CN108796531B - Method for cleanly and thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metal and producing hydrogen gas by-product - Google Patents

Method for cleanly and thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metal and producing hydrogen gas by-product Download PDF

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CN108796531B
CN108796531B CN201810685425.9A CN201810685425A CN108796531B CN 108796531 B CN108796531 B CN 108796531B CN 201810685425 A CN201810685425 A CN 201810685425A CN 108796531 B CN108796531 B CN 108796531B
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黄丽萍
单利媛
潘玉珍
全燮
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Abstract

The invention belongs to the technical field of wastewater treatment, and discloses a method for cleanly and thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metals and producing hydrogen as a byproduct. A barrel type microbial electrolytic cell consisting of an anode and a cathode; the anode and the cathode are made of carbon-based materials such as carbon felt and carbon fiber; the anode and the cathode are respectively separated by a stainless steel net and the stainless steel net is used as an electron leading-out/leading-in component; the solution in the reactor is a metal-organic mixed solution composed of tungsten and molybdenum and organic matters, the concentration is 1-2500 mg/L, the pH is 3.0-8.0, and the conductivity is 0.3-3 mS/cm; the anode and the cathode are connected with the data collection system and an external power supply through external resistors, and the external resistor value is 10-1000 omega. The invention provides a new method for cleanly and thoroughly removing tungsten-molybdenum organic wastewater and simultaneously producing hydrogen as a byproduct, and the whole process is clean and environment-friendly.

Description

Method for cleanly and thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metal and producing hydrogen gas by-product
Technical Field
The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for completely treating tungsten-molybdenum and organic mixed wastewater by using a microbial electrolytic cell and synchronously recovering valuable metals and by-product hydrogen.
Background
Tungsten and molybdenum are rare metals which are widely applied in the fields of chemical industry, metallurgy, materials and the like. Mixed wastewater containing tungsten, molybdenum and organic matters is generated in the processes of mining and smelting of tungsten and molybdenum associated ores, product preparation and use, so that risks and hidden dangers are brought to the environment and ecology, and resource waste is caused. On the other hand, the tungsten and molybdenum mining from the mine not only leads to the exhaustion of tungsten and molybdenum resources, but also consumes much more energy in the mining process than the energy consumed by recycling waste products. Therefore, valuable metals in the wastewater in the processes of mining, producing, using and the like of the resources for recovering tungsten and molybdenum have important environmental and ecological significance as well as social and economic significance. The main treatment method of the tungsten-molybdenum-containing wastewater at present comprises the following steps: precipitation methods (CN201010165455.0, CN98123639.1, CN200710053864.X, etc.), solvent extraction methods (CN201210350518.9, CN200910043895.6, CN201610252191.X, etc.), ion exchange methods (CN201110315011.5, CN201610014324.X, CN201611104581.9, etc.). For the mixed wastewater of heavy metals and organic matters, the treatment technology mainly comprises physical and chemical methods such as adsorption (CN201610894710.2, CN201510738031.1, CN201620925008.3 and the like); a combination of physical and biological methods (CN201610374914.3, CN201710665161.6, CN201710565332.8, etc.) is also possible. For example, patent CN201710665161.6 uses a combined process including pretreatment, coagulation sedimentation, physical adsorption, oxidation-reduction reaction, biological anaerobic and aerobic processes to treat organic pollutants and mixed wastewater of nickel, lead, chromium, manganese, etc. The method has the defects of high cost, large energy consumption, complex process, low efficiency, secondary pollution, more byproducts and the like. The method for synchronously recycling valuable metals by seeking for clean and effective treatment of tungsten-molybdenum and organic mixed wastewater attracts attention.
