WO2018184391A1 - 一种磁分离同步去除络合态重金属和有机物的方法 - Google Patents

一种磁分离同步去除络合态重金属和有机物的方法 Download PDF

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WO2018184391A1
WO2018184391A1 PCT/CN2017/111276 CN2017111276W WO2018184391A1 WO 2018184391 A1 WO2018184391 A1 WO 2018184391A1 CN 2017111276 W CN2017111276 W CN 2017111276W WO 2018184391 A1 WO2018184391 A1 WO 2018184391A1
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wastewater
reaction
catalyst
tank
concentration
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French (fr)
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吴德礼
田泽源
张亚雷
马鲁铭
朱劲松
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同济大学
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Priority claimed from CN201710216650.3A external-priority patent/CN106927547B/zh
Priority claimed from CN201710565332.8A external-priority patent/CN107324587B/zh
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Publication of WO2018184391A1 publication Critical patent/WO2018184391A1/zh
Priority to US16/594,427 priority Critical patent/US11117822B2/en

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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C02F1/705—Reduction by metals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F2001/5218—Crystallization
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/02—Specific form of oxidant
    • C02F2305/023—Reactive oxygen species, singlet oxygen, OH radical

Definitions

  • the invention belongs to the field of environmental protection water pollution control, and particularly relates to a method for synchronously removing complex heavy metals and organic substances by magnetic iron-based materials, and is a green oxidation water pollution control technology.
  • the traditional treatment methods include redox method, chemical precipitation method, adsorption method, ion exchange method and membrane separation method.
  • the chemical precipitation method includes a sulfide precipitation method, a chelate precipitation method, and the like, and is combined with a heavy metal in a complexed heavy metal by adding an S 2 ⁇ or a chelating agent to form a stable precipitate to be separated from the complexing agent.
  • the treatment effect is not good, the amount of mud produced is large, and the sulfide itself is not easy to separate, and it will cause secondary pollution.
  • the adsorption method and the ion exchange method perform adsorption and separation without changing the chemical form of the complex heavy metal, but have the disadvantages of limited removal capacity and difficulty in regeneration.
  • the membrane separation method can effectively remove the electrolyte, but the water quality requirements are high, and the deposition of metal hydroxides, carbonate compounds and the like easily lead to membrane fouling, which requires frequent cleaning and replacement.
  • the reduction method reduces the heavy metal ions in the complexed heavy metal by a reducing agent to precipitate a low-valent heavy metal compound or a simple substance, thereby separating from the complexing agent to achieve cleavage.
  • the above method can only achieve the failure to decompose the organic substances coexisting in the wastewater.
  • Oxidation method uses various oxidants such as H 2 O 2 , ozone, sodium hypochlorite, ferrate, and permanganate to oxidatively decompose the complexing agent in the complexed heavy metal to reduce the organic content.
  • the released free metal ions can be further removed by subsequent chemical precipitation.
  • this method requires a large amount of oxidant and a high cost. Therefore, it is imperative to find a method that is low in cost and at the same time achieves clogging and oxidative degradation of organic matter.
  • Iron-based materials are used for the removal of various pollutants, including organic matter and heavy metals, due to various reactivity such as coagulation, adsorption, catalysis, redox and the like.
  • iron-based materials have good reducibility.
  • the heavy metals in the complexed heavy metals can be reduced and separated under pH neutral conditions to achieve the clogging.
  • Peak uses iron filings as a reducing agent to treat EDTA solution Copper ion ( ⁇ , et al. Treatment of complexed copper ions in EDTA solution by iron filings internal electrolysis method [J]. Chinese Journal of Environmental Science, 2011, 31(5): 897-904.).
  • Patent of invention "treatment method of wastewater containing complexed copper (201110447955.8)” uses ferrous sulfate as a reducing agent, first converts copper into cuprous ion under acidic conditions, and then converts to copper hydroxide under alkaline conditions or Precipitation of cuprous hydroxide.
  • the pH of the solution needs to be adjusted, and the process of acid-based alkali is experienced, the reaction process is long, and the reduction of divalent iron ions is weak, and the iron filings are easy to agglomerate.
  • only heavy metals are removed, and the organic matter therein cannot be effectively removed.
  • U.S. Patent 7,220,360 B2 treats surface-polishing wastewater by removing organic matter by a conventional Fenton reaction and removing heavy metal ions by ferrite.
  • US Patent 7785038B2 uses zero-valent iron and persulfate to degrade organic matter in soil and groundwater, and has good removal effects on volatile and semi-volatile organic compounds such as trichloroethylene and dichloromethane.
  • U.S. Patent 4,724,084 processes aircraft manufacturing wastewater by continuous chemical regulation, and the removal of heavy metals and organics is achieved by two consecutive stages of Fenton reaction, lime neutralization, and multimeric coagulation.
  • these technologies additionally add oxidizing agents such as H 2 O 2 , persulfate, and ferrate, which increase the processing cost.
  • Molecular oxygen in the air is a green and environmentally friendly oxidant because of its low cost, wide source and no secondary pollution. Oxygen itself cannot oxidize organic pollutants, but activation of molecular oxygen by a catalyst can produce active species such as O 2 ⁇ - , H 2 O 2 , ⁇ OH, etc. for oxidative degradation of organic matter.
  • existing molecular oxygen activation techniques are generally carried out by preparing complex metal catalysts, which are expensive and difficult to use productively.
  • the development of molecular oxygen activation technology that is beneficial to engineering applications is an important research direction. Reports on the activation of molecular oxygen to produce free radicals by iron-based materials have gradually increased in recent years.
  • the object of the present invention is to solve the problems and deficiencies of the existing industrial wastewater treatment technology of coexisting heavy metal and organic matter by using a new reaction process by generating a novel magnetic iron-based material in situ.
