Combined filler of microbial fuel cell for wastewater treatment

Abstract

The invention relates to a combined filler of a microbial fuel cell for wastewater treatment, which comprises a filler A, a filler B, a filler C and a filler D. The filler A is adsorptive activated carbon, the filler B is broken coke and coke powder of a coking plant, the filler C is chemical recovery solid waste, and the filler D is blast furnace iron slag. The four fillers in the combined filler are calculated according to different material layer heights, and the combination ratio of the filler A to the filler B to the filler C to the filler D to the filler C to the filler D is 50%-60%, 20%-25%, 10%-20% and 5%-10%. When the microbial fuel cell is used for coking wastewater treatment, the production and operation cost is reduced, meanwhile, the fuel cell treatment efficiency is improved, and solid waste discharge of an iron and steel plant is reduced.

Description

Technical Field

[0001] The present application relates to the field of coking wastewater treatment, and particularly relates to a combined filler for a microbial fuel cell used for wastewater treatment. Background Art

[0002] In recent years, converting pollutants through biological action to generate electricity, while in-situ coupling with catalytic electrode oxidation to treat organic pollutants in water, and realizing the bioenergy-driven catalytic advanced oxidation process to efficiently purify industrial wastewater has received wide attention. In this new water treatment technology, due to the in-situ coupling of bioelectrochemical microorganisms and bioelectrocatalysis, the biological action and catalytic action are efficiently synergistic, improving the efficiency and load of water treatment. The effluent not only meets the requirements of treatment indicators, but also reduces space-time occupation, shortens the process, and can greatly reduce the water treatment cost. The bioelectrochemical water treatment technology mainly relies on bioelectricity-producing bacteria adapted to the anaerobic conditions of the anode and the electrocatalytic action of the cathode under aerobic conditions to achieve water treatment. The anode and cathode are separated by an ion exchange membrane / non-woven fabric diaphragm / sand bin.

[0003] Filling a filler in the anode chamber of a microbial fuel cell can provide a place for microorganisms to attach and grow, forming a biofilm system. The material composition and surface properties of the filler in the anode chamber will directly affect the attachment, growth, reproduction, and activity of microorganisms on the filler surface. A good filler can increase the contact area between the anode and microorganisms, promoting electron transfer; it can expand the electroactive range of the anode, improve wastewater treatment and energy recovery rate, and significantly increase the biomass in the biochemical pool without affecting the sedimentation effect of the mud and water in the biochemical pool, thereby improving the sewage treatment effect. Therefore, the selection of the anode filler is one of the core technologies of microbial fuel cells.

[0004] Patent 202110956031.4 discloses a water treatment filler composition, a filler device and its application. The combination of four types of fillers includes: polypropylene, calcium carbonate powder, basalt fiber, coupling agent and toughening agent, polybutylene succinate, butanediol ester, poly(β-hydroxybutyrate-co-valerate), straw powder, etc. The composition is complex and the raw material cost is high. Moreover, its main purpose is to remove nitrogen and phosphorus substances in water, and it is not suitable for coking wastewater. Patent ZL202322797327.3 discloses a double-layer structure iron-carbon filler-artificial wetland-microbial fuel cell. A recycled waste iron / biochar filler layer is filled between the inner and outer barrels. From bottom to top in the inner barrel are a zeolite layer and an iron-carbon filler layer; an anode is buried in the zeolite layer, and a cathode is buried at the top of the iron-carbon filler layer. Iron-carbon microelectrolysis includes an anode material (iron powder, iron filings or sponge iron) and a cathode material (activated carbon, coke or tar). During the slow corrosion process of the anode iron, electrons can be released and transferred to the cathode carbon, forming countless microscopic primary batteries. The cathode then transfers the electrons to pollutants in different forms in the environment, thereby achieving efficient degradation of pollutants. However, for coking wastewater, there are many internal organic substances and harmful substances, which corrode the iron too fast, and the filler needs to be replenished frequently, consuming more manpower and increasing costs. Patent ZL202310863777.X discloses a method for realizing deep denitrification of sewage by using waste activated carbon filler. After steps such as pickling, water washing, drying, and screening of the waste activated carbon, it is prepared into a denitrification filter material for strengthening the deep denitrification of domestic sewage treatment plants, and the waste is recycled very well. However, for microbial fuel cells, the efficiency is insufficient and the treatment capacity is insufficient, unable to meet the anode requirements of fuel cells. Patent ZL202111621587.4 discloses a preparation method and a filler system of a water treatment filler capable of loading microorganisms. After secondary forming and secondary roasting of silicon carbide particles, the porosity and specific surface area of the finally formed silicon carbide particles are significantly improved. When used as a microbial filler, compared with silicon carbide particles without the above treatment, the purification ability of COD is significantly enhanced. However, the price of silicon carbide is higher than that of ordinary activated carbon, which poses a certain economic pressure for large-scale treatment of coking wastewater, and the pretreatment process is relatively complex, with high time and economic costs.

