CN202643494U - Biological deoxidation denitrification device used in oxidative environment groundwater - Google Patents

Abstract

The utility model relates to a biological deoxidation denitrification device used in oxidative environment groundwater. The device is a double-layer & double-media permeable reactive barrier. The permeable reactive barrier is consisted of an upstream pine bark layer and a downstream zero valent iron layer. The device is disposed in downstream soil and groundwater layer of nitrate nitrogen polluted oxidative environment groundwater pollution plume, and realizes biological deoxidation denitrification in oxidative environment groundwater through three main ways of aerobic respiration, heterotrophic denitrification and autotrophic denitrification of aerobic heterotrophic bacteria.

Description

Biological deoxidation nitrogen rejection facility in a kind of well-oxygenated environment underground water

Technical field

The utility model relates to the deoxygenation nitrogen rejection facility that polluted underground water is carried out biological restoration, is specifically related to the associated plant of a kind of novel biological deoxidation-heterotrophism/autotrophic denitrification coupling.

Background technology

Nitrate nitrogen (NO ₃-N) be one of the most general pollutent in the underground water in the world wide, it pollutes has become global environment and health problem.Except the Antarctica, in the underground water in other 6 continents, all found the NO of high density ₃-N.Human body is taken in high NO ₃-N can cause serious disease even death.Long-term exposure is in NO ₃-N and nitrite nitrogen (NO ₂-N) can cause diuresis, splenorrhagia, " blue baby's disease " etc.During 1945-1970, there are 2000 examples " blue baby's disease " in the whole world, and 8% death is wherein arranged.In addition, NO ₃-N and NO ₂-N is the precursor of nitroso compound (N-nitroso Compounds, NOCs).NOCs can cause hypertension, cancer, deformity and sudden change.Along with the development of global economy, the usage quantitys such as agriculture nitrogen fertilizer, wastewater irrigation, rubbish place increase gradually, cause NO ₃-N enters underground environment in a large number.Therefore can predict NO ₃-N will enlarge increasingly to the harm of public health and environment.

According to the difference of required carbon source kind, biological denitrificaion is divided into heterotrophism denitrogenation (Heterotrophic Denitrification, HD) and autotrophic denitrification (Autotrophic Denitrification, AD).

The heterotrophism denitrogenation refer to the heterotrophism denitrifier utilize organic carbon matrix as electron donor and energy source and be tending towards utilizing organic carbon as the cell carbon source with NO ₃-N is reduced to the process of gaseous nitrogen.The heterotrophism denitrogenation is relative ubiquity in soil, settling, underground water, yet obtainable organic carbon reduces along with the increase of the degree of depth under the earth's surface, has caused denitrification rates to reduce gradually, even in dark waterbearing stratum biological denitrificaion is not occuring.As seen, available inherent organic carbon source has restricted the application of heterotrophism denitride technology in the underground water.

Recently, numerous investigators have assessed the cellulose-based potential application that the solid organic carbon source is used for the heterotrophism denitrogenation that adds.Cotton is the purest cellulose family carbon source, has the highest external surface area, shows very excellent NO ₃-N removes ability, does not cause nitrite accumulation [Volokita et al., Biological denitrification of drinking water using newspaper.Water Research, 1996a, 30:965-971; Volokita et al., Denitrification of groundwater using cotton as energy source.Water Science and Technology, 1996b, 34 (1-2): 379-385.], but cotton can cause initial operating stage reactor water outlet dissolved organic carbon (Dissolved Organic Carbon, DOC) increase, main is that its hardness is less, is difficult to large-scale application in Practical Project.Wheat straw is used for Drinking Water biological denitrificaion [Soares and Abeliovich, Wheat straw as substrate for water denitrification.Water Research, 1998,32:3790-3794.] time, denitrification rates is the highest within the first week, present subsequently minimizing trend, wheat straw can not the supply organic carbon that continue steady in a long-term.Saliling et al. has investigated hardwood bits and wheat straw, hardwood bits and wheat straw had been distinguished loss 16.2% and 37.7% after the result showed 140 days, so their limited [Saliling et al.Wood chips and wheat straw as alternative biofilter media for denitrification reactors treating aquaculture and other wastewaters with high nitrate concentrations.Aquacultural Engineering in work-ing life, 2007,37:222-233.].Find in Drinking Water denitrogenation that Volokita et al. carries out when utilizing newspaper as the carbon source research, although fully denitrogenation and without NO of reaction column ₂-N accumulation, but initial stage (＜12 days) water outlet DOC is higher, and As time goes on irreversible reduction appears in denitrification ability.Greenan et al. has estimated the denitrification effect of 4 kinds of organic carbon sources in biofilter, the removal ability is followed successively by from high to low: corn stalk〉cardboard〉wood chip+soya-bean oil〉wood chip, the alienation nitrate reduction only accounts for 1%[Greenan et al.Comparing carbon substrates for denitrification of subsurface drainage water.Journal of Environmental Quality to the contribution of clearance, 2006,35:824-829.].The cellulose solids organic carbon source awaits further research and development.

Autotrophic denitrification refer to the autotrophic denitrification bacterium utilize carbonic acid gas or bicarbonate radical as carbon source utilize simultaneously hydrogen or reducible sulfur as electron donor and energy source with NO ₃-N is reduced to the process of gaseous nitrogen.The hydrogen autotrophic denitrification owing to there are following four important factors, serious restriction the application of this technology:

1. hydrogen solubility is low, and utilization ratio is low, and gas phase is limited to matrix transmission and the substance transfer of liquid phase;

2. need injecting systems, hydrogen is expensive, and construction costs and operation and maintenance cost are high;

3. obtainable carbonic acid gas is limited in the underground water;

Hydrogen in use, transportation and storage with O ₂Inflammable and explosive after mixing.

Till et al. has proposed Zero-valent Iron (Zero Valent Iron, ZVI) autotrophic denitrification method [the Till et al.Fe (0)-supported autotrophic denitrification.Environmental Science and Technology that supports, 1998,32:634-639.], this method can overcome the shortcomings such as above-mentioned hydrogen mass transfer limit.ZVI can produce cathode hydrogen in the Anaerobic Corrosion process, but and in the water bacterium utilize the dissolving of hydrogenase accelerating anode ZVI.Biological and abiotic NO in the autotrophic denitrification process ₃-N reduction can cause that the pH value increases in the water.For this problem, a kind of capsule-type KH of Rust et al. research and development ₂PO ₄Buffer reagent can maintain the pH value [Rust et al.Control of pH during denitrification in subsurface sediment microcosms using encapsulated phosphate buffer.Water Research within the desirable scope, 2000,34:1447-1454.], [Rust et al.Laboratory sand column study of encapsulated buffer release for potential in situ pH control.Journal of Contaminant Hydrology, 2002,54:81-98.], iron ore (FeS ₂) can effectively control the increase of pH value as the pH buffer reagent.According to document, AD than the advantage of HD is: biomass is few; Stop up few; The toxicity harm of some organic carbons is little; Organic carbon content is few in the denitrogenation water; Subsequent disposal is simple.

The metabolism of autotrophic denitrification bacteria growing is slow than the heterotrophism denitrifier, and generation time is long.But there is not competition from the heterotrophism denitrifier in the autotrophic denitrification bacterium because of the different of carbon source and electron acceptor(EA), so two kinds of bacterium can symbiosis in system.Della Rocca et al. has proposed the method that a kind of heterotrophism combines with autotrophic denitrification and has processed Drinking Water [Della Rocca et al.An heterotrophic/autotrophic denitrification (HAD) approach for nitrate removal from drinking water.Process Biochemistry, 2006,41:1022-1028.], [Della Rocca et al.Heterotrophic/autotrophic denitrification (HAD) of drinking water:prospective use for permeable reactive barrier.Desalination 210 (2007) 194-204.].In their research, iron plane flower and cotton are respectively placed on the columns bottom and top layer, adopt the bottom water intake mode.DO comes the biological support denitrogenation in the iron plane flower minimizing water, also can produce cathode hydrogen and promote autotrophic denitrification, and cotton is used for supporting the heterotrophism denitrogenation.Experimental result shows that this method can obtain higher denitrification rates, and ZVI has strengthened biological denitrificaion, still or water inlet NO low at flow velocity ₃In the high situation of-N, find high density NH in the water outlet ₄-N, NH ₄-N significantly reduces nitrogen removal performance and microbiostatic activity.Su and Puls report cotton boll compost unitary system is than the NO of cotton boll compost+ZVI or cotton boll compost+settling dual system and cotton boll compost+triple systems of ZVI+ settling ₃-N removes speed and wants high [Su and Puls, Nitrate Reduction by Zerovalent Iron:Effects of Formate, Oxalate, Citrate, Chloride, Sulfate, Borate, and Phosphate.Environmental Science and Technology, 2004,38:2715-2720.].This has hinted the ZVI passivation biological denitrificaion in cotton boll compost+ZVI system.

