio.

BOD ₅ is 98%, COD is choosing the right filter material, the running cost is 90%, and Cr (III) is 96%.

On, S is at 96%.

SBR method The SBR process has relatively high COD and S2_, and the operating cost is relatively small. The removal rate of suspended solids and Cr is relatively low, and maintenance is difficult. 93.3%, 99.0%, 90.3%,

99.4%.

The above treatment process is very limited in terms of reduction of sewage discharge, reduction of chemical materials, and reduction of production cost. If you want to realize the full recycling of waste water from pre-soaking to dyeing all the processes, it is an extremely complicated and difficult problem to solve, and often accompanied by the following problems: The gray skin weight gain rate and blue skin leather yield rate are reduced by 1.5. %-3.5%, shrinkage temperature drops 1.5 °C-3.5 °C, it will also damage the blue grain surface, the grain surface becomes thicker, the color becomes darker, and even the "matte face" phenomenon, resulting in some performance indicators of leather Not meeting the requirements.

Summary of the invention

The object of the present invention is to realize repeated recycling and reuse of waste water from pre-soaking to dyeing. In addition to normal volatilization and inevitable leakage in the natural state, the recovery rate of wastewater can reach

100%, completely solved the problem of tannery sewage discharge, and the performance indexes of the finished leather produced by the company all meet the requirements, and effectively reduced the rate of tanned pine, and improved the firmness and fullness of the finished leather. It can realize 15%-55% of saving materials, such as saving 35%-65% of chrome powder, and saving more than 90% of some chemicals. Individual chemicals such as salt can save 100%.

The technical solution of the present invention is as follows:

A recycling project for achieving near zero discharge of tannery wastewater, characterized by stepping in pre-soaking water, main immersion water, ash ash, ash ash, deliming softening, chrome pickling, retanning, neutralization, dyeing process Independent wastewater recycling, including the following steps:

(1) Pre-soaking process wastewater reuse: The process consists of collecting waste water after each pre-soaking process, filtering the waste solids, stirring evenly, placing it on the pre-dip water drum or grooving; Pre-soaking of the skin; detecting the amount of microorganisms in the wastewater to determine the amount of the bactericide;

(2) Water immersion process wastewater reuse: The process consists of collecting the waste water after each immersion process, taking care of the waste solids, stirring evenly, placing it next to the immersion drum or grooving; Detecting the amount of microorganisms in the wastewater to determine the amount of fungicide;

(3) Reuse of waste water in the liming process; the process consists of collecting waste water after the end of each liming process, filtering the waste solids therein, stirring evenly, placing it on the immersion drum or grooving; Leaching of the skin; filtering is required during the liming process;

(4) Waste water reuse in the ash-removing process; the process is to collect the waste water after the end of each ash-removing process, filter the waste solids therein, stir evenly, and place it on the side of the ash drum or the grooving; Leather ash

(5) De-ashing and softening process wastewater reuse; the process is to collect the waste water after each deashing and softening process, filter the waste solids therein, stir evenly, and place it next to the deashing and softening drum; Deashing and softening of the next batch of skin;

(6) Reusing effluent chrome tanning process wastewater; the process is to collect the waste water after each chrome tanning process, filter the waste solids, stir evenly, and place it next to the chrome-plated chrome-plated drum; The pickled chrome tanning of the next batch of skin;

(7) Re-use of the wastewater from the reclamation process; the process consists of collecting the waste water after the end of each reclamation process, filtering the waste solids therein, stirring them evenly, and placing them next to the re-twisting drum;鞣

(8) Reusing the wastewater in the neutralization process; the process is to collect the wastewater after the end of each neutralization process, filter the waste solids therein, stir evenly, and place it next to the neutral drum; with;

(9) Dyeing process wastewater reuse; the process consists in collecting waste water after each dyeing process, filtering the waste solids therein, stirring uniformly, and placing it next to the dyeing drum; for dyeing the lower batch of skin.

In the above steps, filtration is carried out using equipment with a pore size of lmm-5mm, such as a filter screen; after the end of each process, the normal volatilization and unavoidable leakage in the natural state are removed, and the collected wastewater is completely reused. , supplemented with fresh water. Each process wastewater collection device shall be equipped with a stirring device or artificially stirred; the pre-soaked and limed skin shall be used for meat removal and skin peeling, and the wastewater generated during meat removal and skin processing shall be separately collected into the corresponding wastewater. The collection device is ready for recycling. The skin treated by pre-soaking, main immersion, liming, ash, deliming, chrome tanning, retanning, neutralization and dyeing process is free of the conventional water washing step; if washing is carried out, the washing wastewater is recycled. Use; When recycling the washing water of the gray skin, the acid should be added to adjust the pH to 5-12.