[0005] Therefore, none of these fillers is an excellent filler option for the anode chamber in the microbial battery system for coking wastewater treatment. In view of this, a new type of combined filler for microbial fuel cells is designed. It mainly uses commercially available activated carbon with a relatively low price, and at the same time adds solid wastes such as coke powder from steel plants, waste ceramics / molecular sieves, and iron slag. This not only reduces the amount of activated carbon used and controls costs, but also reuses solid wastes, reduces the discharge of solid wastes from the factory, realizes the recycling of resources, and can also improve the efficiency of microbial fuel cells, which is a three-win method. Summary of the Invention

[0006] The present invention provides a combined filler for a microbial fuel cell used in wastewater treatment, aiming to reduce the production and operation costs while improving the treatment efficiency of the fuel cell and reducing the solid waste discharge from steel plants when using the microbial fuel cell to treat coking wastewater.

[0007] To achieve the above object, the present invention is implemented by the following technical solutions:

[0008] A combined filler for a microbial fuel cell used in wastewater treatment includes four fillers, namely filler A, filler B, filler C, and filler D. The filler A is adsorbent activated carbon, the filler B is crushed coke and coke powder from a coking plant, the filler C is solid waste from chemical product recovery, and the filler D is blast furnace slag. In the combined filler, the four fillers are calculated according to different layer heights, 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%.

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

[0010] The pore structure of the activated carbon used in filler A is mainly microporous structure and can have a certain amount of mesoporous structure, and the isothermal adsorption curve belongs to a typical type I isothermal adsorption curve.

[0011] The solid waste from chemical product recovery includes waste activated carbon, waste ceramic balls, and waste molecular sieves, which can provide macropores for the growth of microorganisms and support for the filler at the same time. The solid waste from chemical product recovery needs to be regenerated before use, mainly to remove sulfur and nitrogen compounds in the material, and the particle size ≤ 10 mm.

[0012] The crushed coke and coke powder used in filler B are by-products of coke from the coking process. The particle size of filler B ≤ 10 mm, and the coke with a particle size greater than 10 mm needs to be crushed before adding; the particle size of filler D ≤ 10 mm. The blast furnace slag used in filler D is solid waste from a steel plant, which can provide trace metal elements for microorganisms, can partially neutralize the acidic substances in coking wastewater, and improve the efficiency of the microbial fuel cell to decompose organic matter. The blast furnace slag with a particle size greater than 10 mm needs to be crushed before adding.

[0013] The combined filler is laid flat in layers of filler A, filler B, filler C, and filler D in the anode chamber of the microbial fuel cell, and the layer height accounts for 1 / 3 - 1 / 2 of the anode chamber height.

[0014] The described combined packing is formed by laying packing A, packing B, packing C, and packing D in layers and then tightly wrapping them with carbon felt, and placing them into a porous outer shell for packaging into a packing unit and putting it into the anode chamber for use.

