High-strength light ceramsite for moving bed bio-membrane reactor and production process of high-strength light ceramsite

Abstract

The invention discloses a high-strength lightweight ceramsite for a moving bed bio-membrane reactor and a production process thereof, the high-strength lightweight ceramsite is prepared by mixing dried sludge, anorthite, diatomite and activated carbon in proportion to form a base material, and spraying a type I spray liquid and a type II spray liquid according to a granulation stage when the base material is granulated, the I-type spraying liquid takes deionized water as a base solution, and the base solution contains an aqueous solution of 3-5 wt% of sodium alpha-olefin sulfonate, 1.8-2.4 wt% of polyacrylamide and 0.5-1.5 wt% of dextrin, and the II-type spraying liquid takes deionized water as a base solution, and the base solution contains an aqueous solution of 5-6 wt% of sodium alpha-olefin sulfonate, 0.2-0.5 wt% of polymaleic anhydride and 1.5-2.7 wt% of polyethylene glycol. The spraying temperatures of the I-type spraying liquid and the II-type spraying liquid are controlled by adopting a'mother nucleus forming stage 'and a'mother nucleus growing stage', so that the spherical greenware forms a uniform particle internal structure, and the spherical greenware has higher specific surface area, porosity and strength.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste utilization, and in particular to high-strength lightweight ceramsite for a moving bed biofilm reactor and a production process thereof. Background Art

[0002] Lightweight expanded clay is inexpensive and easy to obtain. It has a rough surface and rich pore structure inside. It can form more stable aerobic zones and anoxic / anaerobic zones in different parts of the expanded clay, providing a stable microenvironment for the simultaneous nitrification and denitrification process of the entire reactor. It is very suitable as a substitute for MBBR plastic fillers.

[0003] At present, the main raw materials for preparing expanded clay for water treatment in my country are clay and shale, which account for 50% and 33% of expanded clay raw materials respectively. Only a small part of expanded clay is prepared using fly ash, domestic sewage sludge, river drying sludge and other solid wastes as raw materials, which does not meet the requirements of sustainable development. Dredging and drying sludge contains rich SiO2, Al2O3 and alkaline earth metal components, which are similar to the properties of shale and clay. Without adding or adding a small amount of auxiliary raw materials, expanded clay with good performance can be fired through appropriate processes. According to statistics, the amount of dried sludge brought by dredging in the Bohai Rim, Yangtze River Delta and Pearl River Delta in my country is 1 billion m3 each year. 3 If such a large amount of dredged and dried sludge is not properly handled, it will not only occupy a large amount of land resources but also cause secondary pollution to the surrounding environment. Using dredged and dried sludge to prepare water treatment expanded clay is a new way to achieve "waste treatment with waste".

[0004] However, the ceramsite prepared with solid waste such as dried sludge as raw materials still has some unstable strength problems under the premise of being lightweight. Therefore, it is necessary to start from the raw material formula design and production process of ceramsite to prepare high-strength and lightweight ceramsite. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-strength lightweight ceramsite for a moving bed biofilm reactor and a production process thereof.

[0006] The technical scheme of the present invention is: a high-strength light ceramsite for a moving bed biofilm reactor, wherein the high-strength light ceramsite is a base material composed of dried sludge, calcium feldspar, diatomaceous earth and activated carbon in a ratio of 30-40%: 30-40%: 15-30%: 5-10% by mass, and the high-strength light ceramsite is obtained by spraying type I spray liquid and type II spray liquid in the granulation stage during the granulation of the base material.

[0007] Among them, the type I spray liquid is a base liquid with deionized water, and the base liquid contains 3-5wt% of sodium α-olefin sulfonate, 1.8-2.4wt% of polyacrylamide and 0.5-1.5wt% of dextrin in an aqueous solution; the type II spray liquid is a base liquid with deionized water, and the base liquid contains 5-6wt% of sodium α-olefin sulfonate, 0.2-0.5wt% of polymaleic anhydride and 1.5-2.7wt% of polyethylene glycol in an aqueous solution.