The initial wastewater used in the present invention is derived from traditional pre-soaked water, main immersion water, liming, ash, deliming softening, chrome pickling, retanning, neutralization and dyeing processes, and the composition of various wastewaters is It is known to those skilled in the art; in general, pre-soaked water, main immersion wastewater contains water immersion agent, NaCl, Na ₂ C0 ₃ , degreaser, oil and its decomposition products, hair, keratin, mucin, Meat, blood, etc., in which, in general, the residual degreasing agent content in the wastewater is usually 15%-30% of the initial amount, and the residual water immersion agent content in the wastewater is usually 15%-25% of the initial amount, and the residual in the wastewater (0 ₃ content is usually 30%-50% of the initial amount; ash and fly ash wastewater contains oil and its decomposition products, salts, lime, liming agent, S ² , 0H, Na\ Ca ²⁺ , Protein and its decomposition products, enzymes and amines, etc., in which, in general, the residual lime in the wastewater is usually 37%-55% of the initial amount, and the residual Na ₂ S content in the ash wastewater is usually 2. 4g/l-3. 2g/l; deashing and softening wastewater contains protein and its decomposition products, deashing agent, degreasing agent, oil and its decomposition products, enzymes and ammonium salts, amines, etc. The enzyme content is usually 30%-50% of the initial amount, and the residual ammonium salt content in the wastewater is usually 30%-40% of the initial amount; the chrome-tantalum wastewater contains Cr ³⁺ , Cl, S0, protein and its decomposition products. , oils and their decomposition products, etc., in which residual Cr ^{3+ in} wastewater is usually 2g/l-3. 2g/l, CI is usually 7g/l_15g/l, the residual acid content in the wastewater is usually 30%-45% of the initial dosage; the reclaimed wastewater contains Na ⁺ , Cr ³⁺ And organic tanning agents, etc.; neutralizing wastewater contains neutral salts; in the dyeing process, chemical materials such as fatliquors, dyes and organic dyeing agents are used, and most of them are absorbed into the wastewater, except for a part of them. The pollutants belong to macromolecular organic matter, and the concentration is high, but the biodegradation rate is very slow. If any of the above wastewaters are discharged arbitrarily, it will not only cause great pollution to the environment, but also cause great waste of resources.

Preferably, the pre-immersion water, the main immersion water and the liming process can adopt the same drum or grooving, and the pre-immersion water, the main immersion water and the ash ash wastewater are respectively collected beside the rotating drum, and the drum or the grooving is controlled by the valve. The collecting device performs wastewater discharge; specifically, when the pre-soaking water, the main immersion water and the immersion ash are used in the same drum or grooving, a valve 1 is arranged on the drum or the sump for discharging the pre-soaked water to the corresponding a wastewater collection device, and at the same time, a valve 2 is arranged on the drum or the groove for discharging the main immersion wastewater to the corresponding wastewater collection device, and at the same time, a valve 3 is arranged on the drum or the groove for The ash effluent wastewater is discharged to the corresponding wastewater collection device; when the pre-dip water is discharged, the valve 1 is opened, the valves 2, 3 are closed, and the wastewater is discharged to the corresponding wastewater collection device through the branch pipe; when the main immersion wastewater is discharged, the valve 2 is opened, the valve 1, 3 is closed, the waste water is discharged to the corresponding wastewater collection device through the diversion pipe; when the ash discharge wastewater is discharged, the valves 1, 2 are closed, the valve 3 is opened, and the waste water is discharged to the corresponding wastewater collection device through the branch pipe.

Similarly, the same detonating drum can be used for the deashing softening and chrome pickling process, and the deashing softening and chromic acid chrome-tantalum wastewater are collected separately beside the rotating drum, and the drum is controlled to discharge the wastewater to each collecting device by means of a valve. Specifically, when the deashing softening and the pickling chrome are used together with a rotating drum, a valve 4 is disposed on the rotating drum for discharging the deliming and softening wastewater to the corresponding wastewater collecting device, and at the same time, on the rotating drum A valve 5 is provided for discharging the chrome-dyed cerium waste water to a corresponding wastewater collection device. When the deashing and softening wastewater is discharged, the valve 4 is opened, the valve 5 is closed, and the waste water is discharged to the corresponding wastewater collecting device through the diverting pipe; when the chromic acid leaching waste water is discharged, the valve 4 is closed, the valve 5 is opened, and the waste water is discharged through the diverting pipe to the corresponding Wastewater collection device.

