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FACTORS AFEECTING THE COAGULATION OF TURBID WATER WITH BLEND COAGULANT MORINGA OLEIFERA _ ALUM

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FACTORS AFEECTING THE COAGULATION OF TURBID WATER WITH BLEND COAGULANT MORINGA OLEIFERA _ ALUM Powered By Docstoc
					  International Journal of Advanced Research OF ADVANCED RESEARCH IN
  INTERNATIONAL JOURNAL in Engineering and Technology (IJARET), ISSN
  0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 4, May – June (2013), © IAEME
             ENGINEERING AND TECHNOLOGY (IJARET)

ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
                                                                          IJARET
Volume 4, Issue 4, May – June 2013, pp. 181-190
© IAEME: www.iaeme.com/ijaret.asp
Journal Impact Factor (2013): 5.8376 (Calculated by GISI)
                                                                         ©IAEME
www.jifactor.com




    FACTORS AFEECTING THE COAGULATION OF TURBID WATER
      WITH BLEND COAGULANT MORINGA OLEIFERA & ALUM

                                    Dr. S. A. Halkude1, C. P. Pise2
             1
                 Professor and Principal, Department of Civil Engineering, Walchand Institute of
                                    Technology, Solapur, Maharashtra, India
   2
       Research Scholar and Assistant Professor, Department of Civil Engineering, SKN Sinhgad
               College of Engineering Pandharpur, Dist-Solapur, Maharashtra, India


   ABSTRACT

           The scope of the present study is optimizing the parameters which affect coagulation
  of turbid water namely, slow mix velocity gradient, dose of blend coagulant Moringa Oleifera
  & Alum, basin parameters with different initial turbidity water samples. Initially these
  parameters are varied randomly, while keeping all other parameters constant for carrying out
  optimization. Optimum dose for removal turbidity using blend coagulant required for the
  different initial turbid water samples (e.g, 150 NTU, 300 NTU and 500 NTU), is found out.
  While other parameters like jar configurations, velocity gradient, slow mixing time,
  settlement time are kept constant. Dose of coagulant which is found to be optimum during the
  initial study is used in the all the testing. Results are analyzed by preparing the graphs of
  Dose versus Residual turbidity. Effect of various jar configurations such as Circular Non
  Baffled Jar (CNBJ), Circular Baffled Jar (CBJ), Square Non Baffled Jar (SNBJ) and Square
  Baffled Jar (SBJ) is studied, while all other parameters are kept constant. The dose of
  coagulant is again optimized with respect to Jar Configurations by observing the effect of
  different Jar Configurations and results are analyzed. Also the study for different velocity
  gradients like 40 s-1, 65 s-1 and 90 s-1 is carried out, while other parameters are kept constant
  except SBJ and CBJ, which are found most influential. Results are analyzed & presented in
  the graphs between residual turbidity versus velocity gradient.

  KEYWORDS: Blended coagulant, Moringa Oleifera, Optimization, coagulation, velocity
  gradient, Basin Parameter.