The Microbial Electrolytic Cells (MECs) are used for transferring electrons in organic matters extracted by anode electrochemically active microorganisms to a cathode through an external circuit under a small applied voltage, and an electron acceptor such as O is arranged on the cathode2、NO3 -、H+And a clean and effective technology for reducing and recovering valuable products (hydrogen, metal and the like) by metal ions and the like. At present, the metals recovered from MECs include Cu (II), Ag (I), Zn (II), Hg (II), Cd (II), Ni (II), Cr (VI), Cd (II), Sn (II) or Sn (IV), Fe (II) or Fe (III) (CN 201310345579.0; CN 201410175987.0; 201710316396.4; Jiang et al, Inter J Hydrogen Energy 2014,39: 654-663; Luo et al, J Hazard Mater 2014,270: 153-159; Xin et al, BioResour Technol 2009,100: 6163-6169; Chenet al, BioResour Technol2013,147: 332-337; Zhang et al, J PowerSources 2015,273: 1103-1113). For the removal and recovery of tungsten and molybdenum metals, there are also reports of patents 201611002755.0 and 201610031987.2, Huang et al (Chem Eng J327 (2017) 584-. Due to the electron donor characteristics of organic matters, the organic matters cannot be degraded by a cathode with reducibility. Therefore, the metalorganic mixed wastewater cannot be removed simultaneously in the cathode chambers of the dual-chamber MECs; especially if the pH is not too low or too high (e.g. 3.0)<pH<8.0) and satisfying the existence of electrochemically active microorganisms, the single-chamber MECs has great advantages. Although there are also a few reports of single chamber MECs treating metal-organic mixtures (Abourached et al, WaterRes 2014,51: 228-; and is limited to mixtures of organics and single metals. Reports that the single-chamber MECs treatment technology of the tungsten-molybdenum organic mixed wastewater is combined and the effluent quality reaches the standard and is discharged are not seen yet.
According to the invention, MECs are used for recovering tungsten-molybdenum organic mixed wastewater and valuable metals and hydrogen as by-products. The metal and organic matter concentration in the effluent reaches the discharge standard through the modes of complete circular flow, organic substrate sodium acetate supplement and acid addition and pH adjustment: the COD concentration reaches the national first-class A discharge standard (GB18918-2002), and the tungsten-molybdenum concentration is lower than the concentration limit value of directly discharged wastewater (GB 21/1627-2008). The invention overcomes the limitation of double-chamber MECs on treating mixed wastewater of organic and tungsten molybdenum or other metals (CN 201610031987.2; CN 201611002755.0; Huang et al, Chem Eng J327 (2017) 584-.
The technical principle of the invention is as follows: the redox potentials of W (VI) and Mo (VI) are 0.386V and 0.606V, respectively, typically as in WO4 2-And MoO4 2-Are present. For the waste water mixed by tungsten and molybdenum and organic (expressed as sodium acetate), the electrochemically active microorganisms on the surface of the anode electrode take sodium acetate as fuel (reaction formula (1)), electrons are transferred to the cathode through an external circuit, and meanwhile, under the driving of a small voltage, WO with higher oxidation-reduction potential is adopted4 2-And MoO4 2-And proton hydrogen generated by microbial metabolism is subjected to reduction reaction on the surface of a cathode electrode or under the catalysis of electrochemically active microbes at the cathode (reaction formulas (2) to (4)):
Figure BDA0001711549100000031
Figure BDA0001711549100000032
2H++2e-→H2(4)
disclosure of Invention
The invention provides a novel method for cleanly treating tungsten-molybdenum organic mixed wastewater by using MECs, simultaneously recovering valuable metals and producing hydrogen as a byproduct. Specifically, a single-chamber MECs reactor is designed by combining multiple effects of tungsten-molybdenum reduction reaction, electrochemical activity microorganism catalysis organic matter extraction of electrons and proton hydrogen, and catalysis of W (VI) and Mo (VI) reduction, and the purposes of thoroughly treating tungsten-molybdenum organic mixed wastewater, recovering tungsten-molybdenum metal and producing hydrogen by-product are achieved by changing the combined action mode of hydraulic retention time, supplementing organic carbon, adding a small amount of acid and adjusting pH.
The technical scheme of the invention is as follows:
a clean method for thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metals and producing hydrogen as by-products comprises the following steps:
the single-chamber cylindrical MECs are adopted, the cathode and the anode are made of carbon felts as electrode materials, the stainless steel net supports and separates the anode and the cathode and leads electrons out of or into a circuit, and the electrode distance between the cathode and the anode is 1.0 cm; the tungsten-molybdenum organic mixed wastewater is a mixed solution which is manually prepared and consists of sodium acetate, tungstate and molybdate, the pH value is 3.0-8.0, and the conductivity is 0.3-3 mS/cm; the MECs are connected with the data acquisition system through external resistors; the applied voltage is 0.3-1.2V, the external resistance is 10-1000 omega, and the cathode potential is-1.50-0.46V.