Similarly, the same drum can be used for the retanning, neutralization and dyeing processes. The retanning, neutralization and dyeing wastewater are collected separately next to the drum, and the drum is controlled by the valve to discharge the wastewater to the collecting devices. Specifically, when a drum is used for retanning, neutralization and dyeing, a valve 6 is provided on the drum for discharging the retanning waste water to the corresponding wastewater collecting device, and at the same time, a valve 7 is provided on the drum. , for discharging the neutralized wastewater to the corresponding wastewater collecting device, and at the same time, setting a valve 8 on the rotating drum for discharging the dyeing wastewater to the corresponding wastewater collecting device. When discharging the reclamation wastewater, the valve 6 is opened, the valves 7, 8 are closed, and the waste water is discharged to the corresponding wastewater collecting device through the diverting pipe; when the neutralizing wastewater is discharged, the valve 7 is opened, the valves 6, 8 are closed, and the waste water is discharged through the diverting pipe to Corresponding waste water collection device; When discharging the dyeing wastewater, the valves 6, 7 are closed, the valve 8 is opened, and the waste water is discharged to the corresponding wastewater collecting device through the branch pipe. In the recycling process of the wastewater of the present invention, for the processes of pre-soaking water, main immersion water, ash ash, ash ash, deashing softening, chrome pickling, retanning, neutralization and dyeing, the wastewater recycling process may be The degree of viscosity of each wastewater is cleaned, the waste solids are removed, and microorganisms, proteases, pH, chromium ions, calcium ions, sulfides and other related components in the wastewater are detected, and the wastewater is continuously recycled. For example, the waste water is cleaned by pressure filtration, and the waste solid separated by pressure filtration is used for filling or brick making or other uses, and the separated waste water is discharged into each waste water collection device for recycling. The cycle of wastewater cleaning treatment is longer than conventional treatment methods, and the treatment is simple.

The invention has the following beneficial effects:

The invention realizes recycling and recycling of waste water from pre-soaking to dyeing process in the tanning, and can be repeatedly recycled and reused, and almost no sewage is discharged, thereby completely solving the problem of tanning pollution, especially using waste chromium liquid, late rehydration The temperature rise is 3 ° C - 15 ° C less than the conventional process, saving energy. The performance indexes of the finished leather produced by the above all meet the requirements, and the rate of tanned pine is effectively reduced, and the compactness and fullness of the leather are improved. Compared with the fresh water process, after the end of each process, the waste produced is 5%-40% of the fresh water process, and at the same time can save 15%-55% of the material, such as saving 35% of the chromium powder- 65%, part of the material can achieve more than 90% savings, individual chemicals such as salt can achieve 100% savings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic flow diagram of a cycle engineering for achieving near zero discharge of tannery wastewater in accordance with the present invention.

detailed description

The present invention is further described below in conjunction with FIG. 1 and the embodiment: Example 1

As shown in Fig. 1, in the pre-soaking process, the pre-soaked wastewater is discharged into the pre-soaked wastewater tank, the waste solids are filtered, stirred uniformly, and then input into the pre-dip water drum by the alkali-resistant pump, using the pre-soaked wastewater. The process of pre-soaking is: 200% pre-soaked water, 0. 25% bactericide, 15 minutes; 0. 35% immersion aid, 0.2% degreasing agent, 0.2% soda ash, 20 minutes / stop for 40 minutes, transfer and combine 4 times; pre-immersion water to discharge waste water into the wastewater pool; remove the fur to the meat, and then carry out the main water immersion;

In the main immersion process, the main immersion wastewater is discharged into the main immersion wastewater tank, the waste solids are filtered, stirred uniformly, and then input into the main immersion drum by the alkali-resistant pump, and the main immersion water is used for the main immersion process: Raw skin weight meter, 200% main immersion water, 0. 7% immersion aid, 0. 3% degreaser, 0.5% soda ash, 0.1% Na ₂ S, 40 minutes / stop for 40 minutes, transfer combination 3 times; 0. 3% fungicide, 20 minutes, then 3 minutes per revolution / 57 minutes, overnight; the next day for 40 minutes; the main water is discharged into the wastewater pool;