[0008] Description: By using calcium feldspar as a regulator in the sintering formula of expanded clay to improve the mechanical strength of the fired expanded clay, and using diatomaceous earth as a binder and flux to fire the expanded clay, the sintering temperature can be reduced, the formation of the molten liquid phase can be promoted, and the use of activated carbon can further enhance the adsorption capacity of the high-strength and lightweight expanded clay. The above-mentioned ratio of dried sludge, calcium feldspar, diatomaceous earth and activated carbon can improve the performance of the high-strength and lightweight expanded clay.

[0009] Furthermore, the polyethylene glycol is polyethylene glycol 200 or polyethylene glycol 400.

[0010] Description: Polyethylene glycol 200 has good water solubility and good compatibility with many components. It also has excellent lubricity, moisturizing properties, and dispersibility. Polyethylene glycol 400 also has good water solubility and a wide range of solvent compatibility. In theory, the effect of using polyethylene glycol 400 in the present invention will be relatively better. However, since the price of polyethylene glycol 400 is higher than that of polyethylene glycol 200, polyethylene glycol 200 has a higher cost-effectiveness, so it can be selected according to actual production needs.

[0011] The present invention also provides a production process of high-strength lightweight ceramsite for a moving bed biofilm reactor, comprising the following steps:

[0012] S1. Select dried sludge, calcium feldspar, diatomaceous earth and activated carbon in proportion, grind the dried sludge, calcium feldspar, diatomaceous earth and activated carbon through a 100-mesh sieve, and stir and mix for 5 minutes to obtain a mixed material;

[0013] S2. Granulate the mixed material in a granulator. During the granulation process, spray the type I spray liquid and the type II spray liquid at a solid-liquid ratio of 1g:0.1-0.3ml. Specifically,

[0014] S2-1. During the core forming stage, the spray temperature of the Type II spray liquid is controlled at 60-65°C.

[0015] S2-2, during the growth stage of the mother core, the spray temperature of the type II spray liquid is cooled to 50-55°C at a cooling rate of 3-5°C / s, and then the type II spray liquid is replaced with the type I spray liquid of the same temperature, and the temperature is continuously cooled at a cooling rate of 3-5°C / s until a spherical pottery blank of a desired size is obtained;

[0016] S3, drying the spherical ceramic blank in an electric drying oven at 100-110°C for 4-6 hours, then calcining it in a muffle furnace, and cooling it to room temperature with the furnace to obtain high-strength and lightweight ceramsite.

[0017] Furthermore, the moisture content of the spherical ceramic blank is controlled at 8-24%.

[0018] Note: Because the diatomaceous earth in the ingredients has strong water absorption properties, the greater the amount added, the more water will be needed in the granulation process. After further experimental research, it was determined that when the moisture content of the ball is between 8 and 24%, the spherical ceramic blank is easier to shape and no powder will fall off.

[0019] Furthermore, the particle size of the spherical ceramic blank is 10 to 15 mm.

[0020] Note: If the diameter of the ball is too small, sintering is likely to occur, and if it is too large, it is difficult to burn through. Therefore, the diameter of the spherical ceramic blank is more suitable within the above range.

[0021] Furthermore, the calcination method is: pre-calcining at 320-370°C for 8-15 minutes, then uniformly heating the temperature to 1050-1150°C at a heating rate of 20°C / min, and sintering at 1050-1150°C for 4-8 minutes.

[0022] Description: By preheating the spherical ceramic blank first, the residual moisture can be well removed, and the explosion caused by the rapid temperature change can be avoided. The spherical ceramic blank can be adjusted to achieve the best expansion effect. By uniformly heating the spherical ceramic blank at a heating rate of 20°C / min, the spherical ceramic blank is heated to the above sintering temperature, and high-strength and lightweight ceramsite can be prepared.

[0023] Furthermore, the upper limit of the cooling temperature is 15-20°C.

[0024] Note: Since too low water temperature may cause the droplets to evaporate too slowly, prolonging the granulation time, and when the water temperature is low, the droplets evaporate slowly, which may cause the particles to be irregular or flat. Therefore, the use of the above low temperature limit can ensure the granulation efficiency and effect.

[0025] Furthermore, during the growth stage of the mother core, ultrasonic treatment with an ultrasonic power of 50 to 100 W and a frequency of 20 to 35 KHz is added until a spherical ceramic blank of a desired size is obtained.

