CN103803703B - A kind of Nanoscale Iron and microorganism act synergistically the method for synchronous denitrification dephosphorizing - Google Patents

Abstract

Particle diameter required for the first-selected crushing and screening of limonite ore obtains, under hydrogen or carbon monoxide atmosphere, high temperature reduction prepares that group will be made up of Nanoscale Iron, the particulate material of the millimeter particle diameter of tool vesicular structure characteristic, Nanoscale Iron slow releasing hydrogen in statu nascendi atom in this particulate material and hydrogen, chemical reduction nitrate.Meanwhile, this particulate material has higher voidage, and the hydrogen that the function anaerobion denitrifying bacteria that particulate material is inner and outer surface material attachment is abundant discharges with Nanoscale Iron and water reaction reduces nitrate for electron donor; The dependence nitrate iron-oxidizing bacteria of attachment also has the effect of reduction nitrate.Nitrate in waste water is removed under Nanoscale Iron chemical action and anaerobion synergy.Nanoscale Iron and water are under chemical reaction, anaerobion are oxidized and act synergistically, and porous particle thing surfaces externally and internally constantly forms ferrous iron and ferric hydroxide, promote the chemisorption of phosphorus in water, thus reach the effect of synchronous denitrification dephosphorizing.

Description

A kind of Nanoscale Iron and microorganism act synergistically the method for synchronous denitrification dephosphorizing

One, technical field

The present invention relates to the method for micro-polluted water advanced treatment, specifically prevent the treatment of domestic sewage advanced method of body eutrophication.

Two, background technology

Because China's rapid economic development, urbanization process are accelerated, macronutrient nitrogen phosphorus enters the water bodys such as lake, causes the lakes such as such as Chaohu, Taihu Lake, Dian Chi and the serious eutrophication of city appearance water body.In order to the pollution that controls environment, country drops into huge fund and carries out municipal sewage treatment Facilities Construction, improves the processing rate of city domestic sewage.But, current city domestic sewage process generally adopts oxic activated sludge process, Chinese scholars also studies biological dephosphorization technique energetically, but the concentration of total nitrogen, total phosphorus still reaches 20-35mg/L, 0.3-3.0mg/L respectively in biological treatment water outlet, be 10-50 times of water body in lake second standard.Although sanitary sewage disposal reaches standard of drainage, for the water body of eutrophication, without any nitrogen phosphorus environmental capacity, need ecotope waste water being carried out to stricter denitrogenation dephosphorizing guarantee water body.In addition, along with urban development, lack of water phenomenon is more and more serious, and the resource utilization of waste water is development trend, sewage treatment plants secondary treatment yielding water will be used for the application of the resource utilization such as recirculated cooling water, city appearance water body, all needs further denitrogenation dephosphorizing could meet waste water reclaiming application requiring.Cheap high-efficient denitrification and dephosphorization material and technology are the active demands of national FUTURE ENVIRONMENT protection.

Long-term drinking height nitrate underground water, can cause that the trained reflex of children's sense of hearing and vision is blunt, intelligence declines, cause diabetes, hypertension, hyperthyroidism.Nitrate can be converted into nitrite, various directly carcinogenic, teratogenesis, mutagenic nitroso compound in body, produces very large harm (Alvarez, 2007) to HUMAN HEALTH.Due to the excessive use of chemical fertilizer, shallow ground water azotate pollution has been quite general environmental problem.As the cities such as Xi'an, Changchun, Chengdu nitrate in groundwater content big area exceed standard, Changchun nitrate in groundwater content is up to 392mgL ^-1(World Health Organization's regulation nitrate is not more than 10mg/L, and nitrite should not be greater than 0.91mg/L).The groundwater azotate pollution in China " three Norths " area is especially serious, and in " three Norths " area, particularly rural area, great majority are using underground water as domestic water.In order to ensure drinking water safety, need development underground water denitrogenation material and technology.

The treatment technology of nitrate nitrogen in underground water can be divided into physico-chemical process, biological process and chemical reduction method three class.Physico-chemical process comprises electrodialysis, reverse osmosis, ion exchange treatment, although these methods well can remove the nitrate in water, to the poor selectivity of nitrate, processing cost is high, produce the waste liquid of rich nitrate, be difficult to apply containing in nitrate water treatment at lower concentration.