In the liming process, the ash wastewater is discharged into the ash effluent tank, the waste solids are filtered, stirred evenly, and then input into the immersion drum by the alkali-resistant pump, and the liming process using the ash wastewater is: Weight, 70% waste ash, 1. 0% ash auxiliaries, 0. 15% NaHS, 30 minutes; 1. 2% lime, 30 minutes / stop for 30 minutes; 0. 5% NaHS, turn 20 Minutes/stop for 20 minutes; start filter; 0. 5% Na ₂ S, 0. 8% lime, 0.1% degreaser, 20 minutes/stop for 30 minutes, transfer combined for 3 times; 20% waste ash , 0. 5% Na ₂ S, 0. 5% ash auxiliaries, 1. 0% lime, 20 minutes / stop for 20 minutes, transfer combined 2 times; then 10 minutes / stop for 20 minutes, transfer combination 6 times; 80% waste ash, 10 minutes; then 5 minutes per stop / 55 minutes, overnight; ash is discharged into the wastewater tank; the gray skin is removed to the skin, and then the ash is removed;

In the ashing process, the ash wastewater is discharged into the ash wastewater tank, and the waste solids are filtered and stirred. The ash is 0. 8% lime, 0.2% sodium sulfide, 0. 8% lime, 0. 2% sodium sulfide, 0. 4% ash auxiliaries, 0. 10% Na0H, 30 minutes/stop for 40 minutes, then 5 minutes/55 minutes per revolution, combined with 6 times of overnight transfer; overnight; waste ash is discharged into the wastewater tank;

In the deliming and softening process, the deliming and softening wastewater is discharged into the deliming and softening wastewater pool, and the waste solids therein are filtered, stirred uniformly, and then input into the deliming and softening drum by the acid and alkali resistant pump, and deashing and softening is performed by using the wastewater. The process is: in terms of the weight of the gray, 100% deashing and softening wastewater, 0.2% degreasing agent, 0.6% deashing agent, 1. 2% ammonium sulfate, 0.2% hydrochloric acid, 0.3% acetic acid, 40 minutes; 0. 25% softening enzyme, transfer for 30 minutes; deashing and softening to end the discharge of wastewater into the wastewater pool;

In the chromic acid pickling process, the chromic acid leaching wastewater is discharged into the lagoon, the waste solids are filtered, stirred evenly, and then input by an acid-resistant pump to the chrome-plated chrome-dip drum, dip by leaching chrome-tantalum wastewater The chrome tanning process is: 90% chromic acid chrome wastewater, adjusted to pH 0.7 with sulfuric acid, 0.25% antifungal agent, for 10 minutes; 0.5% formic acid, 20 minutes; 0.3 % sulfuric acid, divided into three times, every 10 minutes, then 90 minutes; 0.2% fatliquoring, 30 minutes, 1.5 hours; 1.8% chromium powder, 30 minutes; 2.2% chromium powder, 1 hour; 0.5% sodium formate, 30 minutes; 0.25% alkali-raising agent, 4 hours; 80% chromic acid leaching wastewater, heating to 35 °C, 3 hours; chromic acid leaching to discharge wastewater into the wastewater pool;

In the reclamation process, the reclaimed wastewater is discharged into the reclamation wastewater tank, the waste solids are filtered, stirred evenly, and then input by the acid-resistant pump to the re-twisting drum, and the reclaiming process using the reclaimed wastewater is: The weight of the leather, 90% of the reclaimed wastewater, the pH was adjusted to 2.5 with sulfuric acid, and the temperature was adjusted to 36. C, 0.3% formic acid, for 30 minutes; 1.5% acrylic retanning agent, for 30 minutes; 1.0% chromium powder, 0.3% fatliquor, for 60 minutes; 1.0% fatty aldehyde, for 30 minutes; 0.8% sodium formate, 0.2 % baking soda, turn for 60 minutes, then turn 10 minutes / stop for 50 minutes, transfer and combine 5 times, pH requirement 2.8-4.8; After the reclamation, the wastewater is discharged into the wastewater pool;

