Management of process performance at low water temperatures in respect of filamentous organisms Management of process performance at low water temperatures in respect of filamentous organisms

Management of process performance at low water temperatures in respect of filamentous organisms

  • 期刊名字:环境科学学报
  • 文件大小:520kb
  • 论文作者:WANG Zeng-zhang,NIU Zhi-qing,P
  • 作者单位:Taiyuan University of Technology,Helsinki University of Technology
  • 更新时间:2020-07-08
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论文简介

Journl of Enionnental Sciences Vol. 16.No. I.pp.JI3- 116,2004N-29Article ID: 101-0742( 201-0113-14CLC nunber: X703 Document code: AManagement of process performance at low water temperatures in respect offilamentous organismsW ANG Zeng- zhang',NIU hi-qing' ,PELKONEN MARKKU2(1. Taiyuan Univensity of Technology, China. E-mail: wangzeng27 @ yahoo . com; 2. Helsinki University of Tchnology, Finland)because of the peak settler load. A survey was made in 10 Finnish waste water treatment plants( WWTP' s) and the total extended flamentlength and DSVI in halt of the plants exceeded the limits ,which indicates sludge bulking(15 km/g ss and 1S0 ml/g respectively). Thedominant organism was Microthix paricella. the abundance of which was 59.22% of total extended flament length on average.Chemicals were tested to control the filaments. and it was found that special attention has to be paid to maintaining the ntrification at lowtemperature. A dosage of(H2O, -based) oxidants contrlled the growth of Microthrix parvicella effectively and rapidly, whereas with theuse of aluminium hydroxidechlonde a2 to S-week period was needed to decrease the filament length.Keywords: low temperature; activated sludge; bulking; Microthnix paricella ; chemical control; ntrifcationmonitor the abundance during seveal monbs in winter and in spring.IntroductionThe filament length was determined in a microsope a total extendedWhen nitmgen renoval is applied in the activated sludge process infilament length. m/g ss by calculating crossings of filaments ina grid inNordie conditions, a cuther long sludge retention time(SRT) is required a known anount of sample(50山) under cover slip by using usuallyin winter and springtime, when the process temperature is 6- 12C for200 x magnification,The organismg were identifed with staining 2procedures( Jenkins, 1993; Seviour, 1993) . The relative abundances ofused. From the basis of a prelininary survey it was found that this leadsdiflerent species were estimated by using the grid and crossingsto some problems with filarnentous organisms, especially Microhrixcalculatinn.paricella. Therefore a more: extensive study was started to get a moreBatch tests were made to estimalte the impact of oxidants on the tolulcomprehensive picture of the problems .extended filament length and nitrifieation rate. Activated sludge batchesFarlier experience has shown that, when Micothrix paricella is thewere aerated in 1-I. beakers and dfferent dosages were added in paralleldominant oganism and nitification has to be: maintained at lowtest vessels. The samples were taken 3 h after dosage 10 determine thefilament lengh and 2.5 h afer dosage to analyze the viabilit of theflament growth, such as operation with the shortest possible SRT to allowsludge wih ATP ( adenosine triphosphate) measurement by using thenirification, which means inereasing the food to microorganism ratiobioluminescence method( Kahru, 1991). The same batches were also(Dillner, 1998; Knoop, 1998). The SRT can be shortened by an used to monitor the minification rate by adding NH.-N (50 mg/L) andadditional 20%一30%, when the pH is maintained at a higher level ofHCO3 buffer one hour afer the oxidant dosage. Samples were taken7.2- -7.6, to favour the growth of nitifiers in the system( Pllkonen,belween 1.2 and 3 h afer the oxidant dosage and fltrated. The sum of1999) for example during the most difieruh period. Hlowever, in this wayNO2 -N and NO.-N was anal!zed from the fltrated samples with FIA(nowthe prblemns may stil remain and bulking and/or foaning can requireinjection analyais) to calculate the nitrification cate. The nitnificationaditional control actions. Therefore, the use of chemicals has beentests were repeated after 24 h. 