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INTRODUCTION

         Ability of Moringa oleifera in the removal of many contaminants from water effluents
is well known since long time. [1, 2]. As a tropical multipurpose tree, M. oleifera is
commonly known as the miracle tree [3] because of its wide variety of benefits that cover
from nutritional issues [4] to cosmetics [5]. Among many other properties, Moringa oleifera
seeds contain a coagulant protein to be used either in drinking water clarification [6] or
wastewater treatment [7]. It is said to be one of the most effective natural coagulants and the
investigation on these kinds of water treatment agents is growing day by day [8]. The raw
origin of this coagulant makes its speciation difficult; however researchers have identified the
coagulant component from M. oleifera seed extract as a cationic protein [9,10] is in
general agreement in considering it as formed of that dimeric proteins with a molecular
weight in the range of 6.5–14 k Da. The use of Moringa Oleifera as a coagulant is full of
advantages, when compared with traditional alum or ferric salts [11].
         The drawbacks of chemical coagulants is well known, there is a need to develop
alternative, cost effective and environmentally friendly coagulants. A number of effective
coagulants from plant origin have been identified: Nirmali [12]; Okra [13]; red bean, sugar
and red maize [14], Moringa oleifera [15], and a natural coagulant from animal origin;
chitosan. Natural mineral coagulants have also been used including fluvial clays and earth
from termite hills. Of all plant material investigated, it is observed that seeds of Moringa
Oleifera are one of the most effective sources of coagulant for water treatment.
         In laboratory and field tests, seed of Moringa Oleifera have shown promise as a
coagulant in the clarification of turbid water [16, 17, and 18]. The seeds contain water soluble
positively charged proteins that act as an effective coagulant however the crude moringa
extract (though efficient in removal of turbidity) increased the organic load in the treated
water [19].
         Moringa Oleifera as natural coagulant is reported to have many advantages over
chemical coagulant e.g. Alum. Use of chemical coagulant has constrains of pH and alkalinity.
However, Moringa Oleifera has been reported to be free of these constraints. Sludge product
with Moringa Oleifera is reported to be four to five times compact than that produced with
alum. Turbidity removal can be achieved with Moringa Oleifera. The use of Moringa
Oleifera as a coagulant is mostly used in water treatment that too on small scale and major
work has been reported in laboratory scale water treatment that too on small scale. The
Moringa oleifera is not used in field because of the some drawbacks of Moringa oleifera as it
requires large amounts of seeds for small water treatment plant. Also, the settling time is
more. If the blended coagulant of Moringa oleifera & alum is used then the drawbacks of
alum and moringa oleifera is reduced and this blend coagulant gives best results. [20, 21]
         The investigations carried out using the conventional jar test have been used to
evaluate the coordination efficiency of Moringa Oleifera in the treatment of surface waters &
synthetic waters.
         At present, in most of such studies the physical parameters like slow mixing velocity
gradient & time, rapid mixing velocity gradient & time are determined according to standard
jar test values for alum coagulation. The only parameter varied in most of the cases is dose of
blend of Moringa Oleifera & alum. Further more studies into the interaction between physical
parameters affecting coagulation like slow mix, rapid mix rates & time is not studied. In this
study laboratory investigation is carried out to determine the multiple effects of physical
parameters of slow mixing grades & dose of coagulant & basin parameters & initial

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particulate concentration (turbidity) on coagulation of turbid water with blend of Moringa
Oleifera & alum. The three parameters slow mix velocity gradient, doses of blend coagulant
Moringa Oleifera & alum, and basin parameters. These three parameters are varied, while
keeping other parameters constant & study is carried out for arriving at an optimum dose of
Moringa Oleifera & alum.

MATERIALS AND METHODS

Preparation of Seed Extracts:
        Tree dried Moringa Oleifera seeds are procured from local trees. Good quality seeds
are then picked up and crushed to fine powder. Then 5 gm of seed powder is mixed with 500
ml distilled water for 2 minutes. Then mixture is kept for 2 mins. Again mixture is stirred for
1 min. Then, mixture is filtered through Muslin Cloth. Filtrate is diluted by distilled water to
make it up to 500 ml. Resulting stock solution is having approximate concentration of 10000
mg/l (1%). Fresh stock solutions are prepared every day for the one day’s experimental run.

Preparation of 1% Alum Solution:
      1 gm of the Alum is mixed with 100 ml of distilled water. This mixture is stirred for 5
minutes so that all the Alum powder is soluble into the distilled water. This Alum solution is
of 1 % concentration. When the Alum is added to the turbid sample the acidity is increased.
For neutralizing the induced acidity by Alum, 1% Lime dose is added with it. Also this Lime
doses helps in pH correction.

Preparation of 1% Lime Solution:
      1 gm of the Lime is mixed with 100 ml of distilled water. This mixture is stirred for 5
minutes so that all the Lime powder is soluble into the distilled water. This Lime solution is
of 1 % concentration. For finding the doses of the Alum using the jar test the following doses
of Alum and Lime solution, should be added into the sample.