Surface water and rain infiltration supply and sewage recharge etc. and can cause underground water to be rich in dissolved oxygen (Dissolved Oxygen, DO) and form well-oxygenated environment.Oxygen can bring tremendous influence to underground Hydrochemical Composition and migration of element, the more important thing is and can limit biological denitrificaion, mainly based on three kinds of reasons: the reversible inhibition of denitrogenation enzymic activity; Gene expression regulation; Electronics competition with nitrate radical.Therefore, biological denitrificaion needs to carry out in anoxic or anaerobic environment.Dissolved oxygen was on impact [the G ó mez et al.Influence of carbon source on nitrate removal of contaminated groundwater in a denitrifying submerged filter.Journal of Hazardous Materials of Processes of Nitrate Removal from Ground Water when G ó mez et al. had investigated ethanol, methyl alcohol and sucrose as the liquid carbon source, 2000,80:69-80.].The result shows that the existence of DO has reduced the clearance of inorganic nitrogen and caused the increase of water outlet nitrite, finds also that simultaneously the biological denitrificaion of ethanol and methyl alcohol support is subjected to the influence degree of DO less than sucrose.Be not difficult to find out that the ability that different carbon sources are removed DO is different different with the influence degree that is subjected to DO.

The ZVI that exists with forms such as iron plane flower, Nanoscale Iron, particle iron, cast iron, iron filings and iron powders is used for NO ₃The research of-N chemical reduction and autotrophic denitrification has caused investigator's concern [Cheng et al., Reduction of nitrate to ammonia by zero-valent iron, Chemosphere, 1997,35:2689-2695; Till et al., Fe (0)-supported autotrophic denitrification, Environmental Science and Technology, 1998,32:634-639; Huang et al., Nitrate reduction by metallic iron, Water Research, 1998,32:2257-2264.; Westerhoff and James, Nitrate removal in zero-valent iron packed columns, Water Research, 2003,37:1818-1830.; Choe et al., Nitrate reduction by zero-valent iron under different pH regimes, Applied Geochemistrv, 2004,19:335-342; Yang and Lee, Chemical reduction of nitrate by nanosized iron:kinetics and pathways, Water Research, 2005,39:884-894; Ahn et al., Enhanced reduction of nitrate by zero-valent iron at elevated temperatures, Journal of Hazardous Materials, 2008,156:17-22], however the ZVI that exists with the sponge iron form there is not yet report.

More than studies show that, searching releases that carbon is stable, long service life, cheapness, SOLID ORGANIC carbon source that hardness is high, explore new ZVI and have form, inquire into the biological deoxidation Nitrogen Removal Mechanism, the research and development high effect nontoxic is without the novel combination technique of the biological deoxidation-heterotrophism of nitrogen by product/autotrophic denitrification coupling, to have important theory value and practical significance to the groundwater pollution reparation, also using for the technology of biological denitrificaion provides a better development prospect.

Permeable reactive grid (Permeable Reactive Barriers, PRBs) be that the eighties in 20th century is by the based technique for in-situ remediation of a kind of groundwater pollution of US EPA proposition, it mainly is comprised of permeable reaction medium, when polluted underground water is flowed through the grid body under self hydraulic gradient effect, the series reaction such as pollutent and medium precipitate, absorption, redox and bio-degradation reactions are purified underground water.This technology ecotope disturbance is little, does not need pump to take out and the ground treatment system, can also process on the spot, has avoided the secondary pollution of the defeated process of collection, has saved power charge and working cost.These advantages so that the PRB technology in the underground water based technique for in-situ remediation, be with a wide range of applications.

In January, 1996, the shallow ground water denitrogenation PRB in that New Zealand has built up long 35m, a wide 1.5m, dark 1.5m fills sawdust [Schipper and in it Nitrate removal from groundwaterusing a denitrification wall amended with sawdust:Field trial, Journal of Environmental Quality, 1998,27:664-668; Schipper and

Nitrate removal from groundwater and denitrification rates in a porous treatment wall amended with sawdust, Ecological Engineering, 2000,14:269-278; Schipper and

Five years of nitrate removal, denitrification and carbon dynamics in a denitrification wall, Water Research, 2001,35:3473-3477].Operation result shows that available organic carbon reduces gradually in 200 days of initial operating stage, keep relative stability subsequently, and underground water in the PRB bottom phenomenon has occured to stream.

During 1992～1993 years, carry out PRB biological denitrificaion research 4 field test sites, utilized the coverture, hardwood sawdust etc. of sawdust, fallen leaves compost matter, grain, coarse grained wood as carbon source.Operation shows, denitrification rates can reach 15～30mg N/L/d[Robertson et al, Nitrate removal rates in a 15-year-old permeable reactive barrier treating septic system nitrate.Ground Water Monitoring and Remediation, 2008,28:65-72].Be not difficult to find out that the PRB during engineering is used adopts individual layer single reaction medium single channel to reach the purpose of nitrate removal mostly.The theoretical investigation of the denitrogenation PRB of two (many) approach of two (many) medium of two (many) layers awaits further deeply.

The utility model content

For the problems referred to above of prior art, the utility model investigator improves individual layer PRB, has researched and developed the two medium osmosis reaction of a kind of bilayer grid (Double-Layer ﹠amp; Double-Media Permeable Reactive Barrier, DLDM-PRB), it can be effectively applied to biological deoxidation denitrogenation in the well-oxygenated environment underground water.

For achieving the above object, the utility model provides biological deoxidation nitrogen rejection facility in a kind of well-oxygenated environment underground water, and it is double-deck two medium osmosis reaction grid; This permeable reactive grid is made of upstream pine tree cortex and downstream Zero-valent Iron layer.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, the particle diameter of this Cortex Pini is preferably 2.0～11.0mm.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, this Zero-valent Iron is preferably sponge iron, its Fe ⁰Content〉60.6%, particle diameter is preferably 0.15～2.0mm.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, the mass ratio of this Cortex Pini and sponge iron is preferably 6～8:7～9.

Aforesaid biological deoxidation nitrogen rejection facility wherein, also comprises sand grains in this downstream layer, particle diameter is preferably 0.45～2.0mm, Cortex Pini: sponge iron: the mass ratio of sand grains is preferably 6～8:7～9:7～8, more preferably 71:80:74; Per unit volumetric loading (g N/m ³/ d), the consumption of Cortex Pini, sponge iron and sand grains is respectively 0.3～0.4kg, 3.5～4.5kg and 3.5～4kg.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, the Thickness Ratio of this upstream pine tree cortex and downstream Zero-valent Iron layer is preferably 95～120:24～36, more preferably 54:15; Per unit volumetric loading (g N/m ³/ d), the thickness of upstream layer and downstream layer is respectively 4.75～6cm, 1.2～1.8cm.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, this sand grains can be natural river sand.

Aforesaid biological deoxidation nitrogen rejection facility, wherein, this device can be water proof funnel gate-type or diaphragm wall formula.

The beneficial effects of the utility model are:

The utility model is for well-oxygenated environment nitrate nitrogen in ground water (NO ₃-N) the two medium osmosis of a kind of bilayer of design react grid (DLDM-PRB), and it is to be made of upstream pine tree cortex and downstream Zero-valent Iron layer.

Wherein, Cortex Pini is as organic carbon source, and the sustainable release organic carbon that do not break is sought the aerobic repiration deoxygenation for aerobic heterotrophic bacterium electron donor is provided, thereby removes the dissolved oxygen that affects the biological denitrificaion process, creates anoxic or anaerobic environment; Simultaneously growth, breathing and the denitrogenation for the heterotrophism denitrifier provides carbon source and energy source; More than the product carbonic acid gas of two processes provide inorganic carbon source for follow-up autotrophic denitrification.Cortex Pini is as the cellulose family organic carbon source, with the Mierocrystalline cellulose organic carbon sources such as cotton, newspaper, straw relatively, have that shock resistance is strong, carbon source discharges stable, longer duration, cheap advantage.

The cathode hydrogen that the Zero-valent Iron Anaerobic Corrosion produces promotes the metabolism of autotrophic denitrification bacterium and strengthens the autotrophic denitrification ability that as electron donor and energy source Zero-valent Iron can be removed a small amount of NO by chemical reduction simultaneously ₃-N.Sponge iron has the ultimate compression strength height as the Zero-valent Iron filler, not efflorescence, does not harden, and the advantage of loose and porous inner surface, its specific surface area that provides are 5～10 times of common iron filings.