The single-chamber MECs reactor of the invention needs to maintain anaerobic environment in the operation process, and can realize anaerobic condition by introducing nitrogen.
The single-chamber MECs reactor of the invention can completely circulate after organic carbon sources (such as sodium acetate or glucose) are added to the effluent water of tungsten-molybdenum organic mixed wastewater treatment.
The single-chamber MECs reactor of the invention treats the effluent of tungsten-molybdenum organic mixed wastewater, and needs to add acid (such as sulfuric acid or hydrochloric acid) to adjust the pH of the influent while the effluent is completely circulated after the organic carbon source is added.
And supplementing an organic substance which is sodium acetate or glucose into the effluent of the reactor, wherein the addition amount is 50-1000 mg/L, and adding a small amount of sulfuric acid or hydrochloric acid while completely circulating, wherein the addition amount is 2.6-47.4 mu M.
The mixed wastewater of the invention comprises the following water inlet components: 178mg/LNa2WO4·2H2O,266mg/LNa2MoO4·2H2O,1200mg/LCH3COONa,383mg/L(NH4)2SO4,13.6mg/L KH2PO4(ii) a 12.5mL/L mineral element; 12.5mL/L vitamin; wherein the mineral elements comprise 3.0g/LMgSO4；0.5g/LMnSO4·H2O；1.0g/LNaCl；0.1g/LFeSO4·7H2O；0.1g/LCaCl2·2H2O；0.1g/LCoCl2·6H2O；0.13g/LZnCl2；0.01g/LCuSO4·5H2O；0.01g/LKAl(SO4)2·12H2O；0.01g/LH3BO3；0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B1(ii) a 5.0g/L vitamin B2(ii) a 5.0g/L vitamin B3(ii) a 5.0g/L vitamin B5(ii) a 10.0g/L vitamin B6(ii) a 2.0g/L vitamin B11(ii) a 2.0g/L of vitamin H; 5.0g/L p-aminobenzoic acid; 5.0g/L lipoic acid; 1.5g/L nitrilotriacetic acid.
And the MECs are inoculated to the sludge of a clarification tank of a sewage treatment plant as a bacteria source for domesticating the electrochemical active microorganisms. The pH value of the sludge in the clarification tank is 7.0-8.0; the conductivity is 1.0-2.0 mS/cm; the suspended solid is 10-20 g/L; the chemical oxygen demand is 100-1000 mg/L.
The flow of the MECs in the operation stage comprises the following steps: organic matters in the tungsten-molybdenum organic mixed wastewater are oxidized by electrochemically active microorganisms on the surface of an anode (reaction formula (1)), protons generated in the process reach the surface of a cathode under the driving of small applied voltage, meanwhile, electrons generated by microorganisms metabolizing the organic matters are led into the cathode through an external circuit, and WO is applied to the cathode electrode4 2-、MoO4 2-And the proton hydrogen will receive the electrons provided by the cathode or the electrochemically active microorganisms to undergo a reduction reaction (equations (2) - (4)), to form and deposit the lower valence tungsten and molybdenum oxides, and to form clean H2。
The solution in the single-chamber MECs is organic wastewater containing tungsten molybdate, and the tungsten molybdenum content and COD concentration in the effluent reach the discharge standard through the combined action mode of complete circular flow operation after organic substances (such as sodium acetate or glucose) are supplemented and pH adjustment by adding acid (such as sulfuric acid or hydrochloric acid) (GB21/1627-2008 and GB 18918-2002). The invention has good practical application prospect and has environmental, ecological, social and economic benefits.
