Effects of different acclimations on high solution bacteria in coal-gas wastewater degradation

Journal of Harbin Institute of Technology( Neuo Series), Vol. 17, No. 3, 2010Effects of different acclimations on high solution bacteriain coal-gas wastewater degradationL Yu fei, HAN Hong-jun, WANG Ying-wei, FANG Fang, WANG Wei李雨霏,韩洪军王英伟,方芳,王伟(1. College of Forestry, Northeast Forestry University, Harbin 150040, China, liyufei3359@ 1632. State Key Laboratory of Urban Water Resources and Environment, Harbin Institute of Technology, HarbinChinaAbstract To make microbial community be applied more easily in practical biotreatment engineering, three ac-climation processes were carried out in lab scale. Three kinds of mixed microorganism cultures with degradabili-ty for a gas-making plant wastewater were obtained. The degradation experiments results of coal-gas wastewaterindicated that different acclimation processes had obviously impacted on degradability of microbial communitynd under high sludge loading rate, mixed microorganism culture I (obtained by H. S B as bacteria source andraw wastewater as alone carbon and energy source )presented stronger degradability for coal gasificationwastewater than the others. COD removal rate of mixed culture I can reach 57. 6% under very low MLSS whenthe influent COD is 900 mg/L. Meanwhile, the results of microscopic examination showed that Protozoa, mainlyepistylis and Vorticella species, were stronger activity and larger quantities in mixed culture IKey words: coal chemical engineering; water treatment; acclimatization; degradability high solution bacteriaCLC number: TUgsDocument code: AArticle ID:10059113(2010)03038904Coal gas is a kind of clean fuel. The coalHigh Solution Bacteria(H S B)containing hundredsion wastewater that contaminated with complex com- of species microorganism was used specially inpounds has been a serious environmental problem for wastewater treatment and had been successfully used indecades in China. However, a large amount of several coking plant for decades 5-6. To make complexwastewater is also produced in the process of coal gasi- microbial community more adaptive and be easier to befication. The effuent is contaminated with complex or- applied in practical engineering, in the study, H S. Bganic compounds, such as phenols, ammonia, polycy. and mature sludge from a coke plant were respectivelyclic aromatic hydrocarbons, and fatty acid, etc It has used as inoculation bacteria source, which were acclibeen a serious environmental problem for decades in mated by pretreated coal-gas wastewater containing orChinanuncontaining glucose in batch reactors. The objective ofBiodegradation is the main method for coal gasifi- the section experiments is to ascertain which domestica-As the tion ways is the one of the most effective and which in-wastewater is of high strength and toxicity to microor- oculation bacteria source is more suitable for a coal-gasganism, conventional activated sludge system for coal- wastewater by doing a comparative analysis of degrada-stewater treatment is not efficient in reducing tion efficiencyCoD to meet the discharge standard. Biologicalhancement technology, especially biological enhance- 1 Materials and Methodsment technology of aiming at refractory and inhibitoryorganics, is considered to be particularly necessa- 1.1 Experiment Set-upThe experiment set-up is shown in Fig. 1.ThreeThe cardinal procedure in the process of treating reactors( plastic bucket )were set, consisting of aera-refractory and toxic wastewater is the acclimation for ac- tion head, hose and air bump. One air pump suppliedtivated sludge. Now most of inoculation sludge in coke- with gas for three reactors so that aeration rate were ba-plant and coal gasification plant is taken from mature sically in accordance with each othesludge in the other coke plant. Whereas different water 1. 2 Inoculation Bacteria Sourcequality must cause that degradation ability of the sludgecant achieve the expected goal中国煤化工Received 2009-05-23CNMHGSponsored by the National High Technology Research and Development Program of China(863 Program)( Grant No. 2007 AA06A411)Journal of Harbin Institute of Technology( New Series), Vol 17, No 3, 2010treatment and haduccessfully used in several co- into demanded concentration when changing influentant for decstrength. The experiments were operated about 172)Mature sludge from aeration tank of Nanjing 22C at room temperature PH was maintained at 6.58. 