厌氧氨氧化

厌氧氨氧化
厌氧氨氧化

Journal of Hazardous Materials 250–251 (2013) 431–438

Contents lists available at SciVerse ScienceDirect

Journal of Hazardous

Materials

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j h a z m a

t

Denitri?cation performance and microbial diversity in a packed-bed bioreactor using biodegradable polymer as carbon source and bio?lm support

Zhiqiang Shen a ,b ,Yuexi Zhou a ,Jun Hu b ,Jianlong Wang b ,c ,?

a

Chinese Research Academy of Environmental Sciences,Beijing 100012,PR China

b

Laboratory of Environmental Technology,INET,Tsinghua University,Beijing 100084,PR China c

Beijing Key Laboratory of Fine Ceramics,Tsinghua University,Beijing 100084,PR China

h i g h l i g h t s

Starch/PCL (SPCL)blend was prepared and used for biological denitri?cation.

The microbial community of attached bio?lm was analyzsed by metagenomic method. The vast majority of species bio?lm (99.71%)belonged to six major phyla. Proteobacteria were the most abundant phylum (85.50%).

Diaphorobacter and Acidovorax was 52.75%of identi?ed denitrifying bacteria.

a r t i c l e

i n f o

Article history:

Received 15October 2012

Received in revised form 10February 2013Accepted 13February 2013

Available online 20 February 2013

Keywords:Nitrate Bio?lm

Microbial community Denitri?cation

Solid carbon source

a b s t r a c t

A novel kind of biodegradable polymer,i.e.,starch/polycaprolactone (SPCL)was prepared and used as carbon source and bio?lm support for biological denitri?cation in a packed-bed bioreactor.The deni-tri?cation performances and microbial diversity of bio?lm under different operating conditions were investigated.The results showed that the average denitri?cation rate was 0.64±0.06kg N/(m 3d),and NH 3–N formation (below 1mg/L)was observed during denitri?cation.The nitrate removal ef?ciency at 15?C was only 55.06%of that at 25?C.An initial excess release of DOC could be caused by rapid biodegra-dation of starch in the surfaces of SPCL granules,then it decreased to 10.08mg/L.The vast majority of species on SPCL bio?lm sample (99.71%)belonged to six major phyla:Proteobacteria,Bacteroidetes,Chloro?exi,Firmicutes,Spirochaetes and Actinobacteria.Proteobacteria were the most abundant phylum (85.50%)and mainly consisted of ?-proteobacteria (82.39%).Diaphorobacter and Acidovorax constituted 52.75%of the identi?ed genera which were denitrifying bacteria.

? 2013 Elsevier B.V. All rights reserved.

1.Introduction

The “solid-phase denitri?cation”is a new type of heterotrophic biological denitri?cation in which insoluble biodegradable poly-mers were used as bio?lm carrier and carbon source simulta-neously [1,2].Solid substrates were used as alternatives to liquid carbon sources,which are accessible only by microbial enzymatic attack,so it can avoid the risk of overdosing in liquid carbon sources supported denitri?cation system [1].In the past few years,solid substrates have been investigated as a carbon source in the biolog-ical denitri?cation of drinking water [3,4],groundwater [5],land?ll

?Corresponding author at:Laboratory of Environmental Technology,INET,Tsinghua University,Beijing 100084,China.Tel.:+861062784843;fax:+861062771150.

E-mail addresses:wangjl@https://www.360docs.net/doc/943499439.html, ,wangjl@https://www.360docs.net/doc/943499439.html, (J.Wang).

leachate [6,7]and recirculated aquaculture system [1,8].Water body is susceptible to the over use of fertilizers and pesticides in agriculture ?elds,then the simultaneous removal of nitrate and pesticides has been studied using solid substrates as carbon sources and bio?lm carrier [9–11].Furthermore,some researchers have also studied the feasibility of using biodegradable compounds as carbon sources and bio?lm carrier for nitrogen removal in simul-taneous nitri?cation and denitri?cation (SND)system [12–14].There are two kinds of solid carbon sources which have been investigated for denitri?cation,synthetic polymers and natural materials especially the cellulose-rich https://www.360docs.net/doc/943499439.html,monly,syn-thetic polymers are thermoplastic which are easy processed to various shapes to ?t the demand of different denitri?cation process.In the “solid-phase denitri?cation”system,synthetic polymers including polyhydroxyalkanoates (PHAs)[2]and polycaprolactone (PCL)[1,8,15]were prepared to granules for denitri?cation,mean-while,PCL also can be prepared to plates for use [16].Comparing with the expensive synthetic polymers,natural materials including

0304-3894/$–see front matter ? 2013 Elsevier B.V. All rights reserved.https://www.360docs.net/doc/943499439.html,/10.1016/j.jhazmat.2013.02.026

432Z.Shen et al./Journal of Hazardous Materials250–251 (2013) 431–438 wheat straw[10,17],cotton[18],waste newspaper[19],pine bark

[6],crab-shell chitin[5]were much cheaper but may bring ammo-

nia[5],high DOC and color problems in ef?uent[3].Therefore,the

key issue of“solid-phase denitri?cation”is to develop new solid

substrates with low denitri?cation cost and without deterioration

of ef?uent water quality.

Blending with some cheap organic materials is a most

potential method to lower the price of products especially

in biodegradable plastics production?https://www.360docs.net/doc/943499439.html,paring with

other biodegradable thermoplastic polymers,starch is an abun-

dant renewable polysaccharide with better biodegradability and

low cost.Aliphatic polyesters are biodegradable thermoplastic

polymers with good processability,thermal stability,excellent

mechanical properties,good water resistance,and dimensional sta-

bility[20].So it is a potential way to blend starch with aliphatic

polyesters for production of biodegradable plastics.Aliphatic

polyesters such as PCL[21–23],poly(butylene succinate)(PBS)

[24],poly(hydroxybutyrate-covalerate)(PHBV)[25]and poly(lactic

acid)(PLA)[26,27]were widely adopted to blend with starch for

biodegradable plastics production or medical application.

Recently,we investigated the feasibility of using cross-linked

starch/polycaprolactone blends as solid carbon source and bio?lm

carrier for denitri?cation[28].The main objective of this study was:

(1)to evaluate the denitri?cation ability of starch/polycaprolactone

(SPCL)blends serving both as carbon source and bio?lm carrier;(2)

to assess the effect of operating conditions(i.e.nitrate loading rates,

temperature and initial pH)on denitri?cation under continuous-

mode;(3)to analyze the microbial community structure of bio?lm

attached on SPCL.

2.Materials and methods

2.1.Materials

The polycaprolactone(PCL)used in this study has a molecular

weight of60,000g/mol(Dalton).The cornstarch used in this study

is technical grade.Starch/PCL(SPCL)blends were prepared by twin-

screw extruder.The main characters of SPCL are listed as follows:

Starch,55.44%;PCL,30.00%;Additives(plasticizer and coupling

agent),14.56%;Calculated surface area,1833.33m2/m3.

2.2.Experiment apparatus

Continuous experiments were carried out in a laboratory-scale

packed-bed set-up(Fig.1)using50mm inner diameter by500mm

height cylindrical Plexiglas.A Plexiglas mesh disc(48mm diam-

eter,2mm pore size)was placed at the lower end of the column

as support for the packing material.SPCL granules were used

as

Fig.1.Schematic display of the experimental set-up.carbon source and carrier for bio?lm growth,and packing the col-umn up to a height of250mm(273g).

