Preparation method of sludge biochar filler, micro-electrolysis coupled constructed wetland and application of micro-electrolysis coupled constructed wetland

Abstract

The invention discloses a preparation method of a sludge biochar filler, which comprises the following specific steps: air-drying sludge, crushing and sieving; iron powder, the treated sludge and kaolin are weighed and put into a granulator, distilled water is added, and a ceramic blank with the diameter being 4-8 mm is prepared; and naturally airing the ceramic blank, and carrying out oxygen-isolated calcination in a muffle furnace to obtain the sludge biochar filler. The invention also discloses an artificial wetland coupled with micro-electrolysis, and the iron powder is organically combined with the sludge and the kaolin, so that the removal rate of sulfadiazine in a water body is increased; the sludge biochar filler prepared by the constructed wetland is combined with the filling mode disclosed by the invention, so that the removal rate of sulfadiazine can reach up to 100%. According to the constructed wetland, the community structure of microorganisms in the constructed wetland and the life activity of the microorganisms are adjusted by adjusting the filler design and the operating condition, so that the removal effect of the constructed wetland on pollutants is improved.

Description

Technical Field

[0001] The present invention belongs to the field of sewage treatment, and in particular relates to a method for preparing a sludge biochar filler and an artificial wetland coupled with micro-electrolysis and its application. Background Art

[0002] With the widespread use of antibiotics, they are used in large quantities and in a wide variety of types. Compared with other types of antibiotics, sulfonamide antibiotics, as antibacterial drugs used by humans and animals, are not only used in huge quantities. They are also hydrophilic, not easy to hydrolyze, and have high persistence, and are detected in large quantities in environmental antibiotic residues. At the same time, sulfonamide antibiotics exist in large quantities in environmental media at low concentrations for a long time, posing a threat to environmental ecology and human health.

[0003] At present, the commonly used methods for treating antibiotic wastewater include physical, chemical and biochemical methods. Physical and chemical methods generally have disadvantages such as high energy consumption and high cost. Compared with them, artificial wetlands have the advantages of convenient construction, low energy consumption and no secondary pollution, but antibiotics and their degradation products will inhibit microbial activity and reduce the removal capacity of traditional artificial wetlands. Compared with traditional artificial wetland matrices such as gravel, zeolite, slag, and biochar, the iron-carbon matrix has a significantly stronger ability to adsorb and remove pollutants. At present, it has been reported that the combination of iron-carbon micro-electrolysis technology and microbial treatment has a good removal effect on sewage containing antibiotics such as tetracycline and quinolone antibiotics.

[0004] In constructed wetlands, the nature of the filler and the filling method will greatly affect the removal effect of the constructed wetland on pollutants. Studies have shown that in vertical subsurface flow constructed wetlands, microbial degradation has a greater impact on the removal of sulfonamides and is more effective than matrix adsorption or hydrolysis. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide an artificial wetland coupled with micro-electrolysis, which uses fillers prepared from sludge in combination with a specific filling method to effectively improve the removal rate of sulfonamide antibiotics in water.

[0006] Another object of the present invention is to provide a method for preparing sludge biochar filler.

[0007] Another object of the present invention is to provide an application of an artificial wetland coupled with micro-electrolysis The purpose of the present invention is achieved through the following technical solutions: A method for preparing sludge biochar filler comprises the following specific steps: (1) Air-dry the sludge, crush it and sieve it; (2) Weigh iron powder, the sludge treated in step (1) and kaolin, put them into a granulator, add distilled water, and prepare a ceramic embryo with a diameter of 4-8 mm; (3) The ceramic embryo is naturally dried, and then calcined in a muffle furnace to obtain the sludge biochar filler.

[0008] Preferably, the ceramic embryo is round; Preferably, the sludge biochar filler comprises the following components by weight: 1~6 parts of iron powder; 2 parts of sludge; 5 parts of kaolin.

[0009] Preferably, the iron powder particle size is 80-300 mesh.

[0010] Preferably, the kaolin particle size is preferably 200-300 mesh.

[0011] Preferably, the mass ratio of the iron powder, sludge and kaolin is 2:2:5.

[0012] Preferably, the specific steps of step (1) are as follows: The sludge leaving the factory is naturally air-dried for 3 to 7 days until it is completely air-dried. The air-dried sludge is crushed through a 20-mesh sieve, and the target particle size is 0.1 to 0.85 mm. Preferably, the specific steps of calcining in step (3) include: The air-dried ceramic embryo is calcined and carbonized at 400-600° C., then kept warm for 50-70 minutes, and then heated to 900-1050° C. and sintered for 5-15 minutes to prepare the sludge biochar filler.