5 by adding appropriate volume of sodium bicar-Air pumpbonate solution Dissolved Oxygen(Do )value in theaerobic reactor was kept between 2perimental period. Adding proper dosage KH, PO, waHosedue to getting a balanced nutrition requirement basedonC:N:P=100:5:11. 4 Experiment ProceduresAeration200 mL H. S B and matured sludge were addednto reactors respectively. Domestication experimentswere divided into two periods. In the Stage I, the ini-Fig1 Diagram of the experiment instrument and equipment tial CoD of the inflow substrate was always kept about500 mg/L, that is, about 500 mg/L coal-gasThe bacteria source and carbon source of domesti. wastewater was added into Reactor (a), meanwhile a-cation are shown in Tab. 1bout 250 mg/L coal-gas wastewater and about 250 mg/L glucose were added into Reactors (b)and(c)Tab. 1 The bacteria source and carbon source duringCOd were measured every day for 10 d and COD con-domesticationsumptions were replenished with the wastewater or halfReactor(a) Reactor(b) Reactor(c)wastewater and half-glucose. In the Stage II, the influH S Bmature sludgent concentration indicated in Tab. 2)were corre-spondingly in100 mg/L of the lastarbon andas cod kept constant after changing influentwastewater+wastewater十cnergy sourcwastewater. All domestication tests ended when CODreached 1000 mg/L. Finally, equivalent coal-gas1. 3 Experiment Conditionswastewater was added to three reactors and biodegradaRaw wastewater, the chemical oxygention tests for wastewater of initial concentration lessCoD)about 6000 mg/L, collected from Harbthan 1500 mg/L were carried out: COD removal ratesGasification Factory after extraction of phenwere compared and bacterium and Protozoa in sludgewere examined by microscope simultaneouslyremoval of ammonia ). The wastewater would be diluteTab 2 Wastewater and glucose proportion of influent in the Stage IlInflow Wastewatertor(b)Concentration/ (mg L-1)Raw wastewater/% Glucose/%Raw wastewater/% Glucose/%00000000010001001001. 5 Analytical Methods and Instruments2 Results and discussiondeprived of aerating for half hour. After filtering by fil- 2.1 COD Removal during Domestication Progresster paper, COD of sample water was analyzed by 5B-1The reactors were seeded respectively with H S. BModel COD speedy testing instrument. The other main and mature sludge from aeration tank of Nanjing Co-instrument included Biological microscope BX51- king中国煤化工 d after two daysOLYPUS, Japan), PH Device( PHS-3B Model, Shang- expduring Stage I ofHai), Dissolved Oxygen Metre(JPB-607 Model, Shang- acCNMH Gring the beginningHaiof 4 days, COD removal was as follows Reactor (c)>390Journal of Harbin Institute of Technology(New Series), Vol 17, No 3, 2010Reactor(b), which testified that mature sludge had actors( b)and(c) took no more advantage. On thefaster adaptability. With the prolongation of time, COD contraryB in Reactor (a), which had alwaysremoval in Reactor (b)exceeded in Reactor(c) be- been tolerance to all of coal-gas wastewater, had thecause H S B gradually adapted to the wastewater. highest efficiency 50. 2% at about COD of 1000mg/LCOD removal in Reactors( b)and(c)had always influent. Being microbial proliferation was inhibited bybeen higher than COD removal in Reactor (a)e poisonous wastewater, the mass concentration ofThe cause may be that glucose added into Reac- MISS in Reactors(a),(b) and(c)merely reachedtors(c)and(b)is easily biodegradable, whereas o- to 561 mg/L, 593 mg/L and 776mg/L respectively atver all hard-degradation wastewater was filled into Re- the end of acclimationactor(a). COD consumptions in Reactors (c)andb)contained the portion of most glucose, so seeming-ly COD removal in Reactor(a)was the least one. Additionally, directly replenishment with wastewater orwastewater and glucose without water exchange wouldlead to nonbiodegradable organics accumulating, whichwas the reasonof cod removal continual decline andcould be testified by do level rising gradually at theend of the microorganism acclimation. It can also be40050060070080090010001100seen from Fig. 2 that