'The tests were performned at roomstudied to evaluate how the manipulation of the population could hetemperature (20气). Oxidant dosages belnw 20 m/L are considered a .managed to decrease the albundance of filamenls, without negativelynedium-level dosage, and over 20 mng/L a high dosage . Two dfferentalecting the mirifcation. Since the nirifcation is very sensitive tooxidanls, A and B. were used, and H2 O2 as the main oxidant compoundtemperature effects, the possible decrease of nitrification activity can leadin both.toa long period with unstable nitrogen renoval, which may lead tw2 Results and discussionproblens with the efuemt requirements. On the other hand, the stlershave their highest load during the low water temperaure( spring) period,In the survey the total extended filament length was found 1o bewhich is why the control actions have a high impact on the plantrather high (Fig.1). on average 17 km/g ss. and the varialion wasperfornance .large 7 - -42 with a standard deviation of 9.92 km/g ss. In half of theplants the total exended flament length exeeded 15 km/g ss, and also1 Methodsin half of the plants the sludge stleabiblity was worsened, when the ISVISamples from a lolal of 10 activated sludge plants were anulyzed forwas over 150 ml/g. Both these limits can be considered to indicatethe alundance of diferent filamentous organisms in the sludge. Thesludge bulking. The impact of SRT can be seen in that three of a total ofsurvey was conducted during springtime. when the process temperatures中国煤化工,abundlance values. Thewere 11一16C. A more detailed sunvey was earried 0ul for Iwo plants 10non-niproportions of MicrothrirMYHCNMHGFoundation item: The National Techoology Agency of Finland14WANC Zeng zhang et al .Vol.16口Aeration sludgethe exces growth of M. panielal . Based on the results of other suveys(W aner, 200; Eikelboom, 1998) Microhrie priela sem m le by .far the most important flamnent . The delopment of fianents in theshudge is shown in Fig. 2, which idieates the most dificoht situationduring February- April. The period from Oetober to May is operated withhigher SRT due to the lower temperature.Serial oumber of WWTP's器。。Fig. | The lolal exlended flaments lengh in 10 Finmish WwTP'sparicella of the total extended flamet length. On avergeof M. panicllal in activated sludge was 59.2 %。Other speies thatwere regularly found were Type0675, Type0041 and H. hydrossis in theDe.5 Ja.12 Feb.2 Fe.23 Marcb15Apru April26 Jm 7nimngen renoval poesses.. Type02IN and Type0961 were bouhdominant seeies in only one plant (both non ninifying). Detailed dataare shown in Table 1. The resuls showed that efors are needed to contolpedenitnficetion plant during lhe ceold perind ( average vaues of prallel lines)Table 1 Types of flamentous bacteria in diTerent stagesFilamentouseInluent liquorPre- stdte liquorRulking sraion sludgebacteriaOceurrenceDominance. %OceurenceDoeninance, 强M. Paricella20.9128.92859.22H. hydrosts .1.351.20Begpintou0.450.96Typr06750.483.876.740.210.145.72Noreardia pp.0.04N. limieola 1-M0.500.800.07Tinshrix I-00.130.79N. Lmiola I1.43Type041132.001.12Type18631071.3553.060.01Type02IN1.281.52 .13.27Tpre09612.239.139.231.01Typr08030.32Number of plants9M. Paricela39.1268.56H. hydros2.064.63Begginton0.055.2211.12Type004I4.5912.51Norcardia 印p0.25N. limiceda I -13.64Thiothrix 1-N. Iiminlan IType0411 .Typx02IN20.0013.19Typr096115.07Type1701Type0803_5_3The results of laboratory Lests 10 control the flament population are impact of the high dosage of both xidants on the nitrfcation rate wasshown in Fig. 3. A medium- level dosage deereased the filament lengthstrongly ihibtive, whereas the middle dosage inhibited 25%一35% theby approximately 25% with both oxidants. and a high dosge 33%-niri中国煤化工“- cation tet(I- -3 h after the37%。The impact of oxidants on the amount of active biomass was ad15% - -units higher thannegligible except for oridant B. which clearly had a negative ffeet al ain thMYHCN M H Gee of which can be regardedhigh fed level by reducing ATP-concentation 71% (Fig. 4). The rather small . This also indiceales some recovery of nitification on a longerNo.1.Mangement of process perlormance at lo” waler lemperatures in respeet of filamentous organisins115time seale : These results sugstede a need for careful opinizaion of thethat frequent control artions are needed.dosage in order 10o maintain the nitfcation.n A maximum of口Reclative ATP-coccatration。Lohibition of inficationoaproximately 10%- 20% inhibitin can be acped depending on the1cireumstanees, and especially temperature.0.According to the result of labortory test, a full scale test was0,engaged in a WWTP of which the schematie layouts of wuler lines are国given in Fig. 5. The impact of oxidants on the filaments is rapid, anRefereoceOxiduntA OxidantA. Oxidant BOxidaot B,besed on the fl-scale test its impaet can be scen for approximately onebighmiddlenonth, afer which a high flament lengh value was achieved eagain(Fig. 6). The incdiate decrease in the fiament Jengh was 35% -ig.4 Impact of oxidant adion on aetive hinmas ( measured a ATP) andon inhibition of nitrfcation in balch tests( mediumn and high dosage levels)40%。