Microorganism denitrification is the important method that waste water removes nitrate, generally adopts in the nitrogenous trade effluent of height.Microorganism denitrification needs the biochemical reaction keeping anaerobic environment, enough organic carbon sources ensure microbial metabolism and denitrification denitrogenation.Xiang Shuizhong adds organism (generally using methyl alcohol, ethanol etc.) and causes that cost is high, organic substance residues, is not suitable for the advanced treatment of city domestic sewage secondary treatment yielding water.The denitration that biological denitrification is applied to underground water has carried out a lot of discussion abroad, except add organism cause Organic substance in water residual except, also have microorganism and remain the problem with peculiar smell, affect drinking water quality, be difficult to apply.Exploring as the method Chinese scholars improved utilizes electrochemistry to produce hydrogen to carry out biological denitrification, and to avoid the organic negative effect adding and bring, the obstacle that this technology exists is that anode material consumption is very large, and cost is very high.In recent years, both at home and abroad also at exploration autotrophic microorganism denitride technology, with reducing inorganic thing if hydrogen or sulphur are for electron donor, nitric nitrogen is converted into N ₂, be a kind of promising nitrate purification techniques, but can denitrogenation autotrophic microorganism (thiobacillus denitrificans) utilize iron sulfide to complete nitrate reduction as electron donor, yet there are no report.

Chemical reduction denitration is the new denitride technology method paid close attention to both at home and abroad, and chemical reduction comprises Pt/Pd-Cu bimetallic catalytic hydrogen reducing, Zero-valent Iron reduction, metallic aluminium reduction method.The defect of precious metal catalyst reduction denitration is expensive catalyst.The defect of Zero-valent Iron reduction denitration produces more ammonium ion, and meanwhile, Zero-valent Iron passivation is relatively more serious, and consumption zeroth order chalybeate amount is very high.Nanometer iron powder has reduction denitration effect preferably, substantially do not produce ammonium ion, but the preparation cost of nanometer iron powder is very high, is also difficult to application.

Lime precipitation, molysite deposition method, the process of aluminium salt precipitation method are generally used in the process of Coal Gas Washing Cycling Water phosphorus.Calcium phosphate solubility product is comparatively large, can not produce a desired effect with lime treatment low phosphorus.When phosphorus concentration in water is very low, iron, aluminum ion and phosphate radical form colloidal sol, and solubleness is large, are difficult to separate from water, adding pharmaceutical quantities greatly, causing iron, aluminum metal ion residues amount high, producing secondary pollution problem to reach dephosphorization treatment effect.Therefore, molysite and aluminium salt can not be directly used in the precipitation process of low phosphorus.

Existing a lot of scholar has done a lot of research in absorption method dephosphorization both at home and abroad, conventional dephosphorization adsorbent mainly contains natural mineral matter and the solid waste such as zeolite, calcite, wilkinite, attapulgite, vermiculite, red mud, flyash, these clay minerals and material have certain adsorption to phosphorus, but loading capacity is low.In order to improve the adsorptive power of dephosphorization adsorbent, a lot of scholar carries out the preparation research except phosphorus composite material, comprise and make the metal ions such as carrier loaded La, Ce, Fe with organic waste, be carrier loaded La, Al, Fe with mineral such as quartz sand, montmorillonite, attapulgite, zeolites and prepare modified adsorbent, these compound adsorbents have higher dephosphorization adsorption.From domestic and international result of study, it is adsorbent surface active ingredient Fe that above-mentioned matrix material has better adsorbing reason ³⁺, Al ³⁺, La ³⁺, Ce ³⁺oxyhydroxide and phosphate radical have stronger chemical bonding effect.High with rare-earth element modified sorbing material dephosphorization efficiency by using, but expensive, and the prospect applied is little.Surface recombination Fe ³⁺, Al ³⁺oxyhydroxide, or constantly can discharge active iron, aluminum ions cheap mineral material will have larger potentiality in waste water advanced dephosphorization adsorbent, namely iron sulfide is can the cheap mineral material of continuous slow releasing iron ion in aerobic environment, should have potentiality in dephosphorization adsorbent.Absorption method because of dephosphorization process simple, phosphor-removing effect is good and be subject to a lot of domestic and international investigator and more pay close attention to.

