This paper discusses the performance of soIid-liquid separation pfocess at the Sg  Kampar Water Treatment works

Abd Aziz, Assoc. Prof. Dr Hamidi

Adlan, Ir Dr Mohd Nordin

Hasan, Rahmat

Mohd Isa, Ir Mohd Yusuf

Zainal Abidin, Abd Razak

English

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ffi+frfiffiknmm --Ag17fA Study on The Perfomance of SedimentationTank At The sungai Kampar water Treatmeny PlantIr Dr Mohd Nordin AdlanlAssoc. Prof. Dr Hamidi Abd AzizrIr Mohd Yusuf Mohd IsazAbd Razak Zainal AbidinzRahmat Hasan3r School of Civil Engineering, Universiti Sains Malaysia'Perak Branch CamPus, 31750 Tronoh'2 Lembaga Air Perak, IPoh'3 Former student, School of Civil Engineering,Universiti Sains Malaysia, 37750 Tronoh'ABSTRACTThis paper discusses the performance of so.Iid-liquid separation pfoc:ss a1 t!.e ss Kampar watu Treatymt wotltr samplings of raw uanilseilimentationtreatediaterweremadeand'theresaltswere'analysed. Itwisfoundthatadditiona.l.iar.testmustbeconiluctedwhenttis a sudilen clunge in the raw utater quality. Furthermore the retentiin time in thi tank need to be studied for the optimising of the solid-lit,separation Process.INTRODUCTIONSedimentation involves the removal ofsolids particles from a suspension.bysettling under graviry prior to filtration(Barne-s et al., l98l). ln order to achieveor to permit suspended solids to settleout of the water by graviry the velocityof flow must be reduced and underlaminar condition (Twort et aI., 7985)'There are many different designs ofsedimentation tanks and according toTwort et al' (1985) the approach is stillempirical. However in most cases theremust be an equal distribution of waterat the inlet with a reduced velocity sothat the flocs are not breaking up' Theprinciples governing the design ofirorizonta seaimentation basins are welldocumented in standard texts(American Water Works Association'1990; Schulz and Okun, 1984; Twort efal., 1985; Smethurst, 1988).The design of sedimentation basin canbe classified into two namely horizontalflow and uP-flow units. According toSchulz and Okun (1984) horizontal flowtank has performed considerably wellfor decadis. Removal of rurbidiry forthe raw water can be uP to 957ofotlowing an effective coagulation andflocculation.The rate of coagulation of particles in aIiquid dePends on the number ofcoilisions betweeen particles due to theirrelative motion (Coulson et al-, 1991)'When that motion is mainlY due toBrownian movement, it is termed asperikinetic coagulation. If the relativemotion is caused by velociry gradientscoagulation, it is termed as orthokinetic'In 1917, von Smoluchowski obtained thecollision frequency I, of particles usingthe following equation (Coulson et al',1991):I,=4tDrrnr(ar*as)(1)where, a1 is the central reference particle,a2 is the radius of particles. n2 is thenumber of concentratiol, D13= DfD2;D1 and D2 are absolute diffusioncoefficients given by Stokes-Einsteinequation:Dr = KT l(6frInr)Dz= KT l(6nlnz)(3)where, K is the Boltzmann's constant(-1.38x10-zr|/'( and T is thetemperature in oK-Smoluchowski model leads to the resultthat the total number of collision per unitvolume in unit time is given bY:N =?n'Gdt3where n is the number of Particlesunit volume, G is the velocitY gradand d is the Particle diameter.With regard to floccrrlation, CamP 'Stein (1943) demonstrated that thespof flocculation is directly proPottioythe velocity gradient at a Point' ll.be determini by the number of contberween floc Particles, in unit dmgassuming thi flocs are in.s.P\lI;;;;, -""; and stein (1e43) indisthai the totai number of contacts pqtime is given bY the followingIN=lN,N"(d,+d.)6where N1 is the number ofdiameter d1 and N2 is theparticle of diameter d2'hvdrodYnamics ofdesigneis often usedaccount for thisWells and LaUberte (198)there are uncertaintiesclarusafetYbehaviour. The latter maYfollowing factors:ill$tits$i iut utert utlaysiI tEeuer$iI nEfe[)irstitBttsr ul eu$iuc.el.s ntlrlsls (llerth lntlth)lysed on its turbiditY forroximately two weeks. The objectivesolids and temperaturediffirentials within the tank'be summarised that theof solid-liquid seParationis depending on theI and phYsical Processes.reaction involves with theof approPriate