ABSTRACT
This study examined the treatment of simulated Cibacron green dye-basedastewater. The simulated wastewater characterization revealed presence of high COD, colour, chromium, Lead and other pollutants through proximate analysis. Jar test procedure was applied using Luffa cylindrica seed extract (LCSE) as bio-coagulant, aluminum sulphate (alum) and the combination of both. The effects of coagulant dosage, pH, stirring time and temperature on the reduction of colour, COD, chromium and Lead ions were examined using theoagulants. The Luffa cylindrica seed (LCS) was also characterized usingurier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction analysis technique (XRD), X-ray fluorescence (XRF) and thermo gravimetric analysis (TGA). The process was optimized through response surface methodology (RSM) using a three-level Box-Behnken design (BBD). LCS was found to be a cationic polypeptide (polymer) with carboxylic and hydroxylic functional groups. Despite the good performance of alum and LCSE individually, the combination of LCSE and alum performed better with reduced alum dose and at better operating conditions. Comparative performance also indicated that LCSE performed better than alum with respect to the process conditions such as dosage and pH. It was observed that bio-coagulant used in combination with lower concentration of alum (LCSE+0.25g/L alum) was more effective in reducing colour, Chromium and Lead ion from the dye-based wastewater. This combination does not only achieve the highest reduction efficiencies but the process is also eco-friendly. The colour removal efficiency (97.294%), COD removal (55.3673%) and Chromium removal (87.3245%) were achieved at optimum dosage (5.14g/l), pH (7.68), stirring time (29.02mins) and temperature (31.12oC), respectively. The statistical analysis showed that the model is adequate for the experimental data. The maximum kinetic rate constant, Km, of 0.012 L/g/L, was obtained with coagulant dosage (6g/L), at pH (4), temperature (25oC), stirring time (30mins) and coagulation period, t1/2 of 183.6s while the minimum rate, Km, of 0.0007 L/g/L, was observed with coagulant dosage (6g/L), pH (10), temperature of 25oC, stirring time (30mins) and coagulation period, t1/2 of 135.0s. From the foregoing, it is evident that the use of LCSE or in combination with alum, will not only treat dye-based wastewater effectively, but will contribute to greener environment.
TABLE OF CONTENTS
Cover page
Dedication i
Acknowledgement ii
Table of contents iii
List of tables v
List of figures vii
Abstract ix
CHAPTER
1
INTRODUCTION
1.1 Background 1
1.2 Statement
of Problem 5
1.3 Aim
of Study 5
1.4 Justification
of the Study 6
1.5 Scope
of Study 6
CHAPTER
2
LITERATURE
REVIEW
2.1 Introduction 8
2.2 Dyeing
9
2.2.1
Stages of dyeing 9
2.2.2 Process of dyeing 10
2.2.2.1
Batch process 10
2.2.2.2
Continuous process 10
2.3 Characteristics
of Dye Wastewater 11
2.3.1 Colour 12
2.3.2 Biological
oxygen demand (BOD) 12
2.3.3 Chemical oxygen demand (COD) 13
2.3.4 Dissolved
oxygen (DO) 13
2.3.5
Total dissolved solids (TDS) and total
suspended solids (TSS) 14
2.3.6 pH 14
2.3.7 Turbidity
15
2.3.8 Metal 16
2.4 Heavy
Metals 17
2.4.1 Hazardous
health effects of lead and permissible limits 17
2.4.1.1 Effects on human health 17
2.4.2 Hazardous
health effect of arsenic and permissible limits 18
2.4.2.1
Effects on human health 18
2.4.3 Hazardous
health effect of chromium and permissible limits 19
2.4.3.1
Effects on human health 20
2.4.4 Hazardous
health effect of cadmium and permissible limits 20
2.4.4.1 Effects
on human health 20
2.5 Dye 20
2.5.1 Classification
of dye 21
2.5.1.1 Natural
dye 21
2.5.1.2
Synthetic dyes 22
2.5.1.2.1 Basic (cationic dye) 22
2.5.1.2.2 Acid dye 23
2.5.1.2.3
Direct (substantive) dyes) 24
2.5.1.2.4 Disperse dye 24
