A combined packing for a microbial fuel cell for wastewater treatment

Abstract

The present application relates to a kind of combined fillings of microbial fuel cell for wastewater treatment, including four fillings of filler A, filler B, filler C and filler D, the filler A is adsorbed activated carbon, filler B is coking plant's crushed coke and coke powder, filler C is solid waste of chemical production recovery, filler D is blast furnace iron slag, four fillings in the combined filling are calculated with different material layer height, and the combination ratio is that filler A accounts for 50%~60%, filler B accounts for 20%~25%, filler C accounts for 10%~20%, and filler D accounts for 5%~10%.When coking wastewater is treated using microbial fuel cell, the production operation cost is reduced, and the fuel cell treatment efficiency is improved, and the solid waste discharge of steel plant is reduced.

Description

Technical Field

[0001] This application relates to the field of coking wastewater treatment, and in particular to a composite packing material for a microbial fuel cell used in wastewater treatment. Background Technology

[0002] In recent years, the utilization of biological processes to convert pollutants into electricity, combined with in-situ coupled catalytic electrode oxidation to treat organic pollutants in water, has garnered widespread attention for its efficient purification of industrial wastewater. This novel water treatment technology, through the in-situ coupling of bioelectrochemical microorganisms and bioelectrocatalysis, effectively synergizes biological and catalytic processes, improving water treatment efficiency and load. The effluent not only meets treatment requirements but also reduces time and space commitment, shortens the process, and significantly lowers water treatment costs. Bioelectrochemical water treatment technology primarily relies on electrogenic bacteria adapted to anaerobic conditions at the anode and electrocatalysis at the cathode under aerobic conditions to achieve water treatment. The anode and cathode are separated by ion exchange membranes / non-woven membranes / sand chambers.

[0003] Filling the anode chamber of a microbial fuel cell with packing material provides a site for microorganisms to attach and grow, forming a biofilm system. The material composition and surface properties of the anode packing material directly affect the attachment, growth, reproduction, and activity of microorganisms on its surface. Good packing material can increase the contact area between the anode and microorganisms, promoting electron transport; it can also expand the electroactive range of the anode, improving wastewater treatment and energy recovery rates; and, without affecting the sludge-water separation effect in the biological treatment tank, it can significantly increase the biomass of the biological treatment tank, thereby improving wastewater treatment efficiency. Therefore, the selection of anode packing material is one of the core technologies of microbial fuel cells.

[0004] Patent 202110956031.4 discloses a water treatment packing composition, packing device, and its application. The four types of packing combinations include: polypropylene, calcium carbonate powder, basalt fiber, coupling agent and toughening agent, polysuccinic acid, butylene glycol ester, poly(β-hydroxybutyrate) valerate, and straw powder, etc. The composition is complex, the raw material cost is high, and its main purpose is to remove nitrogen and phosphorus substances from water, making it unsuitable for coking wastewater. Patent ZL202322797327.3 discloses a double-layer structure iron-carbon packing-artificial wetland-microbial fuel cell. A recycled waste iron / biochar packing layer is filled between the inner and outer tanks. The inner tank contains a zeolite layer and an iron-carbon packing layer from bottom to top. An anode is buried within the zeolite layer, and a cathode is buried on top of the iron-carbon packing layer. Iron-carbon microelectrolysis includes an anode material (iron powder, iron filings, or sponge iron) and a cathode material (activated carbon, coke, or tar). The slow corrosion of the iron anode releases electrons that transfer to the carbon cathode, forming numerous microscopic galvanic cells. The cathode then transfers electrons to pollutants in different forms within the environment, achieving efficient degradation of pollutants. However, coking wastewater contains a large amount of organic matter and harmful substances, causing rapid iron corrosion and requiring frequent replenishment of packing material, increasing manpower and costs. Patent ZL202310863777.X discloses a method for deep denitrification of wastewater using waste activated carbon packing material. After acid washing, water washing, drying, and sieving, the waste activated carbon is prepared into denitrification filter media for enhancing deep denitrification in domestic wastewater treatment plants, effectively recycling waste. However, for microbial fuel cells, the efficiency is insufficient, the processing capacity is inadequate, and it cannot meet the anode requirements of fuel cells. Patent ZL202111621587.4 discloses a method for preparing a water treatment filler capable of supporting microorganisms and a filler system. The method involves secondary molding and secondary calcination of silicon carbide particles, significantly improving the porosity and specific surface area of ​​the final silicon carbide particles. When used as a microbial filler, it exhibits a significantly enhanced COD purification capacity compared to untreated silicon carbide particles. However, silicon carbide is more expensive than ordinary activated carbon, posing a certain economic burden for large-scale treatment of coking wastewater. Furthermore, the pretreatment process is relatively complex, resulting in higher time and economic costs.

