International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 12
134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
Influence Of Coag-Flocculation Operating Conditions
In The Remediation Of Pharmaceutical Effluent
Using Pleurotus Tuberregium Sclerotium Coagulant.
* Ugonabo V. I.
1, Menkiti M. C.
2, Ajemba R. O.
3 and Onukwuli D. O.
4
1,2,3,4Department of Chemical Engineering Nnamdi Azikiwe University, Awka, Nigeria
Corresponding Author: *E-Mail: [email protected], Phone No. +2348033481851
Abstract-- The influence of coag-flocculation operating
conditions on the performance of Pleurotus Tuberregium
Sclerotium in Pharmaceutical effluent was investigated at room
temperature. This was determined at varying coag-flocculation
operating conditions such as time (2,4,6,10,20,30,40)x60 sec;
dosage (0.1 – 0.7) x10-3kg/m3, and pH 1,3,5,7,10,13. Conventional
nephelometric Jar test apparatus was employed to evaluate these
effects while pleurotus tuberregium sclerotium was prepared
according to the method described therein. The results obtained
were used to evaluate the coag-flocculation kinetic parameters
such as reaction rate (-r), αth order coag-flocculation constant k,
coagulation period ½, evaluated initial total dissolved solid
particles Co, etc. The maximum pleurotus tuberregium
sclerotium coagulant performance is recorded at K of 6E – 04
m3/kg.s, and Co of 1000 m3/kg while the minimum parametric
performance is recorded at k of 9E – 06 m3/kg.s; dosages of (0.2,
0.3) x10-3 kg/m3 ;pH of 5, 3; ½ of 120.77 sec, 120.77 sec and Co of
1000 m3/kg each. The maximum value of coag-flocculation
efficiency E(%) recorded is 95.54%. The results have
established at the conditions of the experiment that pleurotus
tuberregium sclerotium coagulant can favorable be compared
with alum at all pH .
Index Term-- Influence, coag-flocculation, operational
conditions, pharmaceutical effluent, pleurotus tuberregium.
I. INTRODUCTION
Pharmaceutical production processes are among the most
environmentally unfriendly industrial processes, because they
produce high turbid wastewaters very rich in suspended and
colloidal materials [1] . These colloids may include organic
and inorganic particulates. Recent investigations showed that
naturally occurring organic materials, particularly the pool of
dissolved organic carbon, caused strong stabilization of
inorganic particulates in water [2] . In addition, in the presence
of naturally occurring organic materials, the coagulation
kinetics of inorganic particulates mainly depended on the
characteristics and the concentration of natural organics, rather
than inorganic particulates themselves [3] . The presence of
these colloidal materials in water bodies, hinders
photosynthetic activity and also deplets dissolved oxygen
content, making it very unfit for both aquatic animals and
plants which invariable causes an imbalance in the ecosystem
[4],[5],[6] . Colloidal materials normally have charges on their
surface, which result in the stabilization of the suspension. On
addition chemicals, the surface phenomenon of such colloidal
materials could be changed or dissolved particles precipitated
out to ease separation of solids either by gravity or filtration
option. The conversion of stable state dispersion to the
unstable state is referred to as destabilization and the
processes of destabilization are coagulation and flocculation
[7],[8],[9] . Though the two terms are used interchangeably,
but they are not the same. Coagulation is the destabilization of
colloidal particles caused by charge neutralization on addition
of inorganic chemical (coagulant). On the other hand,
flocculation is the aggregation of particles in suspension to
form larger agglomerates called flocs.
Coagulation-flocculation process is remarkable for achieving
maximum removal of COD, TDSP, TSS etc in industrial
wastewater treatment [10]. On the strength of that we
investigated the effect of coagulant dosage, polyelectrolyte
dosage, pH of solution and addition of polyelectrolyte as
coagulant aid and found to be important parameters for
effective treatment of beverage industrial wastewater.
Due to many problems associated with the synthetic
coagulants such as aluminum sulphate which is used
worldwide in the treatment of water and wastewater. Hence, a
special attention has been given to the environmental friendly
coagulant, Pleurotus Tuberregium Sclerotium (PTS).
Pleurotus Teberregium Sclerotium (PTS) is from the king
tuber mushroom, an edible gilled fungus native to the tropics
including African (in the South-West Province of Cameroon,
Eastern and Western parts of Nigeria), Asia and Australaria
[11].
Previous study show that sclerotia is from the family
pleurotacae, very rich source of mineral with a rich protein
content in form of essential amino acids 25.93g on each 100g
of the sample11
. The powder obtained from the mycella of the
edible king mushroom, Pleurotus Teberregium is used as a
soup thickener because of its ability to swell in water and add
bulk to the soup and significant biomedical applications (as
paracetamol tablet disintegrant) [12] . These qualities
aforementioned necessitated its use as a coagulant.