2.3.Experiment procedures

SPCL granules were used as bio?lm carrier and electron donor to support biological denitri?cation.Synthetic water(adding NaNO3 and KH2PO4to tap water,and N:P(w/w)=5:1)seeded with acti-vated sludge which collected from a local municipal wastewater treatment plant(with the?nal concentration of800mg/L MLSS) was pumped into the bottom of column at a?ow rate of4.1mL/min (HRT=2h).Unless otherwise indicated,temperature was25±1?C, and pH and DO were not controlled.After a stable denitri?cation performance obtained,?ow rate was then increased stepwise to study the effect of nitrate loading rates(lasted184d).Then,deni-tri?cation performance at low temperature(15±1?C)was studied (lasted20d).The effect of pH on denitri?cation was investigated using1M hydrochloric acid and sodium hydroxide to control the pH of synthetic water to4.5,6,9and10.5(lasted74d).Samples were taken from the ef?uent to monitor NO3–N,NO2–N,NH3–N, pH and DOC.

2.4.Analytical methods

Samples were taken and?ltered through0.45?m membrane before analysis.NO3–N was determined by UV-spectrophotometer (Shimadzu UV-3100)at220nm and275nm,and NO2–N and NH3–N were assayed by hydrochloric acid naphthyl ethylenedi-amine spectrophotometry method and hypochlorite-salicylic acid spectrophotometry method,respectively[29].Dissolved organic carbon(DOC)was detected using a TOC analyzer(HACH,IL530TOC-TN).Samples were neither acidi?ed nor sparged during analysis. The pH value was measured with pH meter.The morphology of the samples was examined using a SEM(Fei Quanta200).Bio?lm was taken from the column reactor after being operated for280d.DNA from bio?lm was extracted directly using glass beads to mechanical lysis of SPCL granulars(with bio?lm).

The volumetric denitri?cation rate R vd in kg/(m3d) NO3–N+NO2–N(total soluble oxidized nitrogen species)of the reactor is given by the Eq.(1):

R vd=0.024×Q D

×(C in?C ef)

V(1) where C in is the in?uent NO3–N+NO2–N concentrations(mg/L)and C ef is the ef?uent NO3–N+NO2–N concentrations.Q D is the?ow rate(L/h)and V is the reactor volume(L).

Nitrate removal ef?ciency(N re)is de?ned by the equation(2): N re=100×(NO3

?N in?NO3?N ef?NO2?N ef?NH3?N ef)

NO3?N in

(2) where NO3–N in is the in?uent NO3–N concentration,NO3–N ef, NO2–N ef and NH3–N ef are the ef?uent NO3–N,NO2–N and NH3–N concentrations,respectively(negligible accumulation of gaseous-N by-products and organic-N).

2.5.Pyrosequencing

2.5.1.DNA extraction and puri?cation

Genomic DNA was extracted using E.Z.N.A.Soil DNA Kit (OMEGA).

2.5.2.PCR ampli?cation

For each sample,we ampli?ed V1-V3region of bacterial16S rRNA genes using a broadly conserved primer set(27F and533R). The forward primer(5 -GCC TTG CCA GCC CGC TCA GAG AGT TTG

Z.Shen et al./Journal of Hazardous Materials250–251 (2013) 431–438433

ATC CTG GCT CAG-3 )contained the454Life Sciences primer B sequence and the broadly conserved bacterial primer27F.The reverse primer(5 -GCC TCC CTC GCG CCA TCA GNN NNN NNN NNT TAC CGC GGC TGC TGG CAC-3 )contained the454Life Sci-ences primer A sequence,a unique10-nt barcode used to tag each PCR product(designated by NNNNNNNNNN),and the broad-range bacterial primer533R.PCR reactions were carried out in tripli-cate20-?L reactions with0.4?M forward and reverse primers, 1-?L template DNA,250nM dNTP and1×FastPfu Buffer.All dilu-tions were carried out using certi?ed DNA-free PCR water.Thermal cycling consisted of initial denaturation at95?C for2min followed by25cycles of denaturation at95?C for30s,annealing at55?C for 30s,and extension at72?C for30s,with a?nal extension of5min at72?C.Replicate amplicons were pooled and visualized on2.0% agarose gels using SYBR Safe DNA gel stain in0.5×TBE.Amplicons were puri?ed using AxyPrep TM DNA Gel Extraction Kit(AXYGEN) according to the manufacturer’s instructions.

2.5.

3.Amplicon,quantitation,pooling and pyrosequencing

Amplicon DNA concentrations were measured using the Quant-iT PicoGreen dsDNA reagent and kit(Invitrogen).DNA samples were diluted in30?L1X TE,an equal volume2X PicoGreen working solution was added in a total reaction volume of60?L in minicell cuvette.Fluorescence was measured on a Turner Biosystems TBS-380Fluorometer using the465-485/515-575-nm excitation/emission?lter pair.Following quantitation,cleaned amplicons were combined in equimolar ratios into a single tube.

Pyrosequencing was carried out on a454Life Sciences Genome Sequencer FLX Titanium instrument(Roche)by Shanghai Majorbio Bio-pharm Biotechnology Co.Ltd.(Shanghai,China),the sequenc-ing data was analyzed by Mothur[30].

3.Results and discussion

3.1.Effect of nitrate loading rates on denitri?cation

The effect of nitrate loading rates on denitri?cation was studied varying the nitrate loading rates between0.60and1.20kg/(m3d) through changing the in?uent nitrate concentration and the?ow rate(Figs.2and3,Table1).As the formation of bio?lm on the surface of SPCL,nitrate removal ef?ciency increased gradually and reached98.42%at the7th d,and then it became stable during the period of days8–25(Fig.2).The lag time(=period of adaptation of denitrifying microorganisms)of PCL was16days in recirculated aquaculture systems[1].The lag time of SPCL was only7d,indi-cating that PCL blending with starch can signi?cantly shorten the lag time in solid denitri?cation system.When the nitrate loading rate increased from0.60to1.20kg/(m3d)(at the25th d),the ef?u-ent nitrate and nitrite concentrations increased signi?cantly,and a very sharp decline of nitrate removal rate was observed simul-taneously(phase2).These changes may be due to the high nitrate loading rates which exceeded the denitri?cation capability of the system.Keeping a constant?ow rate(8.2mL/min)and decreasing in?uent nitrate concentration to25mg/L at the60th d,the ef?uent nitrate and nitrite concentrations decreased sharply and ca.90% nitrate removal rate reached(phase3).Further increasing nitrate loading rate to0.72kg/(m3d)at the100th d,a little?uctuation

of

Fig.2.Denitri?cation performances of SPCL at different nitrate loading rates. denitri?cation performance was observed(phase4).Nitrite is an intermediate of nitrate reduction.In this study,nitrite concentra-tion was below1mg/L when high nitrate removal rate reached.The formation of NH3–N(below ca.1mg/L)was observed,possibly due to the dissimilatory nitrate reduction to ammonia(DNRA)process, which was also observed in anaerobic sediments by Kelso et al.[31]. Honda and Osawa[16]also found that a0.1mg/L NH3–N increased in denitri?cation system using PCL as substrate.

Table1

The volumetric denitri?cation rate R vd at different nitrate loading rates.