[0026] Note: Through the auxiliary treatment of the above-mentioned ultrasonic parameters, the granulation effect of ceramsite can be improved by coordinating the change of spraying temperature during the growth stage of the mother core, the shape and size of the particles can be more controllable, and the pore distribution can be more uniform, thereby obtaining high-strength and lightweight ceramsite with better performance.

[0027] The beneficial effects of the present invention are:

[0028] 1) The present invention controls the spraying temperature of type I spray liquid and type II spray liquid in the "mother nucleus forming stage" and "mother nucleus growing stage". At the same time, since the temperature exceeds 55°C, the use effect of polyacrylamide will be reduced to a certain extent. Therefore, on this basis, we divide it into type I spray liquid and type II spray liquid according to the composition of deionized water and its use temperature, so that appropriate water temperature and corresponding type of deionized water are used in different stages, which is conducive to promoting the effect of type I spray liquid and type II spray liquid so that the spherical ceramic blank forms a uniform particle internal structure, so that it has a higher specific surface area, porosity and strength.

[0029] 2) The present invention adds an appropriate amount of dextrin to the deionized water of the type I spray liquid, based on the sodium α-olefin sulfonate and polyacrylamide, and adds an appropriate amount of polymaleic anhydride to the deionized water of the type II spray liquid, based on the sodium α-olefin sulfonate and polyethylene glycol. By adding polymers such as the sodium α-olefin sulfonate, polyacrylamide, polymaleic anhydride and dextrin during the granulation process, the cohesion of the ceramsite can be increased, thereby improving the strength of the ceramsite. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a process flow chart for the preparation of high-strength and lightweight expanded clay. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific implementation methods to better reflect the advantages of the present invention.

[0032] Embodiment 1: A high-strength lightweight ceramsite for a moving bed biofilm reactor, wherein the high-strength lightweight ceramsite is composed of a base material of dried sludge, calcium feldspar, diatomaceous earth, and activated carbon mixed in a ratio of 35%:35%:23%:7% by mass, and the high-strength lightweight ceramsite is obtained by spraying Type I spray liquid and Type II spray liquid in sequence during granulation of the base material, wherein the Type I spray liquid is based on deionized water, and the base liquid contains 4.2wt% of sodium α-olefin sulfonate, 2.1wt% of polyacrylamide and 1.2wt% of dextrin in an aqueous solution, the Type II spray liquid is based on deionized water, and the base liquid contains 5.5wt% of sodium α-olefin sulfonate, 0.4wt% of polymaleic anhydride and 2.4wt% of polyethylene glycol 400 in an aqueous solution, and the dried sludge is obtained by concentrating, filtering and drying the bottom mud, and the water content is less than 5%.

[0033] Example 2: This example provides a production process for high-strength lightweight ceramsite for a moving bed biofilm reactor according to Example 1, such as Figure 1 As shown, the following steps are included:

[0034] S1. Select dried sludge, calcium feldspar, diatomaceous earth and activated carbon in proportion, grind the dried sludge, calcium feldspar, diatomaceous earth and activated carbon through a 100-mesh sieve, and stir and mix for 5 minutes to obtain a mixed material;

[0035] S2. Granulate the mixed material in a granulator. During the granulation process, spray type I spray liquid and type II spray liquid at a solid-liquid ratio of 1g:0.2ml. Specifically,

[0036] S2-1. During the core forming stage, the spray temperature of the Type II spray liquid is controlled at 63°C.

[0037] S2-2, during the growth stage of the mother core, the spray temperature of the type II spray liquid is cooled to 51°C at a cooling rate of 4°C / s, and then the type II spray liquid is replaced with the type I spray liquid of the same temperature, and the temperature is further cooled to 19°C at a cooling rate of 4°C / s until a spherical ceramic blank with a particle size of 10 mm is obtained, and the moisture content of the spherical ceramic blank is controlled at 16%;

[0038] S3. Dry the spherical ceramic blank in an electric drying oven at 105°C for 6 hours, then roast it in a muffle furnace, pre-fire it at 355°C for 10 minutes, then increase the temperature to 1120°C at a uniform rate of 20°C / min, sinter it at 1120°C for 6 minutes, and cool it to room temperature with the furnace to obtain high-strength and lightweight ceramsite.