Drawings
FIG. 1 is a flow chart (A) and a reactor structure schematic diagram (B) of a single-chamber MECs for treating tungsten-molybdenum organic mixed wastewater and simultaneously recovering metals and by-producing hydrogen;
FIG. 2 shows the tungsten recovery rate, molybdenum recovery rate, COD removal rate (A), hydrogen production rate, effluent metal separation coefficient (B), electrode potential and loop current density (C), effluent pH and effluent conductivity (D) of the tungsten-molybdenum organic mixed wastewater of example 1 when the tungsten-molybdenum organic mixed wastewater is subjected to single-chamber MECs for 24 h;
FIG. 3 is a comparison of the closed loop (A) and open loop (B) of the system under the condition of complete circulation flow operation and acid addition regulation for tungsten-molybdenum recovery rate after the tungsten-molybdenum organic mixed wastewater of example 1 is subjected to single-chamber MECs for 24h of residence time;
FIG. 4 is a comparison of the removal rate of COD and the hydrogen production in effluent by a closed loop (A) and an open loop (B) of the system under the conditions of supplementing sodium acetate and completely circulating and flowing operation and adjusting by adding acid in a flow after the tungsten-molybdenum organic mixed wastewater of example 1 is operated by single-chamber MECs for 24 h;
FIG. 5 is a comparison of the pH and conductivity of effluent from closed (A) and open (B) systems in full cycle operation with acid addition regulation, with sodium acetate supplementation, after 24h residence time of single chamber MECs, for tungsten molybdenum organic mixed wastewater of example 1;
FIG. 6 shows the comparison of the metal separation coefficient of effluent and free biomass for closed loop (A) and open loop (B) of the system under the condition of adding acid to the system, after the tungsten-molybdenum organic mixed wastewater of example 1 is subjected to single-chamber MECs for 24h of residence time, is supplemented with sodium acetate and is completely circulated and operated.
In the figure: 1, nitrogen gas; 2, tungsten-molybdenum organic mixed wastewater; 3 refluxing tungsten-molybdenum organic mixed wastewater; 4, feeding tungsten-molybdenum organic mixed wastewater; 5, a water pump; 6a liquid flow meter; 7, a water inlet; 8MECs reactor; 9, water outlet; 10 external small power supply; 11 a data acquisition system; 12 resistance; 13 a reference electrode; 14 cathode stainless steel mesh; 15 an anode stainless steel mesh; 16 a hydrogen gas collection bag; a 17 carbon felt cathode; an 18 carbon felt anode.
Detailed Description
The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.
Example 1
The method comprises the following steps: single-chamber cylindrical MECs were constructed and assembled as shown in fig. 1: the tube-shape MECs is the organic glass material, and the outside parcel one deck tinfoil is used for keeping out of the sun. Wherein the outer diameter is 34.0cm, the height is 45.0cm, and the total volume is 40.8L. The reactor is provided with a headspace with the inner diameter of 18.0cm, the height of 2.0cm and the volume of 0.5L; a gas collecting bag with the maximum volume of 1.0L is arranged at the headspace; the bottom of the cylinder is provided with a water inlet pipe with the inner diameter of 1.0cm, and the top of the cylinder is provided with a water outlet pipe with the inner diameter of 1.0 cm. The anode carbon felt is 69.2cm multiplied by 40cm multiplied by 1cm, the cathode carbon felt is 56.6cm multiplied by 40cm multiplied by 1cm, the carbon felt is sequentially soaked in 1.0M NaOH and 1.0M HCl solution for 24 hours to remove surface impurities, and then the carbon felt is washed and soaked in deionized water until the water is neutral; the size of the anode conductive stainless steel net (304, 14 mesh) is 69.2cm x 40cm, and the size of the cathode stainless steel net is 56.6cm x 40 cm. The effective working volume of the mounted MECs is 38L.
Step two: an external power supply is connected to the loop through a small external resistance of 10 ohms, and the voltages of the two groups of resistors are collected and the current is calculated through a computer and a data acquisition system; the cathode potential is collected from the reference electrode and the anode potential can be calculated from the cathode potential.