Biological deoxidation-the heterotrophism of application said apparatus/autotrophic denitrification method (BD-HAD) has heterotrophism denitrogenation, autotrophic denitrification and three kinds of Approach of Removal of Nitrogens of chemical reduction.In the pine tree cortex of upstream, deoxygenation is carried out in the organic carbon battalion aerobic repiration that aerobic heterotrophic bacterium utilizes Cortex Pini to discharge, and for biological denitrificaion provides anoxic or anaerobic environment, produces simultaneously carbonic acid gas.The organic carbon that heterotrophism denitrifier in the pine tree cortex utilizes Cortex Pini to discharge carries out denitrogenation as organic carbon source, produces simultaneously carbonic acid gas.In the Zero-valent Iron layer of downstream, the sponge iron Anaerobic Corrosion produces cathode hydrogen, and sponge iron is removed a small amount of NO by chemical reduction simultaneously ₃-N.Autotrophic denitrification bacterium in the pine tree cortex utilizes cathode hydrogen as electron donor and energy source, utilizes carbonic acid gas to carry out autotrophic denitrification as inorganic carbon source.Three kinds of Approach of Removal of Nitrogens exist symbiosis, collaborative and promoter action, and wherein the heterotrophism denitrogenation is topmost Approach of Removal of Nitrogen.

Use apparatus and method of the present utility model, the DO clearance is stabilized between 90.83%～97.34%.When flow velocity between 0.15～0.29m/d, the water inlet NO ₃-N is between 22～104mg/L the time, NO ₃-N clearance＞95%, denitrification process is without NO ₂-N accumulation.

Simultaneously, the DLDM-PRB water outlet can significantly not change the pH value of natural groundwater environment, and microorganism can grow in a relatively more suitable pH value environment in the grid, does not need to add the pH buffer reagent.

Cortex Pini and sponge iron lower cost for material, natural being easy to get in the utility model device.This apparatus structure is simple, is applicable to the biological restoration of underground water, and significant advantage is arranged on economy and the feature of environmental protection.

Description of drawings

Fig. 1 is the structural representation of biological deoxidation nitrogen rejection facility and laying state graph in the embodiment 1 well-oxygenated environment underground water.

Fig. 2 is for pressing the laboratory simulation column device figure of the double-deck two medium osmosis reaction grids of biological deoxidation-heterotrophism among the utility model embodiment 3/autotrophic denitrification (BD-HAD DLDM-PRB).

Fig. 3 is that the DO of BD-HAD DLDM-PRB is with the variation diagram of PV.

Fig. 4 is the water outlet NO of BD-HAD DLDM-PRB ₂-N is with the variation diagram of volume of voids (Pore Volume, PV).

Fig. 5 is the water outlet NH of BD-HAD DLDM-PRB ₄-N is with the variation diagram of PV.

Fig. 6 is that the pH value of BD-HAD DLDM-PRB is with the variation diagram of PV.

Fig. 7 is that the water outlet total organic carbon (Total Organic Carbon, TOC) of BD-HAD DLDM-PRB is with the variation diagram of PV.

Fig. 8 is the NO of BD-HAD DLDM-PRB ₃-N and clearance thereof are along the variation diagram of journey.

Fig. 9 is the NO of BD-HAD DLDM-PRB ₂-N and NH ₄-N along the journey variation diagram.

Figure 10 be the DO of BD-HAD DLDM-PRB and TOC along the journey variation diagram.

Figure 11 is the variation diagram of DO with the reaction times.

Figure 12 is NO in the reaction flask ₃-N clearance is with the variation diagram in reaction times.

Figure 13 is NH in the reaction flask ₄The generation of-N is with the variation diagram in reaction times.

Figure 14 is the graph of a relation of denitrification rates and water temperature during the BD-HAD denitrogenation in the reaction flask.

Figure 15 be in the reaction flask during BD-HAD denitrogenation " three nitrogen " with the variation diagram in reaction times.

Embodiment

Unless otherwise defined, all technology used herein and scientific terminology and the utility model routine of relating to the those of ordinary skill of technical field is understood identical meanings.

For example term " sponge iron " herein is in rotary kiln, shaft furnace or other reactors, and with coal, coke, Sweet natural gas or hydrogen make iron ore or iron ore pellets carry out low-temperature reduction under the condition that is lower than the material melting temperature, become cavernous product.The iron that wherein is reduced out is tiny iron nuclear, the group of examining under a microscope likeness in form sponge.The sponge iron main component is iron, and ultimate compression strength is high, not efflorescence, does not harden, and loose and porous inner surface, its specific surface area that provides are 5～10 times of common iron filings.

Term " Cortex Pini " is trunk crust and the endothelium of Pinaceae pine genus plant herein, and by the pine tree cell wall components, its main component is Mierocrystalline cellulose ((C ₆H ₁₀O ₅) _n), also contain the impurity that some exists with the residual form of wax, colloid and protein.Mierocrystalline cellulose is comprised of the covalently bound long-chain of linear glucose unit, is a kind of polysaccharide that the occurring in nature distribution is the widest, content is maximum, accounts for more than 50% of vegitabilia's carbon content.The utility model can use commercially available or natural various Cortex Pinis both at home and abroad.

The main component of term " natural river sand " is take silico-aluminates such as quartz, feldspar and hornblendes as main herein, and contains the carbonate mineralss such as a certain amount of rhombspar, calcite, and above mineral composition can account for more than 95% of overall proportion.Above-mentioned multi mineral crystallization degree is good, and each mineral characteristic peak d value and standard spectrum collection of illustrative plates (PDF card) data are basically identical.

Term " permeable reactive grid (PRBs) " is a kind of based technique for in-situ remediation of groundwater pollution herein, it is a dependent response district that is filled with permeable Active reaction medium (liquid, solid-state or gaseous state), when polluted underground water under self hydraulic gradient effect during by reaction zone pollutent (such as chlorinated hydrocarbon, heavy metal, nucleic, inorganic nitrogen etc.) can be biodegradable, fix, absorption, precipitation, removal, redox, catalyzed oxidation or catalytic reduction.Can contain among the grid PRBs reductive agent reducing medium, the fixing metal of the volatile organic matter of degrading network (chela) mixture medium, the microorganism growth breeding needed nutrition of biological respinse and or oxygen medium etc. in order to strengthen biological treatment or other reagent.

Term " the double-deck two medium osmosis reaction grids (BD-HADDLDM-PRB) of biological deoxidation-heterotrophism/autotrophic denitrification " is a kind of take the biological deoxidation denitrogenation as main PRB herein, and this PRB is mainly by SOLID ORGANIC carbon source layer with the Zero-valent Iron layer is two-layer forms.The continual release organic carbon of organic carbon source provides electron donor for aerobic heterotrophic bacterium deoxygenation, provides carbon source and energy source for the growth of heterotrophism denitrifier, breathing and denitrogenation simultaneously.The product carbonic acid gas of biological deoxidation and two kinds of processes of heterotrophism denitrogenation provides inorganic carbon source for autotrophic denitrification.The cathode hydrogen that the sponge iron Anaerobic Corrosion produces promotes the metabolism of autotrophic denitrification bacterium and strengthens the autotrophic denitrification ability that as electron donor and energy source sponge iron can be removed a small amount of NO by chemical reduction simultaneously ₃-N.

" excess oxygen " among this paper embodiment refers to contain in the water dissolved oxygen 3.0～9.0mg/L.

" neutral meta-alkali " among this paper embodiment refers to water body pH 7.0～9.0.

Below in conjunction with example preferred version of the present utility model is specifically described, this example is not the restriction to the utility model protection domain.

Biological deoxidation nitrogen rejection facility in the embodiment 1 well-oxygenated environment underground water

As shown in Figure 1, the biological deoxidation nitrogen rejection facility is the two medium osmosis reaction of bilayer grid in the well-oxygenated environment underground water of the present utility model, and it is made of upstream layer 1 and downstream layer 2, doses Cortex Pini in this upstream layer 1, doses Zero-valent Iron and sand grains in this downstream layer 2.The particle diameter of Cortex Pini is 2.0～11.0mm.Zero-valent Iron can be sponge iron, its Fe ⁰Content〉60.6%, particle diameter is 0.15～2.0mm.Sand grains can be natural river sand, and particle diameter is 0.45～2.0mm, and the effect of sand grains is to avoid sponge iron to harden into piece and to keep the downstream layer hydraulics constant.The quality of Cortex Pini, sponge iron and sand grains is respectively 7.1kg, 8.0kg, 7.4kg.The thickness of upstream layer and downstream layer is respectively 108cm, 30cm.