  • the invention generates an iron-based material in situ by adding ferrous species to the wastewater and the original heavy metal ions in the wastewater.
  • Iron-based materials rich in low-cost transition metals have good catalytic ability to activate molecular oxygen to degrade organic matter.
  • Adding magnetic Fe 3 O 4 nanoparticles as magnetic species to the material can improve the effect of adsorbing heavy metals, and can enhance the solid-liquid separation effect of the wastewater in the magnetic separation reaction, thereby saving reaction time.
  • concentration of carbonate in the material By regulating the concentration of carbonate in the material, the reducibility of the iron-based material can be further improved, and the subsequent activation of the molecular oxygen reaction can be promoted.
  • the reaction process mainly includes four steps of anoxic reaction, incubation reaction, aerobic reaction and magnetic separation reaction.
  • anoxic reaction By regulating dissolved oxygen, under the condition of anoxic conditions, the reduction of the complexed heavy metal can be achieved by the reduction of the iron-based material, and the heavy metal ions are removed, and the catalyst with activated molecular oxygen function is generated in situ.
  • the unique incubation reaction achieves high-density and ultra-uniform reaction of the catalyst sludge and improves the catalytic effect of the catalyst.
  • the iron-based catalyst can catalyze the production of strong oxidizing species by molecular oxygen and oxidatively degrade organic pollutants in wastewater.
  • the wastewater is subjected to rapid solid-liquid separation in the magnetic separation reaction zone to ensure the quality of the effluent.
  • the object of the present invention is to solve the problems and deficiencies of the existing industrial wastewater treatment technology of complex metal and organic materials coexisting, and to provide a completely new method.
  • the reduction of the nucleation simultaneously generates a catalyst with activated molecular oxygen function, which catalyzes the production of strong oxidizing species by molecular oxygen. It not only realizes the removal of heavy metal crystal precipitation, but also catalyzes the oxidative degradation of organic pollutants, thereby creatively achieving green oxidation, shortening the treatment process, improving the processing efficiency, reducing the economic cost, and promoting the industrial application of technology.
  • a method for synchronously removing complex heavy metals and organic substances in wastewater by magnetic iron-based materials using the following steps:
  • Anoxic reaction ferrous species are added to industrial wastewater containing complex heavy metals and organic matter, and then the above wastewater is added to an anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0. Then, according to the concentration of the original CO 3 2- in the wastewater, a 2 mol/L Na 2 CO 3 solution is added to make the concentration of CO 3 2- in the wastewater more than 500 mg/L, and 2 g/L of Fe 3 O 4 nanoparticles are added, and the reaction is carried out. 10-30 min to generate a higher activity FeM catalyst in situ;
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and the oxygenation reaction in the aerobic tank is performed with an aeration amount of 2-5 L/(min ⁇ L wastewater) for 30-120 min, using the high generated in the hatchery tank.
  • the active catalyst activates molecular oxygen in water to generate a strong oxidizing species of hydroxyl radicals to oxidize and remove organic matter in the wastewater, and aerating with air or pure oxygen;
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to be 500-2000G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 2-5%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • the heavy metal ions contained in the industrial wastewater are one or more of Cu, Ag, Co, Ni, Pd, Cr or Mn; the complexing agent is citric acid, tartaric acid, ethylenediaminetetraacetic acid (EDTA) or ammonia.
  • EDTA ethylenediaminetetraacetic acid
  • NTA triacetic acid
  • the ferrous species is selected from one or more of FeSO 4 ⁇ 7H 2 O, FeSO 4 or FeCl 2 .
  • the ratio of the molar concentration of Fe in the ferrous species to the sum M of the molar concentrations of all metal ions in the wastewater is greater than 2:1.
  • the ratio of the mass concentration of Fe to the COD concentration of the wastewater in the ferrous species is greater than 3:1.
  • the sodium dithionite dosage is 10-100 mg/L.
  • the invention utilizes the addition of Fe(II) and the heavy metal ions in the solution to form the FeM catalyst in situ, and under the condition of isolating oxygen, the structural state iron plays the reaction property of adsorption and reduction.
  • Na 2 CO 3 solution to control the concentration of the waste water of CO 3 2-, CO 3 2- ion since the potential (Z / r, charge / radius ) in the large anion, a larger attraction to hydroxyl groups, and Fe (II) It has strong affinity and enters the structural ferrous complex structure layer, which can enhance the reducing ability of the structural ferrous complex and reduce the redox potential of the system.
  • the catalyst By introducing air and oxygen into the wastewater, the catalyst reacts with molecular oxygen to produce active oxidizing substances such as O 2 ⁇ - , H 2 O 2 , ⁇ OH, which can degrade organic pollutants.
  • active oxidizing substances such as O 2 ⁇ - , H 2 O 2 , ⁇ OH
  • the organic ligands such as EDTA can accelerate the Fenton reaction and promote the formation of active oxides by coordinating with Fe(II) and Fe(III).
  • the heavy metal ions released by oxygen oxidation are removed by alkali precipitation.
  • the structural ferrous complex reduces some Cu(II) in Cu-EDTA to Cu(0).
  • the structural state The ferrous complex reduces the reduction ability of copper and gradually reduces it to Cu(I).
  • Cu(II) in Cu-EDTA is separated from the complexing agent EDTA by being reduced to solid Cu(0) and Cu(I), and is removed by solid-liquid separation.
  • the reaction equation for the Cu-EDTA cleavage process is as follows:
  • the low-cost new Cu catalyst has good ability to activate molecular oxygen, and the reaction equation is as follows:
  • the anoxic conditions favor the formation of the catalyst and fully ensure the reducing ability of the catalyst.