Apparently, no major studies have been done to clarify
pharmaceutical effluent by using Pleurotus Tuberregium
Sclerotium Powder in Coagulation- Flocculation Process.
Therefore, this work was carried to evaluate the effect of
Pleurotus Tuberregium Sclerotium coagulant (PTSC) in
clarifying pharmaceutical effluent in coagulation-flocculation
process in different experimental conditions. The coag-
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134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
flocculation operational conditions needed to achieve the best
performance of PTSC in Coag-flocculation process were
determined. Also the results obtained from PTS coagulant is
compared with that of Aluminum sulphate at 2400sec settling
time.
II. THEORETICAL DESCRIPTION AND MODEL
DEVELOPMENT.
Assuming monodisperse system with a coagulant of high
cationic charge in an anionic suspension, bi particle collision,
the general model for perikinetic coag-flocculation is given
[13].
=
∑αβ (Vi, Vj)CiCj - ∑αβ(Vi, Vj)CiCk
(1) i+j=k
i=1
Where =
is the rate of change of concentration of
particle size k (conc./ time)
Where α is the particle collision efficiency (fraction of
collisions that result in particle attachment, is the collision
function (rate that particles are brought into contact by
Brownian, shear, and differential sedimentation),Vi,j is the
velocity of the particle size class i,j, C is the particle
concentration in a size interval.
The first term of equation 1, represents the formation of
particle size K by collision of particle size i and j. The second
term represents the loss of particle size k by collision with all
other particles. The value of for Brownian transport
mechanism is given [13] .
вr =
Ρ
(2)
Where Boltzman’s constant (j / k)
- is the viscosity of the fluid (effluent medium)
p - is collision efficiency
T - is the absolute temperature (k)
The general equation representing aggregation rate of particles
is obtained by solving the combination of equations 1 and 2
analytically to yield.
=
α
(3)
Where is the total particle concentration at time t, = Ck
(kg/m3)
K is the αth
order coagulation-flocculation constant
α is the order of coagulation-flocculation.
And K =
BR (4)
Where BR is collision factor for Brownian transport
Also, BR = p kR (5)
Combining equations 3, 4 and 5 yields
p
α (6)
Where is the Von smoluchowski rate constant for rapid
coagulation
Given by [14],[15] as
1 (7)
= 2a (8)
Where D1 is particle diffusion coefficient, a is particle radius
From Einstein’s equation, particle Diffusion coefficient is
given by [14],[16]
as
D1 = KBT
B (9)
Where B is the friction factor, from stokes equation:
B = 6πղa
(10)
Where is viscosity of the fluid (coagulating and flocculating
effluent medium)
combining 6 to 10 gives
α (11)
Comparing equations 3 and 11 show that k =
(12)
For perikinetic aggregation α Theoretically equals 2 (i.e. α =
2) as reported by [14],[17],[18]
From fick’s law
Jf = D4πRp2
(13)
Where Jf is flux – number of particles per unit surface
entering sphere with radius r
Re-arranging and integrating equation 13 at initial condition
Ct = 0, Rp = 2a
Jf Rp
4πD1 o
= ∫
Ct
(14)
Jf = 8πD1aCo
(15)
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134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
For central particle of same size undergoing Brownian motion,
the initial rate of rapid coagulation –
flocculation is
-
= Jf Co
(16)
On substitution of equation 15 into 16 yields
- dCt = 8πaD1 Co p (17)
dt
Also on substitution of equations 9 and 10 into 17 gives
- dCt = 8πa KBT Co p (18)
dt 6 a
Thus - dCt = 4 p KBT C02 (19)
dt 3 η
Similarly at t > 0
-
2
(20)
η
Hence equation 20 has confirmed the theoretical value α = 2
For α = 2, equation 3 yields
= -KCt
2
(21)
Re – arranging and integrating equation 21, yields
∫
t = - K ∫
(22)
Ct2
= Kt +
(23)
Plot of
VS.t gives a slope of K and intercept of
From equation 23, making Ct the subject matter yields a
relation for the evaluation of coagulation period, ½
Thus Ct = Co
1 + Co Kt
(24)
Similarly, Ct = Co
1 +
(25)
Let =
(26)
Putting equation 26 into equation 25 produces
Ct = Co
1 +
(27)
When t = , equation 27, yields Ct =
(28)
Therefore as Co 0.5Co; ½
Hence ½ = 1
0.5CoK
(29)
For particle concentration or aggregation of singlets, doublets
and triplets
(Being controlled by Brownian mechanism) as a function of
time (t ≤ 40 mins)
at early stages, can be obtained by solving equation 1 exactly,
resulting in
general expression of nth
order
t 1 n-1
2 KCo
Cn(t)
(30)
Co =
1 + t n+1
2
n-1
Similarly Cn(t) = ⁄
Co n+1 (31)
1 + t/1
Equation 31 gives a general expression for particle of nth
order
Hence for singlets (n = 1)
1
C1 = Co (1 + t/
1)
2
(32)
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For doublets (n = 2)
(t/1)
C2 = Co (1 + t/1)
3
(33)
For triplets (n = 3)
C3 = Co (t/1)
3
(1 + t/1)
4
(34)
Evaluation of coagulation – flocculation efficiency is given as
Co - Ct
E(%) = Co x 100
(35)
III. MATERIALS AND METHODS
A. Materials collection, preparation and
characterization.