Step three: preparing water inflow: 178mg/LNa2WO4·2H2O,266mg/LNa2MoO4·2H2O,1200mg/LCH3COONa,383mg/L(NH4)2SO4,13.6mg/LKH2PO4Mineral elements of 12.5mL/L and vitamins of 12.5 mL/L; wherein the mineral elements comprise 3.0g/LMgSO4；0.5g/LMnSO4·H2O；1.0g/LNaCl；0.1g/LFeSO4·7H2O；0.1g/LCaCl2·2H2O；0.1g/LCoCl2·6H2O；0.13g/LZnCl2；0.01g/L CuSO4·5H2O；0.01g/LKAl(SO4)2·12H2O；0.01g/LH3BO3；0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B1(ii) a 5.0g/L vitamin B2(ii) a 5.0g/L vitamin B3(ii) a 5.0g/L vitamin B5(ii) a 10.0g/L vitamin B6(ii) a 2.0g/L vitamin B11(ii) a 2.0g/L of vitamin H; 5.0g/L p-aminobenzoic acid; 5.0g/L lipoic acid; 1.5g/L nitrilotriacetic acid. The 38L nutrient solution was continuously aerated with nitrogen and pumped into MECs while inoculating 100g of clarifier sludge from a sewage treatment plant (da lian dong river sewage treatment plant).
Step four: the reactor is placed at room temperature (20-25 ℃) for enrichment and domestication of electrochemical active bacteria, voltage is applied to be 0.5V, external resistance is connected to be 100 omega, and solution is not pumped in during domestication. And when the current is reduced to be below 0.02mA, completing one period, supplementing the nutrient solution, and when the system current is stable and repeated in three continuous periods, indicating that the domestication of the electrochemical active bacteria is successful.
Step five: preparing a solution: 178mg/LNa2WO4·2H2O,266mg/LNa2MoO4·2H2O,
1200mg/LCH3COONa,383mg/L(NH4)2SO4,13.6mg/LKH2PO4Mineral elements of 12.5mL/L and vitamins of 12.5 mL/L; wherein, 3.0g/LMgSO4；0.5g/LMnSO4·H2O；1.0g/LNaCl；0.1g/LFeSO4·7H2O；0.1g/LCaCl2·2H2O；0.1g/LCoCl2·6H2O；0.13g/LZnCl2；0.01g/LCuSO4·5H2O；0.01g/LKAl(SO4)2·12H2O；0.01g/LH3BO3；0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B1(ii) a 5.0g/L vitamin B2(ii) a 5.0g/L vitamin B3(ii) a 5.0g/L vitamin B5(ii) a 10.0g/L vitamin B6(ii) a 2.0g/L vitamin B11(ii) a 2.0g/L of vitamin H; 5.0g/L p-aminobenzoic acid; 5.0g/L lipoic acid; 1.5g/L nitrilotriacetic acid. Adjusting the initial pH of the tungsten-molybdenum organic mixed solution to 3.0 and the conductivity to 3.0mS/cm, pumping into MECs after nitrogen exposure, and operating under the condition of hydraulic retention for 24 hours;
step six: because tungsten and molybdenum cannot be completely removed under the hydraulic retention of 24 hours, the organic carbon source is insufficient, the pH value of the effluent is increased, the tungsten and molybdenum deposition is reduced, and the like, 150mg/L of sodium acetate is supplemented to the effluent, the effluent is completely circulated, and H is fed every 0.5 hour2SO4(23.7. mu.M) pH was adjusted.
Step seven: in parallel with step six, the MECs control reactor was run under open circuit conditions, carbon source supplementation and acid addition were the same as in closed circuit conditions, and the effect of loop current on reactor performance was compared accordingly.
Step eight: analyzing the W (VI) and Mo (VI) concentrations in the water every 2h, and calculating the recovery rate of the tungsten and molybdenum metals; simultaneously analyzing the pH, the conductivity and the free biomass of the effluent; analysis of H every 12H2Content, effluent COD content. Calculation of tungsten recovery (. alpha.)WPercent) and molybdenum recovery rate (alpha)MoPercent), tungsten-molybdenum separation coefficient (epsilon), effluent COD removal rate (alpha, percent) and reduction metal energy efficiency (eta)MetalAnd% and energy efficiency (. eta.) for hydrogen generationHydrogen gasAnd (%) are as shown in formulas (5) to (10).