Preparation of Moringa Oleifera & Alum Solution:
       Moringa Oleifera & Alum Solution are prepared separately and entered separately with
Alum first and Moringa Oleifera a couple of seconds later. But, for preparation of blend
coagulant the optimum dosage found for different initial turbidity samples are taken as base
line and different proportions of alum and Moringa Oleifera are tested for removing the
turbidity from jar test, then it is observed that for 150 NTU initial turbidity, the optimum dose
of the Alum is reduced to 75 % and the optimum dose of the Moringa Oleifera is reduced to
40 % then this blended coagulant gives the minimum residual turbidity. Similarly for 300
NTU & 500 NTU initial turbidity, the optimum dose of the Alum is reduced to 62.5 % and
the optimum dose of the Moringa Oleifera is reduced to 25 % then this blended coagulant
gives the minimum residual turbidity.

Preparation of turbid water sample:
       5gm of kaolin clay is mixed to 500 ml distilled water. Mixed clay sample is allowed
for soaking for 24 hrs. Suspension is then stirred in the rapid stirrer so as to achieve uniform
and homogeneous sample. Resulting suspension is found to be colloidal and used as stock
solution for preparation of turbid water samples. Everyday stock sample of kaolin clay is
diluted to tap water to desired turbidity.

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EXPERIMENTATION METHOD

          Mainly the scope of the work is to deal with the slow mixing parameters which
affect the effective floc formation and settlement characteristics of the turbid water. Entire
work comprises of three stages, viz. Optimum dose determination, effect of different jar
parameter and effect of different velocity gradient of slow mixing, at the same time, rapid
mixing procedure is kept constant throughout all the experimental runs. Entire work is
divided into three different stages. In each stage one variable is changed while others are kept
constant. In all the stages, rapid mixing is done at approximately 120 rpm for the time
interval of 2 minutes so as to achieve uniform dispersion of coagulant.

Optimum dose determination:
       The optimum dose required for the different initial turbidities like, 150 NTU, 300
NTU and 500 NTU dealt while other parameters like jar configurations, velocity gradient,
slow mixing time, settlement time are kept constant for all the initial turbidity ranges. Dose of
Blend coagulant which is found to be optimum is used in the all the testing. Results are
analyzed by preparing the graphs between Doses versus respective Residual turbidity.

Effect of different jar parameter:
        The effect of different jar configuration like SBJ, SNBJ, CNBJ, and CBJ while other
parameters like, slow mixing time and velocity gradient, settling time are kept constant. In
this Part dosage of coagulant is again optimized with respect to different Jar Configurations
and effect of different Jar Configurations is tested. In this Part results are analyzed by
working out the variations in the residual turbidity with respect to Jar Configurations which is
reflected in the graphs.

Effect of different velocity gradient:
       Effect of different velocity gradients like 40 s-1, 65 s-1 and 90 s-1 while other
parameters like jars, slow mixing time, settling time are kept constant. SBJ and CBJ are used
as they are found to be most effective during the trial. Results are analyzed by preparing the
graphs between residual turbidity versus velocity gradient.

        Table -1 show different types of jars used in the experiment with their dimensions and
figures Table- 2 shows various physical parameters considered in the experiment and Table -
3 shows the optimum dose of blend coagulant for different initial turbidity samples.




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                                 Table 1: Types of Jars

     Sr.    Type of jar       Dimensions (Internal)              Photo         No. of jars

   1.      Square          10 cm (L) × 10 cm (B) ×16                               3
           Baffled Jar     cm(H) With 4 baffles(one
           (SBJ)           on each side) of 1.2 cm ×
                           0.2 cm all along the height

   2.      Square Non-     10cm(L) × 10 cm (B) ×16                                 3
           baffled Jar     cm(H)
           (SNBJ)



   3.      Circular Non-   12 cm (dia) × 16 cm (H)                                 3
           Baffled Jar
           (CNBJ)


   4.      Circular        12 cm (dia) × 16 cm (H)                                 3
           Baffled Jar     With 4 baffles(one at each
           (CBJ)           quadrant point) of 1.2 cm ×
                           0.2 cm all along the height



Procedure Followed For Determination of Velocity Gradient (G):

                                      P
                               G=
                                     Vµ                                      …. (1)
                     Where,
                                   µ = Viscosity (N.s/m2)
                                   P = Power input (N.m/s)
                                  V = Volume of mixing basin (m3)