Static state domestication and the enrichment of embodiment 2 microorganisms

2.1 material and instrument

Cortex Pini: technical grade, particle diameter are 2.0～11.0mm, BET=0.46m ²/ g,

Available from vegetables fully stocked wood flowers market in Beijing;

Sponge iron: technical grade, Fe ⁰＞60.6%, major impurity is SiO ₂, particle diameter is 0.15～2.0mm, opens green source company limited available from Beijing;

Sand: natural river sand, particle diameter are 0.45～2.0mm;

NaHCO ₃: Beijing Chemical Plant (analytical pure);

NaNO ₃: Shantou City Xilong Chemical Co., Ltd;

K ₂HPO ₄: Beijing fine chemistry industry limited liability company;

Wide-mouth frosted bottle (20L).

Microbial inoculant bacterium source: soil in the Beijing suburb corn field (subsurface 0.3m place) is taken from the inoculation bacterium source of aerobic heterotrophic bacterium, heterotrophism denitrifier and autotrophic denitrification bacterium, and particle diameter is 0.15～0.45mm, cryopreservation (4 ℃) for subsequent use;

Simulated groundwater: in tap water, add NaNO ₃And NaHCO ₃Formulated, NO after the configuration ₃-N and NaHCO ₃Concentration be respectively 22.6mg/L and 350mg/L, the tap water composition specifically sees Table 1.

Table 1 tap water quality

Annotate: unit is that mg/L(removes the pH value); ND is not for detecting

2.2 the domestication of microorganism is cultivated

Wide-mouth frosted bottle carries out lucifuge, the static cultivation of microorganism within it as the domestication culturing bottle, adopts Cortex Pini that carbon source is provided, and provides hydrogen by sponge iron, adds NaHCO ₃Increase inorganic carbon.Corn field soil: Cortex Pini: sponge iron: water=3:3:3:400(mass ratio), NaHCO ₃, NO ₃-N, K ₂HPO ₄-P concentration is respectively 350mg/L, 23mg/L, 3mg/L.Regulating initial DO is 3.5～8.0mg/L.DO and NO in bottle ₃During-N approach exhaustion, carry out the microorganism enrichment and cultivate.

2.3 the enrichment culture of microorganism

Stir the domestication culturing bottle, leave standstill 0.5h after, shift the outstanding turbid mixed bacteria liquid in upper strata of proper volume to another wide-mouth frosted bottle, replenish simulated groundwater, bacterium liquid: water=1:10(volume ratio).Cortex Pini in this bottle: sponge iron: the mass ratio of water, initial NaHCO ₃, NO ₃-N, K ₂HPO ₄The conditions such as the concentration of-P and initial DO value are identical with 2.2 joint domestication cultivation stages.Take identical step and envrionment conditions, order is cultivated mixed bacteria liquid of future generation.

By PCR and 16Sr RNA molecular biology method, the mixed bacteria liquid of enrichment culture is identified.In this bacterium liquid aerobic heterotrophism Pseudomonas Adhaeribacter(proportion in clone library is arranged is 1%), Flavobacterium (Flavisolibacter) (proportion is 3% in clone library) and Flavobacterium(proportion in clone library be 3%); Heterotrophism denitrogenation Pseudomonas has Rhodopseudomonas (Pseudomonas) (proportion is 14% in clone library), bacillus (Bacillus) (proportion is 1% in clone library), Steroidobacter (proportion is 1% in clone library) and new sphingolipid Pseudomonas (Novosphingobium) (proportion is 5% in clone library); The autotrophic denitrification bacterium has Rhodopseudomonas (Pseudomonas) (proportion is 4% in clone library).

The preparation of the double-deck two medium osmosis reaction grids of embodiment 3 biological deoxidations-heterotrophism/autotrophic denitrification (BD-HAD DLDM-PRB) and at underground water DO and NO ₃Application during-N removes

3.1 material and instrument

Cortex Pini: technical grade, particle diameter are 2.0～11.0mm, BET=0.46m ²/ g,

Available from vegetables fully stocked wood flowers market in Beijing;

Sponge iron: technical grade, particle diameter are 0.15～2.0mm, Fe ⁰＞be 60.6%, major impurity is SiO ₂, BET=0.49m ²/ g,

Open green source company limited available from Beijing, particle diameter is 0.15～2.0mm;

Sand: natural river sand, particle diameter are 0.45～2.0mm.

3.2BD-HAD the preparation of DLDM-PRB

1) screening Cortex Pini, the particle diameter of selecting is 2.0～11.0mm; The screening sponge iron, the particle diameter of selecting is 0.15～2.0mm; Riddled sand, the particle diameter of selecting are 0.45～2.0mm.

2) take by weighing respectively Cortex Pini, sponge iron, sand, three's mass ratio is 71:80:74.

3) Cortex Pini is added in the room of upstream layer 1 of embodiment 1 described PRB, form the pine tree cortex.

4) place container to stir sponge iron and sand, add subsequently in the room of downstream layer 2 of same PRB, form the sponge iron layer.

5) Thickness Ratio of pine tree cortex and iron layer is 54:15, and the thickness of pine tree cortex is 108cm, and the thickness of iron layer is 30cm.Make BD-HAD DLDM-PRB by above step.The structure formation of this PRB can be water proof funnel gate-type or diaphragm wall formula.

3.3 DO and NO in the removal underground water ₃-N

As shown in Figure 1, the BD-HAD DLDM-PRB of preparation in 3.2 is placed the downstream (perpendicular with groundwater flow) of polluted underground water, how to be infused in this PRB in 2.3 joints through for the microorganisms of enrichment culture, injection rate accounts for 45% of PRB volume of voids.When the underground water that pollutes passed through BD-HAD DLDM-PRB, in the pine tree cortex of upstream, the continual release organic carbon of Cortex Pini provided electron donor for aerobic heterotrophic bacterium deoxygenation, provides carbon source and energy source for the growth of heterotrophism denitrifier, breathing and denitrogenation simultaneously; Aerobic heterotrophic bacterium utilizes the aerobic repiration of organic carbon battalion to carry out deoxygenation, and for biological denitrificaion provides anoxic or anaerobic environment, the heterotrophism denitrifier and the autotrophic denitrification bacterium that are beneficial to the pine tree cortex carry out denitrogenation; The product carbonic acid gas of biological deoxidation and two kinds of processes of heterotrophism denitrogenation provides inorganic carbon source for autotrophic denitrification.In the Zero-valent Iron layer of downstream, the cathode hydrogen that the sponge iron Anaerobic Corrosion produces strengthens the autotrophic denitrification ability as electron donor and energy source, and sponge iron is removed a small amount of NO by chemical reduction simultaneously ₃-N.Aerobic heterotrophic bacterium aerobic repiration, heterotrophism denitrogenation, autotrophic denitrification and chemical reduction acting in conjunction so that the polluted underground water under the well-oxygenated environment be purified, wherein aerobic heterotrophic bacterium aerobic repiration is topmost deoxygenation approach, and the heterotrophism denitrogenation is topmost Approach of Removal of Nitrogen.

The performance study of embodiment 4 BD-HAD DLDM-PRB

4.1 laboratory apparatus and material

The inoculation bacterium liquid of PRB: the microorganism of enrichment culture among the embodiment 2;

PRB: according to the BD-HAD DLDM-PRB of embodiment 3 preparations;

NaHCO ₃: Beijing Chemical Plant (analytical pure);

NaNO ₃: Shantou City Xilong Chemical Co., Ltd;

K ₂HPO ₄: Beijing fine chemistry industry limited liability company;

Peristaltic pump: BT100-1F, the DG-4 pump head is joined by Baoding LanGe constant flow pump Co., Ltd;

Simulated groundwater: by the tap water preparation, the tap water composition sees Table 1.

4.2BD-HAD DLDM-PRB simulates column device

As shown in Figure 2, it is the laboratory simulation column device of BD-HAD DLDM-PRB among the cover embodiment 3, and internal diameter is 20.6cm, total height 150cm, and the turnover water end (W.E.) respectively is covered with the high cobble of 6cm 21, plays the effects such as support, buffering, filtration, gas collection and protection.In the Filled Dielectrics district of reaction column, the bottom is pine tree cortex 22(virtual height 108cm), be used to provide organic carbon and serve as microbe carrier, in main biological deoxidation and the biological denitrificaion situation investigated of this layer; The top is the mixture layer 23(virtual height 30cm of sponge iron and sand), be used for producing cathode hydrogen and serve as microbe carrier, mainly investigate the chemical reduction deoxygenation and denitrogenate and the biological denitrificaion situation at this layer.The volume of voids of this post is 24.77L, and average pore is 54.28%.Different heights at reaction column arranges water sample hole 24, and sewage storage facilities 26 connects peristaltic pump 25 and supplies water for reaction column, adopts bottom water inlet, center water distribution manner, and the top water outlet connects waste liquid cylinder 27.

