CN114436627A

CN114436627A - Deodorizing ceramsite and preparation method thereof

Info

Publication number: CN114436627A
Application number: CN202210086543.4A
Authority: CN
Inventors: 郑俊; 程晓玲; 孙云东; 连宏伟; 孙婧; 郧诚新
Original assignee: Huaqi Environment Protection Science And Technology Co ltd
Current assignee: Huaqi Environment Protection Science And Technology Co ltd
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2022-05-06

Abstract

The invention discloses a deodorizing ceramsite and a preparation method thereof, belonging to the technical field of waste gas treatment. The ceramsite comprises the following components: 10-20% of dry sludge, 20-30% of fly ash, 30-50% of bentonite, 10-20% of clay, 5-10% of pore-forming agent and 5-10% of alkaline substance; the preparation method comprises the following steps: firstly, all the raw materials except the pore-forming agent are uniformly mixed and granulated, then the raw material balls after primary granulation, the pore-forming agent and other raw materials are uniformly mixed and granulated again, and finally the mixture is dried, preheated, roasted and cooled. The ceramsite prepared by the method has rich outer pores, ensures the growth of microorganisms, avoids the condition of filler blockage caused by excessive propagation of the microorganisms, has the strength and the corrosion resistance meeting the use requirements of a deodorizing filter tank, has an acidity buffer function, effectively ensures the odor removal effect, has a simple preparation process and low energy consumption, and achieves the aim of recycling resources.

Description

Deodorizing ceramsite and preparation method thereof

Technical Field

The invention belongs to the technical field of waste gas treatment, and particularly relates to deodorizing ceramsite and a preparation method thereof.

Background

Along with the development of social economy, the improvement of living standard and the increasing increase of public environmental awareness, odor and corresponding odor treatment serving as subsidiary products of sewage plants are also receiving more and more attention. The town sewage treatment system has the characteristics of complex and changeable components, toxicity, harm, remarkable dynamic load, continuous pollution discharge, proximity to residential areas and the like due to the particularity, and odor generated by the town sewage treatment system is often sudden in a short time, is difficult to capture and collect, and brings difficulty to treatment.

The currently common technology for treating malodorous gas in the engineering of sewage treatment plants mainly comprises a biological filter, a biological trickling filter, plant extract deodorization, activated carbon adsorption, high-energy ion deodorization, chemical deodorization, active oxygen deodorization and the like. The biological treatment technology is a new technology for treating malodorous gas developed in recent decades, and compared with the conventional physical and chemical treatment technologies such as absorption, adsorption, catalysis, incineration and the like, the biological treatment technology has the advantages of good treatment effect, no secondary pollution, low investment and operation cost, easiness in management and the like. Especially, the method shows superiority when treating the malodorous gas with large flow and low concentration, and is widely applied to the treatment of the malodorous gas of urban sewage treatment plants.

The fillers used in the deodorization biological filter can be divided into three types, namely inorganic fillers, organic fillers and composite fillers according to the material. The inorganic filler mainly comprises ceramsite, volcanic rock and the like, and is most commonly used due to the characteristics of good physical property and film forming effect, long service life, relatively low price and the like; the organic filler mainly comprises bark, bamboo charcoal and the like, can provide organic matters for microorganisms to serve as a nutrient source, does not need to additionally add nutrient substances for the microorganisms in the operation process, but can be rotten in the biological filter, so that the strength of the organic filler is reduced, and finally the filter bed filler is hardened, the airflow is short-circuited, and the operation resistance is increased; the composite filler is characterized in that inorganic filler and organic filler are simultaneously filled in a biological filter as the name suggests, although the composite filler integrates the advantages of the inorganic filler and the organic filler, the inherent defects of the organic filler still restrict the economical efficiency, the purification efficiency and the service life of the biological filter tower. Although the inorganic filler is commonly used, the existing inorganic filler is lack of special ceramsite or volcanic filler in the field of deodorization, so that the inorganic filler has the defects that the inorganic filler is difficult to solve in the actual use process:

(1) the building ceramsite has light relative density, but the water absorption of the common building ceramsite is low, so that water is always continuously sprayed to the filler in the actual operation process to keep the humidity of the filler. In addition, the roughness of the surface of the building ceramsite is low, the building ceramsite is mainly internal pores, and microorganisms mainly grow in the interior of the ceramsite, so that the odor removal efficiency is reduced.