2.5.1.2.5 Sulphur dyes 25
2.5.1.2.6 Mordant dyes 26
2.5.1.2.7 Vat dye 26
2.5.1.2.8 Reactive dyes 27
2.5.1.2.9 Azo
dye 28
2.5.2 Properties of dyes 28
2.5.3 Application of dye 29
2.5.4
Hazardous effects of dye 30
2.5.5 Methods of dye removal 30
2.5.5.1
Chemical method 30
2.5.5.1.1
Ozonation 31
2.5.5.1.2 Photocatalytic technique 31
2.5.5.1.3 Electrochemical destruction
technique 31
2.5.5.2 Biological method 32
2.5.5.2.1
Aerobic degradation. 32
2.5.5.2.2
Anaerobic treatment 32
2.5.5.2.3
Decolourization 32
2.5.5.3
Physical method 32
2.5.5.3.1
Ion exchange 33
2.5.5.3.2
Filtration 33
2.5.5.3.2
Irradiation 33
2.5.5.3.4 Coagulation 33
2.5.6 Mechanism
of coagulation 34
2.5.6.1 Electrostatic coagulation 35
2.5.6.2 Adsorptive coagulation 35
2.5.6.3 Precipitation or sweep
coagulation 36
2.5.7 Coagulants
37
2.5.7.1 Chemical coagulants 37
2.5.7.2 Natural coagulants 38
2.5.7.2.1Luffa
cylindrica 39
2.6 Comparison
between Natural and Chemical Coagulants 40
2.7 Application
of Some Natural coagulants 42
2.8 Process
of Coagulation 43
2.9
Jar Test 44
2.10 Process
Factors Influencing Coagulation 44
2.10.1 Solution pH 44
2.10.2 Temperature 45
2.10.3 Coagulant dosage 45
2.10.4 Initial dye concentration 46
2.10.5 Stirring time 46
2.11 Coagulation Kinetics Model
Description and Theoretical Principles 46
2.11.1 Brownian motion 46
2.12
Process Optimization 51
2.12.1 Response surface methodology (RSM)
51
2.12.2.Step involved in RSM 52
2.12.3
Process optimization in chemical engineering 52
2.13
Instrumentation for Coagulation Research. 53
CHAPTER 3
MATERIALS AND METHODS
3.1 Materials 55
3.2 Methods 55
3.2.1 Preparation of alum coagulant 55
3.2.2
Preparation of natural coagulant. 55
3.2.2.1
Characterization of LCSE 57
3.2.3
Preparation of synthetic dye wastewater (SDWW) 57
3.2.3.1
Characterization of SDWW 58
3.2.4
Coagulation procedure 58
3.2.4.1
Effect of dosage 59
3.2.4.2 Effect of pH 59
3.2.4.3 Effect of stirring time 60
3.2.4.4 Effect of temperature 60
3.2.4.5 Removal Efficiency 60
3.3 Design
of Experiment 61
3.3.1 Analysis
of data 63
3.3.2 Evaluation
of the kinetics of the process 63
CHAPTER
4
RESULTS
AND DISCUSSION
4.1 Characterization
Results 64
4.1.1 Characteristics
of SDWW 64
4.1.2 Characteristics
of LCS 65
4.1.3 XRD
result of LCS and Sludge 65
4.1.4 SEM
Analysis 66
4.1.5 FTIR
Analysis 68
4.1.6 XRF
Analysis 70
4.1.7 TGA
Analysis 71
4.2 Preliminary
study on the Coagulation Efficiency of Different Coagulant
Alternatives (OFAT) 72
4.2.1 Effect
of coagulant dosage on colour removal, COD and heavy metal from
dye-based
wastewater at initial pH of 6.7 73
4.2.2 Effect
of solution pH on colour removal, COD, and heavy metal from dye-based
wastewater using
optimum coagulant dosage 80
4.2.3 Effect
of stirring time on colour removal, COD and heavy metal from dye-based
wastewater using optimum coagulant dosage and
solution pH 83
4.2.4 Effect
of temperature on colour removal, COD and heavy metal removal from dye-
based wastewater using
optimum coagulant dosage, solution pH and stirring time.88
4.3 Coagulation
Kinetics Parameter 93
4.5 Regression
Model Development 98
4.6 Operation Parameters Evaluation 104
4.7 Response
Surface Factors 104
4.8 Optimization Analysis 117
CHAPTER
5
CONCLUSION
AND RECOMMENDATION 118
REFERENCES
LIST OF TABLES
Table Title
Page
2.1 Textile
industry Effluent characteristic 9
2.2 Different categories of textile industries
with their associated contaminants 11
2.3 Characteristics of a typical textile mill
effluent (Kaduna) 16
2.4 Applications of some dyes 29
2.5 Hazardous effect of some dyes to human 30
2.6 Comparison
between chemical and natural coagulants
41
2.7 Summary of some natural coagulants used
in wastewater treatment 42
2.8 Analytical techniques used in coagulation
research 54
3.1 Experimental
design 62
3.2 Experimental
runs 62
4.1 Characteristics
of SDWW 64