Phase Operating date(d)Flow rate(mL/min)In?uent NO3–N(mg/L)HRT(h)NO3–N loading rate(kg/(m3d))R vd(kg/(m3d)) 10–25 4.15020.600.53±0.09a

226–598.2501 1.200.54±0.22

360–1008.22510.600.59±0.03 4101–18416.4150.50.720.64±0.06

a Mean±standard deviation.

434Z.Shen et al./Journal of Hazardous Materials 250–251 (2013) 431–438

0.6

0.8 1.0 1.2

0.6

0.8

1.0

1.2

N i t r a t e r e m o v e d [k g /(m 3·d )]

Nitrate load [kg/(m 3

·d)]

Fig.3.Average nitrate removal rates under different loading rates.

The variations of DOC and pH in ef?uent are also depicted in

Fig.2.During the start-up period,a quick release of DOC occurred,and reached maximum 61.30mg/L at the 14th d.The high DOC might allow rapid microbial growth and the fast colonization on the substrate therefore high removal of nitrate was observed.DOC will accumulate when the amount of released dissolved organic carbon exceeded the need of microbes for both growth and denitri?cation.During the start-up period,once microbes stick and proliferate to SPCL granules,they secrete enzymes to biodegrade starch or PCL and use them as carbon source.Since starch is more biosuscep-tible than PCL in starch/PCL blends [21,32],so the accumulated of DOC may be mainly derived from the biodegradation of starch (on the surface of SPCL granules)during the start-up period.HRT may be an important factor affecting the release and accumulation of DOC.At the 24th d,the ?ow rate was changed to 8.2mL/min (HRT changed from 2h to 1h),the average DOC in the ef?uent decreased to 19.60mg/L (phases 2and 3).Further increasing the ?ow rate to 16.4mL/min (HRT =0.5h),the average DOC decreased to 10.08mg/L (phase 4).The previous work also found that HRT has an important in?uence on DOC accumulation using cross-linked starch/PCL blends as solid carbon and bio?lm carrier for denitri?-cation [28].Aslan and Türkman [3]also found that DOC decreased with increasing ?ow rate in ?xed-bed denitri?cation system using wheat straw as substrate.

Shear force has signi?cant in?uences on the structure of the bio?lm and mass transfer.A higher shear force may result in a thin-ner and denser bio?lm [33],but it has a dual effect on the behaviors of mass transfer in bio?lm,i.e.high turbulence would facilitate sub-strate diffusion in bio?lms;however,shearforce-enhanced bio?lm density in turn reduces the diffusivity of substrate in bio?lms.The observed diffusivity of substrate would be a net result of these two phenomena [34].Celmer et al.[35]found that high shear force proved to be effective in improving denitri?cation rate by reducing the thickness of the bio?https://www.360docs.net/doc/943499439.html,paring phases 1with 3(Table 1),under a constant nitrate loading rate (0.60kg/(m 3d))the average denitri?cation rate improved since ?ow rate increased from 4.1to 8.2mL/min.Thus,the need of carbon source for biological denitri-?cation increased,which might be a main result of the decrease of DOC.DOC values did not exceed 5–7mg/L when using PCL as solid carbon source in recirculated aquaculture systems [1].In this study,DOC was higher than net PCL supported denitri?cation sys-tem,which probably due to the addition of starch and a high starch content (starch:PCL (w/w)=1.848)in the blends,meanwhile the difference of PCL may be another reason though it maybe play a less important role in the high DOC problem.

The values of pH decreased slightly from a range of 6.89–7.87

(in?uent)to a range of 6.47–7.48(ef?uent)in the period of days 26–184.The decrease of pH values probably be due to organic acids produced from carbon source by microbial metabolism,and neu-tralization alkalinity represented by denitri?ers [15].When PCL immersed in enzyme lipase solution,the quantity of acid liberated was coincided with its biodegradability [36].After immersed into lysozyme solution,the pH of media containing pure PCL scaffolds was lower than the initial pH due to the acidic degradation products of the PCL component [37].

Increasing nitrate loading rate properly,the average denitri?ca-tion rate increased (phases 3and 4)while over-loading of nitrate (phase 2)could not improve the denitri?cation performance (Fig.3and Table 1).Under the same nitrate loading rate,increasing the ?ow rate led to a higher average denitri?cation rate (phases 1and 3).

3.2.Denitri?cation performance at low temperature

At the 185th d,the temperature was decreased to 15?C (except temperature,other operating parameters equaled to phase 4)to study the denitri?cation performance at low https://www.360docs.net/doc/943499439.html,pared to phase 4at 25?C (Fig.2),the ef?uent average nitrate concentrations increased signi?cantly and reached 7.03±0.36mg/L,nitrate removal ef?ciency was 47.50%.Though nitrate removal was inhibited at low temperature,nitrite accu-mulation was low (below 0.6mg/L).The average denitri?cation rate was 0.34±0.01kg/(m 3d),indicating that temperature was an important parameter for denitri?cation performance.A very sharp decline of denitri?cation rate was also observed in wheat straw or cotton supported denitri?cation system when tempera-ture decreased [9,18].

As denitri?cation rate decreased,the demand of carbon source for biological denitri?cation decreased.Meanwhile,the amount of released dissolved organic carbon should be reduced since the enzymatic degradation process of starch/PCL blends affected by temperature.PCL showed a slight biodegradability under aquatic conditions at the mesophilic temperature [38],but the biodegrad-ability of PCL was 92%in the diluted sludge at the thermophilic temperature [39].At 15?C,average DOC was 4.59mg/L,which was only 45.54%of the value in phase 4at 25?C.pH values slightly decreased from a range of 6.90–7.57(in?uent)to a range of 6.72–7.05(ef?uent).

3.3.Effect of pH on denitri?cation performance

The denitri?cation performance at different initial pH (4.5–10.5)was studied (except initial pH,other operating parameters equaled to phase 4).Compared with uncontrolled initial pH condition (phase 4,Fig.2),increase of ef?uent nitrate and decrease of nitrate removal rate were observed at both acid and basic condition,indi-cating that when pH was beyond the optimal range,denitri?cation enzymatic activity was inhibited.It was similar to the optimal pH range reported for denitri?cation [40,41].

At acidic pH (4.5and 6),the average denitri?cation rates at pH of 4.5and 6were 0.46±0.05and 0.51±0.04kg/(m 3d),respectively.These values were signi?cantly lower than the value in phase 4(average pH ca.7.23),which was 0.64±0.06kg/(m 3d)(Table 1).In addition,the ef?uent nitrite and DOC concentrations at pH of 4.5were higher than the values at pH of 6.It was interesting to note that the average denitri?cation rate increased from 0.35±0.03to 0.52±0.02kg/(m 3d)when pH increased from 9to 10.5,which might be due to the higher DOC release and accumulation at pH of 10.5than 9.At basic condition,more organic acid products were produced to neutralize the alkalinity,which con?rmed by pH change.These excess release of dissolved organic carbon should be

Z.Shen et al./Journal of Hazardous Materials250–251 (2013) 431–438

435

Fig.4.Photograph of fresh SPCL(a);SEM images of bio?lm attached on SPCL(b);fresh SPCL(c);and used SPCL(d).

exceeded the need of microbes for denitri?cation,so a higher DOC accumulation was observed at basic condition than acidic or neu-tral condition.Ef?uent pH tended to be neutral both at acidic and basic initial conditions,which would be a net result of acidity by acidic degradation products and alkalinity derived from denitri?-cation.NH3–N was produced over the pH range of4.5–10.5,but the concentration was below1.00mg/L.