[0013] More preferably, the air-dried ceramic embryo is calcined and carbonized at 400° C., then kept warm for 60 minutes, and then heated to 900° C. and sintered for 5 minutes to prepare the sludge biochar filler.

[0014] More preferably, the air-dried ceramic blank is calcined and carbonized at 400° C., and then kept warm for 60 minutes.

[0015] A micro-electrolysis coupled artificial wetland, wherein the filler of the artificial wetland comprises the sludge biochar filler, ceramsite and river sand; the volume ratio of the ceramsite, the sludge biochar filler and the river sand is 1:0.8~1.3:0.8~1.3, and the filling methods of the three include mixed filling and layered filling; the mixed filling is to uniformly mix the river sand, ceramsite and the sludge biochar filler of equal volume and then fill to 90cm.

[0016] Preferably, the layered filling is to fill the ceramsite, sludge biochar filler and river sand from bottom to top until a height of 90 cm.

[0017] Preferably, the height of each layer of filler is 10 cm or 30 cm.

[0018] Preferably, the particle size of the sludge biochar filler is 4-6 mm, the particle size of the ceramsite is 4-6 mm, and the particle size of the river sand is 1-2 mm.

[0019] Preferably, the ceramsite is commercially available ceramsite.

[0020] An application of an artificial wetland coupled with micro-electrolysis is applied to water pollution treatment, wherein the water pollution treatment includes the treatment of sulfonamide antibiotics in water bodies.

[0021] Preferably, the water pollution treatment also includes treating chemical oxygen demand, ammonia nitrogen and total phosphorus in the water body.

[0022] The present invention has the following advantages and beneficial effects compared with the prior art: (1) The sludge biochar filler disclosed in the present invention is prepared by natural air drying, which does not require additional energy and is low in cost. The sludge does not need to undergo complex pre-treatment steps before it can participate in the preparation of the sludge biochar filler. The organic combination of iron powder, sludge and kaolin improves the removal rate of sulfadiazine in the water body. The artificial wetland uses sludge biochar filler combined with a suitable filling method, and the removal rate of sulfadiazine can reach up to 100%.

[0023] (2) The present invention adjusts the artificial wetland of the filler design and operating conditions, changes the artificial wetland environment, sets a suitable filler filling method, and regulates the community structure of microorganisms inside the artificial wetland and the life activities of microorganisms, thereby improving the removal effect of pollutants by the artificial wetland. The microbial degradation process of sulfonamide drugs includes aerobic biodegradation and anaerobic biodegradation, and the activity of microorganisms will significantly affect the removal efficiency. The present invention utilizes the biological metabolism of naturally grown microorganisms to remove pollutants, reducing operating costs. The mixed filling method significantly changes the microbial community structure, thereby affecting the removal efficiency of pollutants, providing a suitable physical and chemical environment, and promoting the stable growth and reproduction of microorganisms that can decompose sulfadiazine.

[0024] (3) The present invention introduces sludge biochar fillers to enable the artificial wetland to achieve efficient degradation of multiple pollutants, especially the removal capacity of sulfonamide antibiotic pollutants has been significantly improved, effectively solving the problems of unsatisfactory pollutant removal effect and unstable effluent effect of traditional artificial wetland fillers. Sludge biochar fillers have a large number of active adsorption sites, which can effectively remove antibiotics in water, thereby helping to remove conventional pollutants such as COD. In addition, the surface of the sludge biochar filler is loaded with Fe, which further improves the removal capacity of pollutants, so that the present invention can not only remove conventional pollutants, but also effectively deal with special pollutants, and the raw material for preparation is sludge from sewage treatment plants. It has a wide source and low cost, and effectively solves the problem of disposal of sludge leaving the factory.

[0025] (4) Studies have shown that pyrolysis temperature affects the biochar yield. At higher temperatures, the volatiles in the sludge charcoal are completely analyzed. As the pyrolysis temperature increases, the yield of pyrolysis gas increases and the pyrolysis charcoal yield decreases. On the other hand, within a certain temperature range, when the pyrolysis temperature is high, it helps to form the internal pore structure of the biochar, thereby increasing the porosity and specific surface area. The present invention adopts a one-step two-stage calcination process to prepare sludge biochar filler, which is simple and convenient to operate. In the slow and low-temperature pyrolysis process, the sludge biochar yield is guaranteed; and then the ceramsite filler is fired at the high temperature stage while fixing harmful substances such as heavy metals in the sludge, thereby reducing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Actual picture of the sludge biochar filler (green embryo) of the present invention.

[0027] Figure 2 The ability of the sludge biochar filler with different iron contents to sulfadiazine Figure 3 A schematic structural diagram of the sludge biochar artificial wetland of the present invention.