1) Pharmaceutical Effluent (PHE)
The effluent was taken from a pharmaceutical industry
situated at Ogidi, Anambra State, Nigeria. The
characterization of the effluent was determined based on
standard method [19],[20] and presented in table I.
2) Pleurotus Tuberregium Sclerotium Tuber Sample
Pleurotus Tuberregium Sclerotium Tuber Sample (precursor to
PTSC) was sourced from Enugwu-Ukwu, Anambra State,
Nigeria. In the preparation of PTSC, the outer surface of the
pleurotus tuber was carefully removed with knife to ensure
that it is free from debris. Subsequently it was broken into
smaller units and sun-dried for one week to remove the
inherent moisture. The sample was crushed into powdered
form using laboratory mortar and pestle. After which it was
sun-dried again for 3 hrs to ensure that no residual moisture is
left. Finally, the powdered sample was then sieved using mesh
size of 4µm, subseequently characterized on the basis of
AOAC standard method [21] and used for the entire
experiment. The characterization result is presented in table
II.
B. Coag-flocculation Experiments.
Experiment were conducted using conventional Jar test
apparatus. Appropriate dose of PTSC in the range of (0.1- 0.7)
x10-3
kg/m3 was added to 250ml of pharmaceutical effluent.
The suspension, tuned to pH range 1 – 13 by addition of
10MHCL/NaOH was subjected to 2 minutes of rapid mixing
(120 rpm), 20 minutes of slow mixing (10rpm) and followed
by 40 minutes settling. During settling, samples were
withdrawn from 2cm depth and changes in TDSP
concentration measured for kinetic analysis (Lab –Tech.
Model 212R Turbidimeter) at various time intervals of
(2,4,6,10,20,30 and 40)x60sec. The whole experiment was
carried out at room temperature. The results obtained were
subsequently fitted in appropriate kinetic models for
evaluation.
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Table I
Characteristic of pharmaceutical industry effluent sample before treatment
Parameter Values
Temperature (oC) 28
Electrical conductivity (µs/cm) 4.9 x 102
pH 3.87
Phenol (mg/l) Nil
Odor acidic
Total hardness (mg/l) 6,000
Calcium (mg/l) 594
Magnesium (mg/l) 250
Chlorides (mg/l) 100
Dissolved oxygen (mg/l) 20
Biochemical oxygen Demand (mg/l) 50
Turbidity (mg/l) 1256
Iron (mg/l) Nil
Nitrate (mg/l) Nil
Total acidity (mg/l) 250
Total dissolved solids (mg/l) 225
Total suspended solids (mg/l) 57.25
Total viable court (cfu/mil) 9 x 101
Total coliform MPN/ 100ml Nil
Total coliform count, cfu/nil 1 x 101
Faecal count MPN/mL Nil
Clostridium perfrigens MPN/ml Nil
Table II
Characteristics of Pleurotus Tuberregium Sclerotium coagulant precursor (Pleurotus Tuberregium Sclerotium plant)
Parameter Value
Moisture content % 15.00
Ash content % 5.00
Fat content % 9.00
Crude fibre % 15.00
Crude protein % 35.70
Carbohydrate % 5.51
International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 17
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Table III
Coag-flocculation functional parameters for varying pH and constant dosage of 0.1 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.648 0.910 0.897 0.80 0.763 0.945
K(m3/kg.S) 8E-05 2E-05 6E-04 3E-05 1E-04 1E-04