4.2 Proximate composition of LCS 65
4.3 Chemical Composition of LCS/ Sludge 70
4.4 Comparison of the effectiveness of Alum, LCSE
and combination of
both
as coagulants 93
4.5 Coagulation kinetic parameter at
different dosages 96
4.6 Coagulation kinetic parameter at
different pH 97
4.7 Coagulation kinetic parameter at
different stirring time 97
4.8 Coagulation kinetic parameter at
different temperature 98
4.9 Design of experiment result 100
4.10 ANOVA
for RSM (colour removal) 101
4.11 ANOVA
for RSM (COD removal) 102
4.12 ANOVA for RSM (Cr3+ Removal) 103
4.13 Optimal conditions and optimization
results 106
4.14 Model confirmatory analysis
107
LIST OF FIGURES
Figure Title Page
2.1 Skin
infection Associated with Arsenic metal
19
2.2
Natural indigo 22
2.3
Basic brown dye 23
2.4
Acid yellow 24
2.5
Direct orange 24
2.6
a) Disperse yellow 3, b) Disperse
Red 4 c) Disperse Blue 25
2.7
Sulphur red 25
2.8
Mordant red 26
2.9 Vat blue 27
2.10 a) Reactive blue 5 b)
Cibacron green 27
2.11 Bluish
red azoic dye 28
2.12 Coagulation-flocculation
process 43
3.1
LC fruit/sponge/seed 56
3.2 LCS
powder 57
3.3 Untreated and treated SDWW 58
4.1 XRD of LCS 66
4.2
XRD of sludge 66
4.3 SEM
of LCS /sludge 67
4.4
FTIR Analysis of LCS/sludge 69
4.5 TGA
Result a) LCS b) Sludge c) combination sketch 72
4.6 Effect
of dosage on a) Colour removal b) COD removal c) Cr3+ removal d) Pb2+
removal
using Alum (A), LCSE (B) and combination of both (C) 77
4.7 Effect
of solution pH on a) Colour removal b) COD removal c) Cr3+ removal
d) Pb2+
removal using Alum (A), LCSE (B) and combination of both (C) 82
4.8 Effect
of stirring time on a) Colour removal b) COD removal c) Cr3+ removal
d) Pb2+
removal using Alum (A), LCSE (B) and combination of both (C) 87
4.9 Effect
of temperature on a) Colour removal b) COD removal c) Cr3+ removal
d)
Pb2+ removal using Alum (A), LCSE (B) and combination of both (C) 91
4.10 Plot
of 1/Nt versus settling time at different dosages @ constant initial
pH 6.7/
30mins
stirring time 94
4.11 Plot
of 1/Nt versus settling time at different pH@ constant 6g/l/30mins
stirring
time 95
4.12 Plot
of 1/Nt versus settling time at different stirring time @constant
6g/l /pH8/
30mins
stirring time 95
4.13 Plot
of 1/Nt versus settling time
at different Temperatures @ constant 6g/l/pH10/
30mins
stirring time 96
4.14 3-D
graph for colour removal as a function of a) Dosage and pH b) Dosage and
stirring
time c) Dosage and temperature d) Stirring time and pH e) pH and
temperature f) Stirring time and
temperature 108
4.15 A
3-D graph for COD removal as a function of a) Dosage and pH b) Dosage and
stirring time c) Dosage
and temperature d) pH and stirring time e) pH and
temperature
f) Stirring time and temperature 112
4.16 3-D
graph for Cr3+ removal as a function of a) Dosage and pH b) Dosage
and
stirring time c) Dosage
and temperature d) pH and stirring time e) pH and
temperature
f) Stirring time and temperature 116
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
Environment
is the totality of physical and biological surroundings in which man’s life,
animal and plant species are sustained (Basorun and Olamiju, 2013). Over the
years, the environment has been changed, altered and transformed by human
activities with polluted water from
industries such as food processing (abattoir, vegetable oil etc.), paint,
pharmaceutical, cosmetics, plastic and textile
industries. These industries discharge their effluents into the environment resulting
in the devastation of wildlife, natural habitats, especially water bodies.
These industries have different raw materials which undergo transformation
giving rise to products, byproducts and waste. The generated wastes vary in
composition, and volume and their impact becomes a threat to human health and
environment when not managed properly (Felah, 2013).