4.3BD-HAD the startup of DLDM-PRB

Microorganism after the enrichment culture among the embodiment 2 is injected into the research that is used for the denitrogenation of underground water biological deoxidation in the BD-HAD DLDM-PRB reaction column.The volume percent that injection rate accounts for the reaction column volume of voids is 45%, makes it be in full water state with replenishing Simulated Water in the backward reaction column.Reaction column is wrapped up avoiding fungal growth by aluminium foil.Quick emptying in per 2 days once, and with the bacterium liquid of discharging again by bottom blowback reaction column, make every effort to that microorganism can evenly distribute and rapid biofilm in the post on sponge iron and Cortex Pini.The operation condition of reaction column is set as: flow velocity=0.08m/d; Water inlet DO ≈ 7.5mg/L; Water inlet NO ₃-N ≈ 22.6mg/L; Water inlet pH value is neutral meta-alkali; 16 ℃ of water temperature ≈.After 20 days, NO ₃-N clearance can reach steady state, and so far reaction column starts end.

4.4DO variation

At water inlet NO ₃-N concentration is that 22～104mg/L, flow velocity are under the operational conditions of 0.15～0.29m/d, neutral meta-alkali, investigated the deoxygenation ability of BD-HAD DLDM-PRB, regularly at reaction column entery and delivery port sampling and measuring DO, Inlet and outlet water DO and clearance situation thereof are seen Fig. 3 under the different PV.

As seen from Figure 3, when water inlet DO was between 6.02～8.69mg/L, water outlet DO was between 0.19～0.56mg/L, and clearance is stabilized between 90.83%～97.34%.This result shows that dissolved oxygen can be stablized, be removed efficiently to reaction column.

4.5NO ₃The removal effect of-N

Under the operational conditions of neutral meta-alkali and oxygen enrichment, investigated the denitrogenation situation of BD-HAD DLDM-PRB, regularly at reaction column entery and delivery port sampling and measuring NO ₃-N, NO ₃-N clearance and volumetric loading and flow velocity, water inlet NO ₃The relation of-N concentration sees Table 2.

NO under the different operational conditionss of table 2 ₃The removal situation of-N (neutral meta-alkali, oxygen enrichment)

The processing power of PRB can also be weighed with volumetric loading except weighing with clearance.Volumetric loading has reflected the relation of flow velocity, water inlet substrate concn, clearance and grid useful volume.Herein by adjusting flow velocity or adjusting substrate concn or the two adjusts to obtain different volumetric loadings simultaneously.By as seen from Table 2, at low flow velocity (0.15m/d) and low water inlet NO ₃(corresponding volumetric loading is 1.61gN/m to-N concentration (22.71mg/L) ³/ d)) condition under, NO ₃-N clearance＞95% illustrates that this PRB reaction column is used for underground water NO ₃The removal of-N is effective and feasible.Flow velocity and influent concentration are increased to respectively 0.29m/d and 103.98mg/L so that NO ₃-N load reaches 15.28g N/m ³Behind/the d, clearance still＞95%, NO simultaneously ₃-N load can be up to 15.28gN/m ³/ d), illustrate that this PRB reaction column has good capacity of resisting impact load.When flow velocity between 0.15～0.29m/d, the water inlet NO ₃-N is between 22～104mg/L the time, and clearance＞95% illustrates that with regard to operational conditions the scope of application of this reaction column is wider.

4.6 the research of nitrogen product

At water inlet NO ₃-N concentration is that 22～104mg/L, flow velocity are under the operational conditions of 0.15～0.29m/d, neutral meta-alkali, oxygen enrichment, has investigated the Changing Pattern of nitrogen product in the denitrification process of BD-HAD DLDM-PRB, regularly at reaction column entery and delivery port sampling and measuring NO ₂-N and NH ₄-N, water outlet NO under the different PV ₂-N and NH ₄The changing conditions of-N is seen respectively Fig. 4 and Fig. 5.

Biological denitrificaion is the process of an anoxic or anaerobism, in this process no matter heterotrophism denitrifier or autotrophic denitrification bacterium all with NO ₃ ^-Be reduced into first NO ₂ ^-, be subsequently converted to NO, N ₂O finally changes into N ₂, see formula 1.

NO ₃ ^-→ NO ₂ ^-→ NO (g) → N ₂O (g) → N ₂(g) (formula 1)

NO ₂-N is an intermediate product in the biological denitrification process, and laboratory experiment, field trial and engineering NO often occurs in using ₂-N accumulation phenomenon.When pine tree wood shavings during as carbon source, NO ₂-N concentration is higher than 13mg/L always, yet does not but generate NO when hornbeam is used as carbon source ₂-N[Aslan and Turkman, Biological denitrification of drinking water using various natural organic solid substrates.Water Science and Technology, 2003,48:489-495].In another research, as water inlet NO ₃-N is respectively 50,120 and during 200mg/L, and wood chip and wheat straw all can be caused NO in the water outlet ₂-N concentration reaches [Saliling et al. about 2.0mg/L, Wood chips and wheat straw as alternative biofilter media for denitrification reactors treating aquaculture and other wastewaters with high nitrate concentrations.Aquacultural Engineering, 2007,37:222-233].NO ₂-N accumulation because of nitrite reductase than nitrate reductase to C:N, pH, DO, PO ₄ ^3-And H ₂The environmental factorss such as pressure are more responsive, and denitrifier Pseudomonas difference also can affect NO ₂The generation of-N.

Fig. 4 shows, water outlet NO ₂-N≤0.046mg/L, concentration is lower and be far smaller than NO ₃Therefore the reduction of-N can think that this reaction column does not cause NO ₂-N accumulation, it is very smooth, very abundant, very thorough that this explanation BD-HAD M-PRB denitrification reaction carries out, activity that the environmental factorss such as TOC, temperature, pH value do not suppress nitrite reductase and nitrate reductase can also be described with synthetic, denitrifier is slower or quite than the reduction rate of nitrite to the rate of reduction of nitrate.

On the other hand, in China's drinking water sanitary standard (GB5749-2006) not to NO ₂-N limit value is made and being explicitly called for.Be exposed to NO based on the human body short burst ₂The requirement of-N is foundation, " drinking water sanitary standard " (GB5749-2006), NO of regulation in " World Health Organization's drinking-water quality criterion ", " EU Committee's instruction ", " U.S.'s water quality standard for drinking water and the health consultation " and " Canadian drinking-water quality guidance " ₂-N limit value is followed successively by 0.30mg/L, 0.91mg/L, 0.15mg/L, 1mg/L and 0.97mg/L.As seen, water outlet NO ₂-N concentration does not all surpass these tissues or state specified standards.

As shown in Figure 5, along with the variation of PV, in water outlet, detected NH ₄-N.Can be found out NH by formula 1 ₄-N is not intermediate product and the end product of biological denitrification process.Formula 2 shows that the nitrogen product of ZVI chemical reduction under the neutral meta-alkali condition neither NH ₄-N.More than the analysis showed that NH in the water outlet ₄-N has the source in addition.The fresh Cortex Pini of sterilization is immersed deionized water (Cortex Pini: water=1:80(mass ratio)), rapid stirring 10min, quiet heavy, get supernatant liquor and measure NH ₄-N has detected the NH of high density ₄-N(data are unlisted).Therefore think NH in the water outlet ₄-N derives from reaction medium itself, has been applied in advance ammonia fertilizer available from the Cortex Pini of flowers market as the cultivation matrixes of flowers and plants, has caused NH ₄-N pollutes.

5Fe ⁰+ 2NO ₃ ^-+ 6H ₂O → 5Fe ²⁺+ N ₂+ 12OH ^-(formula 2)

By Fig. 5 also as can be known, NH ₄The Changing Pattern that-N shows is: the starting stage (PV≤6), its concentration reduces rapidly; Its concentration tends towards stability gradually subsequently, and numerical value is (PV=6～14) between 0.40～1.99mg/L.This proves along with the prolongation of working time and the increase of flooding quantity, the NH in the reaction column on the Cortex Pini ₄-N is washed out gradually.Inferring further increases working time, NH ₄-N concentration is expected to further reduction.

4.7pH the variation of value

At water inlet NO ₃-N concentration is that 22～104mg/L, flow velocity are under the operational conditions of 0.15～0.29m/d, oxygen enrichment, investigated the Changing Pattern of pH value in the denitrification process of BD-HAD DLDM-PRB, regularly at reaction column entery and delivery port sampling and measuring pH, Inlet and outlet water pH value and changing conditions thereof are seen Fig. 6 under the different PV.