BR(m3/kg.S) 1.6x10-4 4.0x10-5 1.2x10-3 6.0x10-5 2.0x10-4 2.0x10-4
KR(m3/kg.S) 1.5468x10-19 1.5443x10-19 1.5801x10-19 1.5545x10-19 1.5622x10-19 1.5801x10-19
p(kg-1
) 1.0343x1015 2.5902x1014 7.5944x1015 3.8598x1014 1.2802x1015 1.2657x1015 ½ (Sec) 11.36 53.35 1.81 48.31 14.49 10.87
(-r) 8E-05Nt2 2E-05Nt
2 6E-04Nt2 3E-05Nt
2 1E-04Nt2 1E-04Nt
2
No(m3/kg) 500.00 1000.00 1000.00 1000.00 333.33 1000.00
Table IV Coag-flocculation functional parameters for varying pH and constant dosage of 0.2 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.607 0.670 0.876 0.968 0.865 0.966
K(m3/kg.S) 7E-05 4E-05 9E-06 4E-05 9E-05 2E-04
BR(m3/kg.S) 1.6x10-4 4.0x10-5 1.2x10-3 6.0x10-5 2.0x10-4 2.0x10-4
KR(m3/kg.S) 1.5468x10-19 1.5443x10-19 1.5801x10-19 1.5545x10-19 1.5647x10-19 1.5801x10-19
p(kg-1
) 9.0509x1014 5.1803x1014 1.1392x1014 5.1463x1014 1.1504x1015 2.5315x1015 ½ (Sec) 12.99 27.17 120.77 36.23 16.10 5.43
(-r) 7E-05Nt2 4E-05Nt
2 9E-06Nt2 4E-05Nt
2 9E-05Nt2 2E-04Nt
2
No(m3/kg) 333.33 1666.67 1000.00 1000.00 500.00 1000.00
Table V
Coag-flocculation functional parameters for varying pH and constant dosage of 0.3 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.965 0.919 0.688 0.923 0.834 0.737
K(m3/kg.S) 2E-05 9E-06 4E-05 5E-05 5E-05 2E-04
BR(m3/kg.S) 4.0x10-5 1.8x10-5 8.0x10-5 1.0x10-4 1.0x10-4 4.0x10-4
KR(m3/kg.S) 1.5494x10-19 1.5443x10-19 1.5801x10-19 1.5545x10-19 1.5647x10-19 1.5801x10-19
p(kg-1
) 2.5816x1014 1.1656x1014 5.0630x1014 6.4329x1014 6.3910x1014 2.5315x1015 ½ (Sec) 45.45 120.77 27.17 28.99 28.99 5.453
(-r) 2E-05Nt2 9E-06Nt
2 4E-05Nt2 5E-05Nt
2 5E-05Nt2 2E-04Nt
2
No(m3/kg) 1000.00 1000.00 1111.11 1000.00 500.00 1000.00
Table VI
Coag-flocculation functional parameters for varying pH and constant dosage of 0.4 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.907 0.836 0.868 0.871 0.824 0.761
K(m3/kg.S) 3E-05 1E-05 1E-05 4E-05 8E-05 2E-004
BR(m3/kg.S) 6.0x10-5 2.0x10-5 2x10-5 8.0x10-5 1.6x10-4 4.0x10-4
KR(m3/kg.S) 1.5494x10-19 1.5468x10-19 1.5801x10-19 1.5571x10-19 1.5647x10-19 1.5801x10-19
p(kg-1
) 3.8725x1014 1.2930x1014 1.2657x1014 5.1378x1014 1.0226x1015 1.5315x1015 ½ (Sec) 30.30 108.70 108.70 36.23 18.12 5.43
(-r) 3E-05Nt2 1E-05Nt
2 1E-05Nt2 4E-05Nt
2 8E-05Nt2 2E-04Nt
2
No(m3/kg) 1666.67 1000.00 1000.00 500.00 500.00 333.33
Table VII
Coag-flocculation functional parameters for varying pH and constant dosage of 0.5 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.421 0.863 0.473 0.897 0.786 0.607
K(m3/kg.S) 9E-05 1E-05 1E-05 3E-05 6E-05 1E-05
BR(m3/kg.S) 1.8x10-4 2.0x10-5 2.0x10-5 6.0x10-5 1.2x10-5 2.0x10-4
KR(m3/kg.S) 1.5494x10-19 1.5464x10-19 1.5826x10-19 1.5571x10-19 1.5673x10-19 1.5826x10-19
p(kg-1
) 1.1617x1015 1.2930-x1014 1.2637x1014 3.8533x1014 7.6565 x1013 1.2637x1015 ½ (Sec) 10.10 108.70 108.70 48.31 24.15 10.87
(-r) 9E-05Nt2 1E-05Nt
2 1E-05Nt2 3E-05Nt
2 6E-05Nt2 1E-05Nt
2
No(m3/kg) 333.33 111.11 1000.00 1000.00 1000.00 333.33
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Table VIII
Coag-flocculation functional parameters for varying pH and constant dosage of 0.6 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.662 0.823 0.942 0.979 0.841 0.639
K(m3/kg.S) 7E-05 1E-05 2E-05 4E-05 3E-05 1E-04