The paper that Chinese scholars is delivered, all proves to remove the nitrate in water with Nanoscale Iron, reaches the effect well removing NO3-N and NO2-N, over reduction can not produce ammonia nitrogen.But, Nanoscale Iron dosage is very high, and the mass ratio of Nanoscale Iron and nitric nitrogen will reach 1:40, shows that existing Nanoscale Iron and nitrate, nitrite react utilising efficiency not high, cause the nitrate in Nanoscale Iron process water, nitrite cost high, apply Technological Economy aspect and also there is obstacle.Publication (Haibo Liu, Chen Tianhu) has invented the method utilizing Nanoscale Iron corrosion dephosphorization, shows that Nanoscale Iron and water react and dissolved oxygen in water reacts and forms newborn iron hydroxide, has played dephosphorization adsorption.

Three, summary of the invention

The present invention finds, utilize limonite reduce preparation have vesicular structure Nanoscale Iron can under chemistry and biological synergy high efficiency synchronous denitrogenation dephosphorizing.

Technical solution problem of the present invention, adopts following technical scheme:

A kind of Nanoscale Iron and microorganism act synergistically the method for synchronous denitrification dephosphorizing, the millimeter particle grade particles mixture of the tool high porosity that it is characterized in that thermochemical reduction limonite ore to prepare, vesicular structure, Nanoscale Iron chemical property becomes fixed bed water treatment device, inoculation enrichment is containing denitrifying bacteria, the anaerobion bacterium liquid domestication cultivation relying on nitrate iron-oxidizing bacteria, above-mentioned anaerobion is adhered at particulate matter internal voids and outside surface, be nitrogen nitrate reduction under Nanoscale Iron chemical action and anaerobion synergy, remove nitrate in waste water; Meanwhile, under Nanoscale Iron chemistry and anaerobion oxygenizement, porous particle thing surfaces externally and internally constantly forms ferrous iron and ferric hydroxide, promotes the Adsorption of phosphorus in water, thus realizes the effect of waste water synchronous denitrification dephosphorizing, specifically adopt following steps:

Select limonite ore, Iron grade is not less than 40%, and pyrrhosiderite diameter is wherein not more than 500nm;

Limonite is broken, screening obtains the particulate matter of particle diameter in 0.5-1.0mm, 1.0-3mm, 3-6mm, 6-10mm scope respectively;

Be Nanoscale Iron at 250 DEG C-600 DEG C with hydrogen or Carbon monoxide reduction particulate matter, obtaining dominant be that the particulate material of Nanoscale Iron keeps the particle diameter before calcining and pore structure mutually;

The nano iron particles thing of reduction preparation is packed into general filtering type water treatment building or device, and build fixed bed filtering formula water treatment device, intake-outlet is established respectively in device top and bottom;

The iron-oxidizing bacteria bacterium liquid of enrichment culture denitrifying bacteria, dependence nitrate respectively, bacterium liquid absorbance ODP is greater than 0.2;

The volume ratio of two class bacterium liquid is 1:1 ~ 1:5, mixed bacteria liquid cumulative volume is the 1%-5% of experiment column volume, bacterium liquid infusion is entered fixed bed, then substitute bacterium liquid with pending water and continue Injection Water Treatments device, until discharge air wherein completely, the nitrate concentration 10-100mg/L in pump circulation 24-96 hour maintenance system of liquid wherein, makes above-mentioned anaerobion in nano iron particles material surface biofilm;

Then start normal water process, hydraulic detention time 2-10 hour, particulate material is the carrier of anaerobion, is again the electron donor of anaerobion reduction denitrogenation;

If filtration velocity is reduced to less than 50% of original speed, show that void ratio significantly reduces, because microbial film and secondary iron oxide deposits there occurs blocking, dropout is made after promoting filler 40cm with magneticchuck, under the impact of water, make particulate matter disperse again to form space, and do not destroy attached microbial film, normal operation can be started;

When running water outlet and can not meeting discharge or recycling of water resource requirement, show that material provides electronics to lose efficacy, or adsorption and dephosphorization ability is saturated, shift out half to three/bis-granule materials, supplement new particulate material, move material by magneticchuck and make supplementary new material and original mixing of materials, continue water treatment and run; Or the particulate material all more renewed, re-starts microbe inoculation, biofilm.

