Composite COD (Chemical Oxygen Demand) remover as well as preparation method and application thereof

Abstract

The invention provides a composite COD (Chemical Oxygen Demand) remover as well as a preparation method and application thereof, and the composite COD remover comprises the following components in parts by weight: 20-40 parts of modified sepiolite mineral powder, 40-60 parts of ferrous sulfate, 10-20 parts of crystalline aluminum chloride and 5-10 parts of wooden activated carbon. The composite COD remover provided by the invention can be blended according to different water qualities so as to adapt to the requirements of different water qualities, and the dosage is determined according to the COD value. The composite COD remover provided by the invention is mixed in a dry stirring manner, and the modified sepiolite mineral powder and the wooden activated carbon are fully mixed with the ferrous sulfate and the crystalline aluminum chloride in a dry stirring manner, so that the ferrous sulfate and the crystalline aluminum chloride are uniformly distributed in pores of the modified sepiolite mineral powder and the wooden activated carbon and can be uniformly distributed in a system in a reaction process; for different types of refractory organic matter wastewater, by adjusting the proportions of all the components and utilizing the synergistic effect of all the components, the effect of efficient reaction can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a composite COD remover and a preparation method and application thereof. Background Art

[0002] With the continuous upgrading of sewage discharge indicators, COD emission indicators have become increasingly strict, and conventional biological or chemical methods have been difficult to meet the discharge standards. The use of other methods will result in high operating costs, extremely high treatment costs and operating requirements, which are difficult for enterprises to bear. Most of the existing COD removal agents need to be effective under acidic conditions, and their treatment environment requirements are relatively high, with a pH of about 3, which will increase the treatment cost.

[0003] COD in organic wastewater is divided into colloidal COD and dissolved COD according to its existence form in sewage. Coagulation and sedimentation method can only effectively remove 60% to 90% of colloidal substances and suspended solids SS, and has no direct removal effect on dissolved COD. Advanced oxidation methods (O3, ClO2, Fenton and catalytic oxidation) have the characteristics of high oxidation efficiency and good treatment effect, but due to high construction investment and operation costs, complex processes and strong oxidizing agents are dangerous chemicals, which have been greatly restricted in their application.

[0004] The water quality of wastewater such as landfill leachate, chemical wastewater, coking wastewater, printing and dyeing wastewater, papermaking wastewater, leather wastewater, electroplating wastewater, aquaculture wastewater and food wastewater has the characteristics of complex composition, and the components of COD pollutants are also very different. It is difficult to effectively remove the target pollutants using a single reagent component. In addition, the pH range of the Fenton process reaction in the advanced oxidation method is low, the amount of reagent added is large, and a large amount of sludge is produced. Moreover, the Fenton process construction investment and operating costs are high, the process is complex, and the strong oxidizing reagents are hazardous chemicals, which has led to great restrictions in its implementation and application.

[0005] Therefore, the industry is in urgent need of a new technology of composite COD remover that can efficiently and thoroughly remove different types of difficult-to-degrade organic matter. Summary of the invention

[0006] In order to solve the technical problems of the above-mentioned prior art that there are many types of complex and difficult-to-degrade organic pollutants COD, complex components, and difficult removal, the present invention provides a composite COD remover and its preparation method and application. The present invention proposes to use modified sepiolite powder, ferrous sulfate, crystalline aluminum chloride, and wood activated carbon to remove COD in the above-mentioned sewage. Through the synergistic effect between the components, efficient removal of COD is achieved, solving the problem that the water quality components are complex and difficult to effectively treat. It has a wide applicability for different types of water quality and different types of COD, and broadens the application pH range of traditional Fenton reagents (ferrous sulfate, hydrogen peroxide), reduces the use of hydrogen peroxide, and uses less pH adjustment alkali.

[0007] To achieve the above object, the present invention provides a composite COD remover, which comprises, by weight: 20-40 parts of modified sepiolite powder, 40-60 parts of ferrous sulfate, 10-20 parts of crystalline aluminum chloride, and 5-10 parts of wood activated carbon;

[0008] The modified sepiolite ore powder is obtained by purifying the original sepiolite ore powder and then activating it.

[0009] Furthermore, the preparation method of the modified sepiolite powder comprises the following steps:

[0010] Firstly, the sepiolite ore powder is separated and purified by a wet chemical method in combination with mechanical stirring and a dispersant to obtain a purified sepiolite concentrate;

[0011] The purified sepiolite concentrate is then prepared into a slurry, sulfuric acid is added to the slurry for activation, and the mixture is stirred and reacted at 60-90° C. for 4-12 hours; the slurry is then washed, filtered, and dried to obtain the modified sepiolite ore powder.