H. S. B contained more adaptablebacteria for the coal-gas wastewater than mature sludge Fig 3 Removal rate of COD during stage n of domesticationfrom coking plant by the comparison of Reactor(b)and Reactor(c) if only acclimation time is enough 22 Microscopic ExaminationThe microbial community after acclimating in Reactors(a),(b)and(c) were respectively called as mixed50microorganism cultures I, [and Il. As shown in Fig 4Protozoa mainly Ciliata, Epistylis and Vorticella spewere stronger activity and larger quantities in mixed mi-croorganism culturel, which could be one of the reason oflower SS in the supematant. Bacterial species had slightly10difference between mixed microorganism culture I anmixed microorganism culturel, but Epistylis and Vorticalla predominated in mixed microorganism culture land ses-sile Ciliata had advantage in mixed microorganism cultureFig 2 Removal rate of COd during stage I of domestication I. Absence of protozoa and loose floccus structure mixedwith microorganism cultures ll probably be in that accli-In the stage I, Fig 3 shows that the trend of Cod mation was so short that the mature sludge from cokingremoval first decreased then increased with influent plant could not fully adapted to the new wastewater underconcentration step-wise increase. Reducing proportion experimental conditionsof glucose added to influent made COD removal in Re(b) Mixed cultureⅡ(c) Mixed cultureⅢFig 4 Microscopic examination charts at the end of acclimation2 3 COD Removal for Different Concentrations 77中国煤化工 tration ofCoal-gas WastewaterCNMHGng/ L COD remov-Because of the inhibition from substrate andaulic retention timenass concentration of MLSS(561 mg/L, 593 mg/L and HRT)of 72h was shown as Fig. 5. Cod degradation rateJournal of Harbin Institute of Technology(New Series),Vol. 17, No. 3, 2010was remained between 40%-60% throughout the degradation progress, and COD removal showed decreasing when 3 ConclusionsCOD of inflow concentrations above 1000 mg/L. Mixedmicroorganism culture l, which H. S. B fed on coal-gasAdding glucose or other substrate are not alwayswastewater absence of glucose, had the highest biode- benefit for biodegradability of refractory organics or efflu-gradability. This may be a result of catabolite repression ent including non-biodegradable organic compounds. Inby glucose in Reactors(b)and(c)in domestication pe- the study, the best acclimation way for Harbin coal-gasriod. Papanastasiou indicated that the presence of glustewater is H. S. b as bacteria source and rawcoseinhibit the utilisation of the target substrate. wastewater as alone carbon and energy source. COD re-Satsangee and Ghosh'9also reported the interference in moval rate of mixed microorganism culturelcan still reachphenol uptake by glucose. The curve of Fig. 5 also indi- 57. 6% under 561 mg/L MLSS when the influent CODcated that the highest degradation rate could reached to concentration is 900 my/L Under enough long HRT,57.6% between 600-1000 mg/L by mixed microorganism COD removal rate can exceed 80% for 600 mg/L initialcultureL. The effect of HRT on biodegradation rate( as concentration. Hence H S B has a remarkable potentialshown in Fig. 6)represented that the increase of HRt toas wastewa9 or 10day could improve COD removal rate to above References:80. This result indicated that the effluent reach dig-harge standard was possible under enough long HRT.[1]LiP, Zhao H Z, Wang C, et al. Advancedwastewater by coagulation and zero-valentses. Journal of Hazar Maler, 2007, 147(1-2): 232[2]LiYM, Gu G W, Zhao J F, et al. 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China Environsci,1998,18(5):415-418.[8] Papanastasiou A C, Maier W J. Kinetics of biodegradation of2, 4-Dichlorophenoxyacetate in the presence of glucose. Bio-Mixed culturetechnology and Bioengineering 1982, 24(9): 2001-2011+-. Mixed culture[9] Satsangee R, Ghosh P. Anaerobic degradation of phenol usingan acclimated mixed culture. Applied Microbiology and Bio-Mixed culture Hltechnology,1990,34(1):127-130[10]Yang Tianwang, Zhang Qingming, Wu Hongyitreatment pilot tests in a coking plant using HSBDayleJoumal of Tsinghua Uuiversity( Science and TeclFig 6 Removal rate of COD for 600 mg/L initial concentra-208,48(3):362-366tion under different HRT中国煤化工CNMHG