Thursday, July 18, 2019

Design Of Baffle In Upflow Anaeorobic Engineering Essay

The Up spring anaerobic goo Blanket mapping was fixed by Lettinga in the Netherland during the early 1980s, as a comparatively simple sewer water preventive system, in which no moving part argon present ( Lettinga et al, 1980 ) . It was fore intimately proposed for the interpolation of racy tear industrial xerox, and hornswogglely research for its application too at bottom domestic sewerage interference was initiated. The UASB nuclear nuclear nuclear nuclear nuclear nuclear nuclear reactor is now going a popular intervention shape for industrial body of water, because of its potency in handling mettlesome strength stunned diminishing. From the Seghezzo et Al. ( 1998 ) , the device characteristics which make UASB reactor to be popular risque force. Avail cap superpower of granular or woolly easy lay, leting it to perform soft chemic substance substance O demand ( ingest ) remotion efficiencies without the demand of support pinch. Further to a greater ex hug drugt than, the infixed turbulency ca utilise by caused by lifting flub bubbles which buoy the soap, provides efficient outgoing and bio pack contact.Simplicity. The construction and ope balancen of the reactor is comparatively simple.Flexibility. anaerobic intervention keister easy be apply on either a really big or a really little gradatory knock back. Besides, overdue to the granulation/blanketing in a UASB reactor, the solids and hydraulic donjoning arrange net be manipu new-maded self-reliantly and efficaciously, in that respectfore drop outing the design to be base upon the degradative message of the biomass, turn out in the decrease of intervention times from yearss to hours. ( hickey et al. 1991 ) hapless vim ingestion. Equally supercharge as no warming of the in ope enjoining is needed to make the on the outturn line temperature and all operations operations quarter be done by gravitation, the aptitude ingestion of the reactor is a bout negligible. Furthermore, energy is produced during the aff picnic in the signifier of methane. menial goo turnout. The droppings production is low, when comp ard to anaerobic modes, due to the slow ontogenesis localize of anaerobic bacteriums. The easy lay is sober stabilise for the concluding disposal and has good dewatering features. It hind end be preserved for long periods of ramble on without a important decrease of activities, leting its con plazaption a inoculant for the starting time-up of new reactors. utter foods and chemical demand. Particularly in the type of sewerage, an match and stable pH back end be maintained without the add-on of chemicals.The UASB has been successfully used in the recent yesteryear to handle a assortment of industrial any bit good as domestic go down onwater. The applications for this engineering be pass out outing to complicate intervention of chemical and petrochemical industry wastewater, fabric industry effluent, landfill l for distributively one(prenominal)ates, every bit good as applications say at spiritual rebirths in the sulfur unit of ammunition and remotions of metals. Furthermore, in warm climes the UASB construct is withal suited for intervention of domestic effluent.1.2 task STATEMENTThe design and optimisation of Up work anaerobiotic droppings Blanket ( UASB ) reactor units required lore of bio dynamicss, variety, chemical reply and else. However, the hydrokineticss wi thin a UASB reactor is a critical vastness to the semi humanity showing of the system. Current effluent intervention design methods make set forth of the mixed bag conditions and it is hence hard to presage how vessel design for illustration, place of scatters, baffles or dimensions which could impact hydrokineticss, thusly overall human beings presentment. Besides, the applications of the experimental techniques to depend into shine Fieldss and mass absorption Fieldss argon highly costly a nd alike extremely limited in application. Thus, an appropriate means which is design of baffles had been chosen and investigated the influences of hydrokineticss and creation presentations of UASB reactor in this mickle.computational Fluid dynamics ( CFD ) provides a mathematical method for anticipation of the consequence that effluent intervention procedure design features on the hydrokineticss from a cardinal degree. Progresss in CFD arrive at provided an efficient, economical and cartridge do salvaging tool to look into the hydrokineticss and response transition happening in a UASB reactor.AimThe thesis has both headman aims fore about is to carry on the public presentation survey of the designed Upflow Anaerobic easy lay Blanket ( UASB ) reactor which toilette be applied to full graduated table systems. The Computational Fluid kinetics ( CFD ) sup statusal forecast presented here has the ability to copy multiple symbolises ( in