  • the aerobic tank fully provides oxygen as an oxidant to degrade organic pollutants by aeration.
  • the suspension layer in the hatching tank is mixed into a super-saturated solution, whereby the super-saturated solution is super-uniformly precipitated to prevent local unevenness of the precipitating agent, thereby improving the catalytic activity of the catalyst.
  • the addition of sodium dithionite not only improves the stabilizing removal ability of heavy metals, but also produces a product which can enhance the activated molecular oxygen effect of the catalyst.
  • the present invention has the following advantages:
  • the prepared iron-based material has special reduction and adsorption properties.
  • the ferrous complex used contains a large amount of anion ligand such as a hydroxyl group and an anion intercalation such as CO 3 2- , which results in a very high reduction activity and can reduce various heavy metal ions of the wastewater, so that a certain structure is controlled.
  • Formal ferrous complexes are a key technology of the present invention.
  • reaction conditions are mild, and the catalytic oxidation reaction is carried out under normal temperature and normal pressure and pH neutral conditions.
  • the prepared structural ferrous material has magnetic properties, and the separation speed is fast when the solid-liquid separation is performed, the separation effect is good, and the effluent water quality is ensured.
  • the produced sludge is easily compressed, and the separated magnetic species can be recycled.
  • the innovative design of the hatching tank achieves high-density and ultra-uniform reaction of the catalyst sludge, which is beneficial to the stability of the catalyst and the improvement of the reactivity.
  • Reflow of FeM-containing sludge can enrich the catalyst and ensure the content and quality of the catalyst in the system.
  • Figure 1 is a process flow diagram of the present invention.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in the aerobic tank with an aeration amount of 2L/(min ⁇ L wastewater) for 120 minutes, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to be 500 G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 5%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • Anoxic reaction 1 L of the industrial wastewater was taken, and FeSO 4 ⁇ 7H 2 O 4.17 g was added thereto, and the molar concentration of Fe was 15 mmol/L.
  • the molar concentration of heavy metal ions in wastewater is M. 5.08mmol/L, the molar ratio of Fe to M is 3:1, which meets the technical characteristics of more than 2:1; the COD concentration in wastewater is 168mg/L, Fe concentration and COD concentration. The ratio is 5:1, which meets the technical characteristics of more than 3:1.
  • the adjusted wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in the aerobic tank with an aeration amount of 2L/(min ⁇ L wastewater) for 120 minutes, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to 1000 G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 5%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • Anoxic reaction 1 L of the industrial wastewater was taken, and 5.56 g of FeSO 4 ⁇ 7H 2 O was added thereto, and the molar concentration of Fe was 20 mmol/L.
  • the molar concentration of heavy metal ions in wastewater is 7.0 mmol/L, and the molar ratio of Fe to M is 2.9:1, which is in line with the technical characteristics of more than 2:1; the COD concentration in wastewater is 292 mg/L, Fe concentration and COD concentration.
  • the ratio is 3.8:1, which meets the technical characteristics of more than 3:1.
  • the adjusted wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in the aerobic tank with an aeration amount of 2L/(min ⁇ L wastewater) for 120 minutes, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to 1000 G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 5%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • Anoxic reaction 1 L of the industrial wastewater is taken, because the mass concentration of Fe in the wastewater is 3148 mg/L, that is, the molar concentration is 56 mmol/L.
  • the molar concentration M of heavy metal ions in wastewater is 2.1mmol/L, the molar ratio of Fe to M is 26.2:1, which meets the technical characteristics of more than 2:1; the COD concentration in wastewater is 447mg/L, the mass concentration of Fe and COD
  • the concentration ratio is 7.0:1, which meets the technical characteristics of more than 3:1, so Fe ions are no longer added to the wastewater.
  • the adjusted wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in the aerobic tank with aeration of 3L/(min ⁇ L wastewater) for 30 minutes, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to 1500G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 2%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • Anoxic reaction 1 L of the industrial wastewater was taken, and 16.7 g of FeSO 4 ⁇ 7H 2 O was added thereto, and the molar concentration of Fe was 60 mmol/L.
  • the molar concentration of heavy metal ions in wastewater is M0.42mmol/L, the molar ratio of Fe to M is 2.9:1, which meets the technical characteristics of more than 2:1;
  • the COD concentration in wastewater is 1050mg/L, Fe concentration and COD
  • the concentration ratio is 3.2:1, which meets the technical characteristics of greater than 3:1.
  • the adjusted wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in an aerobic tank with an aeration amount of 5 L/(min ⁇ L wastewater) for 60 min, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to 2000G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 3%, which realizes the enrichment of the catalyst and induces the formation of the catalyst in the anoxic tank. Separation and reuse. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • Anoxic reaction 1 L of the industrial wastewater was taken, and 8.34 g of FeSO 4 ⁇ 7H 2 O was added thereto, and the molar concentration of Fe was 30 mmol/L.
  • the molar concentration of heavy metal ions in wastewater is 13.8mmol / L, the molar ratio of Fe to M is 2.2:1, which meets the technical characteristics of more than 2:1;
  • the concentration of COD in wastewater is 145mg / L, the concentration of Fe and COD
  • the concentration ratio is 11.6:1, which meets the technical characteristics of greater than 3:1.
  • the adjusted wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in an aerobic tank with an aeration amount of 2 L/(min ⁇ L wastewater) for 60 min, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen which produces strong oxidizing species such as hydroxyl radicals, oxidizes and removes organic matter from wastewater.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to above 8.0, and controls the magnetic field strength to 2000G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 4%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species is separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.