[0012] Furthermore, the purified sepiolite concentrate is prepared into a slurry with a mass fraction of 5-15%; the amount of sulfuric acid used is 30-50% of the mass of the sepiolite concentrate.

[0013] Furthermore, the sepiolite ore powder is separated and purified by a wet chemical method in combination with mechanical stirring and a dispersant to obtain a purified sepiolite concentrate; specifically, the sepiolite ore powder is subjected to water immersion treatment and then sieved with a 50-500 mesh sieve, and then a dispersant and a pH adjuster are added and a high-speed disperser is used to fully circulate and stir the slurry, and after dispersion, the slurry is naturally settled to obtain a purified sepiolite concentrate.

[0014] Furthermore, the dispersant is 0.6-1.0 g / L sodium pyrophosphate, the pH adjuster is sodium hydroxide, and the pH value is adjusted to 8-10.

[0015] Furthermore, a high-speed disperser is used for dispersion for 5-30 minutes at a rotation speed of 1200-3000 rpm.

[0016] Furthermore, the content of sepiolite in the purified sepiolite concentrate is 85-99%.

[0017] The present invention also provides a method for preparing the above-mentioned composite COD remover, comprising the following steps:

[0018] The modified sepiolite powder, wood activated carbon, ferrous sulfate and crystalline aluminum chloride are fully dry-mixed so that the ferrous sulfate and crystalline aluminum chloride are evenly distributed in the pores of the modified sepiolite powder and the wood activated carbon to obtain the composite COD remover.

[0019] The present invention also provides the use of the composite COD remover in sewage, wherein the composite COD remover and hydrogen peroxide are directly added into the sewage and stirred to complete the treatment of the sewage.

[0020] Furthermore, the COD value in the sewage ranges from 200 to 3200 mg / L, and the dosage of the composite COD remover is 3‰ to 9‰; wherein, for every 500 mg / L increase in COD, the dosage of the agent increases by 1‰.

[0021] The present invention has the following beneficial effects:

[0022] 1. A composite COD remover provided by the present invention can remove different types of COD and has strong adaptability to different water qualities. It has good treatment effects on low, medium and high molecular weight organic components, and has good treatment effects on dissolved (0.001-0.0013μm), colloidal (0.0013-0.45μm) and granular (0.45-10μm) organic components. The composite COD remover provided by the present invention has good removal effects on different types of difficult biodegradable wastewaters such as printing and dyeing wastewater, coking wastewater, and landfill leachate, and the COD removal rate can reach 89-96%. It has good treatment effects on organic components of different particle sizes such as dissolved, colloidal, and granular, and has volatile fatty acids (VFA), fulvic acid (FA), humic acid (HA) and other organic substances, especially difficult biodegradable humic acid including humic acid (HA) and high molecular weight fulvic acid (FA) can be effectively removed, and the effect of thorough COD removal can be achieved.

[0023] 2. A composite COD remover provided by the present invention can be formulated according to different water qualities to meet the needs of different water qualities. The dosage is determined according to the COD level. The COD value range is: 200-3200 mg / L. When the dosage of the agent is 3‰-9‰, the dosage of the agent increases by 1‰ for every 500 mg / L increase in COD. The reasonable deployment of the formula components needs to be determined according to the proportion of different types of organic matter in the treated sewage. The adjustment is made by measuring the proportion of organic matter such as volatile fatty acids, fulvic acid, and humic acid in the water. Ferrous sulfate is mainly used for the removal of fulvic acid (FA), modified sepiolite adsorption, and crystallized aluminum chloride are mainly used for the removal of humic acid (HA), and wood activated carbon is mainly used for the removal of small molecule volatile fatty acids. Among them, ferrous sulfate removes organic matter through Fenton's advanced oxidation reaction. Specifically, ferrous ions are used to catalyze the decomposition of hydrogen peroxide to produce hydroxyl radicals (·OH). ·OH has a large number of unpaired electrons. Because of its strong tendency to pair electrons, it is an important active oxidant with extremely strong reactivity. Modified sepiolite adsorbs and removes large molecular weight compounds such as aromatic hydrocarbon chains, aldehydes, alcohols, lubricating oils and organic dyes through van der Waals forces, hydrogen bonds and electrostatic attraction. Specifically, the oxygen atoms in the silicon-oxygen tetrahedral layer of the modified sepiolite carry many weak charges, and weak electrostatic attraction occurs between them and the adsorbate. The adsorption is produced by electric force; the water molecules coordinated with the edge magnesium ions can form hydrogen bonds with the adsorbate; the Si-O-Si bond is destroyed and the Si-OH group is formed on the surface of the silicon-oxygen tetrahedron, which reacts with the adsorbate to produce adsorption; the aluminum ions in the crystalline aluminum chloride play a coagulation role in the system, and under the action of the hydrolysis products, the organic matter with larger molecular weight and stronger hydrophobicity in the water is destabilized and aggregated, and thus removed; the wood activated carbon has a wide pore size distribution, large specific surface area, and strong adsorption capacity, and the organic matter with smaller molecular weight in the water is effectively removed under its adsorption.