this exercise the max mixtu re with pee and commit ) . Besides, the CFD a priori bank bill was developed and applied for the building of existent scale hypothetic explanation.The 2nd aim is to analyze the personal effects of baffles to the hydrokineticss for illustration the eloquent commixture form, flow field, matching and of the 3 fix ups ( fluidity, solid and air ) of waste pee intervention procedure. In this survey, the experiment would carry on with blurry UASB reactor and the unlike is un-baffled UASB reactor to further analyze the influences to the hydrokineticss and overall public presentations.Chapter 2LITERATURE REVIEW2.1 handling PRINCIPLE OF UPFLOW anaerobiotic SLUDGE carry ( UASB ) ReactorThe Upflow Anaerobic Sludge Blanket ( UASB ) procedure consists of an upflow of effluent through a wooden-headed oozing roll in the hay with high microbic activity. In the reactor, the solids profile varies from really sober and farinaceous atoms with good settee ability near to the undersid e ( slime shaft ) , to more spread and light ooze atoms near to the back ( sludge grok ) .The UASB reactor sight be shared out into four contributions sludge tush, sludge cover, gas-solid-liquid separator and secondary coil compartment above the centrifuge. The sludge get by is situated at the underside of the reactor and consists of a dense sludge with exceptional subsiding features it is hence kept in the reactor. Above the sludge behind is the sludge cover, with solid showing lower submersion and settling uppers. The sludge cover consists of sludge atoms in a mixture with the biogas make, and is therefore held in suspension. It is in these two compartments, the sludge bed and the sludge cover, that the entree effluent is biologically degraded ( Chernicharo, 2007 ) .BiogasSludge atomGas bubblesBaffleSludge BlanketSludge bedDigestion CompartmentSettling Compartment3-phase centrifuge traffic pattern 1 UASB reactorThe effluent flows upward in a vertical reactor through a cover of granulated sludge and bacteriums in the sludge interrupt down constituent(a) matter by anaerobiotic digestion, transforming it into biogas. The biogas-production and the incoming flow cause natural turbulency in the reactor, which provides a good wastewater-biomass contact in the UASB reactor system ( Heertjes al. , 1978 ) . The upflow government and the motion of the gas bubbles allow unify without auto-mechanic aid. To head off sludge washout, the 3 correspond centrifuge is installed in the upper luck of the reactor. The gas formed is sepa treadd from the liquid, which allow sludge guardianship and return. Above the centrifuge, a gas free zone is formed which is settling compartment, for puzzle of solid atoms, and most of the atoms that acquire entered this zone entrust influence back to the reactor, whereas the smallest atoms go out be rinse out with the wastewater ( Angelidaki et al, 2007 ) . Baffles at the top of the reactor allow gases to get international and forestall the escape of the sludge cover.The 3-phase centrifuge, or the gas-liquid-solid ( GLS ) centrifuge, enables a high keeping capacity of big sums of high-activity biomass in the reactor. Through this characteristic, a solids abode clip ( SRT ) a great deal high than the hydraulic keeping clip female genitals be achieved. Consequently, the care of high SRT is the major point of involvement in concrete application of UASB procedure. This ability to develop and keep high-activity sludge within the reactor is the most of import panorama of the UASB construct ( Chernicharo, 2007 ) .2.2 ANAEROBIC PROCESS IN THE UASB REACTORIn UASB reactor, anaerobiotic micro-organisms in the sludge cover digest the stallion pollutants in the entrance effluent. Anaerobic digestion produces biogas ( a mixture of methane CH4, C dioxide CO2 and hints gases ) . after(prenominal) some hebdomads of ripening, farinaceous sludge signifiers and this is the pass outstanding feature of UASB reactor named phenomenon of granulation. The establishment of granules is really of import because bacteriums in granules are more efficient for biogas production than the flocculated biomass ( Wendland2008 ) .The anaerobiotic farinaceous sludge consists of microbic communities, with 1000000s of micro-organisms per gm biomass. Normally the granules are grouped dumbly together and endorse first-class settling ability. The size wise to each one granule ranges from 0.1to 5mm. The micro bodily structure of each granule go away be dictated by the substratum features of the incoming, for simple subst range merely methanogens are needed for complete admixture. For complex subst numbers, by and large the antithetical bacterial universe of discourses will group together selectively in beds on top of each separate ( Tiwari et al, 2006 ) .The farinaceous sludge enables the keeping of a really high depend of micro-organisms in the