BR(m3/kg.S) 6.0x10-5 2.0x10-5 2x10-5 8.0x10-5 1.6x10-4 4.0x10-4
KR(m3/kg.S) 1.5520x10-19 1.5468x10-19 1.5826x10-19 1.5571x10-19 1.5673x10-19 1.5826x10-19
p(kg-1
) 9.0206x1014 1.2930x1014 2.5275x1014 5.1378x1014 3.8282x1014 1.2637x1015 ½ (Sec) 12.99 108.70 54.35 36.23 48.31 10.87
(-r) 7E-05Nt2 1E-05Nt
2 2E-05Nt2 4E-05Nt
2 3E-05Nt2 1E-04Nt
2
No(m3/kg) 500.00 1428.57 1428.57 1000.00 1000.00 500.00
Table IX
Coag-flocculation functional parameters for varying pH and constant dosage of 0.7 x 10-3 kg/m3 PTSC
Parameter pH=1 pH=3 pH=5 pH=7 pH=10 pH=13
α 2 2 2 2 2 2
R2 0.851 0.652 0.858 0.951 0.627 0.779
K(m3/kg.S) 4E-05 2E-05 1E-05 3E-05 4E-05 2E-04
BR(m3/kg.S) 8.0x10-5 4.0x10-5 2.0x10-5 6.0x10-5 8.0x10-5 4.0x10-4
KR(m3/kg.S) 1.5520x10-19 1.5468x10-19 1.5852x10-19 1.5571x10-19 1.5673x10-19 1.5826x10-19
p(kg-1
) 5.1546x1014 2.5860x1014 1.2617x1014 3.8533x1014 5.1043x1014 2.5275x1015 ½ (Sec) 2273 54.35 108.70 48.31 36.23 5.43
-r) 4E-05Nt2 2E-05Nt
2 1E-05Nt2 3E-05Nt
2 4E-05Nt2 2E-04Nt
2
No(m3/kg) 1000.00 2000.00 1250.00 1000.00 1000.00 500.00
Fig. 1. Selected Plot of Efficiency E (%) Vs Time For 0.2x10-3kg/m3 dosage at
varying pH
Fig. 2. Selected Plot of Efficiency E (%) Vs Time For 0.3x10-3kg/m3 at
varying pH
Fig. 3. Selected Plot of Efficiency E (%) Vs Time For 0.5x10-3kg/m3 dosage at varying pH
Fig. 4. Selected Plot of Efficiency (E %) Vs Dosage at varying pH
0
20
40
60
80
100
2 4 6 10 20 30 40
Effi
cie
ncy
E(
%)
Time (x 60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
0
20
40
60
80
100
120
2 4 6 10 20 30 40
Effi
cie
ncy
E (
%)
Time (x 60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
0
20
40
60
80
100
2 4 6 10 20 30 40
Effi
cie
ncy
E (
%)
Time (x60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
0
20
40
60
80
100
120
0.1 0.2 0.3 0.4 0.5 0.6 0.7
Effi
cie
ncy
E (
%)
Dosage (x10-3kg/m3)
pH=1 at 40mins
pH=3 at 40mins
pH=5 at 40mins
pH=7 at 40mins
pH=10 at 40mins
pH=13 at 40mins
International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 19
134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
Fig. 5. Selected Plot of Efficiency E (%) Vs pH at varying Dosages
Fig. 6. Selected Plot of 1/TDSP Vs Time For 0.1x10-3kg/m3 at varying pH
Fig. 7. Selected Plot of 1/TDSP Vs Time For 0.2x10-3kg/m3 at varying pH
Fig. 8. Selected Plot of 1/TDSP Vs Time For 0.6x10-3kg/m3 at varying pH
Fig. 9. Particle distribution plot for half life of 1.81Sec
Fig. 10. Particle distribution plot for half life of 120.77Sec
0
20
40
60
80
100
120
1 3 5 7 10 13
Effi
cie
ncy
E (
%)
pH
0.1x10-3 kg/m3
0.2x10-3 kg/m3
0.3x10-3 kg/m3
0.4x10-3 kg/m3
0.5x10-3 kg/m3
0.6x10-3 kg/m3
0.7x10-3 kg/m3
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0 20 40 60
!/TD
SP (
m3
/kg)
Time (x60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
0
0.002
0.004
0.006
0.008
0.01
0.012
0 20 40 60
1/T
DSP
m3
/kg
Time (x60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
0
0.002
0.004
0.006
0.008
0.01
0.012
0 20 40 60
1/T
DSP
(m
3/k
g)
Time (x60S)
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
-500
0
500
1000
1500
2000
0 20 40 60
Co
nc.
of
TDSP
(kg
/m3
)
Time (x60S)
Singlet
Doublet
Triplet
Sum
-500
0
500
1000
1500
2000
0 20 40 60
Co
nc.