3.4.SEM observation

SPCL carriers used in this study were cylindrical granules (Fig.4a),and bio?lm attached on their surfaces comprised predo-minately of rod bacteria from SEM observation(Fig.4b).The fresh SPCL displayed an irregular surface(Fig.4c),which will favor the attachment of bacterial cells on the surfaces.Generally,without deformed starch granules is homogeneously dispersed throughout the PCL/starch blends as droplet-like particles[22].The starch parti-cles present in SPCL showed a thermoplastic nature,indicating that it underwent signi?cant https://www.360docs.net/doc/943499439.html,paring the SEM images of the fresh SPCL with the used one,the later one(Fig.4d)showed that its surface covered with pits and pores,the result of biodegradation was visible.

3.5.Microbial community of bio?lm

In SPCL bio?lm sample,most abundant sequences were assigned to the node of bacteria or to its descendants,and a few sequences of eukaryotic organisms were also received. In bacteria,the vast majority of sequences(99.71%)belonged to one of the six major phyla:Proteobacteria,Bacteroidetes,Chloro?exi,Firmicutes,Spirochaetes and Actinobacteria(Fig.5), and Proteobacteria was the most abundant phylum(85.50%) which was mainly?-proteobacteria(82.39%).?-proteobacteria were reported to be abundant in activated sludge of denitrifying reactors[42].

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Fig.5.Relative abundance of the main phyla identi?ed on SPCL bio?lm sample.Only phyla with a relative abundance greater than1%were shown.These six predomi-nant phyla together account for>99.71%of sequences identi?ed.Total numbers of sequences was N=9623.

436Z.Shen et al./Journal of Hazardous Materials 250–251 (2013) 431–438

D

i a p h

o r

o b a c t e r A c i d o v o r a x D

e c h l o r o m o n a s A l i c y c l i p h i l u s R o s e i

f l e x u s P r e v o t e l l a

c e a e u n c u l t u r e

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e p o n e m a C l o a c i b a c t e r i u m P e c t i n a t u s S t e n o t r o p h o m o n a s C e l l u l o m o n a s D e s u l

f o v i b r i o A z o s p i r a F l a v o b a c t e r i u m A n a e r o a r c u s 0

51015202530

35R e l a t i v e a b u n d a n c e (%)

Fig.6.Relative abundance of the main genera identi?ed on SPCL bio?lm sample.Only genera with a relative abundance greater than 1%are shown.These 15pre-dominant genera together account for >93.79%of genera identi?ed.

At the genus level,sequences from SPCL represented 58differ-ent genera,but 53.42%of the sequences were not related to the known bacteria.Diaphorobacter and Acidovorax constituted 52.75%of the identi?ed genera in SPCL bio?lm sample (Fig.6).Diaphorobac-ter was reported to be denitrifying bacteria [43].Both nitrate and nitrite reductase activities were presented in eight strains of Diaphorobacter isolated [44].However,the nitrate reduction rate was 1.5times more than the nitrite reduction in Diaphorobac-ter sp.,but a nitrite accumulation was also received especially at high nitrate concentration,suggesting that Diaphorobacter possi-bly transfers electron sequentially in the denitri?cation system from nitrate to dinitrogen formation [45].Acidovorax species are commonly observed in wastewater treatment reactors and have been shown to be able to metabolize several different carbon sources [46].For example,Acidovorax avenae subsp.avenae LMG 17238can be successfully used ethanol,methanol,sodium acetate,glucose and poly(?-caprolactone)as carbon source for denitri?ca-tion [47].Coates et al.[48]reported two Dechloromonas strains,RCB and JJ that can completely mineralize various mono-aromatic compounds including benzene to CO 2in the absence of O 2with nitrate as the electron acceptor.Hong et al.[49]reported that Alicycliphilus was one of the abundant genus in the denitrifying bioreactor.Alicycliphilus denitri?cans was the main denitri?er that could use nitrate,nitrite,and oxygen as electron acceptors as reported by Mechichi et al.[50].Stenotrophomonas was isolated directly from a continuous up-?ow ?xed-bed denitri?cation reac-tor using poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)granules as bio?lm carrier,carbon source and electron donor [51].Flavobacterium sp.S6was reported as amylolytic bacterial [52].Most species of Desulfovibrio can oxidize organic compounds such as volatile fatty acids (VFA)and lactate incompletely to acetate [53],and Cellulomonas as cellulose-hydrolysing bacterial was found in sludge from a methanogenic reactor treating paper mill wastewater [54].

Rarefaction analysis was used to estimate the richness of total bacterial communities of SPCL bio?lm.The steepness curves were received (Fig.7),suggesting that the sampling completeness is low and a large fraction of the species diversity has not yet been

sampled.

Fig.7.Rarefaction curves of SPCL bio?lm sample.The number of OTUs with different cutoff values was plotted as a function of the number of sequences sampled.The 0.03,0.05and 0.1curves contain OTUs with differences that do not exceed 3%,5%and 10%,respectively.

3.6.Mass balance of carbon and nitrogen for denitri?cation

After operation for 280d,nitrogen and carbon mass balances were calculated according to the carbon consumption and the removed nitrogen,the results are given in Table 2.For carbon bal-ance,the input and residual mass of SPCL in column,the carbon content of SPCL (42.65%)and the loss of C from ef?uent DOC were used to calculate the total carbon utilized by microorganism.For nitrogen balance,in?uent nitrate was total input N,while ef?uent nitrate,nitrite and ammonium concentration were integrated to calculate total output N,thus the total removed N was obtained by total input N subtracting total output N.

The total output N mass was 31.14%of total input,and it mainly due to the over-loading nitrate in phase 2(Fig.2).A large amount loss of C was observed (from ef?uent DOC),probably mainly due to the high release and accumulation of dissolved organic carbon at start-up period.According to the carbon consumed by microorgan-isms,the removal of 1g nitrogen required 1.01g carbon (utilized by microorganism),which is equivalent of 2.36g SPCL.However,due to the release of organic compounds in ef?uent,the required mass of SPCL increased to 4.72g/g N.The consumption PCL for removing 1kg nitrate-N was calculated to be 1.33–1.77kg [1].

Table 2

Mass balance of nitrogen and carbon for denitri?cation.

Item

Mass (g)

Nitrogen In N from in?uent nitrate 104.66Out

N from ef?uent nitrate 26.42N from ef?uent nitrite

4.01N from ef?uent ammonium 2.16Total

Total N input 104.66Total N output 32.59Total N removed

72.08Carbon In C from SPCL

202.96Out

C measured from DOC 72.46Residual Residual C in column 57.80Total

Total C utilized

72.69

Z.Shen et al./Journal of Hazardous Materials250–251 (2013) 431–438437

Theoretically,the amount of PCL required to remove1g nitrogen can be calculated by the following equation(3),and the value is 1.36g[16].

6NO?

3

+C6H10O2→3N2+6CO2+2H2O+6OH?(3) As for starch,denitri?cation can be considered according to the following equation(4):

24NO?