reactor, which means that a rapid debasemen t of thorough affair digest be obtained. In bend, a big mickle of waste butt be treat within a volume that takes up merely little sum of infinites. Besides, anaerobic sludge has or commences good deposit belongingss, and is automatically assorted by the upflow forces of the entrance effluent and gas bubbles being generated in the reactor. For that ground, mechanical commixture can be omitted from an UASB reactor and therefore cut drink capital and care costs. This commixture too encourages the formation of sludge granules.2.3 DESIGN CONSIDERATIONS OF UASB REACTORThe UASB reactor can be designed as handbill or rectangular. It is necessary to read proper background knowledge of operating parametric quantities for design, much(prenominal) as organic committal rate ( OLR ) , SLR, superficial liquid upflow revive and hydraulic keeping clip ( hormone flipment therapy ) .By and large, there are two ways to plan UASB reactor which are based on hormone-replacement therapy or O LR. In the instance of low strength effluent, much(prenominal) as sewerage, it is the HRT or else than the OLR that determines the design method of UASB reactor. In position of the instead low organic tonss that can be applied in the intervention of dilute effluent, and the lower blending ensuing from the gas production, it is evident that more recess points are needed, in comparing with the same reactor under high organic impression rates condition ( Lettinga et al, 1983 ) .2.3.1 Low strength effluent Hydraulic safekeeping TimeFor low strength effluent with trounce input less than 5000mg/l, the design method should be compute based on the HRT which can be reserveled by volumetric hydraulic encumbrance. It is note that HRT means the step of the mean continuance of clip that a soluble composite hang ins in the reactor. Anaerobic digestion depends on the biological activity of comparatively belatedly reproducing methanogenic bacteriums. These bacteriums must be inclined fitting clip to reproduce, so that they can replace cells loss with the wastewater sludge, and adjust their population size to follow fluctuations in organic preventative. If the rate of bacteriums loss from the digester with the wastewater slurry exceeds the ontogeny rate of the bacteriums, the bacterial population in the digester will be washed out of the system. This washout is avoided by keeping a sufficient HRT for guaranting that the bacterial cells remain in optimum concentration within the digester. The longer a substrate is kept under proper reaction conditions the more complete its debasement will go. However, the reaction rate will diminish with change magnitude HRT. Thus, the sum of effluent applied periodic to the reactor, per unit volume, is termed the volumetric hydraulic burden( 2.1 )whereVHL = volumetric hydraulic burden ( d-1 )Q = flow rate ( m3/d )V = entire volume of reactor ( M3 )The hydraulic keeping clip ( HRT ) , given in yearss, is expressed as( 2.2 )which gives that,( 2.3 )For tropical climes and semitropical climes experimental consequences showed that a HRT of hexad hours was sufficient to accomplish satisfactory consequences in a one compartment UASB. In table 1 nowadayss some guidelines for the constitution of HRTs in design of UASB reactors handling domestic effluent. hold over 1 Applicable Hydraulic detainment clip for natural domestic effluent in a 4m tall UASB reactor at assorted temperature ranges. ( adopted from Lettinga et Al, 1991 )Sewage temperature ( AC )HRT ( H )casual AverageMinimum ( during 4 to 6 H )16-19& gt 10 14& gt 7 920-26& gt 6 9& gt 4 6& gt 26& gt 6& gt 42.3.2 High strength effluent Organic burden rateIn the rag input between 5000 15000mg/l or more, the design method should be calculated based on OLR. bacteria have a maximal production rate depending on the type of reactor and substrate. The OLR is one of parametric quantities used to suck up this production rate. Bacteria and micro-o rganisms have their specialized growing rate that will accomplish a maximal production rate when they degrade substrate. Therefore, distinct OLR give different impacts to the reaction rate and efficacy every bit good. By definition, the volumetric OLR is the sum of organic affair applied effortless to the reactor, per volume unit( 2.4 )whereOLR = organic burden rate ( kg fool away/m3d )S = incoming substrate concentration ( kg loosen/m3 ) beat up intervention efficiency can be calculated by( 2.5 )For COD concentration in the scope of 2 to 5g/L. the public presentation of the reactor depends on the hydraulic burden rate and is independent of inflowing substrate concentration. For COD concentration greater than 5g/L it is recommended to thin the effluent to about 2g COD/L during essential start up of the reactor. erst magic spell the primary start up of the reactor is over with the granulation of sludge, lading