In the neutralization process, the neutralized wastewater is discharged into the neutralization wastewater tank, the waste solids are filtered, stirred evenly, and then input into the neutralization drum by the acid-proof pump, and the neutralization process using the neutralization wastewater is: Leather weight meter, 200% neutralized wastewater, temperature adjusted to 35 ° C, 2.0% neutralized tannin, 1.5% sodium formate, 20 minutes; 1.2% baking soda, 3.0% fatliquor, 60 minutes, required: pH Value 4.0-6.5; neutralizing and discharging waste water into the wastewater pool;

In the dyeing process, the dyeing wastewater is discharged into the same color dyeing wastewater tank, the waste solids are filtered, stirred evenly, and then input into the dyeing drum by the acid-proof pump. The dyeing wastewater is dyed by the weight of the shaving leather. , 80% dyeing wastewater, temperature adjusted to 30 ° C, 2.5% acrylic retanning agent, 20 minutes; 4.0% melamine retanning agent, 1.5% wattle bark, 2.0% sulfitized vegetable oil, turn 40 minutes; 2.0% dye, 1.5% compound fatliquor, for 60 minutes, required: Dyeing waste water discharged into the same color wastewater tank;

The above-mentioned pre-soaked water, main immersion water, ash ash, ash ash, deliming softening, chrome pickling, retanning, neutralization and dyeing process are subject to pressure filtration treatment, and the wastewater obtained by pressure filtration is returned to the corresponding wastewater. The pool continues to be recycled and the waste solids obtained by pressure filtration are used for filling pits or other.

The invention may be embodied in other specific forms without departing from the spirit and scope of the invention.

Claims

claims

1. A recycling project that achieves near-zero discharge of tanning wastewater, which is characterized by dividing it into presoaking, main soaking, liming, reliming, deliming and softening, pickling chromium tanning, retanning, neutralization, and dyeing processes. Step by step and independently carry out wastewater recycling;

(1) Reuse of wastewater from the presoaking process: This process consists of collecting the wastewater after each presoaking process, filtering the waste solids, stirring evenly, and placing it next to the presoaking drum or trough; for use in the next batch. pre-soaking water for skins; testing the number of microorganisms in wastewater to determine the amount of fungicide;

(2) Reuse of wastewater from the soaking process: This process is to collect the wastewater after each soaking process, filter the waste solids in it, stir it evenly, and place it next to the soaking drum or groove; it can be used for soaking the next batch of skins. ; Detect the number of microorganisms in wastewater to determine the amount of fungicide;

(3) Reuse of wastewater from the liming process; this process consists in collecting the wastewater after each liming process, filtering the waste solids, stirring evenly, and placing it next to the liming drum or trough; for use in the next batch Liming of skins; wool filtration is required during the liming process;

(4) Reuse of waste water from the re-ashing process; this process consists in collecting the waste water after each re-ashing process, filtering the waste solids in it, mixing it evenly, and placing it next to the re-ashing drum or trough; for use in the next batch The graying of the skin;

(5) Reuse the wastewater from the deliming and softening process; this process consists in collecting the wastewater after each deliming and softening process, filtering the waste solids, stirring evenly, and placing it next to the deliming and softening drum; for use in the next batch deliming and softening of skin;

(6) Reuse of wastewater from the pickling chromium tanning process; this process consists in collecting the wastewater after each pickling chromium tanning process, filtering the waste solids, stirring evenly, and placing it next to the pickling chromium tanning drum; for use Pickled chrome tanning of the next batch of skins;

(7) Reuse of wastewater from the retanning process; This process consists in collecting the wastewater after each retanning process, filtering the waste solids, stirring evenly, and placing it next to the retanning drum; to be used for retanning the next batch of hides. tanning;

(8) Reuse of wastewater from the neutralization process; This process consists of collecting the wastewater after each neutralization process, filtering the waste solids, stirring evenly, and placing it next to the neutralization drum; for use in the neutralization of the next batch of skins. and;

(9) Reuse of wastewater from the dyeing process; this process consists in collecting the wastewater after each dyeing process, filtering the waste solids, stirring evenly, and placing it next to the dyeing drum; for dyeing the next batch of skins.

2. The nine processes described in claim 1 are characterized in that after each process, except for normal volatilization and inevitable leakage in the natural state, all the collected wastewater is reused. When the wastewater is insufficient, fresh water is used. Replenish.

3. The nine processes described in claim 1 are characterized in that after each process, the waste solids produced are 5%-40% of the fresh water process.