A pretreatment process for purifying odorous gases in wet garbage disposal

Abstract

The present invention discloses a pretreatment process for purifying odorous gases in a wet garbage disposal process. A catalytic reaction bed is formed by an iron-based material, copper oxide, manganese dioxide, aluminum oxide, and a carbon-based material. The catalytic reaction bed forms a primary cell during the elution process of a weakly acidic eluent. The electrode products of the new ecology are extremely active and can undergo redox reactions with odorous gases, causing the structure and morphology of the difficult-to-biodegrade parts in the odorous gases to change and transform them into easily biodegradable substances, which is beneficial to improving the treatment efficiency of subsequent biological purification units. In addition, the ferrous ions generated by electrolysis generate trivalent ferrous ions under the action of oxygen, which are hydrolyzed and polymerized to form ferric hydroxide and ferrous hydroxide polymers. The polymers are discharged to the biological bed layer of the biological purification unit along with the eluent. Through adsorption, coagulation, and the like, the mass transfer efficiency of the biological purification unit for odorous gases from the gas phase to the liquid phase is enhanced, thereby improving the purification effect of the biological purification unit.

Description

Technical Field

[0001] The present invention relates to the technical field of wet garbage odor treatment, and in particular to a pretreatment process for purifying odorous gases in a wet garbage disposal process. Background Art

[0002] With the implementation of local regulations on household waste management, the classification of domestic waste has officially taken hold. During the harmless resource recovery process of wet waste, the odor from waste disposal and leachate treatment seriously impacts the quality of life of surrounding residents, becoming a bottleneck in wet waste management. Therefore, selecting appropriate processes to control and manage odors is both necessary and urgent.

[0003] Among the purification methods for this type of odorous waste gas, the biological method is the most widely used and common process. There are many types of odorous pollutants in the wet garbage disposal process, including not only many substances that are difficult to biodegrade, but also many malodorous substances with extremely low olfactory thresholds. It is often difficult to achieve satisfactory results when using biological methods alone to purify this type of odorous waste gas. In order to improve the overall deodorization effect of the biological method on this type of odorous waste gas, it is extremely important to choose a suitable pretreatment process. At present, the pretreatment process used in conjunction with the biological method is mostly spray washing. The spray washing process has limited purification effect on many difficult-to-biodegrade substances, especially odorous components that are difficult to dissolve in water, and the purification effect is even more limited. Therefore, it is very necessary to choose a reasonable pretreatment process technology that has good synergy with the biological method. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a pretreatment process for purifying odorous gases in the process of wet garbage disposal. A catalytic reaction bed is formed by an iron-based material, copper oxide, manganese dioxide, aluminum oxide and carbon-based material. The catalytic reaction bed forms a primary battery during the elution process of a weakly acidic eluent. The electrode products of the new ecology are extremely active and can undergo redox reactions with odorous gases, causing the structure and morphology of the difficult-to-biodegrade parts in the odorous gases to change and transform them into easily biodegradable substances, which is beneficial to improving the treatment efficiency of subsequent biological purification units. In addition, the ferrous ions generated by electrolysis generate trivalent ferrous ions under the action of oxygen, which are hydrolyzed and polymerized to form ferric hydroxide and ferrous hydroxide polymers. The polymers are discharged to the biological bed layer of the biological purification unit with the eluent. Through adsorption, coagulation and other effects, the mass transfer efficiency of the biological purification unit for odorous gases from the gas phase to the liquid phase is enhanced, thereby improving the purification effect of the biological purification unit.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a pretreatment device for purifying odorous gas in a wet garbage disposal process, comprising a pretreatment reactor and a biological treatment unit, wherein the pretreatment reactor is provided with an air inlet, the biological treatment unit is provided with an air outlet, and the pretreatment reactor and the biological treatment unit are connected via a passage 1 and a passage 2;

[0007] The pretreatment reactor consists of a box and a catalytic reaction bed;

[0008] The constituent materials of the catalytic reaction bed layer include: iron-based material, copper oxide, manganese dioxide, aluminum oxide and carbon-based material.

[0009] Preferably, the mass ratio of iron-based material to carbon-based material in the constituent materials of the catalytic reaction bed is 10-30:1, the mass fraction of copper oxide is 0.5-3%, the mass fraction of manganese dioxide is 1-5%, and the mass fraction of aluminum oxide is 70-85%.

[0010] Preferably, the iron-based material is selected from cast iron chips or iron scraps; and the carbon-based material is selected from coke, activated carbon, graphite or coal powder.

[0011] Preferably, the particle size of the iron-based material is 30-80 mm, the particle size of the copper oxide is 10-50 mm, the particle size of the aluminum oxide is 10-50 mm, and the particle size of the carbon-based material is 10-50 mm.