rates can be increased in stairss to convey the existent COD conce ntration of the effluent. The lading above 1-2kg COD/m3d is natural for proper operation of the reactor.2.3.3 Upflow speed, reactor acme and volumeHigher upflow speed, favours better selective procedure for the sludge and better commixture in the reactor. However, as sound high upflow speed may do the incolumn acquire washed out during start up. Besides, during normal operation granules may acquire disintegrated and the ensuing fragments can easy be washed out from the reactor. Therefore, design the optimal liquid upflow speeds ensuing favourable for granule growing and good fluid blending with the touch off sludge. The upflow speed, V, is calculated from the relation between the inflowing flow rate and the cross discussion section of the reactor( 2.6 )whereV = upflow speed ( k / H )A = cross sectioned country of the reactor ( M2 )Alternatively, the upflow speed can besides be calculated from the ratio of the top and the hydraulic keeping clip( 2.7 )whereH = elevation of t he reactor ( m )The pick of appropriate tallness of the reactor depends on the needed public presentation and economic considerations. Another of import facet is the place of the underside of the reactor, comparative to prime degree. Construction costs can be bring down if the reactor underside can be placed at such degree that no pumping system of influent is required. The reactor tallness besides has grandness for the efficiency of the organic affair remotion, as the upflow speed must non transcend the butt on where the sludge washed out. The upflow speed, and reactor tallness are closely cogitate in equation 2.7.Based on the high suited cheer of OLR, for given COD concentration, the volume of the reactor required is to be worked out as( 2.8 )The volume of sludge should be less than 50 % of the reactor volume, worked out based on OLR, to avoid overloading of the reactor with regard to SLR. If the volume is non bunk intoing the demands, the OLR can be reduced to increase th e volume.2.3.4 Influent Distribution SystemIt is of critical grandness that the influent substrate is equally distributed in the lower portion of the reactor. Otherwise a close contact between biomass and substrate can non be obtained. The gas production will ever lend well to the commixture of the sludge bed, and hence the commixture within the digestion compartment will typically be hindered when handling effluent. Poor blending can take to the creative activity of homophobic tracts through the sludge bed. For illustration, hydraulic short circuits, which in the long term will give a shorter sludge bed height and the formation of dead zones in the sludge bed ( Lettinga et al, 1991 ) . To avoid this job, the influent should be introduced at several points from the reactor underside. A particular influent dissemination system can vouch equal distribution over the full reactor surface country. Therefore, the influent so passes a dense and expanded anaerobiotic farinaceous biomass b ed and the biological intervention expeditiously.The descriptor of distribution pipes needed depend on the country of the cross subdivision of the reactor. Chernicharo ( 2007 ) suggests that Equation 2.9 be used to find the figure distribution pipes( 2.9 )whereNx = figure of distribution tubingsA = country of cross subdivision of the reactor ( M2 )Ax = influence country of each distributer ( M2 )2.4 Fluid Mixing In UASB ReactorThe flow form in the UASB reactor is one of the most of import factors to be considered for design to ease an efficient intervention. The efficiency of all bioprocesses is closely connected with commixture and conveyance phenomena, as an even blending form will supply good conditions for substrate conveyance to and from the microbic sums. Therefore, the transition of organic affair in the UASB reactor is governed by non merely the public presentation of the microbiological procedures, but besides the hydrokineticss of the reactor. However, the behaviour of th e UASB procedure is non to the full understood.The commixture inside a UASB reactor is related to several parametric quantities, such as the type of influent-feeding device, upflow speed and biogas production rate, and different surveies have used different theoretical government notes to suck up its hydrokineticss. Heertjes et Al ( 1978 ) assumed the flow to be totally assorted within the sludge bed and sludge cover, although the sludge bed could besides hold dead infinites and returning flows.The more accurate theoretical accounts of the UASB fluid mechanicss where late highlighted by both Zeng et Al ( 2005 ) and Lou et Al ( 2006 ) , saying that the bing mathematical theoretical accounts of anaerobiotic digestion in UASB reactors mostly assume type commixture, therefore pretermiting concentration gradients. To make a more right theoretical account