[0005] Therefore, none of these packing materials are ideal options for the anode chamber of a microbial fuel cell system designed for coking wastewater treatment. To address this, a novel combined packing material for microbial fuel cells was designed. This material primarily utilizes inexpensive commercial activated carbon, while also incorporating solid waste such as coke powder from steel mills, waste ceramics / molecular sieves, and iron slag. This approach reduces activated carbon usage, controls costs, reuses solid waste, reduces solid waste output, and achieves resource recycling. Furthermore, it improves the efficiency of the microbial fuel cell, making it a win-win-win solution. Summary of the Invention

[0006] This invention provides a combined packing material for microbial fuel cells used in wastewater treatment, aiming to reduce production and operating costs while improving fuel cell treatment efficiency and reducing solid waste discharge from steel plants when using microbial fuel cells to treat coking wastewater.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A combined packing material for a microbial fuel cell used for wastewater treatment includes four types of packing materials: packing material A, packing material B, packing material C, and packing material D. Packing material A is activated carbon, packing material B is coke crushing and coke powder from a coking plant, packing material C is solid waste recovered from chemical products, and packing material D is blast furnace slag. The four types of packing materials are combined in the following proportions based on different material layer heights: packing material A accounts for 50%–60%, packing material B accounts for 20%–25%, packing material C accounts for 10%–20%, and packing material D accounts for 5%–10%.

[0009] The activated carbon used in filler A has a particle size of 4-8 mm and a specific surface area of ​​900-1250 m². 2 / g, total pore volume 0.40~0.6cm³ 3 / g, bulk density 0.3~0.5g / cm³ 3 .

[0010] The activated carbon used in filler A has a pore structure that is mainly microporous and may contain a certain amount of mesoporous structure. The isothermal adsorption curve is a typical type I isothermal adsorption curve.

[0011] The recycled solid waste includes waste activated carbon, waste ceramic balls, and waste molecular sieves, which can provide macropores for microbial growth and support for the packing material. The recycled solid waste needs to be regenerated before use, primarily to remove sulfur and nitrogen oxides from the materials, with a particle size ≤10mm.

[0012] The coke crushing and coke powder used in packing B are byproducts of the coking process. The particle size of packing B is ≤10mm; coke particles larger than 10mm need to be crushed before addition. The particle size of packing D is ≤10mm. The blast furnace slag used in packing D is solid waste from steel plants, which can provide trace amounts of metal elements for microorganisms and partially neutralize acidic substances in coking wastewater, improving the efficiency of organic matter decomposition in the microbial fuel cell. Blast furnace slag particles larger than 10mm need to be crushed before addition.

[0013] The combined packing material consists of packing material A, packing material B, packing material C and packing material D laid in layers in the anode chamber of the microbial fuel cell, with the height of the packing layer accounting for 1 / 3 to 1 / 2 of the height of the anode chamber.

[0014] The combined packing is made by layering packing A, packing B, packing C and packing D, wrapping them tightly with carbon felt, and then packaging them into a packing unit in a porous shell for use in the anode chamber.

[0015] The order in which filler A, filler B, filler C, and filler D are laid out in layers is as follows: from bottom to top, filler A is laid out to 2 / 5 of its height, then flattened and compacted; then filler D is placed in and flattened; filler A is laid out to 1 / 5 of its height, then flattened and compacted; filler C is placed in and flattened; filler A is laid out to 1 / 5 of its height, then flattened and compacted; filler B is placed in and flattened; finally, filler A is laid out to 1 / 5 of its height and compacted to complete the packaging.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] A composite packing material for microbial fuel cells used in wastewater treatment aims to reduce production and operating costs, improve fuel cell treatment efficiency, and reduce solid waste discharge from steel plants when using microbial fuel cells to treat coking wastewater. This invention primarily utilizes inexpensive commercial activated carbon, while adding solid waste from steel plants such as coke powder, waste ceramics / molecular sieves, and iron slag. This reduces activated carbon usage, controls costs, reuses solid waste, reduces solid waste output, achieves resource recycling, and improves the efficiency of microbial fuel cells—a triple benefit. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the packing unit in an embodiment of the present invention.

[0019] In the diagram: 1-porous shell, 2-carbon felt, 3-combined filler. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the examples. The following examples are used to specifically illustrate the content of the present invention. These examples are only general descriptions of the content of the present invention and do not limit the content of the present invention.

[0021] Example 1:

[0022] Coconut shell activated carbon was used as filler A, crushed coke was used as filler B, waste molecular sieve was used as filler C, and gas-cooled slag was used as filler D. The combined fillers were directly fed and spread evenly in the anode chamber of a microbial fuel cell. This combined filler and the pure coconut shell activated carbon filler unit were placed in two separate sets of microbial fuel cell anode chambers, inoculated with the same concentration of Shewanella electrogenic bacteria. The influent flow rate of coking wastewater was 50 L / h. A commercially available Co&Ce / AC catalyst was used at the cathode, and changes in voltage and effluent quality were monitored in real time.

[0023] Types of packing Voltage settling time / h Maximum voltage / mV COD treatment ratio Total nitrogen treatment ratio Combined packing 12.4 432.5 93.77 79.23 Coconut shell activated carbon 18 258.2 89.8 72.13

[0024] Coconut shell activated carbon has a particle size of 5-8 mm and a specific surface area of ​​1120 m². 2 / g, total pore volume is 0.48cm³ 3 / g, bulk density is 0.45g / cm³ 3 .