[0024] 3. The composite COD remover provided by the present invention has components that work synergistically with each other to achieve low-cost and high-efficiency removal of COD:

[0025] First, the synergistic effect of crystallized aluminum chloride and ferrous sulfate (Fenton acidic system). After the addition of crystallized aluminum chloride, the pH value decreases and becomes acidic. Acidic conditions (pH value of 3-5) are conducive to the Fenton reaction between ferrous sulfate and hydrogen peroxide. Because the Fenton reaction needs to be carried out under acidic conditions, crystallized aluminum chloride can reduce the pH while playing a coagulation role in the entire system, thereby reducing the amount of sulfuric acid required for the Fenton reaction and the amount of alkali added to adjust the pH back to neutral. In this way, the two work synergistically with each other, which reduces the pH of the entire system and reduces the amount of alkali agent added.

[0026] Second, the synergistic effect of ferrous sulfate (Fenton acid system) and modified sepiolite. The acidic conditions of the Fenton reaction are conducive to the dissolution of magnesium ions in modified sepiolite, which can not only further activate the modified sepiolite, increase the porosity, and enhance the COD adsorption capacity, but also remove COD through chemical precipitation after the magnesium ions are dissolved.

[0027] Third, the synergistic effect of crystalline aluminum chloride and modified sepiolite. The aluminum content of modified sepiolite is the main factor determining its ion exchange capacity. 3+ The introduction of can significantly enhance the acidic center of the modified sepiolite, thereby increasing the adsorption capacity.

[0028] Fourth, modified sepiolite and wood activated carbon have huge specific surface areas. In addition to their strong adsorption capacity, they can also provide a large number of active sites for the Fenton reaction, playing a synergistic role.

[0029] 4. The composite COD remover provided by the present invention has less system sludge production compared with the single ferrous sulfate Fenton agent. This is because the modified sepiolite and wood activated carbon adsorption do not produce sludge, so the amount of sludge produced can be greatly reduced. In addition, the composite COD remover provided by the present invention utilizes the Fenton advanced oxidation reaction, in which ferrous sulfate accounts for 40% to 60%, so the amount of hydrogen peroxide used is less, the amount of strong oxidants used is reduced, and the risks during transportation and use are reduced.

[0030] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 It is a physical picture of the composite COD remover according to the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0034] The composition of organic matter at different particle sizes is very different. The dissolved ones are mainly volatile fatty acids (VFA) and a small amount of low-molecular-weight fulvic acid, while the colloidal ones are mainly humic acid (HA) and high-molecular-weight fulvic acid (FA). There is basically no organic matter in the particle components. For example, the large-molecule organic matter in the leachate, mainly humic acid, is extremely difficult to biodegrade. This type of substance is basically distributed in the colloidal components, while the vast majority of biodegradable organic matter exists in the dissolved components. Therefore, the difficulty in treating refractory organic matter lies in the treatment of humic acid that is difficult to biodegrade, including: humic acid (HA) and high-molecular-weight fulvic acid (FA).

[0035] Therefore, a composite COD remover provided by the present invention can remove different types of COD and has strong adaptability to different water qualities. It has good treatment effects on low, medium and high molecular weight organic components, and has good treatment effects on dissolved (0.001-0.0013 μm), colloidal (0.0013-0.45 μm) and granular (0.45-10 μm) organic components. The composite COD remover provided by the present invention has good removal effects on different types of difficult biodegradable wastewaters such as printing and dyeing wastewater, coking wastewater, and landfill leachate, and the COD removal rate can reach 89-96%. It has good treatment effects on organic components of different particle sizes such as dissolved, colloidal, and granular, and has volatile fatty acids (VFA), fulvic acid (FA), humic acid (HA) and other organic substances, especially difficult biodegradable humic acids including humic acid (HA) and high molecular weight fulvic acid (FA) can be effectively removed, and the effect of thorough COD removal can be achieved.

[0036] The invention provides a composite COD remover, which is composed of the following components in parts by weight: 20-40 parts of modified sepiolite powder, 40-60 parts of ferrous sulfate, 10-20 parts of crystallized aluminum chloride, and 5-10 parts of wood activated carbon; the modified sepiolite powder is obtained by purifying and then activating the original sepiolite powder.