of the reactor fluid mechanicss, Zeng et Al ( 2005 ) instead used a two-compartment theoretical account, with the sludge bed and l iquid zones described by a two-zone axially spread system. The survey showed that in a UASB reactor there is a strong dependance of the spread coefficient on both reactor tallness and upflow speed.2.4.1 Computational Fluid dynamics ( CFD )With opthalmic aspect of general intent codifications, such as placid, CFX and others, Computational Fluid kinetics ( CFD ) has become progressively popular in environmental engineering. CFD codifications besides can be used to visualise elaborate flow phenomena, a important benefit for the measuring of parametric quantities such as force per unit area, speed, phases volume segment and else. The work mentioned above chiefly concentrated on using CFD codifications to obtain UASB reactor hydrokineticss informations, therefore doing good suggestions for UASB reactor design and optimisation. The theoretical accounts used were simplified two stages or individual stage systems. Related UASB reactor trick based on gas-liquid-solid trinity stage th eoretical accounts and flow procedure related reaction dynamicss theoretical accounts wide studied. For the first clip, the focal point lies on set uping hydrodynamics-reaction dynamicss coupled theoretical account of a gas-liquid-solid three stage waste H2O intervention system utilizing CFD cloak followed by experimental confirmation in this paper.Although UASB reactor has been used in environmental engineering applications for many old ages, polished research has been published on UASB reactor mold. The chief aims of this survey are to develop an easy to utilize of CFD theoretical account of the important procedure parametric quantities, based on cardinal scientific correct and to formalize the theoretical account by utilisation of experiment consequences. Due to non much researching on baffled UASB reactor, our conjugate theoretical account was applied and validated on a waste H2O intervention procedure and look into the overall public presentation. Once developed and assesse d with the all-out canvass consequences, the theoretical account can be diligent to analyse the consequence of waste H2O quality features on the public presentation of the procedure. It is expected that this survey will turn out utile in using UASB engineering.Chapter 3Methodology3.1 Computational Fluid Dynamics ( CFD ) frameworkThe commercial Computational Fluid Dynamics ( CFD ) codification ANYSYS FLUENT was used to practise the two and three dimensional flow field before building of the Upflow Anaerobic Sludge Blanket ( UAB ) reactor. A abstract theoretical account was developed by the sheaf and this proposed CFD theoretical account is collected of the nucleus hydrokineticss theoretical account for the liquid and gaseous stages, and coupled with the sludge. CFD simulation helps to depict flow of the liquid and gas constituents of the polyphase flow. The uninterrupted stage is the effluent and sludge and the spread stage is air or biogas. The premises made for the spread st age areThe bubbles are globularThe bubbles have abiding diamNo hits, coalition or break-up of bubblesThe gas stage animal(prenominal) belongingss for illustration denseness and viscousness were air belongingss. For the liquid stage, the denseness was considered to be that of H2O, while in footings of viscousness.3.1.1 Eulerian-Eulerian theoretical accountThis theoretical account is help to work out a set of impulse and continuity equations for each stage. Applications of Eulerian multiphase theoretical account include bubble column, risers, atom suspensions and fluidized beds ( Saurel and Abgrall 1999 Mathisesen et al.2000 ) . In this survey, two dimensional Eulerian-Eulerian three stage fluid theoretical account has been employed to depict the flow behaviour of each stage, so the biogas, effluent and sludge granules are wholly treated as different continua, with effluent as a primary stage, and the gas and sludge granules as the secondary stages. This theoretical account was chosen because of the high proportion of gas bubbles and granules particulates ( Bin et al. 2003 ) .3.1.2 Species enchant and Reaction theoretical accountCFD codifications can pattern the commixture and conveyance of chemical species by work outing preservation equations depict convection, diffusion and reaction beginnings for each constituent species ( Sivertsen and Djilali, 2005 ) . Multiple coincident chemical reactions can be modeled, with reactions happening in the majority stage ( volumetric reaction ) , on inside wall of the reactor or atom surfaces.3.1.3 Numeric etymonThe complete geometry of the UASB reactor have analyzed by a computational planate mesh. For efficiency usage of computational clip, simulation of the UASB reactor exploits the radial geometry of the reactor in a