[0012] The second technical solution of the present invention is to provide a pretreatment process for purifying odorous gas in a wet garbage disposal process based on the above-mentioned odorous gas purification pretreatment device in a wet garbage disposal process, comprising the following steps:

[0013] The pretreatment reactor is eluted with a weak acidic eluent. During the wet garbage disposal process, odorous gas enters the pretreatment reactor through the air inlet. The odorous gas passing through the pretreatment reactor enters the biological treatment unit through passage 1. The weak acidic eluent passing through the pretreatment reactor enters the biological treatment unit through passage 2. The treated odorous gas is discharged through the air outlet.

[0014] The pH value of the weakly acidic eluent is 4.8-5.8.

[0015] In the catalytic reaction bed of the present invention, copper oxide and manganese dioxide serve as catalytic materials, iron and carbon-based materials serve as reaction materials, and aluminum oxide serves as a carrier material. When a weakly acidic eluent passes through the catalytic reaction bed, a potential difference is generated in the liquid phase between the low-potential iron element and the high-potential carbon element. The eluent, which has a certain conductivity, acts as an electrolyte, forming numerous galvanic cells. This generates electrode reactions and a series of redox reactions, producing highly active components and thus initially purifying odorous pollutants. Furthermore, hydrogen sulfide, a typical odorous pollutant, can directly react to form sulfate-based odorless substances, while ammonia directly reacts with the eluent to form ammonium salts. The formation of these salts further increases the conductivity of the reaction bed and also facilitates the decomposition reaction within the catalytic bed.

[0016] During the pretreatment of odorous gases, the pH value of the eluent should be controlled between 4.8 and 5.8. If it is too high, the catalytic reaction will be weak, while if it is too low, too many iron ions will be produced.

[0017] Preferably, the weakly acidic eluent is obtained by mixing an organic acid with water, and the organic acid includes citric acid or oxalic acid.

[0018] The present invention uses medium-strength organic acids such as citric acid and oxalic acid to prepare the eluent. After the reaction in the catalytic reaction bed is completed, these organic acids are discharged to the biological purification unit along with the eluent and serve as a nutrient source for microorganisms, which is beneficial to the domestication and cultivation of the strains in the biological treatment unit.

[0019] Preferably, the weakly acidic eluent further comprises sodium chloride or sodium sulfate, and the amount of sodium chloride or sodium sulfate added is 0.5 to 3‰ of the mass fraction of the weakly acidic eluent.

[0020] In order to enhance the electrolytic reaction intensity of the catalytic reaction bed, the present invention adds an appropriate amount of sodium chloride or sodium sulfate into the weakly acidic eluent.

[0021] Preferably, the elution intensity of the weakly acidic eluent is 0.3 to 2 m 3 / (m 2 ·h).

[0022] Preferably, the weakly acidic eluent passes through the pretreatment reactor once and then enters the biological treatment unit, or circulates through the pretreatment reactor before entering the biological treatment unit.

[0023] When the weak acidic eluent is circulated, an eluent circulation device is connected to the pretreatment reactor, and the pH value of the weak acidic eluent is controlled not to exceed 6.5.

[0024] The beneficial technical effects of the present invention are as follows:

[0025] (1) The catalytic reaction bed material of the present invention can convert odorous gas molecules that are difficult to biodegrade into easily biodegradable components, thereby improving the biodegradability of the biological purification unit.

[0026] (2) The treatment process of the present invention can simultaneously remove the typical malodorous gases hydrogen sulfide and ammonia.

[0027] (3) When the weakly acidic eluent of the present invention passes through the catalytic reaction bed, the acidic conditions can release the iron in the iron-based material to generate new ecological Fe 2+ , and under the action of oxygen in the gas, Fe 2+ Fe generated by oxidation 3+ OH is also generated in the reaction - , and then gradually hydrolyze to form Fe(OH)3 colloidal flocculant with high polymerization degree, which can effectively adsorb and condense odorous gases, thereby enhancing the mass transfer efficiency of odorous gases from gas phase to liquid phase, and ultimately improving the purification effect of the biological method unit.

[0028] (4) The odor gas purification pretreatment process provided by the present invention in the wet garbage disposal process has no waste liquid discharge, is safe and environmentally friendly, and has great promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the process flow of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0031] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] The process flow diagram of Example 1 of the present invention is shown in Figure 1 , Figure 1 In the figure, the solid line is the odorous waste gas line, and the dotted line is the weak acid eluent operation line.

[0035] Example 1

[0036] The high humidity and odorous gas produced during the anaerobic fermentation of wet garbage is selected. The gas temperature is 35-45℃ and the odor concentration exceeds 20,000 (dimensionless). The odorous gas enters the pretreatment reactor from the air inlet and the catalytic reaction bed is eluted with a weak acidic eluent at an intensity of 1m 3 / (m 2 h) The pretreatment reactor is made of fiberglass reinforced plastics, and the catalytic reaction bed is a uniform mixture of cast iron chips, granular activated carbon, copper oxide, manganese dioxide, and aluminum oxide, with the mass fractions of each substance being 20%, 1%, 0.8%, 3%, and 75.2%, respectively.