[0037] The composite COD remover provided by the present invention can remove different types of COD and has strong adaptability to different water qualities. It has good treatment effects on low, medium and high molecular weight organic components, and has good treatment effects on dissolved (0.001-0.0013 μm), colloidal (0.0013-0.45 μm) and granular (0.45-10 μm) organic components. The composite COD remover provided by the present invention has good removal effects on different types of difficult biodegradable wastewaters such as printing and dyeing wastewater, coking wastewater, and landfill leachate, and the COD removal rate can reach 89-96%. It has good treatment effects on organic components of different particle sizes such as dissolved, colloidal, and granular, and has volatile fatty acids (VFA), fulvic acid (FA), humic acid (HA) and other organic substances, especially difficult biodegradable humic acids including humic acid (HA) and high molecular weight fulvic acid (FA) can be effectively removed, and the effect of thorough COD removal can be achieved.

[0038] Sepiolite is a magnesium-rich silicate with two layers of silicon-oxygen tetrahedrons and a middle layer of magnesium-oxygen octahedrons. This special structure determines its excellent adsorption performance. As a natural ore used as a research object for wastewater treatment, sepiolite has good adsorption performance and is cheap. However, natural sepiolite ore has a low grade, high impurity content, weak surface acidity, small channels, and poor thermal stability. These weaknesses limit the application of sepiolite. In order to improve the purity of the original sepiolite, change its surface acidity, increase the two pore structures, and make the surface and interior of sepiolite have a strong adsorption capacity, the sepiolite must be modified first.

[0039] The preparation method of the modified sepiolite powder adopted in the present invention comprises the following steps:

[0040] Step 1: Separate and purify the sepiolite ore powder by wet chemical method in combination with mechanical stirring and dispersant to obtain purified sepiolite concentrate. Specifically, the sepiolite ore powder is sieved with a 50-500 mesh sieve after being treated with water, and then a dispersant and a pH adjuster are added and a high-speed disperser is used to fully circulate and stir the slurry. After dispersion, it is naturally settled to obtain a purified sepiolite concentrate. Among them, the dispersant is 0.6-1.0g / L sodium pyrophosphate, the pH adjuster is sodium hydroxide, and the pH value is adjusted to 8-10. A high-speed disperser is used for dispersion for 5-30min, and the rotation speed is 1200-3000rpm.

[0041] Step 2: prepare the purified sepiolite concentrate into slurry, add sulfuric acid to the slurry for activation, and stir the reaction at 60-90° C. for 4-12 hours; then wash, filter and dry the slurry to obtain the modified sepiolite powder.

[0042] The purified sepiolite concentrate is prepared into a pulp with a mass fraction of 5-15%; and the amount of sulfuric acid used is 30-50% of the mass of the sepiolite concentrate.

[0043] Finally, the content of sepiolite in the purified sepiolite concentrate is 85-99%.

[0044] The present invention also provides a method for preparing the above-mentioned composite COD remover, comprising the following steps:

[0045] The modified sepiolite powder, wood activated carbon, ferrous sulfate and crystalline aluminum chloride are fully dry-mixed so that the ferrous sulfate and crystalline aluminum chloride are evenly distributed in the pores of the modified sepiolite powder and the wood activated carbon to obtain the composite COD remover.

[0046] The present invention also provides the use of the composite COD remover in sewage, wherein the composite COD remover and hydrogen peroxide are directly added into the sewage and stirred to complete the treatment of the sewage.

[0047] Among them, the COD value in the sewage ranges from 200 to 3200 mg / L, and the dosage of the composite COD remover is 3‰-9‰; among them, for every 500 mg / L increase in COD, the dosage of the agent increases by 1‰ accordingly.

[0048] The present invention is explained below with reference to specific examples. In these examples, the parts and percentages are all based on weight.

[0049] Embodiment 1:

[0050] A composite COD remover is composed of the following components in parts by weight: 40 parts of modified sepiolite powder, 45 parts of ferrous sulfate, 10 parts of crystalline aluminum chloride, and 5 parts of wood activated carbon; the modified sepiolite powder is obtained by purifying and activating raw sepiolite powder.

[0051] Embodiment 2:

[0052] A composite COD remover is composed of the following components in parts by weight: 30 parts of modified sepiolite powder, 40 parts of ferrous sulfate, 20 parts of crystalline aluminum chloride, and 10 parts of wood activated carbon; the modified sepiolite powder is obtained by purifying and activating raw sepiolite powder.