which was in the same range as in the batch tests wih the highestdosage. The decrease of filaments could be found in Iwo days. NGIn another fll-scale experiment, aluninium hydroxidechloride wasadverse ffet on nirifcation was found during this period, which wasused lo control filaments in sludge. in which Microthrix paniella wasdue to the optimized oxidant feed( medium level dosage). The pdominant. The chemical was added to return sludge as approxinately 30temperature was around 12C. This sucessful ll-cale experimentmg/L inluent flow for a 6- week period from the start including one weekshows that oxidants can efctively be used 1to contol filaments iwithout chemical feed. In this case, the DSVI and flament lengthMicrothric priela dominant sudge. The rsuts sugsede, however deresed coierbly and the flamemn lengh was 25%一40% lowerand DSVI 40%- -50% lower than in the relerence (closcst pralel) line0.8-5- 6 weeks from the slart. It took, however, 2- -3 weeks before some.0.6-diferences could be nticed betwcen these two lines. Nirifrcalion was; 0.4- .maintained during this period . This result indicates that aluminium salcan efectively be used 10 control M. panicella. This is opposite to theReference OxidantA, OxidaotA, OxidantB, Oxidant B.result of Knapp et al. ( Knapp, 2001), who found that the total flamenthighahundance( and SVI) decreased, but the abundance of M. puricellaFig.3 Impact of oxidant adition on filament lengh in batch testsincreased considerably during the feed period.EfluentN AERInflueatS1s、Eflucot.AAN AERs2Fig.5 The schenatie layouts of wuler linesP-pretle bain; A- anuerobie basin; AN- anoxic basin; AER -aerobic basin; s- -sedinent basin二S2Period of addingoxidants" 28.12,00 16,1,01 31,1,01 28.2.01 28,3,01 17, 4,012,1,0123.1,01 14,2,01 14, 3, 01.4,0129, 5,01Fig.6 Result of a ull-scale 1est 10 manipulale the shudge population with axidaunt A using a medium-leveldusage. Filament length shomn in t1wo process units (S1 and S2, cnnocted in serie)Particular attention has to be paid to maintaining the uitrification,3 Conclusionswhen the population manipulation in applied by chemical means at lowMicrothrix paniella seems to be the most common filament in tempera中国煤化工Finnish wwIP' s, especially in nitrogen removal (long SRT) plantscontolled with HO-during the spring(1I- 16 C) season, and is control is of imnportance tobased.THCNMHGeriments. and a stablemanage the stler load.nitrification could be maintained when an optimized dosage was used.11WANG Zeng -zhang et al .Vol. 16W. pricelladominant sludge could be maipulated with anKnappP. Baungartner D, Schmidt K G. 2001. Bekinplung von Blahschlummadition of aluminiumn hydroxidechloride, but a period of 2-5 weeks wasmit Polyaluniniunhydroxidchborid[J]. KA- Wasseritsehaft Abwasser Abful,needed to achieve a significant reduction of flaments.48 (3): 334- -340.Knop s. Kunst s.1998. Inluence of temperature and sludge loading on activatedReferences:sludke stling. espeially on Microthrir pmricella[J]. Wat Sei & Tech. 37(4- -5):27-35.Dillner w A. Haglund E,Rothnan M,1998. Founing in anaerobie digestesPelonen M. Wang 7. 999. Are sludge luking probems incresing in thecaused by Microtrir priella[J]. Wa Sei & Tech, 37 (4-5): 51--55.EikelboomD I,Andreadakis A. Andreasen K,1998. Sunvey of flamentouspopulations in nutrienl renoval plants in four Eurmpean counries[J]. Wat SciSeriourE M,Lindrea K C. Seviour RJ e al.. 1993. Filamentous barteria in&Tech, 37(4-5); 281-289.activated sludge plants l R ]. Biotechnology Research Centre. la TrobeUniversity Clle of Northem Victoria, Austmlia .JenkinsD, Richard M. Daigger G, 1993. Manual on the caues and cntrol ofactivated sludge bulking and foaming[M]. 2nd edition. london: LewisWnner J. Rurickova I, Krhurkova 0 et al.. 2000. Aectivated sludge pulaiondynumis and wastewater lreatment plant design and operationJ. Wat Sci &Tech, 41 (9): 217- 225.Kahnu A, Pelkonen M, Vilu R ,1991. Applicaion of ATP bolaminesent methodof rapid detemuination of aicrobial biomass on eninmnmental samples: Trial ofthe asy in enuneration o[ lacleia in soil and acivated sludlgrIJI. Med Fac(Received for review September 29, 2002. Areped November II, 2002)Landlbouww Rijksuniv Gent. 56 (4a): 1585- 1587.中国煤化工MYHCNMHG

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