[0025] Example 2:

[0026] Activated carbon from Datong long-flame coal was used as filler A, coke powder was used as filler B, spent activated carbon was used as filler C, and gas-cooled slag was used as filler D. The combined fillers were packaged into cubic filler units with a height of 200 mm, a length of 60 mm, and a width of 60 mm. These units, along with pure long-flame coal activated carbon filler units, were placed in the anode chambers of two sets of microbial fuel cells. The same concentration of Shewanella electrogenic bacteria was inoculated. The influent flow rate of coking wastewater was 30 L / h. A commercially available Co&Ce / AC catalyst was used at the cathode. Voltage and effluent quality changes were monitored in real time.

[0027] Types of packing Voltage settling time / h Maximum voltage / mV COD treatment ratio Total nitrogen treatment ratio Combined packing 10.58 375.2 98.56 85.36 Long-flame coal activated carbon 16 221.2 90.8 77.27

[0028] Datong long-flame coal activated carbon has a particle size of 5-8 mm and a specific surface area of ​​980 m². 2 / g, total pore volume is 0.40cm³ 3 / g, bulk density is 0.45g / cm³ 3 .

[0029] Example 3:

[0030] Taixi anthracite activated carbon was used as filler A, crushed coke was used as filler B, waste ceramics were used as filler C, and gas-cooled slag was used as filler D. The combined fillers were packaged into cubic filler units with a height of 250mm, a length of 75mm, and a width of 75mm. These units, along with the Taixi anthracite activated carbon filler units, were placed in the anode chambers of two sets of microbial fuel cells. The same concentration of Shewanella electrogenic bacteria was inoculated. The influent flow rate of coking wastewater was 40L / h. A commercially available Co&Ce / AC catalyst was used at the cathode. Voltage and effluent quality changes were monitored in real time.

[0031] Types of packing Voltage settling time / h Maximum voltage / mV COD treatment ratio Total nitrogen treatment ratio Combined packing 11.5 402.8 95.59 82.17 Anthracite activated carbon 16.8 231.4 90.2 75.63

[0032] Taixi anthracite activated carbon has a particle size of 4-6 mm and a specific surface area of ​​1210 m². 2 / g, total pore volume is 0.48cm³ 3 / g, bulk density is 0.48g / cm³ 3 .

[0033] The layering sequence of the combined packings in Examples 1-3 above is as follows: From bottom to top, packing A at 2 / 10 height is laid flat and compacted; then packing D at 1 / 10 height is placed and laid flat; then packing A at 1 / 10 height is placed and laid flat and compacted; then packing C at 2 / 10 height is placed and laid flat; then packing A at 1 / 10 height is placed and laid flat and compacted; then packing B at 2 / 10 height is placed and laid flat; finally, packing A at 1 / 10 height is placed and compacted to complete the packaging. The packing unit is formed by tightly wrapping the packing combination 3 with carbon felt 2 and placing it inside a porous outer shell 1 (see...). Figure 1 It is then put into use in the anode chamber. In an example where it is laid directly flat in the anode chamber, the height of the packing unit is 1 / 2 of the height of the anode chamber.

Claims

1. A composite packing material for a microbial fuel cell used in wastewater treatment, characterized in that, The composite packing includes four types of packing materials: packing material A, packing material B, packing material C, and packing material D. Packing material A is activated carbon, packing material B is crushed coke and coke powder from a coking plant, packing material C is solid waste recovered from chemical products, and packing material D is blast furnace slag. The four types of packing materials are combined in the following proportions based on different material layer heights: packing material A accounts for 50%–60%, packing material B accounts for 20%–25%, packing material C accounts for 10%–20%, and packing material D accounts for 5%–10%. The activated carbon used in filler A has a particle size of 4-8 mm and a specific surface area of ​​900-1250 m². 2 / g, total pore volume 0.40~0.6cm³ 3 / g, bulk density 0.3~0.5g / cm³ 3 ; The recycled solid waste includes waste activated carbon, waste ceramic balls, and waste molecular sieves, which provide macropores for microbial growth and support for the packing material; the recycled solid waste is reused after regeneration to remove sulfur and nitrogen oxides from the material, with a particle size ≤10mm; The particle size of filler B is ≤10mm, and the particle size of filler D is ≤10mm; The packing material A, packing material B, packing material C and packing material D are laid in layers in the following order from bottom to top: 2 / 5 height of packing material A, packing material D, 1 / 5 height of packing material A, packing material C, 1 / 5 height of packing material A, packing material B, and 1 / 5 height of packing material A.

2. The combined packing material for a microbial fuel cell used for wastewater treatment according to claim 1, characterized in that, The combined packing material consists of packing material A, packing material B, packing material C and packing material D laid in layers in the anode chamber of the microbial fuel cell, with the height of the packing layer accounting for 1 / 3 to 1 / 2 of the height of the anode chamber.

3. The combined packing material for a microbial fuel cell used in wastewater treatment according to claim 1, characterized in that, The combined packing is made by layering packing A, packing B, packing C and packing D, wrapping them tightly with carbon felt, and then packaging them into a packing unit in a porous shell for use in the anode chamber.

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