Method usefulness of the present invention is:

Limonite belongs to the iron ore that the Mineral Weathering such as iron sulfide, iron carbonate is oxidized secondary formation, and the micron in limonite ore, the goethite crystals of submicron-scale pile up formation vesicular structure in a jumble, have abundant micron, nanovoids.At 300-500 DEG C, hydrogen or Carbon monoxide reduction are while acquisition Nanoscale Iron, the original gap structure of basic maintenance ore.This just makes at high temperature to reduce obtained Nanoscale Iron by the limonite ore of millimeter grade and has abundant micron, nanovoids.This particle diameter is that the nano iron particles thing of millimetre-sized vesicular structure can loading microorganisms in a large number, becomes excellent microbe carrier.

Nanoscale Iron and water effect constantly produce hydrogen, the water body making particulate matter inside and outside keeps anaerobic state, create the enabling environment being suitable for anaerobion growth, be conducive to anaerobion to comprise denitrifying bacteria, rely on the iron-oxidizing bacteria of nitrate, preferably adhere at surface particles, play the synergy of Microbial denitrogenation dephosphorization.

Nanoscale Iron and water react the hydrogen discharged can as electron donor denitrification denitrogenation under denitrifying bacteria effect, speed of response when not having microorganism due to nescent hydrogen and nitrate is slow, cause a large amount of hydrogen to be escaped, this is the reason that the out of stock hydrochlorate efficiency of Nanoscale Iron chemistry is not high.The existence of anaerobion improves hydrogen utilization efficiency, thus reduces the stoichiometric ratio of nitrate in Nanoscale Iron and water.

In addition, in the process of single chemical denitration nitrogen, Nanoscale Iron and water react the ferrous ion discharged, if ferrous iron is remaining in a large number, cause water outlet to produce iron rust, water quality reduces, and this is also one of shortcoming of Nanoscale Iron chemical reduction denitration method.Method of the present invention, the iron-oxidizing bacteria of load dependency nitrate while of on nano iron particles filtrate, be not only that the hydrolysis of insoluble ferric ion produces iron hydroxide precipitation ferrous ions under microbiological oxidation, make use of ferrous ion simultaneously and remove nitrate as electron donor, chemical electron utilising efficiency in the material of raising.The more important thing is that the ferric hydroxide of oxidation generation facilitates again the absorption to phosphorus in water.The synchronous denitrification dephosphorizing denitrogenation that acts synergistically of Nanoscale Iron and microorganism can be expressed as follows with reactional equation:

Nanoscale Iron and water chemistry react: Fe+H ₂o---Fe (OH) ₂+ H ₂

Denitrifying bacteria denitrification reaction: NO ₃ ^-+ H ₂---N ₂+ H ₂o

Rely on nitrate denitrifying bacteria denitrification reaction: Fe (OH) ₂+ NO ₃ ^----N ₂+ Fe (OH) ₃

Chemisorption is except phosphorus reaction: Fe (OH) ₃+ H ₂pO ₄ ^-+ H ⁺---Fe-PO ₄ ^-+ 3H ₂o

This material has higher granule strength and excellent water tolerance, there is superparamagnetic characteristic, magneticchuck can be utilized to load and discharging granular material, when filtrate causes drainage rate significantly to reduce due to biomembranous formation, secondary iron oxide deposits, then can be discharged by magneticchuck improving material, be scattered under the impulse action of water, space between regenerated granule, recovered water-based energy, this can ensure that the chemical valence electronics in Nanoscale Iron is utilized substantially.

Four, accompanying drawing

Fig. 1 particle diameter 1.0-3mm limonite particulate material photo.

Fig. 2 limonite stereoscan photograph.

Particulate material photo after the hydrogen reduction of Fig. 3 limonite.

After the hydrogen reduction of Fig. 4 limonite, particulate material is by attraction photo.

Particulate material stereoscan photograph after the hydrogen reduction of Fig. 5 limonite.

Five, embodiment

Non-limiting examples is described below.

Embodiment

Limonite ore Iron grade is selected to be not less than 40%.

Limonite fragmentation obtains the particulate material of particle diameter 1.0-3mm.Particulate matter at 300 DEG C of hydrogen reducings, the pyrrhosiderite in particulate matter is reduced to fe until anhydrous generation.Hydrogen reduction product fe inherits pyrrhosiderite nano whiskers shape characteristic, but becomes Nanoscale Iron because phase transformation there occurs nanometer.Therefore, the particulate material after hydrogen reduction not only has the chemically reactive of Nanoscale Iron, and maintains again the porosity of limonite and pore property before calcining, enters granule interior provide basic premise for microorganic adhesion.