[0053] Embodiment 3:

[0054] A composite COD remover is composed of the following components in parts by weight: 20 parts of modified sepiolite powder, 60 parts of ferrous sulfate, 15 parts of crystalline aluminum chloride, and 5 parts of wood activated carbon; the modified sepiolite powder is obtained by purifying and activating raw sepiolite powder.

[0055] Comparative Example 1:

[0056] The difference between Comparative Example 1 and Example 3 is that the modified sepiolite powder is not included, and the rest is the same as Example 3.

[0057] Comparative Example 2:

[0058] The difference between Comparative Example 2 and Example 3 is that ferrous sulfate is not included, and the other parts are the same as Example 3.

[0059] Comparative Example 3:

[0060] The difference between Comparative Example 3 and Example 3 is that the crystallized aluminum chloride is not included, and the other parts are the same as Example 3.

[0061] Comparative Example 4:

[0062] The difference between Comparative Example 4 and Example 3 is that wood activated carbon is not included, and the rest is the same as Example 3.

[0063] Comparative Example 5:

[0064] The difference between Comparative Example 5 and Example 3 is that only 100 parts of ferrous sulfate are used.

[0065] Comparative Example 6:

[0066] The difference between Comparative Example 6 and Example 3 is that the sepiolite used is only subjected to the activation step but not the purification step, and the rest is the same as Example 3.

[0067] Comparative Example 7:

[0068] The difference between Comparative Example 7 and Example 3 is that the sepiolite used is only subjected to the purification step but not the activation step, and the rest is the same as Example 3.

[0069] Comparative Example 8:

[0070] The difference between Comparative Example 8 and Example 3 is that the sepiolite used is only not modified, that is, no purification step or activation step is performed, and the original sepiolite mineral powder is used. The rest is the same as Example 3.

[0071] The specific components of Examples 1-3 and Comparative Examples 1-8 are shown in Table 1.

[0072] Table 1

[0073] Ingredients Sepiolite powder Ferrous Sulfate Crystalline aluminum chloride Wood activated carbon Example 1 40 parts (purification + activation) 45 servings 10 servings 5 servings Example 2 30 parts (purification + activation) 40 servings 20 servings 10 servings Example 3 20 parts (purification + activation) 60 servings 15 servings 5 servings Comparative Example 1 0 copies 60 servings 15 servings 5 servings Comparative Example 2 20 parts (purification + activation) 0 copies 15 servings 5 servings Comparative Example 3 20 parts (purification + activation) 60 servings 0 copies 5 servings Comparative Example 4 20 parts (purification + activation) 60 servings 15 servings 0 copies Comparative Example 5 0 copies 100 copies 0 copies 0 copies Comparative Example 6 20 copies (activation only) 60 servings 15 servings 5 servings Comparative Example 7 20 parts (purified only) 60 servings 15 servings 5 servings Comparative Example 8 20 parts (unpurified and activated) 60 servings 15 servings 5 servings

[0074] The COD removers of Examples 1-3 and Comparative Examples 1-8 in Table 1 were added into different polluted waters for sewage treatment.

[0075] Test 1

[0076] The composite COD remover of Example 1 was applied to printing and dyeing wastewater for wastewater treatment.

[0077] Before treatment, the COD of the raw water of printing and dyeing wastewater was 325mg / L and the pH value was 7.2. The dosage of the composite COD remover was 3‰, the pH value after addition was 5.5, the dosage of hydrogen peroxide (27.5%) was 0.437‰, the stirring reaction was 20 minutes, the dosage of liquid alkali (30%) was 0.28‰, the pH value was 7.1, the precipitation was 30 minutes, the effluent COD value was 35mg / L, and the amount of dried sludge was 1.14kg / ton of water.

[0078] Test 2

[0079] The composite COD remover of Example 1 was applied to coking wastewater for wastewater treatment.

[0080] Before treatment, the raw water COD of coking wastewater was 625mg / L and the pH value was 7.8. The dosage of composite COD remover was 4‰, the pH value was 5.2 after the addition, the dosage of hydrogen peroxide (27.5%) was 0.583‰, the stirring reaction was 20 minutes, the dosage of liquid alkali (30%) was 0.35‰, the pH value was 7.2, the precipitation was 30 minutes, the effluent COD was 29mg / L, and the amount of dried sludge was 2.46kg / ton of water.

[0081] Test 3

[0082] The composite COD remover of Example 3 was applied to landfill leachate for sewage treatment.