of
TDSP
(kg
/m3
)
Time (x60S)
Singlet
Doublet
Triplet
Sum
International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 20
134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
Fig. 11. Coag-Flocculation performance at 2400sec for 0.1x10-3kg/m3 PTSC
and Alum dosages in pH varying PHE
IV. RESULTS AND DISCUSSION.
In this work attention were given to the influence of coag-
flocculation operating conditions which include coagulant
dosage, pH of the suspension and settling time in order to
investigate the adsorption capability of pleurotus tuberregium
sclerotium in coag-flocculation process. As high turbidity
nature of pharmaceutical effluent is probable caused by high
level of total dissolved solid particles, to this end, it has been
used as basis to determine the effectiveness of pleurotus
tuberregium sclerotium in the work.
A. Characterization Results
These are presented in tables 1 and 2. From the
results in table 1, the pH value (3.87) obtained indicated that
the PHE is acidic which apparently resulted to the acidic odor
. This attributes suggest the presence of high level of
biological organisms (total viable count, total coliform count
etc) . In addition, the relatively high values of turbidity
(1256mg/l), biochemical oxygen demand (50mg/l) total
dissolved solids (225mg/l) total suspended solids (57.25mg/l),
respectively, show that the PHE has high pollution potentials,
providing a condition for this study. The relatively high
electrical conductivity value (490 µs/cm), indicates that the
PHE sample contains charged ions, suggesting that
coagulation and flocculation treatment method can be applied
to this end. Also, levels of nutrients (Ca, mg) and absence of
heavy metal, implies that the PHE can be recycled for
agricultural purposes (as a soil conditioner). In table 2, the
presence of crude protein extract from PTSC, a water-soluble
cationic peptide with isoelectric point has been shown to be
responsible for the coagulating property inherent in it and
other natural coagulants of this type [22] . It can also be
deduced from the characterization results after treatment,
though not shown, that the acidic odor of PHE sample
drastically reduced after 2400secs of treatment. This is
indication that PTSC, has antimicrobial effect too, in line with
previous works [23],[24] .
B. Effect of settling time on Efficiency. These are presented in the selected plots in figures 1 – 3.
These figure actually indicated the reactive effectiveness of
PTSC to remove soluble reactive TDSP from the
predominantly negatively charged effluent is time dependent.
This phenomenon is possible because early stage of
coagulation witnessed dispersing of the coagulating agents in
the effluent and at this point less sites are available for
adsorption of the particles. Hence sorptive capacity of the
coagulating agents increases with time due to increase in
adsorptive sites. This is supported by the results obtained from
the figures which indicated that best performance are recorded
at maximum coagulating time for all the pH. The significant
feature of the figures show that the best performance are
recorded for pH = 1 and pH = 13. Critical observation of
figures 1 and 3 indicate that starting from t = (20, 6) mins for
pH = 1, 13 there is minimal variations in the E% values
recorded respectively. This phenomenon is an evidence that
the rate of TDSP removal from the effluent by PTSC is
virtually constant for those pH. With the least E > 90%,
proved the effectiveness of PTSC to remove TDSP from the
effluent. This final result, i.e. E% > 90% is an evidence that
this study with PTSC conformed to the principles of rapid
coagulation which is obtained in real life of coag-flocculation
process. This is in agreement with previous similar work [18] .
C. Effect of coagulant dosage on Efficiency. This is presented in figure 4. This actually depicts how
coagulant dosage affected the efficiency at varying effluent
pH medium. The significant feature obtained in the figure
show that the performance of PTSC has minimal variation at
the pH of 13 for all dosages. This is an indication that PTSC
hydrolyzed better in strong alkaline medium. The optimum
performance is recorded at pH =13 for all dosages. At the
optimum dosage there is sufficient coagulating agent to form
adequate bridging linking between particles and also high
degree of dissociation of cationic radicals in the coagulating
agent. Hence there is increase in sorption capacity of the
coagulating agent which led to increase in charge density of
the coagulating agent. This signifies rapid destabilization of
the particles. Hence effective coagulation was achieved with
much low dose of PTSC than would be required for complete
charge neutralization of PTSC. This is supported by the
maximum efficiency of 95.54% recorded at the dosage of 0.3
x 10-3
kg/m3. PTSC performance is found to be charge density
and pH dependent. This is in line with previous similar works
[9],[25].
D. Effect of effluent sample pH on Efficiency.
This is represented in figure 5. It shows the performance of
various dosages of PTSC at varying pH values. It can be
observed that the pH of pharmaceutical effluent sample has an
influence on coagulation process using PTSC. In addition
figure 5 indicate that the efficiency values recorded for pH = 1
0
10
20
30
40
50
60
70
80
90
100
pH=1
pH=3
pH=5
pH=7
pH=10
pH=13
Alum 29.13 51.88 59.71 77.49 93.26 36.75
PTSC 91.09 70.65 62.83 76.38 88.7 92.83
Effi
cie
ncy
(E%
)
Al…
International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 21
134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
and 13, are very close followed by decrease in efficiency
recorded for pH = 3, 5, 7 and 10.