[0015] The order of laying packing A, packing B, packing C, and packing D in layers is as follows: starting from the bottom, packing A with a height of 2 / 5 is laid flat and compacted; then packing D is put in and laid flat; packing A with a height of 1 / 5 is put in and laid flat and compacted; packing C is put in and laid flat; packing A with a height of 1 / 5 is put in and laid flat and compacted; packing B is put in and laid flat; finally, packing A with a height of 1 / 5 is put in and compacted to complete the packaging.

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

[0017] A combined packing for a microbial fuel cell used in wastewater treatment aims to reduce production and operation costs while improving the treatment efficiency of the fuel cell and reducing the solid waste discharge from steel plants when using the microbial fuel cell to treat coking wastewater. The present invention mainly uses commercially available activated carbon with a relatively low price, and at the same time adds solid wastes such as coke powder, waste ceramics / molecular sieves, and iron slag from steel plants. This not only reduces the amount of activated carbon used and controls costs, but also reuses the solid wastes, reduces the solid waste leaving the factory, realizes the recycling of resources, and can also improve the efficiency of the microbial fuel cell, which is a method that kills three birds with one stone. Description of the Drawings

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

[0019] In the figure: 1 - porous outer shell, 2 - carbon felt, 3 - combined packing. Detailed Embodiments

[0020] The following further illustrates the specific embodiments of the present invention in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of the present invention. These embodiments are only general descriptions of the content of the present invention and do not limit the content of the present invention.

[0021] Embodiment 1:

[0022] Using coconut shell charcoal as the activated carbon for packing A, the packing B used is crushed coke, the packing C used is waste molecular sieve, and the packing D used is air-cooled slag. The combined packing is directly fed and laid flat in the anode chamber of the microbial fuel cell, and the pure coconut shell activated carbon packing unit and the combined packing are respectively put into the anode chambers of two groups of microbial fuel cells, inoculated with Shewanella electrogenic bacteria with the same concentration, the inflow of coking wastewater is 50 L / h, and a commercial Co&Ce / AC catalyst is used at the cathode, and the voltage and the change of the effluent quality are detected in real time.

[0023] Type of packing Voltage stabilization time / h Highest voltage / mV COD treatment ratio Total nitrogen treatment ratio Composite packing 12.4 432.5 93.77 79.23 Coconut shell activated carbon 18 258.2 89.8 72.13

[0024] The particle size of coconut shell activated carbon is 5 - 8 mm, and its specific surface area is 1120 m 2 / g, the total pore volume is 0.48 cm 3 / g, and the bulk density is 0.45 g / cm 3 .

[0025] Example 2:

[0026] Using Datong long - flame coal activated carbon as the activated carbon of packing A, coke powder as packing B, waste activated carbon as packing C, and air - cooled slag as packing D. The combined packing is made into a cubic packing unit with a height of 200 mm, a length of 60 mm, and a width of 60 mm. The cubic packing unit and the pure long - flame coal activated carbon packing unit are respectively put into the anode chambers of two microbial fuel cells, inoculated with Shewanella electrogenic bacteria of the same concentration. The influent volume of coking wastewater is 30 L / h, and a certain commercial Co&Ce / AC catalyst is used for the cathode. The voltage and the change of effluent quality are detected in real - time.

[0027] Type of packing Voltage stabilization time / h Highest voltage / mV COD treatment ratio Total nitrogen treatment ratio Composite packing 10.58 375.2 98.56 85.36 Long-flame coal activated carbon 16 221.2 90.8 77.27

[0028] The particle size of Datong long - flame coal activated carbon is 5 - 8 mm, and its specific surface area is 980 m 2 / g, the total pore volume is 0.40 cm 3 / g, and the bulk density is 0.45 g / cm 3 .

[0029] Example 3:

[0030] Using Taixi anthracite activated carbon as the activated carbon of packing A, crushed coke as packing B, waste ceramics as packing C, and air - cooled slag as packing D. The combined packing is made into a cubic packing unit with a height of 250 mm, a length of 75 mm, and a width of 75 mm. The cubic packing unit and the Taixi anthracite activated carbon packing unit are respectively put into the anode chambers of two microbial fuel cells, inoculated with Shewanella electrogenic bacteria of the same concentration. The influent volume of coking wastewater is 40 L / h, and a certain commercial Co&Ce / AC catalyst is used for the cathode. The voltage and the change of effluent quality are detected in real - time.