Figure BDA0001711549100000091
Figure BDA0001711549100000093
Figure BDA0001711549100000094
Figure BDA0001711549100000095
In the formula: c0,WAnd C0,Mo、Ct,WAnd Ct,MoThe concentrations (g/L) of W (VI) and Mo (VI) at the initial and running time t of the tungsten-molybdenum organic mixed wastewater respectively; c0,CODAnd Ct,CODRespectively the COD concentration (g/L) of the tungsten-molybdenum organic mixed wastewater at the initial time and the running time t; n isH2H generated for MECs at run time t2Amount (mol); mW、MMo、MO2Relative atomic or molecular masses (g/mol) of tungsten, molybdenum and oxygen, respectively; v is the effective working volume (L) of the MECs; Δ HH2Is H2Heat of combustion (J/mol); Δ GsIs the Gilles free energy (J/mol) of sodium acetate under standard conditions; eW、EMoStandard potential (V) for the reduction of W (VI), Mo (VI); e is the external voltage (V) of the MECs; i is the current (A) in the MECs loop; t is the reactor run time(s); 2 is the number of electrons (mol/mol) obtained by reduction of the unit mass W (VI), Mo (VI); 4 number of electrons obtained by oxygen per amount of substance (mol/mol); 96485 is the Faraday constant (C/mol e)-)。
As a result: the tungsten recovery rate of the stable operation of the MECs under the retention time of 24h is 66.2-73.7%, the molybdenum recovery rate is 74.1-76.5%, and the effluent COD removal rate is 88.6-92.7% (figure 2A); hydrogen production 0.003m3/m3A metal separation coefficient of about 0.38 (FIG. 2B); the corresponding anode potential is 0.03V, the cathode potential is-0.48V, and the loop current is stabilized at 0.35A/m3(FIG. 2C); the pH of the effluent was stabilized at 6.1 and the conductivity of the effluent was 0.71-0.74mS/cm (FIG. 2D).
In order to completely remove and recover tungsten and molybdenum and discharge the contents of metal and organic matters in effluent after reaching the standard, 150mg/L of sodium acetate is supplemented into effluent which is kept for 24 hours and then the effluent is completely circulated and continuously operated, and simultaneously a small amount of H is fed every 0.5 hour2SO4(23.7. mu.M) pH was adjusted. When the operation is continued for 36h, the tungsten is recoveredThe yield reaches 95 percent, the molybdenum recovery rate reaches 98 percent (figure 3A), and the hydrogen production is 0.0028m3/m3D, the COD removal rate of the effluent is reduced to 62.5 percent (figure 4A), but the absolute amount is increased, and when the operation time is 48 hours, tungsten and molybdenum in the effluent are completely removed and recovered (figure 3A), hydrogen production is 0.0026m3/m3(ii)/d (FIG. 4A), COD removal rate reached 97.1% (FIG. 4A); the energy efficiency for reducing metal is 26.6 plus or minus 0.3 percent, and the energy efficiency for producing hydrogen is 4.9 plus or minus 0.1 percent; the reactor is operated again (48-96 h) by reusing the tungsten-molybdenum organic mixed wastewater inlet water, and repeated operation results are obtained (figures 3A and 4A). In conclusion, after the tungsten-molybdenum organic mixed wastewater is operated for 24 hours after the MECs stay for 24 hours, the effluent is completely circularly operated for 24 hours after 150mg/L sodium acetate is added for one time, a small amount of acid is added for regulation in the process, the tungsten and molybdenum contents of the final effluent are only 0.8mg/L and 0.6mg/L respectively, about 30mg/L of COD is remained, the organic matters reach the national first-class A discharge standard (GB18918-2002), and the metal concentration is lower than the concentration limit value of the directly discharged wastewater (GB21/1627 + 2008). In the open circuit control at the same run time of 36h, tungsten-molybdenum recovery was only 27.9% and 35.1%, respectively (fig. 3B), and COD removal was only 29.6% (fig. 4B). The results clearly show that the current-free system obviously reduces the effects of tungsten and molybdenum metal recovery, organic matter removal and hydrogen production in spite of acid feeding and organic carbon source supplement, and the loop current, the acid feeding and the organic carbon supplement have important effects on thoroughly removing tungsten and molybdenum and organic carbon and producing hydrogen by-product in the system. Furthermore, the effluent pH at 36h was 5.1-5.2, with a conductivity of 0.48mS/cm (FIG. 5A), significantly lower than 6.1 and 0.74mS/cm without acid conditioning (FIG. 2D); the effluent pH was higher than 2.4 in the open-circuit control and conductivity was lower than 3.5mS/cm for the open-circuit control (fig. 5B), mainly due to higher tungsten molybdenum removal and more protic hydrogen consumption by hydrogen evolution under closed-circuit conditions (equations (2) - (4)); meanwhile, more tungsten and molybdenum are removed from the liquid phase, and the conductivity of the solution is naturally reduced. The difference between the free biomass of the closed-circuit effluent and the open-circuit effluent is not large and is between 5.9 and 7.6mg/L (FIG. 6), which indicates that the MECs electrode biomembrane stably operates. Whereas the separation coefficient under closed-loop conditions was zero, indicating complete codeposition of tungsten and molybdenum (fig. 6A).