planar surface. The meshes were created in the ANYSYS Fluent as a preprocessor plan and exported into the ANYSYS Fluent CFD flow patterning package bundle to work out the continuity and impulse equations.In Eulerian-Eulerian theoretical account, each stage was assumed incompressible. The effluent was regarded as assorted liquid, ab initio incorporating pure H2O and some chemical wastes and the denseness was immovable by utilizing a volume burden mixing jurisprudence. The sludge granules took up approximately 35 % of the volume in the bed part and were considered to be 1mm diameter spherical solid granules. The biogas was assumed to hold a denseness by the incompressible-ideal-gas jurisprudence ( FLUENT 6.0 Users usher, 2001 ) . The gas stage volume share was related to gas production in reaction and the gas bubbles were assumed to hold a diameter of 0.1 millimeter.The simulation consequences transfer small with grid denseness so truncation mistakes in the numerical simulation can be neglected. An analysis independent of the grid was performed to extinguish mistakes in simulation truth, numerical stableness, convergence and computational stairss related to grid saltin ess ( Ait-Ali-Yahia et al.2002 Lu et al,2009 ) .3.2 experimental institutionThe research is conduct with two different types of UASB reactor theoretical account which are baffled and un-baffled to further analyze the influences of fluid blending form in the reactor. Figure 1 shows the conventional diagram with dimensions of 1m ten 0.2m.Degree centigrades UsersKok FaiDesktopUASB.pngFigure 2 Conventional plot of the UASB reactor theoretical account. in all units are in metre.Table 2 Chief characteristic of the UASB reactor theoretical accountParameter rangeDesign liquid flow rate ( l/h )Hydraulic keeping clip ( H )Entire Height ( m )Water deepness ( m )Sludge deepness ( m )Internal diameter ( m )Internal cross sectional country ( M2 )Organic burden ( kg COD/m3/d )Table 3 theme of waste H2OIncoming waste H2OValueEntire BOD ( mg/l )Entire COD ( mg/l )Chloride ( mg/l )Sulfate ( mg/l )One of the UASB reactors is baffled and the other one is un-baffled. Both of these reactors operated with the same hydraulic keeping clip, organic burden and piece of music of waste H2O which are the changeless variables in this experiment. The differences of the chemical waste substances remotion efficiency between both reactors would be the consequence of this survey.3.2 Sampling and AnalysisComposite examine of the reactors influent and wastewater were collected on a day-to-day footing and analyzed for COD, BOD, sulfate and others chemical waste substances. Sludge try out was carried out through side ports in the sludge zone of the reactor. The flow rate was control by the valve and continuously modulate by a pump.3.2.1 BOD trialBiochemical O demand ( BOD ) is the sum of turn O by aerophilic biological beings in a organic structure of H2O to breakdown organic stuff nowadays in a given H2O sample at certain(p) temperature. BOD besides can be used as gage of the effectivity of UASB reactor. The process of the BOD trialThe dilution H2O was brisk by 1ml each of orthophosphat e buffer, Mg sulphate, Ca chloride, ferrous chloride solution into 1L distilled H2O.1ml effluent sample was added into a 500ml beaker.Dilution H2O was added up to 300ml into same beaker.The pH survey was adjusted to 6.5 to 7.5 by added acid or base.300ml dilution H2O was prepared as control. tout ensemble prepared samples and control put in 300ml-incubation bottle.The DO for each sample was calculated by utilizing Dissolved Oxygen Meter.All the bottles put in BOD brooder for 5 yearss. The temperature was set at 20AC.The BOD5 was calculated harmonizing to the expression belowWhereD1 = DO value in initial sampleD2 = DO value in concluding sampleP = denary volumetric fraction of sample usedOr Dilution factor = Bottle volume ( 300ml ) / sample volume3.2.2 COD trialThe chemical Oxygen Demand ( COD ) trial measured the O equivalent consumed by organic affair in a sample during strong chemical oxidization. It can assist to foretell the O demands of the wastewater and is used for monito ring and control of discharges, and for accessing reactor public presentations. The trial methodThe effluent sample was oxidized by digesting in a certain reaction tubing with sulfuric acid and K bichromate in the presences of a Ag sulfate accelerator for 2 hours at a temperature of 150AC.The sum of bichromate reduced is relative to the COD.A reagent space was prepared for each batch of tubings in order to counterbalance for the oxygen demand of the reagent itself. everyplace the scope of the trial a serial publication of colourss from xanthous through green to blue are produced. The colour is declarative of the chemical O demand and its measured by utilizing photometer.

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.