Textile sector among other industries, have received great attention
since the large volume of effluents generated can pose problem to the
environment especially water bodies if not well treated before disposal. Textile
industries are important to the nation’s economic development. In India, it
contributes to about 25% of total export earnings and provides employment to
almost ¼th of the total labour force (Sunita et al., 2009). They are also among major contributors to
environmental pollution in the country because of undesirable effluent like dyes
which are not easily degradable (Yildiz et
al., 2018). Production of fabrics from textile factory generate large
amounts of wastewater which come from sizing, sourcing, bleaching, mercerizing,
dyeing, printing and finishing techniques (wet process). Each step releases
highly contaminated wastewater that contain different pollutants like toxic
substances, high organic and inorganic dissolved solids, COD, BOD, and metals;
especially that produced from dyeing process (Falah,
2013).
Dyeing process involves adding colour to the fibre. Usually, to improve
the adsorption between the colour and the fibre, some chemicals additives are added
(Yildiz et al., 2018) which also, contribute
to the pollutants gotten from this stage. This process uses huge volume of
water and chemicals and consequently, giving rise to wastewater that are high
in colour, suspended solid, heavy metals, sulphide, chloride, biochemical
oxygen demand (BOD), chemical oxygen demand (COD) concentration, highly
fluctuating pH, temperature, turbidity and toxic chemical (Khanittha and
Pathumthip, 2015). Its characteristics depend largely on the type of dye used.
The dye applied can be either acidic, basic, synthetic, natural etc.
Cibacron green is one of the reactive dyes used in textile industry which is
not only aesthetically displeasing but also inhibit sunlight penetration into
the stream and affect aquatic ecosystem (Beruk et al., 2018). It has complex aromatic molecular structures which
make it more stable and difficult to biodegrade.
The toxic chemicals with high level of
metallic contents found in dye wastewater have the potential of finding their
way into our drinking water if not treated before discharge. This can cause
kidney disease, neurological problems, blood cell disorder, skin and eye
irritation (Adewale, 2017). It may also contaminate the soil and sediment. The
treatment of dye wastewater (DWW) has been a major issue of environmental
concern. This is because of the adverse effect of dye wastewater on the
environment and the need for wastewater recycling and reuse during production. Adsorption, ion exchange, membrane
filtration, coagulation/flocculation and biological processes have
been employed in the fight against pollution caused by DWW (Khanitha and
Pathumthip, 2015). Coagulation which involves neutralization of charge, is one
of the most effective methods of reducing/removing pollutants from wastewater due to its efficiency and low
capital cost. It enables solid- liquid separation in
wastewater treatment.
The coagulants widely used are
classified into inorganic, and organic polymer coagulants. Though, these
conventional coagulants like aluminum
sulphate (alum), polyaluminium chloride (PACl), polyferric chloride (PFCl),
aminomethyl polyacrylamide etc. are effective in removing dyes (Hans, 2017),
but their negative impacts on human cannot be over-emphasized. Alzheimer and
other related diseases are associated with their usage (Okey et al., 2018). To solve this problem
many types of plants have been developed as either coagulants or coagulant aids
for removing pollutants from dye wastewater because of their availability,
biodegradability, low toxicity, low residual sludge production and more
especially their environmental friendliness. The
direct utilization of plants’ parts as natural coagulant (e.g., using powdered
seeds) is effective. However, further treatment of plants to isolate active
coagulating agents will make it more effective and remove undesired organic
constituents that could increase the organic content in water (Yildiz et al., 2018). Water extraction has
been known to be one of the suitable methods to isolate these active agents,
which could also act as polyelectrolyte in coagulation process (Siong et al., 2019).
This invariably means that these
bio-material extract gotten from plant seeds, leaves and roots, especially
those from their seed can either be used as a coagulant or coagulant aid in the
treatment of DWW. This improves the pH and reduce the concentration of some of
the organic and inorganic coagulant in water; knowing that aluminum ion
concentration of more than 50μg/L becomes toxic to aquatic life (Manisha,
2017).