[0028] Figure 4 The sludge biochar artificial wetland of the present invention has a removal effect on sulfadiazine.

[0029] Figure 5 The sludge biochar artificial wetland of the present invention has a COD removal effect.

[0030] Figure 6 The sludge biochar artificial wetland of the present invention has a removal effect on ammonia nitrogen.

[0031] Figure 7 The TP removal effect of the sludge biochar artificial wetland of the present invention. DETAILED DESCRIPTION

[0032] The purpose of the present invention is further described in detail below with reference to the accompanying drawings and specific examples. The examples cannot be described one by one here, but the implementation methods of the present invention are not therefore limited to the following examples.

[0033] Embodiment 1: This example prepares a sludge biochar filler (1) The sludge was naturally air-dried to constant weight, crushed with a crusher and passed through a 20-mesh sieve to obtain air-dried sludge powder with a particle size of 0.1-0.85 mm.

[0034] (2) Weigh iron powder, sludge, and kaolin in a mass ratio of 2:2:5, mix them evenly, add an appropriate amount of distilled water, and use a granulator to obtain round sludge ceramsite raw material with a diameter of 4-8 mm.

[0035] (3) The product obtained in step (2) was naturally air-dried (3 days) and then placed in a muffle furnace for oxygen calcination at 400°C for 60 minutes, then heated to 900°C for 5 minutes, and then naturally cooled to room temperature to obtain sludge biochar filler, named BC-S0 Example 2 In this embodiment, a sludge biochar filler is prepared, in which the ratio of sludge to kaolin is 2:5 by mass, and no iron powder is added. It is named BC-S2, and the firing conditions are the same as those in Example 1.

[0036] Example 3 In this embodiment, a sludge biochar filler is prepared, and the ratio of iron powder: sludge: kaolin is 4:2:5 by mass, named BC-S4, and the firing conditions are the same as those in Example 1.

[0037] Example 4 In this embodiment, a sludge biochar filler is prepared, and the ratio of iron powder: sludge: kaolin is 6:2:5 by mass, named BC-S6, and the firing conditions are the same as those in Example 1.

[0038] Example 5 In this embodiment, a micro-electrolysis coupled artificial wetland is prepared, using the sludge biochar filler prepared in Example 1 (iron powder, sludge, and kaolin are 2:2:5 respectively); The filling method is as follows: from bottom to top, 30 cm thick commercial ceramsite (particle size 4-6 mm), 30 cm thick sludge biochar filler (4-6 mm), and 30 cm thick river sand (particle size 1-2 mm) are placed in sequence to obtain CW-1; The wastewater to be treated is introduced from top to bottom into the coupled micro-electrolysis system in the artificial wetland, with a hydraulic load of 40 cm / d, and the outer shell is made of PVC pipe.

[0039] Embodiment 6: This embodiment prepares a micro-electrolysis coupled artificial wetland, which is the same as Embodiment 5 except for the filling method. The filling method of this embodiment is: from bottom to top, a 10 cm thick first commercial ceramsite layer (particle size 4-6 mm), a 10 cm thick first sludge biochar filler layer (4-6 mm), and a 10 cm thick first river sand (particle size 1-2 mm) are arranged in sequence, and the filling is repeated twice to obtain CW-2.

[0040] Example 7 This embodiment prepares a micro-electrolysis coupled artificial wetland, which is the same as the embodiment 1 except for the filling method. The filling method of this embodiment is: the same volume of river sand, ordinary expanded clay and sludge biochar filler as in Case 1 is evenly mixed and filled to a height of 90 cm to obtain CW-3.

[0041] The removal rates of sulfadiazine were tested for BC-S0, BC-S2, BC-S4, and BC-S6 respectively; the concentration removal tests of sulfadiazine, ammonia nitrogen, total phosphorus, and COD were carried out on CW-1~3 in Examples 5~7 respectively. Among them, SDZ was analyzed by high performance liquid chromatography (HPLC, Agilent 1260, USA). 0.01% phosphoric acid and acetonitrile (70:30) were used as the mobile phase, and the flow rate was 1mL / min; the concentration of ammonia nitrogen in the water sample was determined by Nessler's reagent spectrophotometry (GB7479-87); total phosphorus (TP) was determined by Lianhua multi-parameter water quality analyzer (5B-6C); the concentration of COD was determined by potassium dichromate method (GB11914-89); Figure 2 The capacity of sludge biochar fillers with different iron contents to sulfadiazine in Examples 1-4 is as follows: Figure 2 It can be seen that the average removal rates of SDZ by BC-S0, BC-S2, BC-S4 and BC-S6 were 1.79 mg / g, 1.04 mg / g, 1.46 mg / g and 1.23 mg / g, respectively. The results showed that the filler without iron powder had the lowest SDZ removal rate and unit adsorption capacity. Adding iron can improve the adsorption capacity of sludge biochar particles for SDZ. With the increase of iron powder addition, the unit adsorption capacity of SDZ decreases. The iron powder addition amount of BC-S4 (4:2:5) and BC-S6 (6:2:5) increases, but its adsorption effect is not as good as BC-S0. When the mass ratio of BC-S0, that is, iron powder: sludge: kaolin, is 2:2:5, the filler has the largest unit adsorption capacity of SDZ and the best removal effect.