coagulant andof collision whereas PhYsicalinvolves with the agglomerationthe particles in a favourablei,esusp"t siot of settled solids andDensitY currrents caused bYpaper discusses the effectiveness ofi liquid separation Process usingand outlet geometrylnflow jet turbulencezone in the tankflow settling basin at theKampar Water Tieatment Works.of raw water and sedimentationted water were collected anddepending on weather condition andupstream activities. During rainy periodthe turbidity may rise well above 300NTU. The increase in turbidiry is mainlydue to rural erosion. However beforethe fallen of tin price, the deterioratingin water quality is mainly due to miningactivities.Samples for turbidity measurementswere taken at the inlet of the treatmentworks and at the outlet weir of thesedimentation tank. At each point threesamples were tested and the averagereadings were used as a rePresentativeturbidity. The retention time in thesedimentation tank was calculatedbased on the volume of the tank andflow rate at the time of the investigation.The tirne of water body reached at theinlet was recorded in order to know thetime to collect the sample at the outletof the tank. The latter was carried outbased on the retention time of the waterbody in the coagulation, flocculation andsedimentation tanks. All turbiditymeasurements were made using Hachturbidimeter, which was standardisedwith latex suspension supplied by themanrrfarhrrerRESULTS AND DISCUSSIONSFig. 1 shows the results the turbidity forraw water and sedimentation treatedwater. It can be seen that the raw waterturbidity had increased to nearly 300NTU during the study period. The latterwas due to heavy rainfall encounteredfor that particular event' The removalof hrrbidity (Fig.1, Series 2) as indicatesby the plotted graph for this event canbe considered satisfactory. However forraw water of lower turbidity readingsat less than 50 NTU (at the samPlingsequence number 7 in Fig. 1) the removalis not satisfactory. Instead of decreasedin turbidity, the result indicated thatthere was in increased in turbidityreading for the sedimentation treatedwater. This result was based on a totalretention time of 7 hours and the dosageof alum was made based on the jar test.Weather record indicated that there wasa downfall in the evening. The lattercaused a sudden change in raw waterquality and may affect the sedimentationtreated water due to the occurrenceshort-circuiting in the flow regime orIack of alertness from the oPerator. Inorder to Prevent the occurrence of thesame event (at the sequence number 7in Fig. 1), it is advantageous for thenovice or experience engineers todevelop a characteristic cr.rrve to identifythe relationship between an optimumchemical dosage for different turbiditiesor suspended solids concentrations.The details of retention time in theflocculation and sedimentation basinsare shown in Fig. 2. The retention timein the coagulation and flocculation tanksduring the study period was calculatedbetween t hour 15 minutes to t hour 45minutes. This indicates that theminimum retention time in thesedimentation tank is 5 hours 45 minutesbased on a total retention time of Thours.From the graph, it can be seen that thetheoretical retention times in the tanksvaried between 7 to 10 hours during thestudy period. The retention time wascalculated based on the volume of thetank divided by the flow rate observedduring the investigation. The retentiontime at the plant is considered not inagreement with those of horizontalbasins recommended bY Schulz andOkun (1984), which is at a maximum of4 hours for small installation withprecarious operation. For sedimentationlanks with good operational procedures,the retention time can be reduced up to2Vz hours. Detailed studY on thegeometry of the sedimentation tankindicated that there is a bottleneck at theinlet of the tank, which may contributeto tulbulent condition in the flowregime. As built plan indicates that thewiter from the distributing channel(after undergone flocculation process)has to pass through a comparativelysmall oPening before entering thesedimentation tank. This opening mayinduce the flocs to break down orbecome unstable. In order to