(2) The volcanic rock has good water absorption performance, and the strength and the surface roughness of the volcanic rock are large, so that the volcanic rock is suitable for being used as a carrier for the growth of microorganisms, but the relative density of the volcanic rock is high, the requirement on the strength of deodorization equipment is large, so that the deodorization cost is high, and because the surface of the volcanic rock is too rough, after the deodorization equipment runs for a period of time, a biomembrane on the surface of the volcanic rock is rapidly propagated, so that the filler is easily blocked, and the removal efficiency of the equipment is influenced.

(3) The existing deodorizing filler, namely ceramsite or volcanic rock, does not have the self-pH adjusting capacity, so that in the normal operation of a deodorizing system, a medicament needs to be added into the system to adjust the pH value of the filler to be neutral, the method not only increases the operation cost, but also influences the normal growth of microorganisms on the filler by the added medicament.

(4) The conventional fillers such as volcanic rock, building ceramsite and the like are not special fillers for deodorization, the product has irregular shape and large particle size difference, and the fillers need to be cleaned before use, so that the use effect is influenced.

Disclosure of Invention

1. Problems to be solved

Aiming at the defects of the existing deodorization filler (mainly volcanic rock and ceramsite), the invention provides a special ceramsite filler for biological deodorization and a preparation method thereof. The ceramsite is prepared based on dewatered sludge and fly ash of a municipal sewage plant, has an acidity buffering function, is simple in preparation process and low in energy consumption, and achieves the purpose of resource recycling.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to a deodorizing ceramsite which is prepared from the following main raw materials of sludge, fly ash, bentonite, clay, a pore-forming agent and an alkaline substance in percentage by mass: 10-20% of dry sludge, 20-30% of fly ash, 30-50% of bentonite, 10-20% of clay, 5-10% of pore-forming agent and 5-10% of alkaline substance.

Wherein, it should be noted that, the alkaline substance adopts magnesium hydroxide or aluminium hydroxide, choose magnesium hydroxide or aluminium hydroxide as the acidity buffer substance, come to neutralize the acidic substance that the microorganism decomposes the odor and produce, it is weak alkali compared with traditional alkali, have unique buffer capacity, when being neutralizing agent, even if excessive, the pH value of the solution will not be too high, and the optimum pH range in the course of operating the deodorizing system is 5.5-9.0, can avoid the pH too high and cause the microorganism to die, therefore it is more suitable to use magnesium hydroxide or aluminium hydroxide to adjust the pH of the packing.

Furthermore, as special ceramsite for deodorization of the biological filter, the prepared ceramsite has the particle size of 20-40 mm and the bulk density of 0.59-0.94 g/cm³The apparent density is 1.20 to 1.59g/cm³The porosity is 40.88% -54.55%, and the water absorption rate for 1h is 21.2% -29.3%.

The main raw material components of the ceramsite of the invention comprise bentonite, fly ash and clay which are ceramic components and play a role of supporting a framework during sintering, and the main chemical component of the ceramsite is SiO₂、Al₂O₃They are the main factor contributing to the strength of the filler. As for the deodorizing porcelain granules, the porcelain granules require a long timeSubject to water and exhaust gas washing and corrosion and must therefore have a certain strength and corrosion resistance, SiO in bentonite, fly ash and clay₂、Al₂O₃The content is rich, and the strength and the corrosion resistance of the formed ceramsite can meet the requirements of the use of the deodorization filter.