3

+5C6H10O5→12N2+30CO2+13H2O+24OH?(4) Theoretically,the amount of starch required to remove1g nitro-gen is2.41g.The contents of starch and PCL in SPCL are55.44%and 30.00%,respectively.So theoretically the amount of SPCL required to remove1g nitrogen is about2.22g.Due to diffusion effects in bio?lm,reaction rate will be limited by the low concentra-tion substrate[55,56].During stable operating,the ef?uent NO3–N was below1mg/L,so the denitri?cation rate is probably limited by nitrate.That means the C/N ratio should be greater than the stoichiometric value.This result was agree with that reported by Aspegren et al.in which the ratio of COD/NO3–N was increased to 4–5in order to secure complete denitri?cation in a MBBR process [57].

4.Conclusions

SPCL,a novel kind of biodegradable polymer,could serve as solid carbon source and bio?lm carrier for denitri?cation.At 0.72kg NO3–N/(m3d)loading rate,a high denitri?cation rate (0.64±0.06kg N/(m3d))was observed with low nitrite accumu-lation.However,an initial excess release of DOC and NH3–N formation were also observed during denitri?cation.Therefore, improvement of SPCL and inhibition of NH3–N formation needs further research.In SPCL bio?lm,Proteobacteria was the most abundant phylum(85.50%).A total of58genera were identi?ed from the SPCL bio?lm,and Diaphorobacter and Acidovorax con-stituted52.75%of the identi?ed genera which were denitrifying bacteria.

Acknowledgements

The authors are grateful to the National Natural Science Foun-dation of China(Grant Nos.50508018;51078210)and the National S&T Major Project(Grant No.2008ZX07102-003)for their?nancial support.

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浅谈厌氧氨氧化及其工艺的研究

浅谈厌氧氨氧化及其工艺的研究 摘要厌氧氨氧化工艺是生物脱氮领域里不断发展起来的新工艺。由于厌氧氨氧化生物脱氨技术在经济方面的优势,成为近来研究的热点。目前,我国对该技术的研究主要处于实验室小试阶段,缺少中试及以上规模厌氧氨氧化工程的实际应用。综述列举了厌氧氨氧化工艺的应用及出现的一些问题,从而为该技术更深入的研究奠定了基础,同时对该技术的进一步发展提出了展望。 关键词厌氧氨氧化;SHARON/ANAMMOX;OLAND;前景 目前,随着工农业生产的发展和人民生活水平的提高,含氮化合物的排放量急剧增加,引起了严重的水体环境污染和水质富营养化问题,许多湖泊水体已不能发挥其正常功能进而影响了工农业和渔业生产。近年来,国内外学者一直在寻找一种低能耗、高效率的新型生物脱氮技术。就目前情况而言,厌氧氨氧化由于是自养的微生物过程、不需要外加碳源以及反硝化、污泥产率低,成为国内外学者研究的热点问题。 1厌氧氨氧化原理 厌氧氨氧化反应是由奥地利理论化学家Engelbert Broda在1977年根据反应的自由能计算而提出的。后来在荷兰Delft技术大学一个中试规模的反硝化流化床中发现了ANAMMOX工艺。厌氧氨氧化是指在厌氧或缺氧条件下,微生物直接以NH4+作为电子供体,以NO3-或NO2-作为电子受体,将NH4+、NO3-或NO2-转变成N2的生物氧化过程。反应方程式如下: NH4++0.85O2→0.435N2+0.13N03-+1.3H2O+1.4H+ (1) ANAMMOX工艺在发生反硝化反应时不需外加碳源。因为反应所产生的吉布斯自由能能够维持自养细菌的生长,这一现象是摩德尔等对使用硫化物作电子供体的流化床反应器中自养菌反硝化运行工况进行仔细观测和研究发现的。 1)存在的问题。厌氧氨氧化工艺启动缓慢,世界上第一座生产性装置的启动时间长达3.5年,过长的启动时间是其工程应用的重大障碍。 厌氧氨氧化菌为自养菌,以CO2为碳源,无需有机物,因此厌氧氨氧化工艺适于处理C/N值较低的含氮废水。在大多数的实际废水中,有机物往往与氨氮共存,不利于厌氧氨氧化菌的生长。厌氧氨氧化的基质为氨和亚硝酸盐,均具毒性,尤以亚硝酸盐毒性更大。厌氧氨氧化工艺的运行稳定性是其工程应用必须解决的重大难题。 2)解决的方法。研究证明,厌氧氨氧化工艺的启动过程依次呈现菌体自溶、活性迟滞、活性提高和活性稳定等4个阶段。为此可采取如下控制对策:①在菌体自溶阶段,消除接种物中的残留有机物,控制反硝化所致的pH过高;②在活

厌氧氨氧化工艺如何处理污水

厌氧氨氧化工艺如何处理污水 1 引言 随着科技的迅速发展,工业化和城市化程度的不断提高,水体富营养化的问题日益严重,使得水资源更加紧张.而氮是引起水体富营养化的主要因素.所以越来越多的国家和地区制定了氮排放标准.因此,研究开发经济、高效的脱氮技术已成为水污染控制工程领域的研究重点. 生物处理法作为19 世纪末废水处理新型技术,与物化处理法相比具有处理费用低,不会对环境造成二次污染等优点.因此,生物处理法至今已成为世界各国污水二、三级处理的主要手段.众所周知氮元素可在相应微生物的作用下转化成各种氧化态和化学形式(目前已知的生物氮循环途径如图 1所示),因此在污水生物脱氮处理中衍生了大量组合工艺.而厌氧氨氧化过程是目前最捷径的生物脱氮过程,因此被誉为最具前景的污水脱氮工艺.为了更好的将厌氧氨氧化工艺应用到实际规模中,本文着重对厌氧氨氧化菌的发现及其与污水处理中常见细菌的协同与竞争关系进行了详细的综述.旨在为厌氧氨氧化工艺在污水生物处理中的应用提供理论依据,并为今后厌氧氨氧化工艺的研究方向提出一些意见. 图 1 氮循环示意图 2 厌氧氨氧化概述 早在1976年,Broda预言在自然界中存在一种以NO-2或NO-3作为电子受体把NH+4氧化成N2的化能自养型细菌.直到1995年,Mulder等处理酵母废水的反硝化流化床反应器内发现了NH+4消失的现象,从而证实了厌氧氨氧化反应的存在. 厌氧氨氧化(Anaerobic ammonium oxidation,Anammox)是在缺氧条件下以亚硝酸盐(NO-2)为电子受体将氨(NH+4)转化成氮气(N2),同时伴随着以亚硝酸盐为电子供体固定CO2并产生硝酸盐(NO-3)的生物过程.执行该过程的微生物称之为厌氧氨氧化菌(Anaerobic ammonium oxidation bacteria,AAOB),其化学计量学方程式如下: 1NH+4+1.32NO-2+0.066HCO-3+0.13H+→ 1.02N2+0.26NO-3+0.066CH2O0.5N0.15+ 2.03H2O

厌氧氨氧化反应器资料总结

厌氧氨氧化的反应器 一、全球运行的厌氧氨氧化的工程实例 表1-2 全球运行的厌氧氨氧化工程实例 Table 1-2 Application of ANAMMOX in the world SHARON-ANAMMOX工艺由荷兰TU Delft大学研究开发,该工艺流程分成两段,第一段是在好氧反应器中将一半的NH4+转化为NO2-,第二段是在厌氧反应器中将剩余的NH4+和NO2-一起直接转化为N2。