  • a magnetic iron-based material synchronously removes complex heavy metals and organic substances in wastewater, and the process thereof is as shown in FIG. 1, and the following steps are taken:
  • Anoxic reaction The influent of industrial wastewater containing complex heavy metals such as Cu, Ag, Co and the like, enters and exits the primary settling tank 1 for preliminary precipitation, and then enters the conditioning tank 2 to contain Cu, Ag, Co.
  • the ferrous phase is added to the industrial wastewater of the complex heavy metal and organic matter.
  • FeSO 4 is added, and the molar ratio of Fe to the molar concentration of all metal ions in the wastewater is 3:1, and the mass of Fe is The ratio of the concentration to the COD concentration of the wastewater is 4:1, and then the above wastewater is added to the anoxic tank 3, and the dissolved oxygen concentration of the wastewater is controlled to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • Aerobic reaction the stabilized catalyst enters the aerobic tank 4, and is oxygenated in the aerobic tank 4 with an aeration amount of 2 L/(min ⁇ L wastewater) for 120 min, using the high activity catalyst produced in the hatchery tank.
  • Magnetic separation reaction The wastewater after the end of the aerobic tank 4 reaction enters the magnetic separation reactor 5, and the pH of the wastewater is adjusted to 9 by adding alkali to control the magnetic field strength to 500 G to achieve solid-liquid separation.
  • the formation of the catalyst and the excess sludge are discharged.
  • the concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor 5 were analyzed.
  • a method for synchronously removing complex heavy metals and organic substances in wastewater by magnetic iron-based materials using the following steps:
  • Anoxic reaction FeCl 2 is added to industrial wastewater containing complex heavy metals and organic substances such as Pd and Cr.
  • the molar ratio of Fe to the molar concentration of all metal ions in the wastewater is 4:1
  • Fe The ratio of the mass concentration to the COD concentration of the wastewater is 5:1
  • the above wastewater is added to the anoxic tank to control the dissolved oxygen concentration of the wastewater to be less than 1.0 mg/L, and the pH is adjusted to 7.0.
  • a 2 mol/L Na 2 CO 3 solution is added to make the concentration of CO 3 2- in the wastewater more than 500 mg/L, and 2 g/L of Fe 3 O 4 nanoparticles are added, and the reaction is carried out. 30 min to generate a higher activity FeM catalyst in situ;
  • Aerobic reaction the stabilized catalyst enters the aerobic tank, and is oxygenated in an aerobic tank with an aeration amount of 5 L/(min ⁇ L wastewater) for 30 min, and the activated water is activated by the high activity catalyst generated in the hatching tank.
  • Molecular oxygen a strong oxidizing species that produces hydroxyl radicals, oxidizes and removes organic matter from wastewater, and aerates with pure oxygen;
  • Magnetic separation reaction The wastewater after the end of the aerobic tank reaction enters the magnetic separation reactor, adjusts the pH of the wastewater to 10, and controls the magnetic field strength to 1000 G to achieve solid-liquid separation. Part of the sludge is returned to the anoxic tank, and the reflux ratio is 5%. The catalyst is enriched and the catalyst is formed in the anoxic tank, and the magnetic species are separated and reused. The concentration of heavy metal ions and COD in the effluent of the magnetic separation reactor were analyzed.