[0083] Before treatment, the COD of the leachate raw water was 1850mg / L and the pH value was 8.3. The dosage was 6‰, the pH value was 5.5 after the dosage, the dosage of hydrogen peroxide (27.5%) was 0.99‰, the stirring reaction lasted for 30 minutes, the dosage of liquid alkali (30%) was 0.3‰, the pH value was 7.2, the precipitation lasted for 30 minutes, the effluent COD was 65mg / L, and the amount of dried sludge was 4.8kg / ton of water.

[0084] Test 4

[0085] The COD remover of Comparative Example 1 was applied to landfill leachate for sewage treatment.

[0086] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 1 was the same as that of Example 3 except that the modified sepiolite powder was not contained. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 603.1 mg / L, and the amount of dried sludge was 4.6 kg / ton of water.

[0087] Test 5

[0088] The COD remover of Comparative Example 2 was applied to landfill leachate for sewage treatment.

[0089] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 2 was the same as that of Example 3 except that ferrous sulfate was not contained. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 960.1 mg / L, and the amount of dried sludge was 1.2 kg / ton of water.

[0090] Test 6

[0091] The COD remover of Comparative Example 3 was applied to landfill leachate for sewage treatment.

[0092] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 3 was the same as that of Example 3 except that it did not contain crystalline aluminum chloride. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 427.3 mg / L, and the amount of dried sludge was 3.84 kg / ton of water.

[0093] Test 7

[0094] The COD remover of Comparative Example 4 was applied to landfill leachate for sewage treatment.

[0095] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 4 was the same as that of Example 3 except that wood activated carbon was not contained. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 379.2 mg / L, and the amount of dried sludge was 4.52 kg / ton of water.

[0096] Test 8

[0097] The COD remover of Comparative Example 5 was applied to landfill leachate for sewage treatment.

[0098] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. Comparative Example 5 is the existing Fenton reagent, and at the same time, 1.55‰ of dilute sulfuric acid (30%), 8‰ of anhydrous ferrous sulfate, and 2.4‰ of hydrogen peroxide (35%) were added, the reaction pH was 3.2, the reaction was stirred for 20 minutes, the pH was adjusted by 2.55‰ of liquid alkali (30%), the pH was 7.2, and the precipitation was carried out for 30 minutes, the effluent COD was 562.4 mg / L, and the amount of dried sludge was 5.15 kg / ton of water.

[0099] Test 9

[0100] The COD remover of Comparative Example 6 was applied to landfill leachate for sewage treatment.

[0101] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 6 contained only activated sepiolite powder, and the other components were the same as those of Example 3. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 327.4 mg / L, and the amount of dried sludge was 4.88 kg / ton of water.

[0102] Test 10

[0103] The COD remover of Comparative Example 7 was applied to landfill leachate for sewage treatment.

[0104] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover formula of Comparative Example 1 contained only purified sepiolite powder, and the other components were the same as those of Example 3. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 384.8 mg / L, and the amount of dried sludge was 4.92 kg / ton of water.

[0105] Test 11

[0106] The COD remover of Comparative Example 8 was applied to landfill leachate for sewage treatment.

[0107] Before treatment, the COD of the original water of the landfill leachate was 1850 mg / L and the pH value was 8.3. The COD remover of Comparative Example 1 contained unpurified activated sepiolite powder, and the other components were the same as those of Example 3. After adding the agent, the pH value was adjusted to 5.5, the amount of hydrogen peroxide (27.5%) was 0.99‰, the reaction was stirred for 30 minutes, the amount of liquid alkali (30%) was 0.3‰, the pH value was 7.2, and the precipitation was carried out for 30 minutes. The effluent COD was 460.6 mg / L, and the amount of dried sludge was 4.96 kg / ton of water.

[0108] The above-prepared reagent was applied to different sewage, and the experimental results are shown in Table 2.

[0109] Table 2

[0110]

[0111]

[0112] It can be seen from Table 2 that the composite COD remover provided by the present invention has a good removal effect on different types of difficult-to-biodegrade wastewaters such as printing and dyeing wastewater, coking wastewater, and landfill leachate, and the COD removal rate can reach 89-96%, and the amount of dry mud produced is also less. When treating landfill leachate in the same way, when using Comparative Example 1, although the amount of dry mud is similar to that of Example 3, the COD removal rate is only 67.4%, while the COD removal rate of Example 3 is as high as 96.4%. This is because the generation of sludge mainly comes from components such as ferrous sulfate and crystalline aluminum chloride. The proportions of the two components in Example 3 and Comparative Example 1 are the same, so the amount of sludge produced is not much different. However, no modified sepiolite powder is added in Comparative Example 1, and the adsorption effect is only provided by wood activated carbon, and there is no chemical precipitation effect, so the COD removal effect is far inferior to that of Example 3.