[0039] In order to verify the use effect of the high-strength lightweight ceramsite of the present invention, the high-strength lightweight ceramsite and the commercially available ceramsite were tested for relevant performance indicators according to the methods specified in "Artificial Ceramsite Filter Material for Water Treatment" and "Light Aggregate and Its Test Method" and compared with the national standards;

[0040] 1) Experimental methods

[0041] The high-strength lightweight ceramsite prepared in Example 1 was used to remove ammonia nitrogen from wastewater. The specific steps of the adsorption experiment were as follows: 2.5 g of high-strength lightweight ceramsite was weighed and put into a 500 mL stoppered conical flask, and 10 mg / L of 250 mL of simulated wastewater was shaken at 120 r / min for 8 h in a 20°C environment, and the supernatant was taken and filtered through a 0.22 μm filter membrane for analysis and determination. Equilibrium concentration;

[0042] The above-mentioned high-strength and lightweight ceramsite is used for microbial loading. The specific steps of the loading experiment process are as follows: a 500mL stoppered glass conical bottle is used to construct a ceramsite microbial loading function evaluation device, which is equipped with an aeration system. The weighed ceramsite is placed in the conical bottle, and 250mL of the composite bacterial solution is added. After continuous cultivation for 7 days, the amount of fixed microorganisms on the ceramsite is determined to evaluate the proliferation of microorganisms on the ceramsite. Among them, the amount of fixed microorganisms on the ceramsite is determined by weighing method, characterized by the volatile solid concentration per unit weight of ceramsite, and the result is expressed in mg VS / (g carrier). Take an appropriate amount of ceramsite and put it into an evaporating dish of known weight, dry it to constant weight at 105℃, and the weight increased by deducting the weight of the evaporating dish is the total solid amount. The evaporating dish is moved into a muffle furnace at 550℃ again for high-temperature ashing to constant weight, and the weight reduced is the volatile solid amount (VolatileSolid, VS). The volatile solid mass divided by the total solid mass is the volatile solid concentration.

[0043] VS = m1-m2 Formula 1

[0044]

[0045] In the formula: m0 is the weight of the evaporating dish, in g; m1 is the weight of the ceramsite and the evaporating dish after drying at 105°C, in g; m2 is the weight of the ceramsite and the evaporating dish after high-temperature incineration at 550°C, in g.

[0046] 2) Experimental results

[0047] Example 1 Specific surface area and porosity of high-strength lightweight ceramsite, the results are shown in Table 1 below:

[0048] Group <![CDATA[Specific surface area (m 2 / g)]]> Porosity(%) Example 1 56.73 58.79

[0049] The results show that the specific surface area and porosity of the high-strength lightweight ceramsite in Example 1 reached 56.73 m 2 / g and 58.79%. In the MBBR process, the large specific surface area and porosity of high-strength lightweight ceramsite are very beneficial to the adsorption of ammonia nitrogen pollutants in wastewater and the biofilm formation of microorganisms. The apparent density of high-strength lightweight ceramsite is closer to the density of water than commercially available ceramsite, which is beneficial for its suspension in MBBR. The compressive strength of high-strength lightweight ceramsite meets the high-strength lightweight coarse aggregate standard of density grade 600 in "Light Aggregates and Their Test Methods" (GB / T17431.2-2010) (bucket density>0.5, ≤0.6g / cm 3; The compressive strength is greater than 4Mpa), which is sufficient to withstand the scouring of air and water flow and the collision and friction between particles during the operation of MBBR, and has a long service life. The ammonia nitrogen adsorption capacity of high-strength lightweight ceramsite is 0.93mg / g, the removal efficiency of ammonium ions in wastewater is 93%, and the bioload is 13.47mg VS / (g carrier). High-strength lightweight ceramsite has high ammonia nitrogen adsorption efficiency and microbial load performance.