图1-7短程硝化与厌氧氨氧化结合工艺流程 Figure1-7The combined SHARON-ANAMMOX process 二、SHARON-ANNOMMOX工艺反应器资料 AN A MM OX的生化反应式为: 因此AN A MM OX反应器进水要求有氨氮和亚硝氮且比例最好为1:1。而S H AR ON工艺的生化反应式为: SHARON(短程反硝化)反应装置 SHARON常用SBR、CSTR反应装置

SHARON(短程反硝化)反应条件控制 (1)当溶解氧(DO)浓度在1.1-1.5mg/L、氨氮负荷0.029kgNH4+--N/KgVSS.d 和PH 值在7.3-7.8时,可以使亚硝酸盐得到稳定积累,出水亚硝态/总硝态氮大于90%,出水NO2--N/NH4+-N接近1.0,满足厌氧氨氧化的进水要求。(2)实现短程硝化的关键是在硝化阶段实现NO2--N的积累,国内外的研究都是着眼于积累NO2--N的控制条件。根据国内外文献报道,SHARON工艺的操作温度以30~35℃为宜,pH适应控制在7.4~8.3之间,溶解氧浓度己控制在1.0~1.5mg/L范围,供氧方式可采用间歇曝气。基质中游离氨浓度调控在5~10mg/L范围内有利于实现短程硝化,污泥(以VSS计)氨负荷为 0.02~1.67kg/(kg·d),泥龄在1~2.5天。 (3)大量国内外试验表明,在废水温度较高、Do较低条件下,利用亚硝酸菌和硝酸菌的不同生长速度,通过控制水力停留时间,将生长速率较慢的硝酸菌冲走,使亚硝酸菌大量积累,可以使短程反硝化成功运行。 ANNOMMOX反应器

厌氧氨氧化基础知识累积

一、世界Anammox的工程应用概述 (2016.12.19生物工程学报)厌氧氨氧化(Anaerobic ammonium oxidation,ANAMMOX)工艺因其高效低耗的优势,在废水生物脱氮领域具有广阔的应用前景。在过去的20年中,许多基于ANAMMOX反应的工艺得以不断研究和应用。综述了各种形式的ANAMMOX工艺,包括短程硝化-厌氧氨氧化、全程自养脱氮、限氧自养硝化反硝化、反硝化氨氧化、好氧反氨化、同步短程硝化-厌氧氨氧化-反硝化耦合、单级厌氧氨氧化短程硝化脱氮工艺。对一体式和分体式工艺运行条件进行了比较,结合ANAMMOX工艺工程(主要包括移动床生物膜,颗粒污泥和序批式反应器系统)应用现状,总结了工程化应用过程中遇到的问题及其解决对策,在此基础上对今后的研究和应用方向进行了展望。今后的研究重点应集中于运行条件的优化和水质障碍因子的解决,尤其是工艺自动化控制系统的开发和特殊废水对工艺性能影响的研究。 厌氧氨氧化(Anaerobicammonium oxidation,ANAMMOX) 工艺,最初由荷兰Delft工业大学于20 世纪末开始研究,并于本世纪初成功开发应用的一种新型废水生物脱氮工艺。它以20 世纪90 年代发现的ANAMMOX 反应(1) 为基础,该反应在厌氧条件下以氨为电子供体,亚硝酸盐为电子受体反应生成氮气,在理念和技术上大大突破了传统的生物脱氮工艺。ANAMMOX 工艺具有脱氮效率高、运行费用低、占地空间小等优点,在污水处理中发展潜力巨大。目前该工艺在处理市政污泥液领域已日趋成熟,位于荷兰鹿特丹Dokhaven 污水厂的世界上首个生产性规模的ANAMMOX 装置容积氮去除速率(NRR) 更是高达9.5 kg N/(m3·d)。此外,ANAMMOX 工艺在发酵工业废水、垃圾渗滤液、养殖废水等高氨氮废水处理领域的推广也逐步开展,在世界各地的工程化应用也呈星火燎原之势。 本文介绍了不同形式的ANAMMOX 工艺,通过比较其运行条件,并结合ANAMMOX 工艺工程应用现状,总结了该工艺工程化应用面临的问题和解决对策,在此基础上对今后的研究和应用方向进行了展望。

厌氧氨氧化

厌氧氨氧化作用即在厌氧条件下由厌氧氨氧化菌利用亚硝酸盐为电子受体,将氨氮氧化为氮气的生物反应过程。这种反应通常对外界条件(pH值、温度、溶解氧等)的要求比较苛刻,但这种反应由于不需要氧气和有机物的参与,因此对其研究和工艺的开发具有可持续发展的意义。 厌氧氨氮化一般前置短程硝化工艺,将废水中的一部分氨氮转化成亚硝酸盐。目前在处理焦化废水、垃圾渗滤液等废水方面已经有成功的运用实例。 厌氧氨氧化是一个微生物反应,反应产物为氮气。具有一些优点:由于氨直接作反硝化反应的电子供体,可免去外源有机物(甲醇),既可节约运行费用,也可防止二次污染;由于氧得到有效利用,供氧能耗下降;由于部分氨没有经过硝化作用而直接参与厌氧氨氧化反应,产酸量下降,产碱量为零,这样可以减少中和所需的化学试剂,降低运行费用,也可以减轻二次污染。 厌氧氨氧化反应是一种化能自养的古菌(俗称Anammox)的反应。简单式为:1NH4+ + 1NO2- → N2 + 2H2O。如果在化学方程式里加入微生物本身,则为:1NH4+ + 1.32NO2- + 0.066 HCO3- + 0.13H+ → 1.02N2 + 0.26 NO3- + 0.066 CH2O0.5N0.15 + 2.03H2O 该古菌为自养型,只需无机碳源CO2,并且在全球碳循环过程中发挥着很重要的作用。在目前污水的氨氮处理上被广为看好。但是由于亚硝酸根含量在大部分污水是不够显著的,所以anammox技术要结合其他技术来使用,比如已经在荷兰鹿特丹投产的Sharon+anammox工艺,就是结合了短程硝化和厌氧氨氧化工艺,还是比较成功的。 利用混合污泥培养厌氧氨氧化颗粒污泥

厌氧氨氧化(ANAMMOX)和全程自养脱氮(CANON)

厌氧氨氧化(ANAMMOX)和全程自养脱氮(CANON) 【格林大讲堂】 厌氧氨氧化是指在厌氧条件下氨氮以亚硝酸盐为电子受体直接被氧化成氮气的过程。 厌氧氨氧化(Anaerobicammoniaoxidation,简称ANAMMOX)是指在厌氧条件下,以Planctomycetalessp为代表的微生物直接以NH4+为电子供体,以NO2-或NO3-为电子受体,将NH4+、NO2-或NO3-转变成N2的生物氧化过程。 武汉格林环保有完善的服务体系和配套的专业环境工程团队,秉着崇高的环保责任和义务长期维护提供免费的污水处理解决方案,是湖北省工业废水运营管理行业中的品牌。18年来公司设计并施工了上百个交钥匙式的污水处理工程。 该过程利用独特的生物机体以硝酸盐作为电子供体把氨氮转化为N2,最大限度的实现了N的循环厌氧硝化,这种耦合的过程对于从厌氧硝化的废水中脱氮具有很好的前景,对于高氨氮低COD的污水由于硝酸盐的部分氧化,大大节省了能源。目前推测厌氧氨氧化有多种途径。 其中一种是羟氨和亚硝酸盐生成N2O的反应,而N2O可以进一步转化为氮气,氨被氧化为羟氨。另一种是氨和羟氨反应生成联氨,联氨被转化成氮气并生成4个还原性[H],还原性[H]被传递到亚硝酸还原系统形成羟氨。第三种是:一方面亚硝酸被还原为NO,NO被还原为N2O,N2O再被还原成N2;另一方面,NH4+被氧化为NH2OH,