The experiment results show that the MECs can thoroughly treat tungsten-molybdenum organic mixed wastewater, synchronously recover valuable metals and produce hydrogen as a byproduct. The invention overcomes the limitation of treating the mixed wastewater of organic and tungsten-molybdenum or other metals by double-chamber MECs, thoroughly recovers valuable metals, removes organic matters and produces hydrogen as a byproduct, provides a feasible new way for recycling and energizing the tungsten-molybdenum organic mixed wastewater, has better environmental pollution treatment, recycling and energizing effects, and has environmental, ecological, social and economic benefits.

Claims (10)

1. A method for cleanly and thoroughly treating tungsten-molybdenum organic mixed wastewater, synchronously recovering metals and producing hydrogen as a byproduct is characterized by comprising the following steps:
the method comprises the steps of adopting a single-chamber cylindrical microbial electrolytic cell as a reactor, adopting carbon felts as electrode materials for a cathode and an anode, supporting and separating the anode and the cathode by a stainless steel net, adopting the stainless steel net as an electron leading-out/leading-in part, enabling the distance between the cathode and the anode to be 1.0cm, connecting the anode and the cathode with a data collecting system and an external power supply through an external resistor, applying an external voltage of 0.3 ~.2V and an external resistor of 10 ~ omega to the tungsten-molybdenum organic mixed wastewater in the reactor, enabling the pH to be 3.0 ~.0 and the conductivity to be 0.3 ~ mS/cm, enabling the anode and the cathode to be connected with the external power supply through the external resistor, enabling the external voltage to be 0.3 ~.2V and the external resistor to be 10 ~ omega, enabling the effluent of the reactor to completely circulate after organic matters are supplemented, enabling the anode potential to be ‒.4 ~ V and the cathode potential to be 389.
2. The method of claim 1, wherein the concentration of tungsten, molybdenum and organic compounds in the solution in the reactor is 1 ~ 2500 mg/L.
3. The process of claim 1 or 2, wherein the reactor effluent is supplemented with an organic substance selected from sodium acetate or glucose in an amount of 50 ~ 1000 mg/L.
4. The method of claim 1 or 2, wherein the reactor effluent is supplemented with sodium acetate or glucose in an amount of 50 ~ 1000mg/L as an organic substance, and a small amount of sulfuric acid or hydrochloric acid is fed while the reactor is completely circulated in an amount of 2.6 ~ 47.4.4. mu.M.
5. The method of claim 3, wherein the reactor effluent is supplemented with sodium acetate or glucose in an amount of 50 ~ 1000mg/L, and a small amount of sulfuric acid or hydrochloric acid is fed while the reactor effluent is completely circulated in an amount of 2.6 ~ 47.4.4. mu.M.