[0050] 3) Experimental comparison

[0051] Comparative Example 1 and Comparative Example 2 are provided. Both Comparative Example 1 and Comparative Example 2 are commercially available ceramsite. The physical and chemical properties of the high-strength and lightweight ceramsite of this embodiment and the commercially available ceramsite of Comparative Examples 1 and 2, as well as the ammonia nitrogen removal rate, adsorption capacity and bioload are tested and compared. The results are shown in Table 2 and Table 3 below:

[0052] Table 2 Physical and chemical properties of ceramsite

[0053] project Example 1 Comparative Example 1 Comparative Example 2 <![CDATA[Detection line a > The sum of the crushing rate and the wear rate (%) 1.81 1.29 2.14 ≤6.00 Mud content (%) 0.26 0.11 0.24 ≤1.00 Solubility in hydrochloric acid (%) 0.95 1.37 2.1 ≤2.00 Void ratio (%) 47.51 38.11 36.11 ≥40.00 <![CDATA[BET specific surface area (m 2 / g)]]> 56.73 1.68 0.52 ≥0.5 Porosity(%) 58.79 43.10 33.10 -- <![CDATA[Apparent density (g / cm 3 )]]> 0.93 1.26 1.45 -- <![CDATA[Bulk density (g / cm 3 )]]> 0.57 0.92 1.22 -- Compressive strength(MPa) 5.1 6.2 5.5 --

[0054] Note: a refers to "Artificial ceramsite filter material for water treatment" (CJ / T299-2008)

[0055] Table 3 Comparison of ammonia nitrogen removal rate, adsorption capacity and bioload of high-strength lightweight ceramsite and commercially available ceramsite

[0056]

[0057]

[0058] The results show that the specific surface area and porosity of commercially available ceramsite are significantly smaller than those of high-strength lightweight ceramsite. Although the compressive strength of commercially available ceramsite is greater than that of high-strength lightweight ceramsite, its bulk density is relatively high, which is not conducive to its suspension in MBBR, and the fluidization energy consumption is relatively large. In addition, commercially available ceramsite basically does not have the ability to adsorb ammonia nitrogen. Its removal rate for ammonia nitrogen wastewater is only 2.3% at most, and its maximum ammonia nitrogen adsorption capacity is only 0.023 mg / g. The adsorption of ammonia nitrogen by commercially available ceramsite may only come from the physical adsorption on the surface of ceramsite. The internal pores of commercially available ceramsite are relatively small, mainly mesopores. As the microorganisms grow, these pores are easily blocked, resulting in the obstruction of the transmission of oxygen and nutrients required for microbial growth and a decrease in biomass. It can be seen that the surface immobilization and proliferation efficiency of microorganisms are closely related to the pore structure of ceramsite. High-strength lightweight ceramsite with a rough surface, an open pore structure and an appropriate proportion of macropores has a stronger microbial loading function, and the ceramsite of the present invention has such a high ammonia nitrogen removal rate, and its strength is not much different from that of commercially available ceramsite. Compared with commercially available ceramsite, high-strength and lightweight expanded clay is more suitable as a suspended carrier for moving bed biofilm reactors.

[0059] Example 3: This example is different from Example 1 in that the high-strength lightweight expanded clay is a base material composed of dried sludge, calcium feldspar, diatomaceous earth, and activated carbon mixed in a ratio of 30%:30%:30%:10% by mass.

[0060] Example 4: This example is different from Example 1 in that the high-strength lightweight expanded clay is a base material composed of dried sludge, calcium feldspar, diatomaceous earth, and activated carbon mixed in a ratio of 40%:40%:15%:5% by mass.

[0061] Example 5: This example is different from Example 1 in that the Type I spray liquid is based on deionized water, and the base liquid contains 3wt% of sodium α-olefin sulfonate, 1.8wt% of polyacrylamide and 0.5wt% of dextrin in water; the Type II spray liquid is based on deionized water, and the base liquid contains 5wt% of sodium α-olefin sulfonate, 0.2wt% of polymaleic anhydride and 1.5wt% of polyethylene glycol 400 in water.

[0062] Example 6: This example is different from Example 1 in that the Type I spray liquid is based on deionized water, and the base liquid contains 5wt% of sodium α-olefin sulfonate, 2.4wt% of polyacrylamide and 1.5wt% of dextrin in water; the Type II spray liquid is based on deionized water, and the base liquid contains 6wt% of sodium α-olefin sulfonate, 0.5wt% of polymaleic anhydride and 2.7wt% of polyethylene glycol 400 in water.