                                    P = D x Vp                                … (2)
                     Where,
                                 D = Drag force on paddles (N)
                                 vp = Velocity of paddles (m/s)
                                        (C × A p × ρ × Vp 2 )
                                   D= D
                                                   2                         … (3)
                     Where,
                                    CD = co-efficient drag, 1.8 for flat blades.
                                    AP = Area of paddles (m2)
                                     ρ = Density of water (kg/ m3)
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                                                                                       (π D N)
                                                                         Vp =
                                                                                         60                                                              … (4)
                            Where,
                                                                           N = r.p.m. (No.)
                                                                          D = Diameter of blades (m)

                                                   500
       Table 2: Physical Parameters with 150, 300, 500 NTU initial turbidity

                                  Sr              Physical Parameters                                                                     Remark
                                  1               Initial Turbidity                                                                       150, 300,
                                                                                                                                          500
                                        2         Concentration of coagulant                                                              1%
                                        3         Slow mix velocity                                                                       30 rpm
                                        4         Slow mixing time                                                                        30 mins
                                        5         Rapid mix velocity                                                                      120 rpm
                                        6         Rapid mixing time                                                                       2 mins
                                        7         Settling time                                                                           30 mins

                                                  3
                                            Table 3: Optimum Dose of Alum & M.O.
                 Sr.                    Turbidity                           Dose                        Residual                               Average
                                         in NTU                            mg/L                         turbidity
                  1                                                      25, 62.5                      8.8    8.1                                 8.45
                  2                              150                     12.5, 75                      4.1    4.9                                  4.5
                  3                                                       10, 100                       7     7.1                                 7.05
                  4                                                        30,125                      8.6    8.5                                 8.55
                  5                              300                      20, 100                      4.5    4.8                                 4.65
                  6                                                       40, 175                      6.8     6                                   6.4
                  7                                                       40, 175                       8     8.8                                  8.4
                  8                              500                      30, 150                      3.8    3.2                                  3.5
                  9                                                       50, 200                       6     6.3                                 6.15



                                                 GRAPH -1 OPTIMUM DOSE OF M.O. & ALUM

                                            10
                       RESIDUAL TURBIDITY




                                             8
                                             6
                                             4
                                             2
                                             0
                                                   25, 62.5
                                                              12.5, 75
                                                                          10, 100
                                                                                    30,125
                                                                                             20, 100
                                                                                                       40, 175
                                                                                                                 40, 175
                                                                                                                           30, 150
                                                                                                                                     50, 200




                                                                                                                                                      SET 1
                                                                                                                                                      SET 2

                                                       150 NTU                        300 NTU                      500 NTU

                                                                         DOSE & INITIAL TURBIDITY



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                                                            GRAPH -2 EFFECT OF JAR PARAMETER
                                           30



                     RESUIDUAL TURBIDITY
                                           25
                                           20
                                           15                                                                 150 NTU
                                           10                                                                 300 NTU
                                            5                                                                 500 NTU
                                            0
                                                     CNBJ            CBJ            SNBJ         SBJ
                                                                     TYPES OF JARS




                                                GRAPH - 3 EFFECT OF JARS WITH OPTIMUM DOSE 20, 100
                                           30                           mg/l
                      RESIDUAL TURBIDITY




                                           25
                                           20
                                           15                                                                 150 NTU
                                           10                                                                 300 NTU
                                            5                                                                 500 NTU
                                            0
                                                     CNBJ            CBJ         SNBJ             SBJ
                                                                      TYPES OF JARS



                                                    GRAPH -4 EFFECT OF SLOW MIX VELOCITY GRADIENT
                                           30
                RESIDUAL TURBIDITY




                                           25
                                           20
                                           15
                                                                                                                 40 s-1
                                           10
                                                                                                                 65 s-1
                                            5
                                                                                                                 90 s-1
                                            0
                                                    SBJ       CBJ          SBJ       CBJ   SBJ          CBJ
                                                      150 NTU                    300 NTU     500 NTU

                                                                    TYPES OF JAR & TURBIDITY




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                                           GRAPH -5 TURBIDITY REMOVAL EFFICIENCY (%)
                                   100

              REMOVAL EFFICIENCY
                                   95

                                   90

                                   85                                                        150 NTU
                                                                                             300 NTU
                                   80
                                                                                             500 NTU
                                   75
                                         SBJ        CBJ     SBJ     CBJ     SBJ        CBJ
                                               40 s-1        65 s-1           90 s-1
                                                SLOW MIX VELOCITY GRADIENT & JARS