The pore-forming agent can be straw powder and other substances, most of the deodorizing ceramsite is directly stacked in the deodorizing equipment, and the relative density of the deodorizing ceramsite cannot be too high in consideration of the bearing capacity of the equipment. The dry sludge contains more organic matters, so the dry sludge can be used as a gas generating component in the ceramsite together with straw powder and the like (namely a pore-forming agent), and can generate H at high temperature₂O、O₂、CO₂And CO and other gases promote the expansion of the filler, reduce the relative density of the ceramsite and increase the porosity of the ceramsite.

The granules for deodorization are generally about 20-40 mm in particle size, and are larger than water treatment granules, so the temperature control requirement during firing is higher. The dry sludge contains more Fe₂O₃，CaO、MgO、Na₂O、K₂And substances such as O and the like can be used as fluxing components from the aspects of resource saving and recycling, so that the melting point of the ceramsite can be reduced in the firing process, the firing range of the pellets is widened, and the firing control is facilitated. The roasting range of the filler is widened, so that gas generation is facilitated, but gas is not easy to escape, and the filler can expand better.

The preparation method of the ceramsite is different from the conventional preparation method of the ceramsite, and mainly the deodorizing ceramsite is mainly characterized in that the surface of the ceramsite is in contact with pollutants, so that the more pores on the surface of the ceramsite are, the more the contact with the pollutants in odor is sufficient, and the better the odor removal efficiency is. Therefore, in the invention, the mixing and granulating of the raw materials are divided into two times: mixing for the first time, namely uniformly mixing the raw materials except the pore-forming agent, and then putting the mixture into a disc granulator for granulation; and after the particle size reaches a certain degree, uniformly mixing the raw material balls obtained by granulation with the pore-forming agent and other raw materials again, and then continuously putting the raw material balls into a granulator for granulation to obtain the final raw material balls. By the method, the finished ceramsite obtained by final firing is ensured to have rich external pores.

Specifically, the preparation process of the invention is shown in fig. 1, and the main preparation steps are as follows:

step one, primary mixing;

and (3) drying the dewatered sludge to constant weight in a drying oven at 105 ℃ for 15-20 min, crushing and sieving by using a crusher, crushing the fly ash, the clay and the like, and sieving. Weighing the sieved sludge, fly ash, bentonite, clay, alkaline substances and the like according to certain weight respectively, and putting the weighed materials into a container to be uniformly mixed.

Step two, primary granulation;

putting the uniformly mixed raw materials into a disc granulator in batches, preparing raw material balls with the diameter of 8-10 mm by using the granulator, and standing for 15-30 min after pelletizing is completed.

Step three, mixing for the second time;

weighing the sieved sludge, fly ash, alkaline substances, pore-forming agent and the like by a certain weight respectively, and putting the weighed sludge, fly ash, alkaline substances, pore-forming agent and the like together with the primary granulated raw material balls into a container for uniformly mixing.

Step four, secondary granulation;

and putting the uniformly mixed raw materials into a disc granulator in batches, and spraying a proper amount of water into the granulator while granulating to avoid layering of granulated material balls. And (3) preparing raw material balls with the diameter of 20-35 mm by using a granulator, and standing for 1-2 hours after pelletizing is completed.

Step five, drying;

the formed raw material ball is firstly dried in a drying furnace at the temperature of 80-105 ℃ for 20-30 min, so that the moisture of the raw material ball is dissipated, and the cracking caused by the evaporation of a large amount of moisture in the subsequent temperature-rising sintering process is prevented.

Step six, preheating;

transferring the dried raw material balls into a furnace for preheating, wherein the preheating temperature is 300-500 ℃, and the preheating time is 20-30 min. The preheating is to avoid the raw material ball from being broken due to the rapid temperature change, and to slowly generate gas to discharge the excessive gas so as to prepare for softening the surface layer of the raw material ball.