[0113] When using Comparative Example 2, although the amount of dry mud is less than that of Example 3, the COD effect is not ideal, and the removal rate is only 48.1%. This is because the ferrous sulfate component is not added to the reagent component, which will reduce the amount of sludge generated, but there is no advanced oxidation reaction in the reagent, which will seriously affect the treatment effect.

[0114] When using Comparative Example 3, although the amount of dry mud is slightly less than that of Example 3, the COD effect is not ideal, and the removal rate is only 76.9%. This is because the crystalline aluminum chloride component is not added to the agent component, which will reduce the amount of sludge generated, but there is no coagulation and precipitation effect in the agent, and aluminum ions can enhance the adsorption capacity of modified sepiolite. If not added, this will affect the use effect of the modified sepiolite component, and will increase the amount of pH adjustment, increasing the cost of using the agent.

[0115] When comparative example 4 is used, the amount of dry mud produced is similar to that of embodiment 3, but the COD effect is lower than that of embodiment 3, and the removal rate is only 79.5%. This is because the sludge is mainly produced from components such as ferrous sulfate and crystalline aluminum chloride. The proportions of the two components in embodiment 3 and comparative example 4 are the same, so the amount of sludge produced is not much different. However, no wood activated carbon is added in comparative example 4, and the adsorption effect is only provided by modified sepiolite, so the COD removal effect is far inferior to that in embodiment 3.

[0116] When comparative example 5 is used, the amount of dry mud produced is more than that of embodiment 3, and the COD removal rate is 69.6%, and the treatment effect is far lower than that of embodiment 3. This is because the sludge is mainly produced from components such as ferrous sulfate and crystalline aluminum chloride, and the components of comparative example 5 are all ferrous sulfate, so the amount of mud produced will increase, and there is only advanced oxidation in the agent, and adsorption, coagulation and sedimentation, and chemical precipitation do not exist, so the COD removal effect is far inferior to that of embodiment 3.

[0117] When comparative example 6 is used, the amount of dry mud produced is similar to that of embodiment 3, but the COD effect is much lower than that of embodiment 3, and the removal rate is 82.3%. This is because the sepiolite has not been purified, and the sepiolite powder used contains more impurities, and the impurity part does not play a corresponding adsorption role, resulting in the COD treatment effect being inferior to that of embodiment 3.

[0118] When comparative example 7 is used, the amount of dry mud produced is similar to that of embodiment 3, but the COD effect is much lower than that of embodiment 3, and the removal rate is only 79.2%. This is because the sepiolite has not been activated, and most of the pore structure of the sepiolite used is not fully opened, resulting in a small specific surface area of ​​the sepiolite, which affects the adsorption effect of the sepiolite, resulting in the COD treatment effect being inferior to that of embodiment 3.

[0119] When comparative example 8 is used, the amount of dry mud produced is similar to that of example 3, but the COD effect is much lower than that of example 3, and the removal rate is only 75.1%. This is because the sepiolite has not been purified and activated, and has many impurities and a small specific surface area, which seriously affects the adsorption effect of the sepiolite, resulting in the COD treatment effect being inferior to that of example 3.

[0120] In summary, the composite COD remover provided by the present invention has a good COD treatment effect mainly because the components work together to achieve efficient COD removal:

[0121] First, the synergistic effect of crystallized aluminum chloride and ferrous sulfate (Fenton acidic system). After the addition of crystallized aluminum chloride, the pH value decreases and becomes acidic. Acidic conditions (pH value of 3-5) are conducive to the Fenton reaction between ferrous sulfate and hydrogen peroxide. Because the Fenton reaction needs to be carried out under acidic conditions, crystallized aluminum chloride can reduce the pH while playing a coagulation role in the entire system, thereby reducing the amount of sulfuric acid required for the Fenton reaction and the amount of alkali added to adjust the pH back to neutral. In this way, the two work synergistically with each other, which reduces the pH of the entire system and reduces the amount of alkali agent added.

[0122] Second, the synergistic effect of ferrous sulfate (Fenton acid system) and modified sepiolite. The acidic conditions of the Fenton reaction are conducive to the dissolution of magnesium ions in modified sepiolite, which can not only further activate the modified sepiolite, increase the porosity, and enhance the COD adsorption capacity, but also remove COD through chemical precipitation after the magnesium ions are dissolved.

[0123] Third, the synergistic effect of crystalline aluminum chloride and modified sepiolite. The aluminum content of modified sepiolite is the main factor determining its ion exchange capacity. 3+ The introduction of can significantly enhance the acidic center of the modified sepiolite, thereby increasing the adsorption capacity.