[0063] Example 7: This example is different from Example 1 in that the polyethylene glycol is polyethylene glycol 200.

[0064] Example 8: This example is different from Example 2 in that, during the granulation process, type I spray liquid and type II spray liquid are sprayed at a solid-liquid ratio of 1g:0.1ml; the moisture content of the spherical ceramic blank is controlled at 8%.

[0065] Example 9: This example is different from Example 2 in that, during the granulation process, type I spray liquid and type II spray liquid are sprayed at a solid-liquid ratio of 1g:0.3ml; the moisture content of the spherical ceramic blank is controlled at 24%.

[0066] Example 10: The difference between this example and Example 2 is that, S2-1, in the mother core forming stage, the spray temperature of the Type II spray liquid is controlled at 60°C, S2-2, in the mother core growth stage, the spray temperature of the Type II spray liquid is cooled to 50°C at a cooling rate of 3°C / s, and then the Type II spray liquid is replaced by the Type I spray liquid at the same temperature, and the cooling rate is continued to be 3°C / s to 15°C, until a spherical ceramic blank with a particle size of 10 mm is obtained.

[0067] Example 11: The difference between this example and Example 2 is that, S2-1, in the mother core forming stage, the spray temperature of the Type II spray liquid is controlled at 65°C, S2-2, in the mother core growth stage, the spray temperature of the Type II spray liquid is cooled to 55°C at a cooling rate of 5°C / s, and then the Type II spray liquid is replaced by a Type I spray liquid at the same temperature, and the cooling rate is continued to be 5°C / s to 20°C until a spherical ceramic blank with a particle size of 10 mm is obtained.

[0068] Example 12: This example is different from Example 2 in that the spherical ceramic blank is dried in an electric drying oven at 100° C. for 4 hours.

[0069] Example 13: This example is different from Example 2 in that the spherical ceramic blank is dried in an electric drying oven at 110° C. for 6 hours.

[0070] Example 14: This example is different from Example 2 in that the temperature is pre-fired at 320°C for 8 min, then the temperature is raised to 1050°C at a uniform rate of 20°C / min, and sintered at 1050°C for 4 min.

[0071] Example 15: This example is different from Example 2 in that the sample is pre-fired at 370°C for 15 min, then the temperature is raised to 1150°C at a constant rate of 20°C / min, and sintered at 1150°C for 8 min.

[0072] Example 16: This example is different from Example 2 in that an ultrasonic treatment with an ultrasonic power of 85W and a frequency of 30KHz is added during the mother core growth stage until a spherical ceramic blank of a desired size is obtained.

[0073] Example 17: This example differs from Example 16 in that an ultrasonic treatment with an ultrasonic power of 50 W and a frequency of 20 KHz is added during the growth stage of the mother core until a spherical ceramic blank of a desired size is obtained.

[0074] Example 18: This example differs from Example 16 in that an ultrasonic treatment with an ultrasonic power of 100 W and a frequency of 35 KHz is added during the growth stage of the mother core until a spherical ceramic blank of a desired size is obtained.

[0075] In order to verify the influence of various production methods of high-strength lightweight ceramsite of the present invention on the use effect of high-strength lightweight ceramsite, the above-mentioned experimental method is used to test and compare the ammonia nitrogen removal rate and compressive strength of the high-strength lightweight ceramsite prepared in each embodiment, and the results are shown in Table 4 below:

[0076]

[0077] The results show that the use of high-strength lightweight ceramsite has a certain impact on the use effect of different production processes, but the use effect of high-strength lightweight ceramsite is significantly better than that of commercially available ceramsite. The analysis is as follows:

[0078] 1) The influence of different raw material ratios on the use of high-strength lightweight ceramsite

[0079] By comparing Example 3 and Example 4 with Example 1, it can be seen that the use effect of the prepared high-strength lightweight ceramsite is affected to a certain extent by using different mass ratios of dried sludge, calcium feldspar, diatomaceous earth and activated carbon. On the basis of Example 1, reducing or increasing the addition ratio of dried sludge and calcium feldspar affects the expansion and microporous structure of the high-strength lightweight ceramsite, resulting in a decrease in its specific surface area and porosity, and causing a certain degree of decrease in its compressive strength. Therefore, the mass ratio of dried sludge, calcium feldspar, diatomaceous earth and activated carbon in Example 1 is relatively optimal.