As seen from Figure 6, water inlet pH value is between 7.74～8.41, substantially is in neutral meta-alkali; Water outlet pH value is between 7.38～8.86, still is in neutral meta-alkali; And △ pH(△ pH=pH _{Water outlet}-pH _{Water inlet}) fluctuation between-0.85 to+0.85.All in all, at NO ₃In-N removal the process, microorganism grows in a relatively more suitable pH value environment in the reaction column, and biological activity is not suppressed, pH above bacteria metabolism restrain oneself the limit (pH=10), do not need additionally to add the pH buffer reagent.Zhang Yanhao etc. [pH is on the impact of hydrogen autotrophic type denitrifying bacteria denitrification capability. Environmental Pollution and Control, 2010,32(4): 40-43] report when initial pH below 6.7 or 9.2 when above, autotrophic denitrification bacterium biological activity can be suppressed.

The pH Changing Pattern of reaction column is different from bibliographical information.Della Rocca et al.(2006) (documentation ﹠ info referring to above) post experimental study of carrying out shows that after Simulated Water was passed through cotton layer again through the ZVI layer, pH presented reduction trend (being down to about 6.8 by 9.5).When Soares et al. finds that cotton is used for the different oxygen denitrogenation of tap water as carbon source, water outlet pH also presents downward trend [Soares et al., Denitrification of groundwater:pilot-plant testing of cotton-packed bioreactor and post-microfiltration.Water Science and Technology, 2000,42,353-359].Shao stays etc. when finding that straw is used for the denitrogenation of sewage heterotrophism as carbon source, water outlet pH in rising trend [Shao stays etc., take straw as carbon source and biofilm carrier remove nitrate in the water.Environmental science, 2009,30 (5): 1414-1419].

Sponge iron chemical reduction deoxygenation can produce OH when denitrogenating (under neutrality or the alkaline condition) and Anaerobic Corrosion ^-Also can produce Fe simultaneously ²⁺( formula 2,3 and 7); Heterotrophism denitrogenation and autotrophic denitrification also can produce OH ^-(formula 4 and 5) so water outlet pH should raise in theory, presents fluctuation but practical operation situation is △ pH.

Fe ⁰+ 2H ₂O → H ₂+ Fe ²⁺+ 2OH ^-(formula 3)

4NO ₃ ^-+ 5CH ₂O → 5CO ₂+ 2N ₂+ 3H ₂O+4OH ^-(formula 4)

2NO ₃ ^-+ 5H ₂→ N ₂+ 4H ₂O+2OH ^-(formula 5)

Contain HCO in the water inlet ₃ ^-, HCO ₃ ^-With OH ^-Neutralization reaction having occured, kept acid base equilibrium, has cushioned pH value of solution.In addition, water inlet also contains a large amount of Cl ^-And SO ₄ ^2-(seeing Table 1), they and Fe ²⁺React and generate H ⁺Reduce pH.

4.8TOC variation

At water inlet NO ₃-N concentration is that 22～104mg/L, flow velocity are under the operational conditions of 0.15～0.29m/d, neutral meta-alkali, oxygen enrichment, inquired into the Changing Pattern of TOC in the denitrification process of BD-HAD DLDM-PRB, regularly at reaction column entery and delivery port sampling and measuring TOC, the TOC of yielding water changing conditions is seen Fig. 7 under the different PV.

As seen from Figure 7, during different PV, all detected TOC in the water outlet, this owing to organic quick release, dissolving in the Cortex Pini, diffusion is in addition biomembranous comes off, runs off, metabolic demand when Cortex Pini not only can satisfy aerobic heterotrophic bacterium aerobic repiration deoxygenation and the denitrogenation of heterotrophism denitrifier is described, and also has residue.Equation of linear regression is used for describing the relation of TOC of yielding water and PV.Can be found out that by Trendline TOC presents the trend of minimizing, but concentration still is higher than similar research report.Della Rocca et al.(2006) (documentation ﹠ info referring to above) studies show that exit TOC is between 6～30mg/L.Volokita et al.(1996a; 1996b) experimental result of (documentation ﹠ info referring to above) shows and shows: cotton is during as carbon source, the about 16mg/L of initial operating stage water outlet DOC, and the later stage peak-peak reaches 30mg/L; Newspaper is during as carbon source, and water outlet DOC can be up to about 230mg/L, and along with the further increase DOC of working time reduces gradually and tends towards stability.This research and bibliographical information can confirm that the cellulose type solid organic carbon source causes the middle TOC concentration of biological denitrificaion water outlet (especially initial operating stage water outlet) higher often.

" 4.9 three nitrogen " along Cheng Bianhua

At water inlet NO ₃-N concentration is that 104mg/L, flow velocity are under the operational conditions of the neutral meta-alkali of 0.29m/d, pH, oxygen enrichment, inquired into " three nitrogen " in the denitrification process of BD-HAD DLDM-PRB along the journey Changing Pattern, regularly at distance post water-in 0cm, 25cm, 65cm, 105cm and 150cm place sampling and measuring " three nitrogen ", " three nitrogen " and NO are located in the different layers position ₃The changing conditions of-N clearance is seen respectively Fig. 8 and Fig. 9.

Fig. 8 shows, feed-water end (＜25cm), NO ₃-N concentration slightly reduces, clearance＜5%.Inoculation bacterium liquid is a kind of mixed bacteria liquid, and this bacterium liquid does not carry out purifying to be cultivated, so there is aerobic heterotrophic bacterium in the bacterium liquid.Higher in feed-water end DO concentration, aerobic heterotrophic bacterium then becomes dominant microflora, and the denitrifier activity is subject to the inhibition of high density DO.In the time of between 25～105cm, NO ₃-N clearance increases to 94.51% of 105cm place by 4.97% of 25cm place.Obviously, in this interval, most of DO has been removed (see figure 3), and DO has not been the restrictive factor of biological denitrificaion, and heterotrophism denitrifier and autotrophic denitrification bacterium are because of NO ₃-N, TOC, CO ₂With the substrate such as negative electrode H sufficient and a large amount of existence, nitric efficiency is high.At water side (105～150cm), NO ₃-N concentration is lower, denitrifier comparatively small amt, therefore removed remaining NO ₃-N(clearance＜5%) gives the credit to the chemical reduction of sponge iron.

As seen from Figure 9, NO ₂-N concentration increases first the trend of rear minimizing along Cheng Chengxian, at the NO of 25cm place ₂-N reaches peak value (1.21mg/L), shows at feed-water end and has caused NO ₂The of short duration accumulation of-N illustrates that existing nitrite reductase activity has been subject to the inhibition of DO or nitrite reductase and has been later than syntheticly, and certainly the rate of reduction of nitrate is faster than the rate of reduction of nitrite.In the time of between 25～105cm, recovered nitrite reductase because the environmental factorss such as DO, substrate are suitable active or strengthened the resultant velocity of nitrite reductase, so NO ₂-N has obtained removal gradually.When height 〉=105cm, NO ₂-N≤0.05mg/L, well below tissue or state specified standards such as China, the World Health Organization, European Union, America ﹠ Canadas.

Also known by Fig. 9, intaking without NH ₄In the situation of-N, the place has all detected NH along journey (comprising water outlet) different layers position ₄-N.At the NH of 65cm place ₄-N concentration has reached peak value (1.52mg/L).In the time of between 65～150cm, NH ₄-N has only reduced 0.26mg/L.Analyze NH in the reaction column as 4.6 joints ₄-N derives from Cortex Pini.

4.10DO and TOC along Cheng Bianhua

At water inlet NO ₃-N concentration is 104mg/L, flow velocity is under the operational conditions of 0.29m/d, neutral meta-alkali, oxygen enrichment, inquired into DO and TOC in the denitrification process of BD-HAD DLDM-PRB along the journey Changing Pattern, regularly at distance post water-in 0cm, 25cm, 65cm, 105cm and the sampling and measuring DO of 150cm place and TOC, the changing conditions of the different layers position DO of place and TOC is seen Figure 10.

As seen from Figure 10, along with the increase of height, DO concentration reduces gradually.At the 25cm place, DO concentration is down to 2.66mg/L by the 5.89mg/L of water inlet; At the 125cm place, continue to be down to 0.72mg/L.This shows that most DO are removed between 0～125cm, illustrate that the reaction column deoxygenation mainly depends on aerobic heterotrophic bacterium aerobic repiration, because only filled Cortex Pini and mixed bacteria liquid between 0～125cm, does not have filling sponge iron.The biological deoxidation process is seen formula 6.

O ₂+ CH ₂O → CO ₂+ H ₂O (formula 6)

When height increased to 150cm by 125cm, DO was down to 0.21mg/L by 0.72mg/L, illustrates that sponge iron has certain deoxygenation ability, and the deoxygenation approach is seen formula 7.