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Abstract

一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，包括缺氧反应、孵化反应、好氧反应、磁分离反应等四个步骤，在缺氧条件下通过利用铁基材料的还原性实现络合态重金属的还原破络，同时原位生成具有活化分子氧功能的催化剂。在好氧条件下通过铁基催化剂催化分子氧产生强氧化性物种，氧化降解有机污染物。并通过磁分离强化污染物的去除。以废治废实现绿色氧化、缩短处理工序，提高处理效率，降低经济成本，推动技术产业化应用。

Description

一种磁分离同步去除络合态重金属和有机物的方法 技术领域
本发明属于环境保护水污染治理领域，具体涉及一种磁性铁基材料同步去除络合态重金属和有机物的方法，是一种绿色氧化水污染治理技术。
背景技术
络合态重金属在工业废水中广泛存在，主要包括金属冶炼业、印刷电路板业、印染业、造纸业、电镀业等行业。当重金属离子与EDTA、酒石酸、柠檬酸、NTA等络合剂结合后，水溶性较高，传统的加碱沉淀法无法将其去除，是废水处理的难点。不仅如此，废水中常常含有大量有机物，需要同时考虑去除。
针对络合态重金属，传统的处理方法主要有氧化还原法、化学沉淀法、吸附法、离子交换法、膜分离法等。化学沉淀法包括硫化物沉淀法、螯合沉淀法等，通过添加S2-或螯合剂与络合态重金属中的重金属结合，形成稳定的沉淀，从而与络合剂分离。但处理效果不佳、产泥量大，而硫化物本身不易分离，且会带来二次污染。吸附法、离子交换法在不改变络合态重金属化学形态的条件下进行吸附和分离，但存在去除容量有限、再生困难的弊端。膜分离法能够有效去除电解质，但对进水水质要求较高，而且金属氢氧化物、碳酸盐化合物等沉积容易导致膜污染，需要经常清洗更换。还原法通过还原剂使络合态重金属中的重金属离子还原析出低价态的重金属化合物或单质，从而与络合剂分离实现破络。以上方法仅能实现破络而无法降解废水中共存的有机物。氧化法破络使用H2O2、臭氧、次氯酸钠、高铁酸盐、高锰酸盐等各种氧化剂可以氧化降解络合态重金属中的络合剂，降低有机物含量。而释放出的游离金属离子，可以通过后续的化学沉淀法进一步去除。然而该方法需要氧化剂量大、成本高。因此寻求一种成本低廉，并同时实现破络并氧化降解有机物的方法势在必行。
铁基材料由于混凝、吸附、催化、氧化还原等多种反应活性，被用于多种污染物的去除，包括有机物与重金属。首先，铁基材料具有较好的还原性。充分利用结构态铁基材料的还原性可以在pH中性条件下将络合态重金属中的重金属还原分离出来，实现破络。鞠峰使用铁屑作为还原剂处理EDTA溶液中络 合铜离子(鞠峰,等.铁屑内电解法处理EDTA溶液中络合铜离子[J].环境科学学报,2011,31(5):897-904.)。络合铜需要首先在酸性条件下进行电化学反应和置换反应，之后在碱性条件下发生混凝反应和新的络合反应以完成破络。发明专利，“含络合铜的废水的处理方法(201110447955.8)”使用硫酸亚铁作为还原剂，先在酸性条件下将铜转换为亚铜离子，再在碱性条件下转化为氢氧化铜或氢氧化亚铜沉淀。但是以上两种方法反应流程均需要调节溶液pH，经历先酸后碱的过程，反应流程长，且二价铁离子还原性较弱，铁屑易结块。而且只是去除重金属，不能有效去除其中的有机物。
一些专利和文献通过外加铁基材料和氧化剂，产生活性氧化性物种从而降解有机物。美国专利7220360B2处理表面抛光废水，一方面通过传统芬顿反应去除有机物，另一方面通过铁氧体去除重金属离子。美国专利7785038B2采用零价铁和过硫酸盐降解土壤与地下水等环境中的有机物，其对于三氯乙烯、二氯甲烷等挥发性、半挥发性有机物具有良好的去除效果。美国专利4724084通过连续化学调控处理飞机制造废水，通过连续两级的芬顿反应、石灰中和法与多聚体混凝法实现重金属和有机物的去除。然而这些技术额外添加了H2O2、过硫酸盐、高铁酸盐等氧化剂，增加了处理成本。
空气中的分子氧，成本低廉、来源广泛、无二次污染，是绿色环保的氧化剂。氧气本身无法氧化有机污染物，但通过催化剂活化分子氧可以产生活性物种，例如O2 ·-、H2O2、·OH等进行有机物的氧化降解。但现有的分子氧活化技术一般是通过制备复杂的金属催化剂进行，价格昂贵，而且难以生产性使用。开发有利于工程应用的分子氧活化技术是重要的研究方向。关于铁基材料活化分子氧产自由基降解有机物的报道近年来逐渐增多。艾智慧等人(Ai,Z.,et al.,Core–Shell Structure Dependent Reactivity of Fe@Fe2O3Nanowires on Aerobic Degradation of 4-Chlorophenol.Environ.Sci.Technol.,2013.47(10):p.5344-5352.)采用Fe@Fe2O3纳米线活化分子氧降解4-氯酚。美国专利8048317B2中使用零价铁或Fe-Pd、Fe-Cu、Fe-Co、Fe-Ni等含有零价铁的双金属混合物，在有氧条件下产生·OH氧化降解有机物。然而，反应需要在酸性条件下进行，且需要外加零价铁或双金属，增加了成本。
发明内容
本发明的目的是通过原位生成一种新型磁性铁基材料，采用一种新的反应流程解决现有络合态重金属与有机物共存工业废水处理技术存在的难题和不足。
本发明通过向废水中添加亚铁物种与废水中原有的重金属离子原位生成铁基材料。富含低价态过渡金属的铁基材料具有良好的催化能力，能够活化分子氧降解有机物。向材料中添加具有磁性的Fe3O4纳米颗粒作为磁种，可以提高吸附重金属的效果，并可以在磁分离反应中增强废水的固液分离效果，节约反应时间。通过调控材料中的碳酸根浓度，能够进一步提高铁基材料的还原性，促进后续活化分子氧反应。
反应流程主要包括缺氧反应、孵化反应、好氧反应、磁分离反应等四个步骤。通过调控溶解氧，在缺氧条件下，利用铁基材料的还原性可以实现络合态重金属的还原破络，去除重金属离子，同时原位生成具有活化分子氧功能的催化剂。独特的孵化反应实现催化剂污泥高密度超均匀反应，提高催化剂的催化效果。通过曝气提供分子氧，铁基催化剂能够催化分子氧产生强氧化性物种，氧化降解废水中的有机污染物。最终废水在磁分离反应区实现快速固液分离，保证出水水质。
本发明的目的是为了解决现有络合态重金属与有机物共存工业废水处理技术存在的难题和不足，提供一种全新的方法。通过废水中重金属离子的调控，还原破络的同时原位生成具有活化分子氧功能的催化剂，催化分子氧产生强氧化性物种。不仅实现重金属结晶沉淀去除，同时催化氧化降解有机污染物，从而创造性地以废治废实现绿色氧化、缩短处理工序，提高处理效率，降低经济成本，推动技术产业化应用。
本发明的目的可以通过以下技术方案来实现：
一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，采用以下步骤：
(1)缺氧反应：向含有络合态重金属和有机物的工业废水中加入亚铁物种，然后将上述废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入2mol/L的Na2CO3溶液，使废水中的 CO3 2-浓度大于500mg/L，并加入2g/L的Fe3O4纳米颗粒，反应10-30min，以原位生成活性较高的FeM催化剂；