[0031] Type of packing Voltage stabilization time / h Highest voltage / mV COD treatment ratio Total nitrogen treatment ratio Composite packing 11.5 402.8 95.59 82.17 Anthracite activated carbon 16.8 231.4 90.2 75.63

[0032] The particle size of Taixi anthracite activated carbon is 4 - 6 mm, and its specific surface area is 1210 m 2 / g, the total pore volume is 0.48 cm 3 / g, and the bulk density is 0.48 g / cm 3 .

[0033] The layered and flat-laying sequence of the combined packing in the above Examples 1-3 is as follows: from bottom to top, there is packing A with a height of 2 / 10, which is paved and compacted; then packing D with a height of 1 / 10 is put in and paved; packing A with a height of 1 / 10 is put in and paved and compacted; packing C with a height of 2 / 10 is put in and paved; packing A with a height of 1 / 10 is put in and paved and compacted; packing B with a height of 2 / 10 is put in and paved; finally, packing A with a height of 1 / 10 is put in and compacted to complete the packaging. The packing unit is formed by wrapping the packing combination 3 with the carbon felt 2 and putting it into the porous outer 1 shell for packaging into a packing unit (see Figure 1 ) and used in the anode chamber. For the example of directly laying flat in the anode chamber, the height of the packing unit accounts for 1 / 2 of the height of the anode chamber.

Claims

1. A composite filler for a microbial fuel cell for wastewater treatment, characterized in that: The invention comprises four kinds of fillers: filler A, filler B, filler C and filler D. The filler A is adsorbed activated carbon, the filler B is crushed coke and coke powder from a coking plant, the filler C is solid waste recovered from chemical products, and the filler D is blast furnace iron slag. The four kinds of fillers in the combined filler are calculated based on different material layer heights, and the combination ratio is that filler A accounts for 50% to 60%, filler B accounts for 20% to 25%, filler C accounts for 10% to 20%, and filler D accounts for 5% to 10%.

2. The combined filler of a microbial fuel cell for wastewater treatment according to claim 1, characterized in that: The activated carbon used in the filler A has a particle size of 4 to 8 mm and a specific surface area of ​​900 to 1250 m 2 / g, total pore volume 0.40~0.6cm 3 / g, bulk density 0.3~0.5g / cm 3 .

3. The combined filler of a microbial fuel cell for wastewater treatment according to claim 1, characterized in that: The chemical product recycled solid waste includes waste activated carbon, waste ceramic balls and waste molecular sieves, which can provide macropores for microbial growth and provide support for fillers. The chemical product recycled solid waste is used after regeneration to remove sulfur and nitrides in the material, and the particle size is ≤10mm.

4. The combined filler of a microbial fuel cell for wastewater treatment according to claim 1, characterized in that: The particle size of the filler B is ≤10 mm, and the particle size of the filler D is ≤10 mm.

5. The combined filler of a microbial fuel cell for wastewater treatment according to claim 1, characterized in that: The combined filler is filler A, filler B, filler C and filler D which are laid in layers in the anode chamber of the microbial fuel cell, and the height of the material layer accounts for 1 / 3 to 1 / 2 of the height of the anode chamber.

6. The combined filler of a microbial fuel cell for wastewater treatment according to claim 1, characterized in that: The combined filler is prepared by laying filler A, filler B, filler C and filler D in layers, wrapping them tightly with carbon felt, placing them in a porous shell and packaging them into a filler unit for use in the anode chamber.

7. A combined filler for a microbial fuel cell for wastewater treatment according to claim 5 or 6, characterized in that: The order of layering the fillers A, B, C and D is: from bottom to top, 2 / 5 of the height of filler A, filler D, 1 / 5 of the height of filler A, filler C, 1 / 5 of the height of filler A, filler B, and 1 / 5 of the height of filler A.

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