[0124] Fourth, modified sepiolite and wood activated carbon have huge specific surface areas. In addition to their strong adsorption capacity, they can also provide a large number of active sites for the Fenton reaction, playing a synergistic promoting role.

[0125] In addition, the composite COD remover provided by the present invention has less system sludge production compared with the single ferrous sulfate Fenton agent, because the modified sepiolite and wood activated carbon adsorption do not produce sludge, so the amount of sludge produced can be greatly reduced. In addition, the composite COD remover provided by the present invention utilizes the Fenton advanced oxidation reaction, in which ferrous sulfate accounts for 40% to 60%, so the amount of hydrogen peroxide used is less, the amount of strong oxidants used is reduced, and the risks during transportation and use are reduced.

[0126] In summary, the composite COD remover provided by the present invention can remove different types of COD and has strong adaptability to different water qualities. It has good treatment effects on low, medium and high molecular weight organic components, and has good treatment effects on dissolved (0.001-0.0013μm), colloidal (0.0013-0.45μm) and granular (0.45-10μm) organic components. The composite COD remover provided by the present invention has good removal effects on different types of difficult biodegradable wastewaters such as printing and dyeing wastewater, coking wastewater, and landfill leachate, and the COD removal rate can reach 89-96%. It has good treatment effects on organic components of different particle sizes such as dissolved, colloidal, and granular, and has volatile fatty acids (VFA), fulvic acid (FA), humic acid (HA) and other organic substances, especially difficult biodegradable humic acids including humic acid (HA) and high molecular weight fulvic acid (FA) can be effectively removed, and the effect of thorough COD removal can be achieved.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite COD remover, characterized in that: Calculated by weight, it includes: 20-40 parts of modified sepiolite powder, 40-60 parts of ferrous sulfate, 10-20 parts of crystalline aluminum chloride, and 5-10 parts of wood activated carbon; The modified sepiolite ore powder is obtained by purifying the original sepiolite ore powder and then activating it.

2. A composite COD remover according to claim 1, characterized in that: The preparation method of the modified sepiolite powder comprises the following steps: Firstly, the sepiolite ore powder is separated and purified by a wet chemical method in combination with mechanical stirring and a dispersant to obtain a purified sepiolite concentrate; The purified sepiolite concentrate is then prepared into a slurry, sulfuric acid is added to the slurry for activation, and the mixture is stirred and reacted at 60-90° C. for 4-12 hours; the slurry is then washed, filtered, and dried to obtain the modified sepiolite ore powder.

3. A composite COD remover according to claim 2, characterized in that: The purified sepiolite concentrate is prepared into a pulp with a mass fraction of 5-15%; the amount of sulfuric acid used is 30-50% of the mass of the sepiolite concentrate.

4. A composite COD remover according to claim 2, characterized in that: Firstly, the sepiolite ore powder is separated and purified by a wet chemical method in combination with mechanical stirring and a dispersant to obtain a purified sepiolite concentrate; specifically, the sepiolite ore powder is subjected to water immersion treatment and then sieved with a 50-500 mesh sieve, and then a dispersant and a pH adjuster are added and a high-speed disperser is used to fully circulate and stir the slurry, and after dispersion, the slurry is naturally settled to obtain a purified sepiolite concentrate.

5. A composite COD remover according to claim 4, characterized in that: The dispersant is 0.6-1.0 g / L sodium pyrophosphate, the pH adjuster is sodium hydroxide, and the pH value is adjusted to 8-10.

6. A composite COD remover according to claim 4, characterized in that: Use a high-speed disperser to disperse for 5-30 minutes at a speed of 1200-3000rpm.

7. A composite COD remover according to claim 2, characterized in that: The content of sepiolite in the purified sepiolite concentrate is 85-99%.

8. A method for preparing a composite COD remover according to any one of claims 1 to 7, characterized in that: The following steps are involved: The modified sepiolite powder, wood activated carbon, ferrous sulfate and crystalline aluminum chloride are fully dry-mixed so that the ferrous sulfate and crystalline aluminum chloride are evenly distributed in the pores of the modified sepiolite powder and the wood activated carbon to obtain the composite COD remover.

9. Use of a composite COD remover as claimed in any one of claims 1 to 7 in sewage, wherein the composite COD remover and hydrogen peroxide are directly added into the sewage and stirred to complete the treatment of the sewage.

10. The use according to claim 9, characterized in that: The COD value in sewage ranges from 200 to 3200 mg / L, and the dosage of the composite COD remover is 3‰ to 9‰; among them, for every 500 mg / L increase in COD, the dosage of the agent increases by 1‰.

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