2Fe ⁰+ O ₂+ 2H ₂O → 2Fe ²⁺+ 4OH ^-(formula 7)

Water inlet DO changes between 5.5～9mg/L, and residual DO is not enough to affect the denitrification effect (seeing Table 2) of BD-HADDLDM-PRB in the post.Although (especially 25～105cm) exist a certain amount of DO to the interior different layers position of post, but the outer aerobic bacteria of microbial film that is attached on the Cortex Pini has stoped DO to enter the microbial film internal layer, guaranteed that internal layer is in anoxic even anaerobic state, the heterotrophism denitrifier and the autotrophic denitrification bacterium that are positioned at like this internal layer have obtained protection; Moreover, the high (see figure 7) of TOC concentration in the post, the heterotrophism denitrifier utilizes NO ₃-N is that the probability of electron acceptor(EA) strengthens, and DO has obtained good buffering to the side effect of denitrogenation.Jin Zanfang etc. find in by the post experimental study of copy paper as weighting material, and Inlet and outlet water DO is respectively 2～6mg/L and 0.6mg/L can guarantee that denitrogenation carries out [Jin Zanfang etc., the research of removing groundwater azotate take paper as carbon source smoothly.Chinese Journal of Applied Ecology, 2004a, 15(12): 2359-2363].Jin Zanfang etc. observe in by the columns experiment of cotton as reaction medium, water inlet DO is 2～6mg/L and water outlet DO smooth denitrogenation [Jin Zanfang etc. still when being 0.9mg/L, remove the research of groundwater azotate take cotton as carbon source. the agro-environment science journal, 2004b, 23(3): 512-515].G ó mez et al.(2000; 2002) (documentation ﹠ info referring to above) also drawn similar conclusion.

By Figure 10 also as can be known, TOC is located all to have detected in different layers position (not comprising water-in), shows the demand that can satisfy aerobic heterotrophic bacterium deoxygenation and the denitrogenation of heterotrophism denitrifier at each layer position TOC; Along with the increase of height, residual organic matter accumulates gradually in the water.

4.11 conclusion

(1) BD-HAD M-PRB reaction column is used for underground water NO ₃The removal of-N is effective and feasible, and its scope of application is wider, has good capacity of resisting impact load.

(2) BD-HAD M-PRB reaction column water outlet NO ₂-N does not surpass tissue or the state specified standards such as China, the World Health Organization, European Union, America ﹠ Canada, its concentration≤0.046mg/L.NH in the reaction column water outlet ₄-N derives from Cortex Pini itself.Dissolved oxygen can be stablized, be removed efficiently to reaction column.Metabolic demand when the TOC that Cortex Pini discharges can satisfy aerobic heterotrophic bacterium aerobic repiration deoxygenation and the denitrogenation of heterotrophism denitrifier.

(3) feed-water end of BD-HAD M-PRB reaction column (＜25cm), NO ₃-N clearance＜5%; In the time of between 25～105cm, clearance increases to 94.51% of 105cm place by 4.97% of 25cm place; In the water side (105～150cm), clearance＜5%.NO ₂-N concentration increases first the trend of rear minimizing along Cheng Chengxian, at the NO of 25cm place ₂Of short duration accumulation has occured in-N.The place has all detected NH along journey different layers position ₄-N, its concentration has reached peak value at the 65cm place.Deoxygenation mainly depends on aerobic heterotrophic bacterium aerobic repiration, and residual DO is not enough to affect the denitrification effect of BD-HAD DLDM-PRB in the post.

The static experiment research of embodiment 5 BD-HAD deoxygenation denitrogenations

5.1 material and instrument

Cortex Pini: technical grade, available from certain flowers market, particle diameter is 0.15～20.0mm;

Sponge iron: technical grade, Fe ⁰Be 60.6%, major impurity is SiO ₂(Beijing open green source company limited), particle diameter is 0.15～2.0mm;

Reaction flask: the Schott bottle (1L, 2L) of being furnished with screw-cap;

The microorganism of mixed bacteria liquid: embodiment 2 enrichment culture;

If no special instructions, used chemical reagent is AG or ACS level.

Simulated groundwater: in the reverse osmosis water of oxygen enrichment, add NaNO ₃, NaHCO ₃, the trace element and other mineral salts formulated (mg/L): NO ₃-N(～22.6); NaHCO ₃(350); DO(4.0～5.2); K ₂HPO ₄(17.4); FeCl ₃6H ₂O(0.53); Na ₂EDTA(7.4); MgCl ₂6H ₂O(40.6); MgSO ₄7H ₂O(49); CaCl ₂6H ₂O(21.9); NaCl(58.5); Na ₂MoO ₄2H ₂O(0.50); CoCl ₂6H ₂O(0.08); ZnSO ₄10H ₂O(0.09); MnCl ₂4H ₂O(0.72).

5.2 biological and abiotic deoxygenation

Experimental investigation has been criticized in employing biological action in the BD-HAD method (referring to aerobic heterotrophic bacterium aerobic repiration) and abiotic effect (referring to the sponge iron chemical reduction) deoxygenation ability separately.Sponge iron used herein carry out high-temperature sterilization process (160 ℃, 4h).Test condition: in the abiotic bottle, initial DO ≈ 5mg/L, sponge iron: water=5:800(mass ratio), neutral meta-alkali; In the biological bottle, initial DO ≈ 5mg/L, Cortex Pini: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), neutral meta-alkali.Equation of linear regression is used for describing the relation in DO and reaction times and estimates complete deoxygenation required time (seeing Figure 11, formula 8 and 9).

Figure 11 shows biological and abiotic effect DO and all have stronger negative linear correlation between the reaction times when existing respectively.According to the linear least-squares analysis, obtain regression equation, specifically see formula 8 and 9:

C _{T, DO}/ C _{0, DO}=-0.5109t+0.9747(R ²=0.9777) (biology) (formula 8)

C _{T, DO}/ C _{0, DO}=-7.0238t+1.0046(R ²=0.9951) (abiotic) (formula 9);

According to formula 8 estimations, aerobic heterotrophic bacterium needed 1.91 days can reach 100% deoxygenation.These are different from result in the BD-HAD DLDM-PRB post experimental study.When flow velocity is that the water conservancy residence time corresponding to 0.29m/d(is about 5 days), the water inlet DO be under the condition of 5.89mg/L, after about 4 days, be down to 0.72mg/L(by initial value and see Figure 10 by DO concentration at the post internal reaction for underground water).The reason of difference is that reaction flask is the system of a sealing, and Cortex Pini, TOC and microorganism etc. do not wash out loss in the system, and biomass is larger in addition.

According to formula 9 estimations, sponge iron only needed 0.14 day can reach 100% deoxygenation.As seen, sponge iron is not yet brought into play the effect (see figure 10) of deoxygenation in the BD-HAD DLDM-PRB reaction column.But the sponge iron chemical reduction among the BD-HAD DLDM-PRB is used for deoxygenation has potential applicability.When underground water surrounding factor (such as water temperature, nutritive element) changes suddenly so that biological deoxidation when losing efficacy, sponge iron can guarantee that BD-HAD DLDM-PRB still can efficiently remove DO.

5.3HD/AD/CR the contribution to the BD-HAD denitrogenation

Figure 12 has assessed initial NO ₃-N is about under 22.6mg/L, the neutral meta-alkali condition BD-HAD, HD, CR, AD+CR, AD, HD+AD+CR to NO ₃The removal situation of-N, the clearance of AD is defined as actual measurement clearance poor of the actual measurement clearance of AD+CR and HD herein; The clearance of HD+AD+CR is defined as the actual measurement clearance sum of actual measurement clearance and the HD of AD+CR.Test condition: in the BD-HAD bottle, initial NO ₃-N ≈ 22.6mg/L, Cortex Pini: water=5:800(mass ratio), sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali; In the HD bottle, initial NO ₃-N ≈ 22.6mg/L, Cortex Pini: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali; In the CR bottle, initial NO ₃-N ≈ 22.6mg/L, sponge iron: water=5:800(mass ratio), oxygen enrichment, neutral meta-alkali; In the AD+CR bottle, initial NO ₃-N ≈ 22.6mg/L, sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali.