The nano iron particles thing of preparation filling experiment post, the denitrifying bacteria of inoculation enrichment culture, the iron-oxidizing bacteria bacterium liquid of dependence nitrate, bacterium liquid ODP value is greater than 0.2.

The volume ratio of two class bacterium liquid is 1:1, and bacterium liquid cumulative volume is 2% of experiment column volume, and in experiment post, nutrient solution peristaltic pump circulates 48 hours, and denitrifying bacteria, dependence nitrate, in granular material surface biofilm, starting according to normal condition water inlet process.Running first 20 days hydraulic detention times controls at 5-10 hour, and after 20 days, hydraulic detention time controls at 2-3 hour, and water outlet reaches three class surface water body water quality standard.

If filtration velocity is reduced to less than 50% of original speed, after promoting filler 40cm with magneticchuck, make dropout, under the impact of water, make particulate matter disperse again to form space, normal operation can be started.

When running water outlet and can not meeting discharge or recycling of water resource requirement, show that material provides electronics to lose efficacy, or adsorption and dephosphorization ability is saturated, the particulate material more renewed.

Claims (1)

1. a Nanoscale Iron and microorganism act synergistically the method for synchronous denitrification dephosphorizing, the millimeter particle grade particles mixture of the tool high porosity that it is characterized in that thermochemical reduction limonite ore to prepare, vesicular structure, Nanoscale Iron chemical property becomes fixed bed water treatment device, inoculation enrichment is containing denitrifying bacteria, the anaerobion bacterium liquid domestication cultivation relying on nitrate iron-oxidizing bacteria, above-mentioned anaerobion is adhered at particulate matter internal voids and outside surface, be nitrogen nitrate reduction under Nanoscale Iron chemical action and anaerobion synergy, remove nitrate in waste water; Meanwhile, under Nanoscale Iron chemistry and anaerobion oxygenizement, porous particle thing surfaces externally and internally constantly forms ferrous iron and ferric hydroxide, promotes the Adsorption of phosphorus in water, thus realizes the effect of waste water synchronous denitrification dephosphorizing, specifically adopt following steps:

Select limonite ore, Iron grade is not less than 40%, and pyrrhosiderite diameter is wherein not more than 500nm;

Limonite is broken, screening obtains the particulate matter of particle diameter in 0.5-1.0mm, 1.0-3mm, 3-6mm, 6-10mm scope respectively;

Be Nanoscale Iron at 250 DEG C-600 DEG C with hydrogen or Carbon monoxide reduction particulate matter, obtaining dominant be that the particulate material of Nanoscale Iron keeps the particle diameter before calcining and pore structure mutually;

The nano iron particles thing of reduction preparation is packed into general filtering type water treatment building or device, and build fixed bed filtering formula water treatment device, intake-outlet is established respectively in device top and bottom;

The iron-oxidizing bacteria bacterium liquid of enrichment culture denitrifying bacteria, dependence nitrate respectively, bacterium liquid absorbance ODP is greater than 0.2;

The volume ratio of two class bacterium liquid is 1:1 ~ 1:5, mixed bacteria liquid cumulative volume is the 1%-5% of experiment column volume, bacterium liquid infusion is entered fixed bed, then substitute bacterium liquid with pending water and continue Injection Water Treatments device, until discharge air wherein completely, the nitrate concentration 10-100mg/L in pump circulation 24-96 hour maintenance system of liquid wherein, makes above-mentioned anaerobion in nano iron particles material surface biofilm;

Then start normal water process, hydraulic detention time 2-10 hour, particulate material is the carrier of anaerobion, is again the electron donor of anaerobion reduction denitrogenation;

If filtration velocity is reduced to less than 50% of original speed, show that void ratio significantly reduces, because microbial film and secondary iron oxide deposits there occurs blocking, dropout is made after promoting filler 40cm with magneticchuck, under the impact of water, make particulate matter disperse again to form space, and do not destroy attached microbial film, normal operation can be started;

When running water outlet and can not meeting discharge or recycling of water resource requirement, show that material provides electronics to lose efficacy, or adsorption and dephosphorization ability is saturated, shift out half to three/bis-granule materials, supplement new particulate material, move material by magneticchuck and make supplementary new material and original mixing of materials, continue water treatment and run; Or the particulate material all more renewed, re-starts microbe inoculation, biofilm.