At pH = 13, optimum efficiency recorded is (95.54%). This is
an indication that sorption capacity of PTSC is optimum at pH
= 13 when the electrostatic interaction of PTSC cations with
anions in solution is at maximum. Therefore the optimum pH
condition of the treatment system is pH of 13. However, it
could be observed that dosage has slight influence on the
efficiency values recorded between pH of 1 and13.
Furthermore, observation indicate that the flocs formed by
PTSC appears rapidly at pH of 13 and form large agglomerate
for easy settling and removal from the system.
E. Coag-flocculation kinetic parameters. The values of coag-flocculation kinetic parameters evaluated
from the standard Jar test results obtained are presented in
tables 3 – 9. The significant feature in the tables indicate that
α= 2, though in real practice, empirical evidence has shown
that in general 1 α 2 [19],[26]. However, for α = 2, is in
line with theoretical expectation of second order reaction
model common to coagulation process [27].
On substitution of α = 2 in equation 3 and solving by integral
method yields equation 23. The values of K are evaluated
from the slopes of graphs represented by selected plots of
figures 6 – 8. For K = 0.5 βBR, the values obtained are less
sensitive to pH of 3 and 13 for dosages of (0.4, 0.5, 0.6) x 10-3
kg/m3; (0.2, 0.3, 0.4, 0.7) x 10
-3 kg/m
3 studied respectively.
This is an indication that the rate per concentration has a
negligible influence on the pH of 3 and 13 as regards to
particle collision rate in such pH media. Tables 3 – 9, indicate
that optimum K is recorded for pH = 5 at 0.1 x 10-3
kg/m3
dosage, though coagulation/flocculation performance at pH of
13 is satisfactory for (0.2, 0.3, 0.4, 0.7)x 10-3
kg/m3 dosages.
These facts are supported by the low values of ½ recorded
between pH = 5 and 13 for the specified dosages, with the pH
= 5, having the lowest value. Generally, from the tables and
equation 29, indicate that the value of ½ inversely affected
that of K. Since K is the aggregation rate of particles during
coagulation/flocculation, it is associated to energy barrier in
between the intending aggregating particles. It is agreeable
that from this analogy and observations from the tables a
lower ½ is a necessary condition for a higher K to be
obtained. Linear regression coefficient (R2) was employed to
evaluate the degree of accuracy of coagulation-flocculation
system (depicted by model equation 23) using PTSC to
remove TDSP from pharmaceutical effluent. Results in tables
3 – 9 show that majority of R2 values obtained are greater than
0.75, suggesting a monolayer and homogenous surface
adsorption which is controlled by electrostatic repulsion
mechanism28
. Hence it can be deduced that the reaction is a
second order with various rate of depletion of TDSP (-r)
posted in tables 3 – 9. This implies that the rate of depletion of
TDSP (-r) is proportional to K and Ct as expressed in equation
3.
Furthermore, the result posted in table 3 – 9 indicate that there
is minimal variation observed in the values of KR obtained.
This is because KR is dependent on the temperature and the
viscosity of the effluent, the viscosity of the effluent sample is
a constant, it is only the temperature, that was varying
minimally because the experiment was performed under room
temperature. At nearly constant value of KR, p is directly
related to BR = 2K. The implication is that high p results in
high kinetic energy to overcome electrostatic repulsion. The
consequence is that the double layer on the solution is diffused
so that the electrostatic repulsion prohibiting the particles to
come close is reduced for a low ½ to be obtained in favor of
high coagulation rate. The results in tables 1 – 7, indicate that
high values of p corresponds to low values of ½ which
suggests presence of shear resistance/electrostatic repulsion in
the system.
The value of ½ obtained are moderately low period that run
into units of seconds instead of milliseconds which had been
obtained elsewhere [13]. The values of Co posted in the tables
were evaluated from intercept of the graphs of selected plots 6
– 8. Equation 23, show that Co is related inversely with K, this
is supported by the values of Co posted in the tables, where
low Co is a condition for high K, with exceptions of tables for
dosages (0.1,0.2 and 0.3)x10-3
kg/m3.