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入连二亚硫酸钠，慢速搅拌60min进行催化剂的老化稳定；
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2-5L/(min·L废水)的曝气量充氧反应30-120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基的强氧化性物种氧化去除废水中的有机物，采用空气或纯氧气进行曝气；
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为500-2000G，实现固液分离。部分污泥回流到缺氧池，回流比为2-5％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
所述的工业废水所含重金属离子为Cu、Ag、Co、Ni、Pd、Cr或Mn中的一种或几种；络合剂为柠檬酸、酒石酸、乙二胺四乙酸(EDTA)或氨三乙酸(NTA)中一种或几种。
所述的亚铁物种选自FeSO4·7H2O、FeSO4或FeCl2中的一种或几种。
所述的亚铁物种中Fe摩尔浓度与废水中所有金属离子摩尔浓度之和M的比例大于2:1。
所述的亚铁物种中Fe的质量浓度与废水COD浓度之比大于3:1。
所述的连二亚硫酸钠投加量为10-100mg/L。
本发明利用外加Fe(II)与溶液中的重金属离子原位生成FeM催化剂，在隔绝氧气的条件下，结构态亚铁发挥吸附、还原等反应性质。通过添加Na2CO3溶液可以控制废水中CO3 2-的浓度，由于CO3 2-在各阴离子中离子势(Z/r，charge/radius)较大，对羟基的引力较大，与Fe(II)有较强的亲和力，进入结构态亚铁络合物结构层中，可以增强结构态亚铁络合物的还原能力，降低体系的氧化还原电位。在还原过程中，重金属离子生成了过渡中间态物质以及零价态金属，例如Cu2O、Cu0、Ag0、Pd0、Ni0等，一方面，这些低价态的新生金属催化剂本身具有较高的活化催化能力；另一方面，各种微纳米颗粒的新生态金属 附着在亚铁络合物表面，能够催化亚铁络合物，进一步增强亚铁络合物的还原能力，从而形成较高活性的FeM复合物活化分子氧。通过向废水通入空气、氧气，催化剂与分子氧反应产生O2 ·-、H2O2、·OH等活性氧化物质，可以降解有机污染物。且EDTA等有机配体本身可以通过与Fe(II)、Fe(III)发生配位作用，加速Fenton反应，促进活性氧化物生成。最后，由于氧气氧化被释放的重金属离子再通过加碱沉淀去除。
以Cu-EDTA为例，在较强的还原性氛围下，结构态亚铁络合物将Cu-EDTA中的部分Cu(II)还原为Cu(0)，随着ORP的升高，结构态亚铁络合物对铜的还原能力降低，逐渐将其还原为Cu(I)。Cu-EDTA中Cu(II)由于被还原为固态的Cu(0)和Cu(I)，而与络合剂EDTA分离，并通过固液分离得到去除。Cu-EDTA破络过程的反应方程式如下：
3CuII-EDTA+7＝Fe(II)+9H2O→
Cu(0)↓+Cu2O↓+2Fe2O3·H2O↓+3H2O↓+3FeII-EDTA+14H+
低价态新生Cu催化剂具有良好的活化分子氧的能力，反应方程式如下：
2Cu+O2+2H2O→2Cu(I)+H2O2+2OH-
Cu+O2+2H2O→Cu(II)+H2O2+2OH-
Cu(I)+H++H2O2→Cu(II)+·OH+H2O
Cu(II)+H2O2→Cu(I)+·O2 -+2H+
在反应流程里，缺氧条件有利于催化剂的形成，并充分保证催化剂的还原能力。而好氧池通过曝气充分提供氧气作为氧化剂降解有机污染物。其中，孵化池中悬浮层混合成为超饱和溶液，由此超饱和溶液得到超均匀沉淀，防止沉淀剂出现局部不均匀，从而提高催化剂的催化活性。投加连二亚硫酸钠，不但可以提高重金属的稳定化去除能力，而且生成产物能提高催化剂的活化分子氧效果。
与现有技术相比，本发明具有以下优点：
(1)实现了废水中重金属和有机物的同时去除，工序简单，处理效率高，而且进行废物综合利用，减少药剂投加量，实现绿色经济的氧化技术。
(2)所制备的铁基材料具有特殊的还原和吸附性能。所使用的亚铁络合物由于含有了大量的羟基等给电子配体以及CO3 2-等阴离子插层，而导致还原活性 非常高，可以还原废水的多种重金属离子，所以控制生成一定结构形态的亚铁络合物是本发明的关键技术。
(3)反应条件温和，催化氧化反应在常温常压、pH中性条件下进行。
(4)充分利用废水中原有的重金属离子原位生成催化剂，不仅保证催化剂活性，提高了有机物的降解效率；同时实现以废治废，节约成本，便于工程应用。
(5)所制备的结构态亚铁材料具有磁性，进行固液分离时分离速度快、分离效果效果好，保证出水水质。产生的污泥易压缩、分离后的磁种可循环使用。
(6)使用氧气作为氧化剂降解有机物，替代H2O2、臭氧、高锰酸盐、过硫酸盐等氧化剂。不仅成本低廉，并且来源广泛，绿色无污染。
(7)孵化池的创新设计实现催化剂污泥高密度超均匀反应，有利于催化剂的稳定和提高反应活性。
(8)含FeM污泥回流可以使催化剂富集，保证体系中催化剂的含量和质量。
(9)当废水原水中含有较高浓度Fe时，可以直接投加碱液调节pH，原位生成各重金属催化体系进行反应，从而节省Fe(II)的用量。
附图说明
图1为本发明的工艺流程图。
图中，1-初沉池、2-调节池、3-缺氧池、4-好氧池、5-磁分离反应器、6-孵化池、7-磁选机。
具体实施方式
下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明，但不以任何形式限制本发明。应当指出的是，对本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进。这些都属于本发明的保护范围。
实施例1
取模拟废水，该水样中主要含有络合态铜，重金属与络合剂摩尔比为 Cu:EDTA＝1:1，EDTA-Cu浓度为0.4mmol/L，pH＝5.0，该水样中污染物初始浓度与去除率见表1。
(1)缺氧反应：取该模拟废水1L，向其中加入FeSO4·7H2O 2.22g，则Fe的摩尔浓度为8mmol/L。废水中重金属离子的摩尔浓度总和M为0.4mmol/L，则Fe与M摩尔比为20:1，符合大于2:1的技术特征；废水中COD浓度为130mg/L，Fe质量浓度与COD浓度之比为3.4:1，符合大于3:1的技术特征。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入5.0mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为600mg/L，并加入2g/L的Fe3O4纳米颗粒，反应10min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入30mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2L/(min·L废水)的曝气量充氧反应120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为500G，实现固液分离。部分污泥回流到缺氧池，回流比为5％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表1 FeM催化剂去除重金属与有机物的效果
污染物 Cu COD
初始浓度(mg/L) 25.6 130
去除率(％) 100 91
实施例2
取某线路板制造厂，pH＝1.9。该水样中污染物初始浓度与去除率见表2。