Step seven, roasting;

the baking temperature and the baking time have important influence on the ceramsite. The roasting temperature is selected to be between 1000 ℃ and 1100 ℃, and the roasting time is 15min to 20 min. When the roasting temperature is too low, the control is improper, and the gas pressure is too high to overflow the glass shell to form open pores, so that the filler has low strength and high water absorption.

Step eight, cooling;

and after the baking is finished, naturally cooling the porcelain granules in the container to room temperature, and taking out the finished porcelain granules.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the components and the firing process of the deodorizing ceramsite are optimally designed, the prepared ceramsite is specially used for deodorizing in a biological filter, the deodorizing effect is good, and compared with the common ceramsite, the deodorizing ceramsite has the advantages that the 1-hour water absorption rate of 21.2-29.3%, the roughness is appropriate, and the bulk density is 0.55-0.94 g/cm³And the apparent density is 1.20-1.59 g/cm³In the range of equal, the deodorant is superior to common ceramsite of other manufacturers, so that the excellent deodorization performance of the deodorant can be effectively ensured;

(2) the main components of the deodorant ceramsite are sludge, fly ash and bentonite, on one hand, the deodorant ceramsite is prepared by adding other substances (such as pore-forming agents) into the components, so that the roughness (namely porosity) of the surface and the interior of the obtained ceramsite is effectively improved; on the other hand, the defects of the existing ceramsite are effectively improved by controlling the adding proportion of each component, so that the strength and the corrosion resistance of the formed ceramsite meet the use requirements of a deodorizing filter, the ceramsite is better used for deodorizing a biological filter, and the ceramsite has higher practicability and economic value;

(3) compared with volcanic rock filler, the deodorizing ceramsite disclosed by the invention has the advantages that the packing density, the apparent density, the water absorption rate for 1 hour and other related performances of the ceramsite are superior to those of the volcanic rock filler; in addition, the surface of the sintered ceramsite is rough, but is much lower than that of volcanic rock filler, so that the excessive growth of a biological film can be effectively avoided;

(4) according to the preparation method of the deodorant ceramsite, the components and the proportion thereof, the preparation process steps and the process parameters are optimally designed, so that the deodorant special ceramsite which is regular in shape, good in product consistency and has the acidity buffering function can be prepared. Meanwhile, the pH value of the deodorization device can be adjusted by putting the ceramsite into the biological filter, so that the pH value can be kept neutral when the device runs, and the cost increase and the influence on the normal growth of microorganisms caused by adding an additional medicament are avoided;

(5) according to the preparation method of the deodorant ceramsite, the conventional preparation process is optimized, and particularly during preparation, the raw materials are mixed and granulated twice, the raw materials except for the pore-forming agent are mixed and granulated for the first time, and after the particle size reaches a certain degree, the granulated raw material balls, the pore-forming agent and other raw materials are mixed again and granulated.

Drawings

FIG. 1 is a schematic view of the overall process for preparing the deodorizing ceramisite of the present invention;

FIG. 2 is a graph showing the results of testing the properties of the ceramsite obtained in each example and comparative example of the present invention;

Detailed Description

The invention is further described with reference to specific examples.

Example 1

As shown in fig. 1, the preparation process of the deodorizing ceramsite in this embodiment is as follows:

respectively putting 5kg of dry sludge, 10kg of fly ash, 25kg of bentonite, 5kg of clay, 2.5kg of pore-forming agent and 2.5kg of alkaline substance into each container; pouring the raw materials except the pore-forming agent into the same container, uniformly mixing, pouring the raw materials into a disc granulator in batches, continuously spraying water to keep the raw materials in a wet state, obtaining raw material balls with the particle size of 7-10 mm after a period of time, standing for 30min, putting the raw material balls obtained in the step, the rest raw materials such as the fly ash and the bentonite and the pore-forming agent into the container, uniformly mixing again, and continuously granulating in the disc granulator to obtain raw material balls with the particle size of 20-25 mm; standing the raw material balls for 2 hours, and then drying the raw material balls in a drying furnace at the temperature of 80-105 ℃ for 30 min; drying, sintering in a high temperature furnace, preheating the filler in a low temperature region of 500 ℃ in the furnace for 30min, then sintering in a high temperature region of 1050 ℃ for 20min, and finally cooling to room temperature to obtain the finished ceramsite.