Finally, the differences noticed in the parameters (K, KR Co,
p) may be due to wrong assumptions that α = 2; mixing of
total dissolved solid particles and coagulating agents in the
solution are properly homogenized prior to coagulation-
flocculation process. These draw-back may be caused by
under dosing or overdosing of the coagulating agent in the
effluent sample, which creates an imbalance in the coagulating
agent/effluent sample ratio. This phenomenon will result in
uneven distribution of the coagulating agents in the effluent
sample, which leads to non-homogeneity of the solution
followed by inadequate attraction of TDSP by coagulant
radicals
F. Effect of time on particle aggregate pattern.
These are presented in figures 9 and 10 for ½ = 1.81 sec and
5.43 sec respectively. The two figures exhibits similar trend
for all the curves. The particles distribution patterns for the
figures are associated with rapid conversion of stable state
dispersion to the unstable state (coagulant complexes or
radicals). In figure 9, at t = (0 – 120)sec, the repulsive
electrostatic interactions and high Zeta potential between the
singlets and sum of the particles are overcome by Van der
waal forces which led to their attraction (i.e sorption of TDSP
in solution to oppositely charged ions). In addition, (120 –
240) sec into the coagulation process witnessed moderate
shear resistance and zeta potential between the particles of
singlet class and that of sum. Also, for the particles class of
doublets and triplets there is no repulsive force in action hence
the energy barrier between them is negligible at t =( 0 – 120
)sec, that is why the forces of attraction predominates.
Moreover, between the trio’s of the class of particles (singlets,
doublets, triplets) and particles sum at coagulation period of t
= (120 – 240)sec, there is moderate potential hump created by
way of double layer formation between them. Subsequently at
International Journal of Engineering & Technology IJET-IJENS Vol:13 No:05 22
134705-9494-IJET-IJENS © October 2013 IJENS I J E N S
(240 – ∞)sec, the particles either acquired high kinetic energy
that enable them to overcome the potential hump or it may
have been eliminated by surface charge neutralization.
Alternatively, it may have been accomplished by either double
layer compression (charge neutralization mechanism or
sorption of coagulant onto the particles surface- bridging
mechanism). This phenomenon is confirmed by the low value
of ½ obtained which might be responsible for the total sweep
flocculation and particle bridging displayed by all the classes
of particle at the time range.
However, in figure 10, the same behavioral pattern as
witnessed above was repeated except that at t = (600 – ∞)sec,
all the classes of particles were able to overcome the repulsive
forces of interactions between them prior to 600sec. This led
to particles entrapment and formation of flocs to larger
agglomerates for easy settling and removal from the system.
The little discrepancy observed in the behavior patterns of the
figures is understandable because of the difference in the ½
values at which they operated.
However, the curves clearly demonstrates the inclusion of
sweeping phenomenon being in action which favors rapid
coagulation-flocculation process.
G. Comparative Removal Efficiency (E%) of Alum
and PTSC.
The comparison of removal efficiency between alum (as a
control) and PTSC at 40mins for 0.1 x 10-3
kg/m3 dosage and
pH 1,3,5,7,10,13 under the same experimental conditions is
presented in figure 11. The figure indicate that the best and
least performances recorded for Alum and PTSC are 93.26%,
92.83% at pH = 10, 13 and 29.13%, 62.83% at pH = 1,5
respectively. In general, for the purposes of comparison the
optimum performance recorded for alum and PTSC are
93.26% and 88.8% at pH of 10. For practical applications and
effectiveness perspective, PTSC at all pH for 0.1 x 10-3
kg/m3
can favorably be compared with alum. The inherent
advantages of PTSC which include environmental friendly,
cheap, abundantly available with simple preparation procedure
makes it attractive for water and wastewater treatment
applications.
V. CONCLUSION.
At the room temperature condition of the experiment, the
coag-flocculation operating conditions were found to have
substantial influence on the performance of PTSC in the
removal of TDSP in pharmaceutical effluent. The value of
percentage of TDSP removed from PHE at 40mins is an
indication of a system controlled by charge neutralization and
floc sweep mechanisms. The system achieved maximum
efficiency of 95.54% at 0.3 x 10-3
kg for pH of 13. The
evaluated experimental results are in agreement with previous
similar works [18],[29].
NOMENCLATURE
PHE: Pharmaceutical Effluent
Co: Evaluated initial total dissolved solid particles
(kg/m3)
TDSP: Total dissolved solid particles (kg/m3)
K: αth
order coag-flocculation constant
p: Collision Efficiency
BR: Collision factor for Brownian Transport
½ : Coagulation Period
E: Coag-flocculation Efficiency
R2: Linear Repression Coefficient
α: Coag-flocculation reaction order
-r: Rate of depletion of final particle concentration (Ct)
PTSC: Pleurotus Tuberregium Sclerotium
coagulant
VI. ACKNOWLEDGEMENT
The authors appreciate the assistance of F.O. Chukwurah of
Quality Control Chemistry Lab. KP Pharmaceutical Industries
Ltd, Ogidi in Anambra State, Nigeria.
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