(1)缺氧反应：取该工业废水1L，向其中加入FeSO4·7H2O 4.17g，则Fe的摩尔浓度为15mmol/L。废水中重金属离子的摩尔浓度总和M为5.08mmol/L，则Fe与M摩尔比为3:1，符合大于2:1的技术特征；废水中COD浓 度为168mg/L，Fe质量浓度与COD浓度之比为5:1，符合大于3:1的技术特征。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入5mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为600mg/L，并加入2g/L的Fe3O4纳米颗粒，反应10min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入50mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2L/(min·L废水)的曝气量充氧反应120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为1000G，实现固液分离。部分污泥回流到缺氧池，回流比为5％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表2 FeM催化剂去除重金属与有机物的效果
污染物 Cu Ni Pb COD
初始浓度(mg/L) 33.4 252 54.2 168
去除率(％) 100 92 100 87
实施例3
取某电镀废水，pH＝3.7，该水样中污染物初始浓度与去除率见表3。
(1)缺氧反应：取该工业废水1L，向其中加入FeSO4·7H2O 5.56g，则Fe的摩尔浓度为20mmol/L。废水中重金属离子的摩尔浓度总和M为7.0mmol/L，则Fe与M摩尔比为2.9:1，符合大于2:1的技术特征；废水中COD浓度为292mg/L，Fe质量浓度与COD浓度之比为3.8:1，符合大于3:1的技术特征。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入5mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为600mg/L，并加入2g/L的Fe3O4纳米颗粒，反应20min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入50mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2L/(min·L废水)的曝气量充氧反应120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为1000G，实现固液分离。部分污泥回流到缺氧池，回流比为5％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表3 FeM催化剂去除重金属与有机物的效果
污染物 Cu Ag Co Cd Ni COD
初始浓度(mg/L) 78.2 0.328 1.15 3.31 335 292
去除率(％) 98 100 100 100 97 84
实施例4
取某钛白粉生产废水，pH＝1.2，该水样中污染物初始浓度与去除率见表4。
(1)缺氧反应：取该工业废水1L，由于废水中Fe的质量浓度为3148mg/L，即摩尔浓度为56mmol/L。而废水中重金属离子的摩尔浓度总和M为2.1mmol/L，则Fe与M摩尔比为26.2:1，符合大于2:1的技术特征；废水中COD浓度为447mg/L，Fe质量浓度与COD浓度之比为7.0:1，符合大于3:1的技术特征，因此不再向废水中外加Fe离子。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入5mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为600mg/L，并加入2g/L的Fe3O4纳米颗粒，反应30min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入80mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以3L/(min·L废水)的曝气量充氧反应30min，利用孵化池中产生的高活性催化剂活化水中的 分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为1500G，实现固液分离。部分污泥回流到缺氧池，回流比为2％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表4 FeM催化剂去除重金属与有机物的效果
污染物 Fe Mn Cr Ni COD
初始浓度(mg/L) 3148 115 2.43 0.426 447
去除率(％) 92 79 100 100 79
实施例5
取某镀件废水，pH＝5.9，废水中CO3 2-的浓度为332mg/L。该水样中污染物初始浓度与去除率见表5。
(1)缺氧反应：取该工业废水1L，向其中加入FeSO4·7H2O 16.7g，则Fe的摩尔浓度为60mmol/L。而废水中重金属离子的摩尔浓度总和M为20.4mmol/L，则Fe与M摩尔比为2.9:1，符合大于2:1的技术特征；废水中COD浓度为1050mg/L，Fe质量浓度与COD浓度之比为3.2:1，符合大于3:1的技术特征。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入3mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为692mg/L，并加入2g/L的Fe3O4纳米颗粒，反应30min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入100mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以5L/(min·L废水)的曝气量充氧反应60min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为2000G，实现固液分离。部分污泥回流到缺氧池，回流比为3％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁 种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表5 FeM催化剂去除重金属与有机物的效果
污染物 Cu Ni Cr COD
初始浓度(mg/L) 267 890 55.2 1050
去除率(％) 97 88 100 67
实施例6
取某冶金废水，pH＝2.0，该水样中污染物初始浓度与去除率见表6。
(1)缺氧反应：取该工业废水1L，向其中加入FeSO4·7H2O 8.34g，则Fe的摩尔浓度为30mmol/L。而废水中重金属离子的摩尔浓度总和M为13.8mmol/L，则Fe与M摩尔比为2.2:1，符合大于2:1的技术特征；废水中COD浓度为145mg/L，Fe质量浓度与COD浓度之比为11.6:1，符合大于3:1的技术特征。将调节好的废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入5mL的2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度为600mg/L，并加入2g/L的Fe3O4纳米颗粒，反应30min，以原位生成活性较高的FeM催化剂。
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入100mg/L的连二亚硫酸钠，慢速搅拌60min进行催化剂的老化和稳定。