[0037] The weakly acidic eluent is prepared with citric acid, and the pH is controlled at 5.0. At the same time, 1‰ of the eluent mass of sodium chloride is added. After passing through the pretreatment reactor, the eluent does not circulate and directly enters the biological treatment unit.

[0038] The filler of the biological treatment unit used in this embodiment is ceramic. At the initial start-up, microbial strains that have been domesticated with organic matter are inoculated into the circulating liquid. The microorganisms use the organic matter dissolved in the liquid phase to metabolize and reproduce, and attach to the surface of the filler to form a microbial film, completing the biofilm process. During the biofilm working process, the organic matter and oxygen in the gas phase are transmitted into the microbial film and utilized by the microorganisms, and the metabolic products are then discharged through diffusion.

[0039] After the odorous gas passes through the pretreatment reactor, the odor concentration drops to below 5000 (dimensionless). After passing through the biological treatment unit, the odor concentration is lower than 1000 (dimensionless), which is far below the existing national odor emission standard limit.

[0040] Comparative Example 1

[0041] The same odorous gas as in Example 1 was used, and was first pretreated in a conventional alkaline washing tower (pH value was 10-11.5), and then passed through the same biological treatment unit as in Example 1.

[0042] After the odorous gas passes through the alkaline washing tower, the odor concentration is still above 10,000 (dimensionless). After passing through the biological treatment unit, the odor concentration exceeds 3,000 (dimensionless).

[0043] Compared with the traditional alkali washing tower + biological method treatment, the pretreatment reactor + biological method treatment provided by the present invention has a stronger pretreatment effect and synergy with the biological method than the traditional alkali washing tower, and has a significant odor purification effect.

[0044] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A purifying and pre-treating device for odorous gases in the process of wet garbage disposal, characterized in that: It includes a pretreatment reactor, a weak acidic eluent and a biological treatment unit, wherein the pretreatment reactor is provided with an air inlet, the biological treatment unit is provided with an air outlet, and the pretreatment reactor and the biological treatment unit are connected through a passage 1 and a passage 2; The pretreatment reactor consists of a box body and a catalytic reaction bed; The catalytic reaction bed comprises iron-based materials, copper oxide, manganese dioxide, aluminum oxide, and carbon-based materials, wherein the mass ratio of the iron-based materials to the carbon-based materials is 10-30:1, the mass fraction of copper oxide is 0.5-3%, the mass fraction of manganese dioxide is 1-5%, and the mass fraction of aluminum oxide is 70-85%. In the catalytic reaction bed, copper oxide and manganese dioxide are catalytic materials, iron-based materials and carbon-based materials are reaction materials, and aluminum oxide is a carrier material; the weakly acidic eluent is used to elute the catalytic reaction bed; The pH value of the weak acidic eluent is 4.8-5.8, and is obtained by mixing an organic acid with water. The organic acid includes citric acid or oxalic acid.

2. The odorous gas purification pretreatment device for wet garbage disposal process according to claim 1 is characterized in that: The iron-based material is selected from cast iron chips or broken iron blocks; the carbon-based material is selected from coke, activated carbon, graphite or coal powder.

3. The odorous gas purification pretreatment device for wet garbage disposal process according to claim 1 is characterized in that: The particle size of the iron-based material is 30-80 mm, the particle size of the copper oxide is 10-50 mm, the particle size of the aluminum oxide is 10-50 mm, and the particle size of the carbon-based material is 10-50 mm.

4. A process for purifying odorous gas in a wet garbage disposal process based on the odorous gas purification pretreatment device in a wet garbage disposal process according to any one of claims 1 to 3, characterized in that: The following steps are involved: The catalytic reaction bed in the pretreatment reactor is eluted with a weak acidic eluent. The odorous gas from the wet garbage disposal process enters the pretreatment reactor through the air inlet, and the odorous gas passing through the pretreatment reactor enters the biological treatment unit through passage 1. The weak acidic eluent passing through the pretreatment reactor enters the biological treatment unit through passage 2, and the treated odorous gas is discharged through the air outlet.

5. The odorous gas purification pretreatment process in the wet garbage disposal process according to claim 4 is characterized in that: The weakly acidic eluent further comprises sodium chloride or sodium sulfate, and the amount of sodium chloride or sodium sulfate added is 0.5-3‰ of the mass fraction of the weakly acidic eluent.

6. The odorous gas purification pretreatment process in the wet garbage disposal process according to claim 4 is characterized in that: The elution intensity of the weak acidic eluent is 0.3~2 m 3 / (m 2 ·h).

7. The odorous gas purification pretreatment process in the wet garbage disposal process according to claim 4 is characterized in that: The weakly acidic eluent passes through the pretreatment reactor once and then enters the biological treatment unit, or circulates through the pretreatment reactor and then enters the biological treatment unit; When the weak acidic eluent is circulated, an eluent circulation device is connected to the pretreatment reactor, and the pH value of the weak acidic eluent is controlled not to exceed 6.5.

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