stabilisethe flocs, a comPartment wasconstructed in the inlet zone. Then thewater was directed to a submerged wallbefore a ProPer sedimentation Processtook plaie. The design of the solid-liquid separation process may be basedon othei treatment works, which hadbeen constmcted overseas or some otherplaces in the country. If an optimisationof solid-liquid separation Process rsrequired, thlre is a need for further studyto Le carried out at this treatment Plant'Mathematical and physical modelling inthe laboratory may be advantageoustounderstand the ambiguity relating to theflow characteristics within the tank'this paper is to evaluate theof sedimentation Process at6g. f.ompar \,VT\AI.AND METHODSKampar Water Treatment Works) is situated on the bank of SgnearKuala Dipang, Perak. Thet plant was commissioned overyears ago and has a capacitY ofimatelv 10 MLD (million litresday). Treated water is supplied tosuch as Malim Nawar, KampongKuala Dipang and a number ofareas in Gopeng. Raw water isto the treatment works from an, which is at a distance of130 metres. The intakeis located on the bank of Sg.The tributary of Sungai DipangSungai Kampar is about 1 kmof the intake. The catchmentis made up of ex-mining land,ral areas and forest reserveda number of aboriginaland Malay reservations. Atown called Sg. Siput South iswithin the catchment area.process involves screening,fl occulation, sedimentation,pH conditioning, fluoridationdisinfection. Raw water quality inof turbidity is always changingffi+f;fr,rykflm$-F@.tCONCLUSIONIt can be concluded that the possibilityof short-circuiting in the flow regime ofthe sedimentation process during asudden change in hrrbidity need to beinvestigated so that the turbidity ofsedimentation treated water is alwaysless that the raw water. The oPeratorshould also be advised to conduct a jartest, monitor and compare the quality ofraw and sedimentation treated waterduring a sudden change in raw waterquality. Further study should be carriedout to optimise the retention time in thesedimentation tank.3503002502o,01234567A9Oays=Fz.>r=-o=FFig.1 - Turbidity readings for raw and sedimentation treated water'Note: Series 1 = turbidity fo'r raw water, Series Zl t.rUiaity for sedimentation treated water and x-axis represents thesequence of sampling obsenration during the study period (an average of 8 observations per day)'Retention Time in the Flocculation and Sedimentation Tankseoo42Turbidity for raw water and sedimentation treated waterREFERENCESAmerican Water Works Association(1990) Water Treatment Plant Design, 3rdEdition, McGraw-Hill.Barnes D., Bliss P. J., Gould B. W. andVallentine H. R. (1981) Water andWastewater Engineering SYstems,Pitman Books Ltd., London.Camp T.R. and Stein P.C. (1943) Velocity-gradients and internal work in fluidmotion. Jour. BostonSoc. Civil Eng.,Vol'XXX, No.4,219-237.Coulson I. M., Richardson f. F.,Backhurst J. R. and Harker J. H. (1991)Chemical Engineering, Vol. 2. PergamonPress, Oxford.Sampling s"qr"I"Schulz C.R. and Okun D.A. (1984)Surface Water Treatment ForCommunities In Developing Countries,'|ohnWiley,USA.Smethurst G. (1988) Basic WaterTreatment for Application World-Wide,2nd Edition, Thomas Telford, London.Twort A.C., Law F.M. and Crowley F.W.(1985) Water Supply, 3rd Edition,Edward Arnold, London.Wells S.A. and Laliberte D.M. (1998)Winter temperature gradient in circularclarifiers, Wat. Environment Research,YoL.70,1274.1210IEi* r - Rc+cnrinn time in the flocculation and sedimentation tank during the study period.

Basic Water Treatment for Application World-Wide, 2nd Edition,

Sampling s&quot;qr&quot;I&quot;

Velocity -gradients and internal work in fluid motion.

Water and Wastewater Engineering SYstems,

Winter temperature gradient in circular clarifiers, Wat. Environment Research, YoL.70,1274. I Ei* r - Rc+cnrinn time in the flocculation and sedimentation tank during the study period.

Works Association

A Study On The Perfomance Of Sedimentation Tank At The Sungai Kampar Water Treatmeny Plant.

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A Study On The Perfomance Of Sedimentation Tank At The Sungai Kampar Water Treatmeny Plant.

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