[0080] 2) Effect of different combinations of type I spray liquid and type II spray liquid on the use effect of high-strength lightweight ceramsite

[0081] By comparing Example 5 and Example 6 with Example 1, it can be seen that the use of Type I spray liquid and Type II spray liquid with different combinations has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. On the basis of Example 1, changing the ratio of sodium α-olefin sulfonate, polyacrylamide and dextrin or changing the ratio of sodium α-olefin sulfonate, polymaleic anhydride and polyethylene glycol 400 affects the granulation effect of high-strength lightweight ceramsite, resulting in a certain degree of reduction in its compressive strength. Therefore, the combination of Type I spray liquid and Type II spray liquid in Example 1 is relatively optimal.

[0082] 3) Effect of different polyethylene glycols on the use of high-strength lightweight ceramsite

[0083] By comparing Example 7 with Example 1, it can be seen that the use of different polyethylene glycols has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. After using polyethylene glycol 200, the ammonia nitrogen adsorption capacity of the high-strength lightweight ceramsite decreased slightly, but the price of polyethylene glycol 200 product is lower. Therefore, polyethylene glycol 200 and polyethylene glycol 400 can be selected based on considerations such as actual production costs.

[0084] 4) Effect of different spherical ceramic blank moisture content on the use effect of high-strength lightweight ceramsite

[0085] By comparing Example 8 and Example 9 with Example 1, it can be seen that the subsequent drying and sintering using different moisture contents of the spherical ceramic blanks has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. On the basis of Example 1, increasing or decreasing the moisture content of the spherical ceramic blanks affects the expansion and microporous structure of the ceramsite, resulting in a decrease in its specific surface area and porosity, causing its compressive strength to decrease to a certain extent. Therefore, the moisture content of the spherical ceramic blanks in Example 1 is relatively optimal.

[0086] 5) Effect of different spraying parameters on the use of high-strength lightweight ceramsite

[0087] By comparing Example 10 and Example 11 with Example 1, it can be seen that the use of different spray parameters for spray granulation has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. On the basis of Example 1, increasing or decreasing the spray temperature change limit affects the expansion and microporous structure of the ceramsite, resulting in a decrease in its specific surface area and porosity, causing its compressive strength to decrease to a certain extent. Therefore, the spray parameters in Example 1 are relatively optimal.

[0088] 6) Effect of different spherical ceramic drying parameters on the use of high-strength lightweight ceramsite

[0089] By comparing Example 12 and Example 13 with Example 1, it can be seen that the use of different spherical ceramic blank drying parameters has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. On the basis of Example 1, lowering or increasing the drying temperature and time will cause its ammonia nitrogen adsorption capacity and microbial load to decrease, but the compressive strength of Example 12 has no obvious change. This may be because the synergistic effect of Example 1 on this basis is not significant. Therefore, the high-strength lightweight ceramsite prepared in Example 1 is relatively optimal, but it can be adjusted as needed according to actual production conditions.

[0090] 7) Effect of different sintering process parameters on the use of high-strength lightweight ceramsite

[0091] By comparing Example 14 and Example 15 with Example 1, it can be seen that the use of different sintering process parameters has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. On the basis of Example 1, the sintering temperature becomes smaller / increased and the sintering time becomes shorter / longer. The sintering temperature and sintering have a great influence on the specific surface area and porosity of the ceramsite. When the sintering temperature is too high or the sintering time is too long, the amount of liquid phase on the surface of the ceramsite increases and the viscosity decreases. These liquid phases will fill into the pores, causing the porosity and specific surface area of ​​the ceramsite to decrease, and the compressive strength is also reduced to a certain extent. Therefore, the high-strength lightweight ceramsite prepared in Example 1 is relatively optimal.