[0042] Figure 3 The schematic diagram of the structure of the sludge biochar artificial wetland of the present invention is composed of Figure 3It can be seen that CW-1 is filled in layers, with the bottom layer being commercial ceramsite, the middle layer being sludge biochar filler, and the top layer being river sand, with each layer being 30 cm high; CW-2 is filled with ceramsite, sludge biochar filler, and river sand at the bottom, middle, and top, respectively, with each layer being 10 cm high and stacked up to 90 cm; CW-3 is a mixture of the three and then filled to a height of 90 cm; Figure 4 is the removal effect of CW-1~3 on sulfadiazine, Figure 4 It can be seen that the removal rate of sulfadiazine by CW-3 (mixed filling) can reach up to 100%.

[0043] Figures 5 to 7 The removal effects of CW-1~3 on COD, ammonia nitrogen and TP are shown respectively. The removal rate of COD in this embodiment is 87.15%~95.03%; the removal rate of ammonia nitrogen is 44.32%~73.60%; and the removal rate of TP is 85.50%~96.91%. Among them, CW-3 has a very high removal rate for various pollutants. It can be seen that the present invention significantly improves the removal capacity of artificial wetlands for antibiotic sulfadiazine, COD, ammonia nitrogen and TP.

[0044] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing sludge biochar filler, characterized in that: The specific steps include: (1) Air-dry the sludge, crush it and sieve it; (2) Weigh iron powder, the sludge treated in step (1) and kaolin, put them into a granulator, add distilled water, and prepare a ceramic embryo with a diameter of 4-8 mm; (3) The ceramic embryo is naturally dried, and then calcined in a muffle furnace to obtain the sludge biochar filler.

2. The method for preparing sludge biochar filler according to claim 1, characterized in that: The sludge biochar filler includes the following components by weight: 1~6 parts of iron powder; 2 parts of sludge; 5 parts of kaolin.

3. The method for preparing sludge biochar filler according to claim 1, characterized in that: The specific steps of step (1) are as follows: The sludge leaving the factory is naturally air-dried for 3 to 7 days until it is completely air-dried. The air-dried sludge is crushed through a 20-mesh sieve, and the target particle size is 0.1 to 0.85 mm.

4. The method for preparing sludge biochar filler according to claim 1, characterized in that: The specific steps of calcining in step (3) include: The air-dried ceramic embryo is calcined and carbonized at 400-600° C., then kept warm for 50-70 minutes, and then heated to 900-1050° C. and sintered for 5-15 minutes to prepare the sludge biochar filler.

5. An artificial wetland coupled with micro-electrolysis, characterized in that: The filler of the artificial wetland includes the sludge biochar filler, ceramsite and river sand prepared according to any one of claims 1 to 4; the volume ratio of the ceramsite, sludge biochar filler and the river sand is 1:0.8~1.3:0.8~1.3, and the filling methods of the three include mixed filling and layered filling; the mixed filling is to evenly mix equal volumes of the river sand, ceramsite and the sludge biochar filler and fill them to 90cm.

6. The micro-electrolysis coupled artificial wetland according to claim 5, characterized in that: The layered filling is to fill the ceramsite, sludge biochar filler and river sand from bottom to top until a height of 90 cm.

7. The artificial wetland coupled with micro-electrolysis according to claim 6, characterized in that: The height of each layer of filler is 10cm or 30cm.

8. The artificial wetland coupled with micro-electrolysis according to claim 5, characterized in that: The particle size of the sludge biochar filler is 4-6 mm, the particle size of the ceramsite is 4-6 mm, and the particle size of the river sand is 1-2 mm.

9. The use of the artificial wetland coupled with micro-electrolysis according to any one of claims 5 to 8, characterized in that: The invention is applied to water pollution treatment, wherein the water pollution treatment includes the treatment of sulfonamide antibiotics in water bodies.

10. The application of the artificial wetland coupled with micro-electrolysis according to claim 9 is characterized in that: The water pollution treatment also includes treating the chemical oxygen demand, ammonia nitrogen and total phosphorus in the water body.

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