NH2OH经N2H4,N2H2被转化为N2。 厌氧氨氧化工艺的优点:可以大幅度地降低硝化反应的充氧能耗;免去反硝化反应的外源电子供体;可节省传统硝化反硝化反应过程中所需的中和试剂;产生的污泥量极少。厌氧氨氧化的不足之处是:到目前为止,厌氧氨氧化的反应机理、参与菌种和各项操作参数不明确。 全程自养脱氮的全过程实在一个反应器中完成,其机理尚不清楚。Hippen等人发现在限制溶解氧(DO浓度为0.8·1.0mg/l)和不加有机碳源的情况下,有超过60%的氨氮转化成N2而得以去除。 同时通过实验证明在低DO浓度下,细菌以亚硝酸根离子为电子受体,以铵根离子为电子供体,最终产物为氮气。有实验用荧光原位杂交技术监测全程自养脱氮反应器中的微生物,发现在反应器处于稳定阶段时即使在限制曝气的情况下,反应器中任然存在有活性的厌氧氨氧化菌,不存在硝化菌。有85%的氨氮转化为氮气。鉴于以上理论,全程自养脱氮可能包括两步第一是将部分氨氮氧化为烟硝酸盐,第二是厌氧氨氧化。

论厌氧氨氧化工艺的应用进展

论厌氧氨氧化工艺的应用进展 本文从网络收集而来,上传到平台为了帮到更多的人,如果您需要使用本文档,请点击下载按钮下载本文档(有偿下载),另外祝您生活愉快,工作顺利,万事如意! 厌氧氨氧化(anaerobic ammonium oxidation,Anammox)工艺因其无需外加有机碳源、脱氮负荷高、运行费用低、占地空间小等优点,已被公认为是目前最经济的生物脱氮工艺之一。近年来,国内外对厌氧氨氧化工艺的研究取得了大量的实验室成果。但是,一方面由于厌氧氨氧化菌(anaerobicammonium oxidizing bacteria,AnAOB)生长缓慢(倍增时间长达11 天)、细胞产率低[m(VSS)/m(NH4+-N)=/g)、对环境条件敏感,另一方面由于实际废水成分复杂,常含有AnAOB 的抑制物质,限制了厌氧氨氧化工艺在实际工程中的大规模应用。因此,有必要对近年来国内外厌氧氨氧化工艺的应用实例和经验进行系统总结,推动该工艺的进一步工业化应用,使之在污水脱氮处理领域发挥更积极的作用。本文介绍了AnAOB 的生物多样性和厌氧氨氧化工艺形式的多样性,重点综述了厌氧氨氧化技术在处理各类废水中的实验室研究和工程应用情况。 1 厌氧氨氧化菌生物多样性

迄今为止,已发现的AnAOB 有6 属18 种,构成了独立的厌氧氨氧化菌科(Anammoxaceae),并且AnAOB 广泛存在于自然生态系统中,如海洋沉积物、淡水沉积物、油田、厌氧海洋盆地、氧极小区、红树林地区、海洋冰块、淡水湖以及海底热泉等。AnAOB 的生态分布多样性是由自身的代谢多样性决定的,也正因如此,厌氧氨氧化在全球氮素循环中扮演重要角色,将其应用于不同水质含氮废水的治理也具有与生俱来的优势和不可估量的潜力。 2 厌氧氨氧化工艺形式多样性 基于厌氧氨氧化原理的工艺形式纷繁多样,包括分体式(两级系统)和一体式(单级系统)两种。一体式有CANON(completely autotrophic nitrogenremoval over nitrite)、OLAND(oxygen limitedautotrophic nitrification and denitrification)、DEAMOX(denitrifying ammonium oxidation)、DEMON(aerobic deammonification)、SNAP(simultaneous partial nitrification,anammox anddenitrification)、SNAD(single-stage nitrogen removalusing anammox and partial nitritation)等工艺;分体式主要有SHARON(single reactor for high activityammonia removal over nitrite)-anammox 工艺。随着工程经验越来越丰富,一体化系统正日益得到青

厌氧氨氧化

厌氧氨氧化 厌氧氨氧化作用即在厌氧条件下由厌氧氨氧化菌利用亚硝酸盐为电子受体,将氨氮氧化为氮气的生物反应过程。这种反应通常对外界条件(pH 值、温度、溶解氧等)的要求比较苛刻,但这种反应由于不需要氧气和有机物的参与,因此对其研究和工艺的开发具有可持续发展的意义。 厌氧氨氮化一般前置短程硝化工艺,将废水中的一部分氨氮转化成亚硝酸盐。目前在处理焦化废水、垃圾渗滤液等废水方面已经有成功的运用实例。 厌氧氨氧化是一个微生物反应,反应产物为氮气。具有一些优点:由于氨直接作反硝化反应的电子供体,可免去外源有机物(甲醇),既可节约运行费用,也可防止二次污染;由于氧得到有效利用,供氧能耗下降;由于部分氨没有经过硝化作用而直接参与厌氧氨氧化反应,产酸量下降,产碱量为零,这样可以减少中和所需的化学试剂,降低运行费用,也可以减轻二次污染。 厌氧氨氧化(Anammox) 厌氧氨氧化的发现 Broda的预言 1977年,奥地利理论化学家Broda根据化学反应热力学,预言自然界存在以硝酸盐或亚硝酸盐为氧化剂的氨氧化反应,因为与以氧为氧化剂的氨氧化反应相比,它们释放出的自由能一点也不逊色。 序号电子受体化学反 应ΔG/(KJ/mol) 1 氧2NH4++3O2→ 2NO2-+2H2O+4H+ -241 2 亚硝酸盐 NH4++NO2-→ N2+2H2O -335 3 硝酸盐 5NH4++3NO3-→ 4N2+9H2O+2H+ -278 既然自然界存在自养型亚硝化细菌,能够催化反应1,那么理论上也应该存在另