Example 2

respectively putting 10kg of dry sludge, 15kg of fly ash, 15kg of bentonite, 5kg of clay, 2.5kg of pore-forming agent and 2.5kg of alkaline substance into each container; pouring the raw materials except the pore-forming agent into the same container, uniformly mixing, pouring the raw materials into a disc granulator in batches, continuously spraying water to keep the raw materials in a wet state, obtaining raw material balls with the particle size of 10-13 mm after a period of time, standing for 30min, putting the raw material balls obtained in the step, the rest raw materials such as the fly ash and the bentonite and the pore-forming agent into the container, uniformly mixing again, and continuously granulating in the disc granulator to obtain raw material balls with the particle size of 20-25 mm; standing the raw material balls for 2 hours, and then drying the raw material balls in a drying furnace at the temperature of 80-105 ℃ for 30 min; drying, sintering in a high temperature furnace, preheating the filler in a low temperature region of 500 ℃ in the furnace for 30min, then sintering in a high temperature region of 1100 ℃ for 20min, and finally cooling to room temperature to obtain the finished ceramsite.

Example 3

respectively putting 7.5kg of dry sludge, 12.5kg of fly ash, 17.5kg of bentonite, 7.5kg of clay, 2.5kg of pore-forming agent and 2.5kg of alkaline substance into each container; pouring the raw materials except the pore-forming agent into the same container, uniformly mixing, pouring the raw materials into a disc granulator in batches, continuously spraying water to keep the raw materials in a wet state, obtaining raw material balls with the particle size of 13-15 mm after a period of time, standing for 30min, putting the raw material balls obtained in the step, the rest raw materials such as the fly ash and the bentonite and the pore-forming agent into the container, uniformly mixing again, and continuously granulating in the disc granulator to obtain raw material balls with the particle size of 25-35 mm; standing the raw material balls for 2 hours, and then drying the raw material balls in a drying furnace at the temperature of 80-105 ℃ for 30 min; drying, sintering in a high temperature furnace, preheating the filler in a low temperature region of 500 ℃ in the furnace for 30min, then sintering in a high temperature region of 1100 ℃ for 20min, and finally cooling to room temperature to obtain the finished ceramsite.

Example 4

respectively putting 5kg of dry sludge, 10kg of fly ash, 15kg of bentonite, 10kg of clay, 5kg of pore-forming agent and 5kg of alkaline substance into each container; pouring the raw materials except the pore-forming agent into the same container, uniformly mixing, pouring the raw materials into a disc granulator in batches, continuously spraying water to keep the raw materials in a wet state, obtaining raw material balls with the particle size of 13-15 mm after a period of time, standing for 30min, putting the raw material balls obtained in the step, the rest raw materials such as the fly ash and the bentonite and the pore-forming agent into the container, uniformly mixing again, and continuously granulating in the disc granulator to obtain raw material balls with the particle size of 25-35 mm; standing the raw material balls for 2 hours, and then drying the raw material balls in a drying furnace at the temperature of 80-105 ℃ for 30 min; drying, sintering in a high temperature furnace, preheating the filler in a low temperature region of 500 ℃ in the furnace for 30min, then sintering in a high temperature region of 1000 ℃ for 20min, and finally cooling to room temperature to obtain the finished ceramsite.

Comparative example 1

The comparative example used commercially available ceramic granules, such as those sold by taizhou shuangying construction materials trade ltd.

Comparative example 2

The comparative example used a commercially available volcanic rock such as one selected from those sold by Tianjin gurris environmental technology, Inc.