[0092] 8) The influence of different granulation spraying processes on the use of high-strength lightweight ceramsite

[0093] By comparing Example 16 with Example 1, it can be seen that after spray granulation is performed in the mother core growth stage using ultrasound, the compressive strength of the prepared high-strength lightweight ceramsite is improved to a certain extent, and the ammonia nitrogen removal rate and adsorption capacity are also improved to a certain extent compared with Example 1; it can be seen that by adding ultrasonic treatment in the mother core growth stage, high-strength lightweight ceramsite with better performance can be obtained;

[0094] At the same time, through the comparison of Example 17, Example 18 and Example 16, it can be seen that the use of different ultrasonic parameters for auxiliary treatment in the mother core growth stage has a certain influence on the use effect of the prepared high-strength lightweight ceramsite. The ultrasonic parameters are adjusted on the basis of Example 16, so that the compressive strength of the prepared high-strength lightweight ceramsite is reduced to a certain extent. Therefore, the ultrasonic parameters prepared in Example 16 are relatively optimal.

Claims

1. A high-strength lightweight ceramsite for a moving bed biofilm reactor, characterized in that: The high-strength lightweight ceramsite is a base material composed of dried sludge, calcium feldspar, diatomaceous earth and activated carbon in a mass percentage ratio of 30-40%: 30-40%: 15-30%: 5-10%, and is sprayed with type I spray liquid and type II spray liquid in the granulation stage to obtain the high-strength lightweight ceramsite. Among them, the type I spray liquid is a base liquid with deionized water, and the base liquid contains 3-5wt% of sodium α-olefin sulfonate, 1.8-2.4wt% of polyacrylamide and 0.5-1.5wt% of dextrin in an aqueous solution; the type II spray liquid is a base liquid with deionized water, and the base liquid contains 5-6wt% of sodium α-olefin sulfonate, 0.2-0.5wt% of polymaleic anhydride and 1.5-2.7wt% of polyethylene glycol in an aqueous solution.

2. The high-strength lightweight ceramsite for a moving bed biofilm reactor according to claim 1, characterized in that: The polyethylene glycol is polyethylene glycol 200 or polyethylene glycol 400.

3. A production process for high-strength lightweight ceramsite for a moving bed biofilm reactor as described in any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Select dried sludge, calcium feldspar, diatomaceous earth and activated carbon in proportion, grind the dried sludge, calcium feldspar, diatomaceous earth and activated carbon through a 100-mesh sieve, and stir and mix for 5 minutes to obtain a mixed material; S2. Granulate the mixed material in a granulator. During the granulation process, spray the type I spray liquid and the type II spray liquid at a solid-liquid ratio of 1g:0.1-0.3ml. Specifically, S2-1. During the core forming stage, the spray temperature of the Type II spray liquid is controlled at 60-65°C. S2-2, during the growth stage of the mother core, the spray temperature of the type II spray liquid is cooled to 50-55°C at a cooling rate of 3-5°C / s, and then the type II spray liquid is replaced with the type I spray liquid of the same temperature, and the temperature is continuously cooled at a cooling rate of 3-5°C / s until a spherical pottery blank of a desired size is obtained; S3, drying the spherical ceramic blank in an electric drying oven at 100-110°C for 4-6 hours, then calcining it in a muffle furnace, and cooling it to room temperature with the furnace to obtain high-strength and lightweight ceramsite.

4. The production process of high-strength lightweight ceramsite for a moving bed biofilm reactor as claimed in claim 3, characterized in that: The water content of the spherical ceramic blank is controlled at 8-24%.

5. The production process of high-strength lightweight ceramsite for a moving bed biofilm reactor as claimed in claim 3, characterized in that: The particle size of the spherical ceramic blank is 10-15 mm, and the moisture content is controlled at 8-24%.

6. The production process of high-strength lightweight ceramsite for a moving bed biofilm reactor as claimed in claim 3, characterized in that: The calcination method comprises: pre-calcining at 320-370° C. for 8-15 minutes, then uniformly heating the temperature to 1050-1150° C. at a heating rate of 20° C. / min, and sintering at 1050-1150° C. for 4-8 minutes.

7. The production process of high-strength lightweight ceramsite for a moving bed biofilm reactor as claimed in claim 3, characterized in that: The upper limit of the cooling temperature is 15-20°C.

8. The production process of high-strength lightweight ceramsite for a moving bed biofilm reactor as claimed in claim 3, characterized in that: During the growth stage of the mother core, ultrasonic treatment with an ultrasonic power of 50 to 100 W and a frequency of 20 to 35 KHz is added until a spherical ceramic blank of a desired size is obtained.

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