一种自养型细菌,能够催化反应2和反应3。由于当时这种细菌还没有被发现,所以,Broda 认为它们是隐藏于自然界的自养型细菌。 Mulder的发现 20世纪80年代末,荷兰Delft工业大学开始研究三级生物处理系统。在试运期间,Mulder等人发现,生物脱氮流化床反应器除了进行人们所熟知的反硝化外,还进行着人们未知的某个反应使氨消失了。进一步观察发现,除了氨不明去向外,硝酸盐和亚硝酸盐也有一半以上不明去向。 而且伴随着氨与硝酸盐(亚硝酸盐)的消失,产气率大幅度提高,气体中的最主要的成分为N2。 对生物脱氮流化床反应器所做的氮素和氧化还原平衡发现,氨与硝酸盐之间的反应基本上按照反应3所预期方式进行。理论值与实测值非常接近。 为了对这一反应结果进行确认,Mulder等人进一步做了分批培养实验。实验证明,氨确实与硝酸盐同步转化;硝酸盐耗尽时,氨转化也停止;添加硝酸盐后,氨转化继续进行。伴随氨和硝酸盐的转化,累计产气量增加;转化停止时,累计产气量不变。气体的主要成分是N2。 至此,Mulder等人认为,生物脱氮流化床反应器中的氨和硝酸盐转化是按Broda 所预言的方式进行的,并将其称为厌氧氨氧化。 厌氧氨氧化的反应机理 Graff等采用15N的示踪实验研究表明,Anammox是通过生物氧化的途径实现的,过程中最可能的电子受体是羟胺(NH2OH),并推测出其代谢途径: 厌氧氨氧化菌首先将NO2-转化成NH2OH,再以NH2OH为电子受体将NH4+氧化生成N2H4;N2H4转化成N2,并为NO2-还原成NH2OH提供电子;实验中有少量NO2-被氧化成NO3-。 厌氧氨氧化涉及的化学反应为: NH2OH + NH3 → N2H4 + H2O N2H4 → N2 + 4[H] HNO2 + 4[H] → NH2OH + H2O 厌氧氨氧化工艺的技术要点 Anammox工艺的关键是获得足量的厌氧氨氧化菌,并将其有效地保持在装置内,

厌氧氨氧化

厌氧氨氧化(Anammox) 一、厌氧氨氧化的发现 1977年,奥地利理论化学家Broda根据化学反应热力学,预言自然界存在以硝酸盐或亚硝酸盐为氧化剂的氨氧化反应,因为与以氧为氧化剂的氨氧化反应相比,它们释放出的自由能一点也不逊色。 序号电子受体化学反应ΔG/(KJ/mol) 1、氧2NH4++3O2→2NO2-+2H2O+4H+ -241 2、亚硝酸盐NH4++NO2-→N2+2H2O -335 3、硝酸盐5NH4++3NO3-→4N2+9H2O+2H+ -278 既然自然界存在自养型亚硝化细菌,能够催化反应1,那么理论上也应该存在另一种自养型细菌,能够催化反应2和反应3。由于当时这种细菌还没有被发现,所以,Broda认为它们是隐藏于自然界的自养型细菌。 20世纪80年代末,荷兰Delft工业大学开始研究三级生物处理系统。在试运期间,Mulder等人发现,生物脱氮流化床反应器除了进行人们所熟知的反硝化外,还进行着人们未知的某个反应使氨消失了。进一步观察发现,除了氨不明去向外,硝酸盐和亚硝酸盐也有一半以上不明去向。而且伴随着氨与硝酸盐(亚硝酸盐)的消失,产气率大幅度提高,气体中的最主要的成分为N2。 对生物脱氮流化床反应器所做的氮素和氧化还原平衡发现,氨与硝酸盐之间的反应基本上按照反应3所预期方式进行。理论值与实测值非常接近。 为了对这一反应结果进行确认,Mulder等人进一步做了分批培养实验。实验证明,氨确实与硝酸盐同步转化;硝酸盐耗尽时,氨转化也停止;添加硝酸盐后,氨转化继续进行。伴随氨和硝酸盐的转化,累计产气量增加;转化停止时,累计产气量不变。气体的主要成分是N2。 至此,Mulder等人认为,生物脱氮流化床反应器中的氨和硝酸盐转化是按Broda所预言的方式进行的,并将其称为厌氧氨氧化。 二、厌氧氨氧化的反应机理

厌氧氨氧化技术生物脱氮机理

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兼氧FMBR工艺介绍-1

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城市污水厌氧氨氧化生物脱氮研究进展

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厌氧氨氧化工艺研究进展 路青* 张振贤付秋爽徐伟涛党酉胜 (河北胜尔邦环保科技有限公司,石家庄,050091) 摘要:厌氧氨氧化技术做为一种新型生物脱氮技术,在废水生物脱氮领域具有良好的应用前景.本文简要介绍了厌氧氨氧化技术的原理,分析总结了国内外对厌氧氨氧化工艺运行参数和影响因素的研究状况,比较了不同污泥源、反应器启动厌氧氨氧化运行过程的优缺点,指出了厌氧氨氧化工艺的应用前景. 关键词:厌氧氨氧化;生物脱氮;反应器 Research Progress on Anaerobic Ammonium Oxidation Process QingLu Zhenxian Zhang Qiushuang Fu Weitao Xu Yousheng Dang (Hebei Superior and Federal Environmental Protection Technology co., Ltd.,Shijiazhuang,050091)Abstract: Anaerobic Ammonia oxidation(Anammox) is a promising process of biological nitrogen removal in wastewater treatment. The mechanism of reaction was reviewed in this paper, Various factors involved in the Anammox process were analysed, the main advantages and disadvantages of different sludge ang reactor on the start-up and operation of Anammox process were compared, the further studies were proposed. Key words: Biological nitrogen removal; anaerobic ammonium oxidation; reactor 前言 废水生物脱氮已经成为水污染控制的一个重要研究方向。对于生化性较差的或高浓度含氮废水,传统生物脱氮工艺处理成本较高。目前,国内外对低碳氮比(C/N)废水处理技术的发展趋势是采用厌氧氨氧化(Anaerobic ammonium oxidation,Anammox)技术。基于Anammox 过程的微生物是自养型微生物,无需添加有机碳源、无需氧气参与、产碱量为零、同时还能减轻二次污染,故而成为目前最经济的新型生物脱氮工艺之一。 据报道[1,2],实验室规模处理模拟废水总氮去除速率最高达26.0 kg/(m3·d),生产性Anammox 反应器处理垃圾渗滤液,总氮去除速率最高达9.5 kg/(m3·d)。另外,Anammox工艺还具有较高的经济效益,对厌氧消化污泥分离液,若采用物理化学法处理,单位处理费用33~83 $/kg N,采用传统生物脱氮技术(全程硝化—反硝化工艺)处理,单位处理费用估计为17~33 $/kg N,若采用Anammox工艺单位处理费用估计为7~10 $/kg N[1]。 Anammox工艺因所具有经济、高效、无二次污染等优点,受到国内外学者的关注。本文参考国内外相关方面的研究情况,就Anammox机理、启动运行过程中的影响因子、污泥源、Anammox反应器、Anammox工艺应用前景作一综述。 Anammox机理 Anammox技术是以NH4+-N为电子供体、NO2--N为电子受体、羟胺和联氨为关键中间产物及氮气为终产物的生物反应。荷兰Delft工业大学于20世纪90年代初开发出了一种三级生物处理系统。在运行三级生物处理系统期间,Mulde[3]等人在其中的生物脱氮流化床反应器中发现,除了反硝化作用所致的各反应物的正常消失外,NH4+也在此条件下消失。由于NH4+和NO3-的消失同时发生且成正相关,他们认为反应器内存在如下反应: 5NH4++3 NO3-→4N2+9H2O+2H+ △G0= -278kJ/mol Van de Graaf[4]等进一步做了分批试验证实,Anammox的确是一个微生物反应,NH4+和NO3-被同步去除,反应产物为N2。 Van de Graaf[5]等随后通过N15标记的NH4+做研究,证明NO2-才是关键的电子受体的自养生物脱氮反应,其反应式:

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