The correlation performance of the ceramsite measured by the correlation method in the national standard of ceramsite filter material QB/T4383-2012 in examples 1-4 and comparative examples 1-2 is shown in FIG. 2.

By analyzing the relevant performance data in fig. 2, it can be seen that the 1h water absorption rate, the cylinder pressure strength and the like of the special deodorant ceramsite are superior to those of the commercially available ceramsite, the special deodorant ceramsite has more external pores, and the surface of the ceramsite is rougher than that of the traditional ceramsite filler.

Compared with volcanic rock filler, the special ceramsite for deodorization prepared by the invention has the advantages that the performances such as bulk density, apparent density and the like of the ceramsite are superior to those of the volcanic rock filler, and the load on a deodorization device is smaller. In addition, the special deodorant ceramsite prepared by the method is regular in shape, the surface roughness of the ceramsite is lower than that of volcanic rock filler, and the excessive growth of a biological film on the surface of the filler can be effectively avoided, so that the gas passing rate is improved.

The special ceramsite for deodorization has the advantages of light density, high strength, high water absorption, good product consistency and the like, can better meet the requirement standard of the filler used in the deodorization biological filter compared with the traditional ceramsite filler and volcanic rock filler, and has wide application prospect.

Claims

1. The deodorizing ceramsite is characterized by comprising the following components in percentage by mass: 10-20% of dry sludge, 20-30% of fly ash, 30-50% of bentonite, 10-20% of clay, 5-10% of pore-forming agent and 5-10% of alkaline substance.

2. The deodorizing ceramsite according to claim 1, wherein: the alkaline substance is magnesium hydroxide or aluminum hydroxide.

3. The deodorant ceramic granule according to any one of claims 1 or 2, wherein: the prepared ceramsite has the particle size of 20-40 mm and the bulk density of 0.55-0.94 g/cm³The apparent density is 1.20 to 1.59g/cm³。

4. The deodorant ceramic granule according to any one of claims 1 or 2, wherein: the prepared ceramsite has the porosity of 40.88-54.55 percent and the water absorption rate of 21.2-29.3 percent after 1 hour.

5. A method for preparing the deodorant ceramsite of any one of claims 1-4, wherein the method comprises the following steps: the method comprises the following steps:

step one, primary mixing;

drying, crushing and sieving the dewatered sludge, crushing and sieving the fly ash and the clay, and putting the sieved sludge, the fly ash, the bentonite, the clay and the alkaline substance into a container for uniformly mixing;

step two, primary granulation;

granulating the uniformly mixed raw materials in the step one to prepare raw material balls;

step three, mixing for the second time;

putting the green balls obtained in the step two, the sieved sludge, the fly ash, the alkaline substance and the pore-forming agent into a container and uniformly mixing;

step four, secondary granulation;

granulating the uniformly mixed raw materials in the third step, and continuing granulation treatment to prepare raw material balls;

and step five, drying, preheating, roasting and cooling.

6. The method for preparing deodorized ceramsite according to claim 5, wherein the method comprises the following steps: in the first step, the drying temperature of the dewatered sludge is 100-110 ℃, and the drying time is 15-20 min.

7. The method for preparing deodorized ceramsite according to claim 5, wherein the method comprises the following steps: in the second step, during primary granulation, controlling the diameter of the raw material balls to be 8-10 mm, and standing for 15-30 min after granulation; and in the fourth step, during secondary granulation, controlling the diameter of the raw material balls to be 20-35 mm, and standing for 1-2 hours after granulation.

8. The method for preparing deodorized ceramsite according to any one of claims 5-7, wherein: and fifthly, controlling the drying temperature to be 80-105 ℃ and the drying time to be 20-30 min during drying.

9. The method for preparing deodorized ceramsite according to any one of claims 5-7, wherein: and fifthly, preheating at 300-500 ℃ for 20-30 min.

10. The method for preparing deodorized ceramsite according to any one of claims 5-7, wherein: in the fifth step, the roasting time is 15-20 min at 1000-1100 ℃.