influence of coag-flocculation operating conditions in the ...coagulation-flocculation process is...

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-

mailto:[email protected]



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)



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)



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.



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



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


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



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



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



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



Table VIII



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



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



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. 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



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…



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



(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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