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2L/(min·L废水)的曝气量充氧反应60min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基等强氧化性物种氧化去除废水中的有机物。
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为2000G，实现固液分离。部分污泥回流到缺氧池，回流比为4％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。
表6 FeM催化剂去除重金属与有机物的效果
污染物 Co Ni Cd Zn COD
初始浓度(mg/L) 9.71 772 3.24 33.0 145
去除率(％) 100 89 100 100 86
实施例7
一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其工艺如图1所示，采用以下步骤：
(1)缺氧反应：含有Cu、Ag、Co等络合态重金属和有机物的工业废水的进水进出初沉池1进行初步沉淀，然后进入到调节池2中，向含有Cu、Ag、Co等络合态重金属和有机物的工业废水中加入亚铁物种，本实施例中加入的是FeSO4，Fe摩尔浓度与废水中所有金属离子摩尔浓度之和M的比例为3:1，Fe的质量浓度与废水COD浓度之比为4:1，然后将上述废水加入缺氧池3，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度大于500mg/L，并加入2g/L的Fe3O4纳米颗粒，反应10min，以原位生成活性较高的FeM催化剂；
(2)孵化反应：缺氧池3的反应结束后上清液进入好氧池4，含有FeM催化剂的污泥进入孵化池6，并加入连二亚硫酸钠，投加量为10mg/L，慢速搅拌60min进行催化剂的老化稳定；
(3)好氧反应：稳定后的催化剂进入好氧池4，在好氧池4中以2L/(min·L废水)的曝气量充氧反应120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基的强氧化性物种氧化去除废水中的有机物，采用空气进行曝气；
(4)磁分离反应：好氧池4反应结束后的废水进入磁分离反应器5，加入碱调节废水的pH到9，控制磁场强度为500G，实现固液分离。磁分离反应器5中污泥进入磁选机7，磁种分离回流至缺氧池3，部分污泥回流到缺氧池3，回流比为2％，实现催化剂的富集和诱导缺氧池中催化剂的生成，剩余污泥排出。分析磁分离反应器5出水中的重金属离子浓度和COD。
实施例8
一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，采用以下步骤：
(1)缺氧反应：向含有Pd、Cr等络合态重金属和有机物的工业废水中加入FeCl2，Fe摩尔浓度与废水中所有金属离子摩尔浓度之和M的比例为4:1， Fe的质量浓度与废水COD浓度之比为5:1，然后将上述废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0。之后根据废水中原有CO3 2-的浓度加入2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度大于500mg/L，并加入2g/L的Fe3O4纳米颗粒，反应30min，以原位生成活性较高的FeM催化剂；
(2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入连二亚硫酸钠，投加量为100mg/L，慢速搅拌60min进行催化剂的老化稳定；
(3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以5L/(min·L废水)的曝气量充氧反应30min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基的强氧化性物种氧化去除废水中的有机物，采用纯氧气进行曝气；
(4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到10，控制磁场强度为1000G，实现固液分离。部分污泥回流到缺氧池，回流比为5％，实现催化剂的富集和诱导缺氧池中催化剂的生成，磁种分离回用。分析磁分离反应器出水中的重金属离子浓度和COD。

Claims (8)

  1. 一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，该方法采用以下步骤：
    (1)缺氧反应：向含有络合态重金属和有机物的工业废水中加入亚铁物种，然后将上述废水加入缺氧池，控制废水溶解氧浓度小于1.0mg/L，调节pH＝7.0，根据废水中原有CO3 2-的浓度加入2mol/L的Na2CO3溶液，使废水中的CO3 2-浓度大于500mg/L，并加入2g/L的Fe3O4纳米颗粒，反应10-30min，以原位生成活性较高的FeM催化剂；
    (2)孵化反应：缺氧池反应结束后上清液进入好氧反应池，含有FeM催化剂的污泥进入孵化池，并加入连二亚硫酸钠，慢速搅拌60min进行催化剂的老化稳定；
    (3)好氧反应：稳定后的催化剂进入好氧池，在好氧池中以2-5L/(min·L废水)的曝气量充氧反应30-120min，利用孵化池中产生的高活性催化剂活化水中的分子氧，产生羟基自由基的强氧化性物种氧化去除废水中的有机物；
    (4)磁分离反应：好氧池反应结束后的废水进入磁分离反应器，调节废水的pH到8.0以上，控制磁场强度为500-2000G，实现固液分离，去除水中的重金属离子。部分污泥回流到缺氧池，磁种分离回用。
  2. 根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，所述的工业废水所含重金属离子为Cu、Ag、Co、Ni、Pd、Cr或Mn中的一种或几种；络合剂为柠檬酸、酒石酸、乙二胺四乙酸(EDTA)或氨三乙酸(NTA)中一种或几种。
  3. 根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，所述的亚铁物种选自FeSO4·7H2O、FeSO4或FeCl2中的一种或几种。
  4. 根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，所述的亚铁物种中Fe摩尔浓度与废水中所有金属离子摩尔浓度之和M的比例大于2:1。
  5. 根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属 和有机物的方法，其特征在于，所述的亚铁物种中Fe的质量浓度与废水COD浓度之比大于3:1。
  6. [根据细则91更正 18.12.2017]　
    根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，所述的连二亚硫酸钠投加量为10-100mg/L。
  7. [根据细则91更正 18.12.2017]　
    根据权利要求1所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，所述的磁分离反应器中的部分污泥回流到缺氧池，通过污泥回流，实现催化剂的富集和诱导催化剂的生成。
  8. [根据细则91更正 18.12.2017]　
    根据权利要求7所述的一种磁性铁基材料同步去除废水中络合态重金属和有机物的方法，其特征在于，污泥的回流比为2-5％。
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