RESULTS AND DISCUSSION

         From the Graph-1, the optimum dose of the blended coagulant for initial turbidity 150
NTU is Alum - 12.5 mg/lit, M.O. – 75 mg/lit. For initial turbidity 300 NTU the optimum dose
of the blended coagulant is Alum – 20 mg/lit, M.O. - 100 mg/lit. For initial turbidity 500
NTU the optimum dose of the blended coagulant is Alum - 30 mg/lit, M.O. - 150 mg/lit.
          From Graph-2, it is found that optimum dose of blend coagulant required for almost
all the initial turbidity in between 150 NTU and 500 NTU is 20 mg/lit for Alum & 100 mg/lit
for M.O. At this blend dose (Alum – 20 mg/lit, + M.O. - 100 mg/lit) floc formation and
particle settling is highest for CBJ jars. This value of optimum dose is higher as compared to
other studies reported. Further increase of coagulant dose, it is observed that Residual
turbidity increase with increasing dose. However, further increase in blend coagulant dose
shows marginal increase in the residual turbidity. Turbidity removal efficiency, in the case of
150 NTU initial turbidity is 95.5%, for 300 NTU initial turbidity, it is 95.35% and for 500
NTU initial turbidity, it is 96.5%. This clearly indicates that increase in the initial turbidity
increases the turbidity removal efficiency. This observation can be explained in terms of the
increase in suspended particles available for adsorption and inter-particle bridge formation.
         The effect of jar parameters, (CBJ, CNBJ, SBJ, SNBJ), with respect to different initial
turbidities is shown by Graph -3. It is seen from the Graph. 2 that SBJ and CBJ are giving
less residual turbidities as compared to their non-baffled counter parts. Baffled jars are
showing approximately 10 % more turbidity removal than the non-baffled jars of respective
types. More turbidity removal in case of Baffled jars is due to vortex formation. This is due to
introduction baffles leading centrifugal forces. These centrifugal forces make them to move
outwards and may make particle to settle down. Second likely reason, the more inter particle
collision because of turbulence created by baffles, leading to higher rate of agglomeration.
All above discussion leads to a conclusion that baffled jars give higher rate of agglomeration,
resulting into higher turbidity removal.
         The Graph-4 shows the effect of slow mix velocity gradient with water sample of
initial turbidity 150 NTU, 300 NTU and 500 NTU. From this graph, it is observed that the
optimum velocity gradient is 65 s-1.

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        It is observed that the all parameters which affect the coagulation activity which are
optimum in earlier experiment shows maximum removal efficiency refers Graph -5. From
the graph-5, it is observed that at slow mix velocity gradient 65 s-1 at which the removal
efficiency for SBJ and CBJ is maximum. The removal efficiency for SBJ for 150 NTU,
300NTU & 500NTU turbidity is 95.2, 96.9, and 97.9 respectively .The removal efficiency for
CBJ for 150 NTU, 300NTU & 500 NTU turbidity is 95, 95.8, and 96 respectively.

CONCLUSIONS

         The coagulation of turbid water is influenced by various parameters such as slow mix
velocity gradient, dose of Blend coagulant Moringa Oleifera (M.O.) & Alum, the basin
Parameters, and initial turbid of water samples.
         The optimum dose of blended coagulant for initial turbidity 150 NTU is Alum - 12.5
mg/lit, M.O. – 75 mg/lit. For initial turbidity 300 NTU the dose is Alum – 20 mg/lit, M.O. -
100 mg/lit and for 500 NTU the optimum dose is Alum - 30 mg/lit, M.O. - 150 mg/lit.
         The efficent jar configuration found is Circular Baffled Jar (CBJ) and Square Baffled
Jar (SBJ), which are producing less residual turbidity as compared to non-baffled Jars.
Baffled jars are showing 10 % more turbidity removal efficiency with respect to non-baffled
jars. , The optimum dose of coagulant is observed to be same for various Jar Configurations,
which is 20 mg/lit for Alum, 100 mg/lit for M.O.
         The optimum slow mix velocity gradient is 65 s-1 at which the turbidity removal
efficiency for SBJ & CBJ is maximum.

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