Numerous studies have been carried out on the treatment of dye wastewater
using different bio- materials. Chito-protein from fish scale has been used to
treat wastewater via coagulation (Okey et
al., 2018). Moringa
stenopetala seed extract has also been
used to remove reactive and direct dye from textile effluent (Gemeda et al., 2019). Lentil extract was used
as coagulant aid in water treatment. This helped to reduce alum concentration
to 40%–50% (Siong et al., 2019). Ordaz-Díaz
et al., (2017) also used Lentil
extract as coagulant aid in pulp and paper wastewater treatment. These findings
revealed that water-soluble extract from the seed of plants have high efficacy in
wastewater treatment. This is because they act as natural
cationic polyelectrolyte and bind to predominantly negatively charged particles
suspended in water (Manisha, 2017). A lot of researches have been done
on luffa cylindrica seed powder but
none on the extract (protein content) which promotes adsorption of particles.
This is the gap in which this research intends to fill; to study the efficiency
of Luffa cylindria seed extract as an eco-friendly coagulant in the
treatment of Cibacron green dye wastewater produced in the laboratory through
coagulation technique.
Luffa cylindrica seed is considered as an alternative to conventional coagulants because
of its biodegradability, non-toxicity, among other properties (Adewale and
Fabiano, 2017). Luffa cylindrica
commonly known as smooth luffa sponge, sponge luffa, vegetable sponge gourd as
well as climbing okra belongs to Cucurbitaceae family. The extract from Luffa cylindrica seed (LCSE) was gotten
by using the same method used by Siong et
al (2019). This work also compared
the use of LCSE, aluminum sulphate (alum) and the combination of both in the
treatment of the reactive dye (Cibacron green) wastewater (DWW). The effects
of the experimental conditions (solution pH, coagulant dosage, stirring time
and the operating temperature) on the performance of the coagulation process
were also studied and optimized. A four-factor Box Behnken Design (Design
Expert version 8.0.1.0) implementing response surface methodology (RSM) was
applied. Analysis of variance (ANOVA), 3-D plot, regression analysis,
interaction and contour plot were used to analyze the study. The coagulation
kinetic were also investigated.
1.2 STATEMENT OF PROBLEM
The use of conventional coagulant like
aluminum sulphate (alum), etc has been popular over the years for the treatment
of dye-based wastewater in most treatment plants. However, its use has posed
some economic, environmental and health problems. Neurological diseases such as
percentile dementia and induction of Alzheimer’s disease have been attributed
to the use of alum (Gomathis et al.,
2017). Also, there is increased sludge production when these chemical coagulants
are used. In addition, these chemical coagulants are non-biodegradable leading
to increase in disposal issues. The high cost of chemical importations results
in loss of foreign exchange to nations. Most chemical coagulants like aluminum shift
the pH of the treated water towards acidic medium. This led to extra cost for
lime which is usually used to bring up the pH. Based on this, the researcher
decided to use the Luffa cylindrica
seed extract (LCSE) as a coagulant and coagulant aid to treat dye-based
wastewater.
1.3 AIM OF STUDY
The
aim of this study was to assess the effectiveness of extract from Luffa cylindrica seed (LCSE) and its
combination with alum on removal of pollutants from simulated dye wastewater
To
achieve the above aim, the objectives were:
1. To characterize the LCS using XRD,
FTIR, XRF, TGA and SEM
2. To characterize the simulated
wastewater
3. To study the efficiency of extract
from Luffa cylindrica seed (LCSE) on
colour, COD, chromium and lead removal from simulated wastewater
4. To study
the effect of coagulant dosage, pH, stirring time and temperature on the on the removal efficiency of colour,
COD, chromium and lead removal
5.
T0 use design of experiment, ANOVA and other statistical parameters to analyze
the process in order to get the optimum condition
6.
To estimate the coagulation kinetic parameters like rate constant,
coagulation half time, rate order etc. during the process.
1.4 SCOPE OF STUDY
The study investigated the efficiency of Luffa cylindrica seed extract (LCSE) and
its combination with alum in the treatment of simulated Cibacron green dye
wastewater (DWW).
This study was restricted to the following:
-
Extraction of an active component from the Luffa cylindrica seed (coagulant)
-
Characterization of the coagulant
using FTIR, SEM, XRD, XRF etc.
-
Monitoring the effect on pH,
coagulant dosage, stirring time and temperature of the effluents on coagulation
performances.
-
Preparation of synthetic dye
wastewater that simulates discharged effluent from textile factory using Cibacron
green dye.
-
Physio-chemical characterization
of the DWW before and after treatment
-
Comparing the decolorisation
efficiency, COD and heavy metal removal efficiency of alum (metallic
coagulant), LCSE (natural coagulant) and their combination.
-
Analysis of the obtained data from
the experimental design (selected coagulant) using ANOVA; 3D surface, contour
and interaction plot were also evaluated.
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