As seen from Figure 12, BD-HAD, HD, CR and AD+CR NO separately ₃-N clearance all increases along with the increase in reaction times, after 16 days, and the NO that in BD-HAD reaction flask, HD reaction flask, CR reaction flask and AD+CR reaction flask, surveys ₃-N clearance can reach 99.40%, 83.06%, 6.19% and 15.29% successively.At any one time, the clearance of CR is very low, and sponge iron chemical reduction NO under neutrality or meta-alkalescence condition is described ₃The ability of-N is less.At any one time, the clearance of AD+CR shows to have the autotrophic denitrification bacterium and the autotrophic denitrification phenomenon has occured in BD-HAD greater than single CR.At any one time, be HD according to the ordering of the height of clearance〉AD〉CR, illustrate that the heterotrophism denitrogenation is the topmost approach of denitrogenating among the BD-HAD.Denitrogenation all contributes to BD-HAD for CR, HD, AD, proves that the three exists symbiosis, collaborative and promoter action in the BD-HAD method.The NO of actual measurement ₃-N clearance is similar to the HD+AD+CR clearance of calculating, illustrates not have other Approach of Removal of Nitrogens in the BD-HAD system.

5.4BD-HAD/HD/AD/CR NH when denitrogenating ₄The generation situation of-N

Figure 13 has enumerated initial NO ₃-N is about that BD-HAD, HD, CR, AD+CR denitrogenate NH in the process under 22.6mg/L, the neutral meta-alkali condition ₄The generation situation of-N.The NH that AD causes ₄-N is defined as the actual measurement NH of AD+CR ₄The actual measurement NH of-N and CR ₄-N's is poor.Test condition: in the BD-HAD bottle, initial NO ₃-N ≈ 22.6mg/L, Cortex Pini: water=5:800(mass ratio), sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali; In the HD bottle, initial NO ₃-N ≈ 22.6mg/L, Cortex Pini: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali; In the CR bottle, initial NO ₃-N ≈ 22.6mg/L, sponge iron: water=5:800(mass ratio), oxygen enrichment, neutral meta-alkali; In the AD+CR bottle, initial NO ₃-N ≈ 22.6mg/L, sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali.

As seen from Figure 13, in BD-HAD and two reaction flasks of CR, all do not detect NH ₄-N is so BD-HAD and CR denitrogenate process without NH ₄-N generates.In the HD reaction flask, only in the time of the 4th day, detect NH ₄-N(0.04mg/L), only account for into 0.20% of water N, denitrogenate in the process without NH so can be considered HD ₄-N generates.Any time has all detected NH in the AD+CR reaction flask ₄-N, but its concentration＜0.1mg/L only account for into 0.37% of water N, denitrogenate process without NH so can be considered AD ₄-N generates.These phenomenons are also further verified NH in the BD-HAD DLDM-PRB water outlet ₄-N derives from Cortex Pini, rather than derives from denitrification process.

5.5 water temperature is on the impact of BD-HAD denitrification effect

With regard to the cotton carbon source, when the heterotrophism denitrification rates in the time of 30 ℃ is roughly 14 ℃ 2 times; With regard to the newspaper carbon source, the NO in the time of 30 ℃ ₃3 times of (Volokita et al., 1996a when-N clearance is about 14 ℃; Volokita et al., 1996b, documentation ﹠ info is referring to above); With regard to the copy paper carbon source, 25 ℃ heterotrophism denitrification rates is 14 ℃ 1.7 times (documentation ﹠ info is referring to above for Jin Zanfang etc., 2004a).As seen, sensitivity and temperature are different because of the difference of solid carbon source kind on the impact of denitrogenation on the variation of temperature for the biological denitrification process take the cellulose family carbon source as the basis.Water temperature has no report to the impact of the BD-HAD denitrogenation of Cortex Pini support in addition.Therefore be necessary to carry out water temperature to the impact research of BD-HAD denitrification effect.At initial NO ₃-N is about under 22.6mg/L, the neutral meta-alkali condition relation of denitrification rates and water temperature and sees Figure 14.Test condition: Cortex Pini: water=5:800(mass ratio), sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment.

As shown in Figure 14, along with the rising of water temperature, denitrification rates also raises: when the denitrification rates in the time of 33.0 ± 1.0 ℃ is 27.5 ± 1.0 ℃ 1.6 times, when being 15.0 ± 1.0 ℃ 3.2 times; When 27.5 the denitrification rates in the time of ± 1.0 ℃ is 15.0 ± 1.0 ℃ 2.0 times.Be not difficult to find out that Cortex Pini BD-HAD denitrogenation is comparatively responsive to the variation of temperature equally.Temperature is higher so that the carbochain of Cortex Pini is easier to be destroyed, and then sufficient TOC more can be provided.Another reason is the rising along with temperature, the flushing of denitrogenation thalline endoenzyme, and accretion rate is accelerated and increment speed is accelerated.Certainly temperature can not be too high, otherwise can cause the endoenzyme sex change of denitrogenation thalline or directly kill denitrifier.

5.6 ammonia nitrogen is on the impact of BD-HAD denitrification effect

Suffer NH ₄-N and NO ₃The common underground water that pollutes of-N is outwardness.On the other hand, also found certain density NH in the water outlet of BD-HADDLDM-PRB reaction column ₄-N.During the two coexistence of therefore having adopted batch experimental investigation, the toxicity of ammonia nitrogen is on the impact of denitrifier activity among the BD-HAD, at initial NO ₃-N is about under 22.6mg/L, the neutral meta-alkali condition " three nitrogen " and sees Figure 15 with the variation in reaction times.Test condition: initial NH ₄-N ≈ 22.6mg/L, initial NO ₃-N ≈ 22.6mg/L, Cortex Pini: water=5:800(mass ratio), sponge iron: water=5:800(mass ratio), bacterium liquid: water=1:10(volume ratio), oxygen enrichment, neutral meta-alkali.

Figure 15 shows, NO ₃-N concentration reduces along with the increase in reaction times.NO after 5 days ₃-N is down to 18.80mg/L by initial 21.46mg/L, and is down to 0.94mg/L after 15 days, and visible ammonia nitrogen substantially without impact, illustrates that ammonia nitrogen does not suppress the activity of denitrifier on the BD-HAD denitrogenation.After it should be noted that 15 days, NH ₄-N concentration has reduced 4.43mg/L.The reason of explaining this phenomenon is likely that the mixed bacteria liquid among the BD-HAD contains anaerobic ammonia oxidizing bacteria, at NH ₄-N and NO ₃Anammox has occured during coexistence in-N, sees formula 10.

3NO ₃ ^-+ 5NH ₄ ⁺→ 2N ₂+ 2H ⁺+ 9H ₂O (formula 10)

According to NH ₄-N reduction is found after utilizing formula 10 to calculate, the NO that consumes because of Anammox ₃-N theoretical value should be 2.66mg/L, so most NO in the water ₃-N is still and obtains removing by the BD-HAD method.

Figure 15 also shows, NO ₂-N＜0.35mg/L, this illustrates NH ₄The existence of-N does not cause NO in the BD-HAD denitrification process ₂The accumulation of-N intermediate product.

What Della Rocca et al.(2006) (documentation ﹠ info referring to above) utilized that the PVC the columns of having loaded iron plane flower and cotton carries out studies show that water outlet contains the NH of 16.5mg/L ₄-N, and NH ₄-N can significantly reduce nitrogen removal performance.In this research, the residual NH of reaction flask ₄-N(16.59mg/L) about the same with above-mentioned value, and nitrogen removal performance has no reduction.Obviously, sponge iron and Cortex Pini BD-HAD method are more colored and cotton BD-HAD method is superior than iron plane.

5.7 conclusion

(1) have HD, AD, CR in the BD-HAD method, the three exists symbiosis, collaborative and promoter action, and HD is the topmost approach of denitrogenating among the BD-HAD.

(2) aerobic heterotrophic bacterium and sponge iron needed respectively 1.91 days and 0.14 day can reach 100% deoxygenation.Sponge iron is used for deoxygenation and has potential applicability.

(3) BD-HAD, HD, AD, CR denitrogenate process all without NH ₄-N generates.

(4) Cortex Pini BD-HAD denitrogenation is comparatively responsive to the variation of temperature equally.Along with the rising of water temperature, denitrification rates also raises: when the denitrification rates in the time of 33.0 ± 1.0 ℃ is 27.5 ± 1.0 ℃ 1.6 times, when being 15.0 ± 1.0 ℃ 3.2 times.

(5) substantially without impact, ammonia nitrogen does not suppress the activity of denitrifier to ammonia nitrogen, does not cause NO in the BD-HAD denitrification process yet on the BD-HAD denitrogenation ₂The accumulation of-N.

Claims (2)

1. biological deoxidation nitrogen rejection facility in the well-oxygenated environment underground water, it is double-deck two medium osmosis reaction grid, it is characterized in that this permeable reactive grid is made of upstream pine tree cortex and downstream Zero-valent Iron layer.

2. biological deoxidation nitrogen rejection facility according to claim 1 is characterized in that, the Thickness Ratio of described upstream pine tree cortex and downstream Zero-valent Iron layer is 95～120:24～36.

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