6. The method according to claim 1, 2 or 5, wherein the tungsten-molybdenum organic mixed wastewater comprises the following components: 178mg/LNa2WO4·2H2O, 266mg/LNa2MoO4·2H2O,1200mg/LCH3COONa,383mg/L(NH4)2SO4,13.6 mg/L KH2PO4(ii) a 12.5mL/L mineral element; 12.5mL/L vitamin; wherein the mineral elements comprise 3.0g/LMgSO4; 0.5g/LMnSO4·H2O;1.0g/LNaCl; 0.1g/LFeSO4·7H2O; 0.1g/LCaCl2·2H2O;0.1g/LCoCl2·6H2O; 0.13g/LZnCl2; 0.01g/LCuSO4·5H2O; 0.01g/LKAl(SO4)2·12H2O;0.01g/LH3BO3; 0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B15.0g/L of vitamin B25.0g/L of vitamin B35.0g/L of vitamin B510.0g/L of vitamin B62.0g/L of vitamin B112.0g/L of vitamin H, 5.0g/L of p-aminobenzoic acid, 5.0g/L of lipoic acid and 1.5g/L of nitrilotriacetic acid.
7. The method according to claim 3, wherein the tungsten-molybdenum organic mixed wastewater comprises the following components: 178mg/LNa2WO4·2H2O, 266mg/LNa2MoO4·2H2O,1200mg/LCH3COONa,383mg/L(NH4)2SO4, 13.6 mg/LKH2PO4(ii) a 12.5mL/L mineral element; 12.5mL/L vitamin; wherein the mineral elements comprise 3.0g/LMgSO4; 0.5g/LMnSO4·H2O;1.0g/LNaCl; 0.1g/LFeSO4·7H2O; 0.1g/LCaCl2·2H2O; 0.1g/LCoCl2·6H2O;0.13g/LZnCl2; 0.01g/LCuSO4·5H2O; 0.01g/LKAl(SO4)2·12H2O; 0.01g/LH3BO3; 0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B15.0g/L of vitamin B25.0g/L of vitamin B35.0g/L of vitamin B510.0g/L of vitamin B62.0g/L of vitamin B112.0g/L of vitamin H, 5.0g/L of p-aminobenzoic acid, 5.0g/L of lipoic acid and 1.5g/L of nitrilotriacetic acid.
8. The method according to claim 4, wherein the tungsten-molybdenum organic mixed wastewater comprises the following components: 178mg/LNa2WO4·2H2O, 266mg/LNa2MoO4·2H2O,1200mg/LCH3COONa,383mg/L(NH4)2SO4, 13.6 mg/LKH2PO4(ii) a 12.5mL/L mineral element; 12.5mL/L vitamin; wherein the mineral elements comprise 3.0g/LMgSO4; 0.5g/LMnSO4·H2O;1.0g/LNaCl; 0.1g/LFeSO4·7H2O; 0.1g/LCaCl2·2H2O; 0.1g/LCoCl2·6H2O;0.13g/LZnCl2; 0.01g/LCuSO4·5H2O; 0.01g/LKAl(SO4)2·12H2O; 0.01g/LH3BO3; 0.024g/LNiCl2·6H2O and 0.024g/LNa2WO4·2H2O; the vitamins include 5.0g/L vitamin B15.0g/L of vitamin B25.0g/L of vitamin B35.0g/L of vitamin B510.0g/L of vitamin B62.0g/L of vitamin B112.0g/L of vitamin H, 5.0g/L of p-aminobenzoic acid, 5.0g/L of lipoic acid and 1.5g/L of nitrilotriacetic acid.
9. The method of claim 1, 2, 5, 7 or 8, characterized in that the microbial electrolysis cell is inoculated with clarification tank sludge of a sewage treatment plant as a bacterial source for acclimating electrochemically active microorganisms, the pH of the clarification tank sludge is 7.0 ~ 8.0.0, the conductivity is 1.0 ~ 2.0.0 mS/cm, the suspended solids are 10 ~ 20g/L, and the chemical oxygen demand is 100 ~ 1000 mg/L.
10. The method of claim 6, wherein the microbial electrolysis cell is inoculated into clarifier sludge of a sewage treatment plant as a bacteria source for domesticating the electrochemically active microorganisms, the clarifier sludge has a pH of 7.0 ~ 8.0.0, an electrical conductivity of 1.0 ~ 2.0.0 mS/cm, a suspended solid content of 10 ~ 20g/L and a chemical oxygen demand of 100 ~ 1000 mg/L.
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