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Zinc and Chromium removal mechanisms from industrial wastewater by using water hyacinth, eicchonia crassipes

( Télécharger le fichier original )
par John Gakwavu Rugigana
National University of Rwanda - Master's in WREM (water resources and environmental management) 2007

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Zinc and Chromium removal mechanisms from
industrial wastewater by water hyacinth, Eichhornia

crassipes (Mart.) Solms-Laubach


MSc. Thesis in WREM November 2007

National University of Rwanda

Faculty of Applied Sciences

Department of Civil Engineering

In collaboration with

Zinc and Chromium removal mechanisms from
industrial wastewater by Water hyacinth, Eichhornia

crassipes (Mart.) Solms-Laubach
Master of Science Thesis


(PhD Research Fellow/ UNESCO-IHE)
I. NHAPI, PhD. (UNESCO-IHE & National University of Rwanda)

A Thesis submitted in partial fulfilment of requirements of the Master of Science degree in Water
Resources and Environmental Management (WREM) at the National University of Rwanda

NUR, November 2007

Statement of originality

I declare that this research report is my own work; unaided work. It is being submitted for the degree of Master of Science in the National University of Rwanda. It has not been submitted before for any degree of examination in any other University.

Gakwavu Rugigana John

Date: November 10th, 2007


When wastewaters are not well purified they can seriously damage surface and
ground water. They can also endanger human and animal health.

The findings, interpretations and conclusions expressed in this study do neither necessarily reflect the views of the National University of Rwanda, Faculty of Applied Sciences nor of the individual members of the MSc committee, nor of their respective employers.

Table of Contents

Statement of originality iii

Table of Contents v

List of tables viii

List of figures ix

List of symbols and abbreviations x

Dedication xi

Acknowledgements xii

Abstract xiii


1.1 Background 1

1.2 Problem description 2

1.3 Objectives 3

1.4 Research questions 3

1.5 Hypotheses 4

1.6 Scope of the research 4

1.7 Report outline 4


2.1 Overview on use of macrophytes in metal removal 5

2.2 Water hyacinth (Eichhornia crassipens (Mart.) Solms. 6

2.2.1 Systematic position 7

2.2.2 Ecological factors 8

2.2.3 Potentials and constraints in using of water hyacinth 8

2.3 Heavy metals 9

2.4 Wastewater 11

2.5 Foliar absorption 12

2.6 Translocation of metals within plants 12

2.7 Uptake 13

Zinc and chromium removal mechanisms from industrial wastewater by water hyacinth (Eichhornia crassipes) (Mart.) Solms-


3.1 Water Hyacinth sampling site description 15

3.2 Methods 16

3.2.1 Description 16

3.2.2 Synthetic wastewater solution preparation 16

3.2.3 Experimental Procedures 16

3.3 Sample Analyses 19

3.3.1 Relative Growth 19

3.3.2 Bioconcentration Factor 19

3.3.3 Metals Accumulation 20


4.1 Variations on plant relative growth 22

4.1.1 Relative growth of water hyacinth plants 22

4.1.2 Discussions on relative growth of water hyacinths 23

4.1.3. Correlation between final fresh weight and relative growth 23

4.2 pH effects and metal concentrations remained in controls (blanks) 24

4.2.1 pH effects in blank samples 24

4.2.2 Zinc concentrations remaining in blank samples 24

4.2.3 Chromium concentrations remained in blank samples 25

4.2.4 Discussions of pH effects on metal concentrations in blank samples 26

4.3 pH variations and Zn(II) and Cr(VI) concentrations in water samples with water

hyacinths 26

4.3.1 Variations of pH on metal removal by the plants 26

4.3.2 Zinc concentrations remaining in water samples after 4 weeks of

experiment. 28

4.3.3 Chromium conc. remaining in water after 4 weeks of experiment 29

4.3.4 Discussions on pH variations and metal removal by the plants 29

4.4 Bioconcentration Factor (BCF) for zinc and chromium 30

4.4.1 Bioconcentration Factor for zinc 30

4.4.2 Bioconcentration Factor for chromium 30

Zinc and chromium removal mechanisms from industrial wastewater by water hyacinth (Eichhornia crassipes) (Mart.) Solms-

4.4.3 Discussions on bioconcentration factor 31

4.5 Bioaccumulation 32

4.5.1 Adsorption of Zinc by water hyacinth plants 32

4.5.2 Total adsorption of zinc 33

4.5.3 Adsorption of chromium by water hyacinth plants 34

4.5.4 Discussions on adsorption mechanism 35

4.6 Uptake mechanism 35

4.6 1 Uptake mechanism for zinc 35

4.6.2 Uptake mechanism for chromium 36

4.6.3 Discussions on uptake mechanism 36

4.7 Translocation Ability (TA) 37

4.7.1 Variation of translocation ability for zinc 37

4.7.2. Variation of translocation ability for chromium 39

4.7.3 Discussions on translocation ability 41


5.1 Conclusions 42

5.2 Recommendations 43

References 44

Appendices 50

Zinc and chromium removal mechanisms from industrial wastewater by water hyacinth (Eichhornia crassipes) (Mart.) Solms-

List of tables

Table 2.1: Maximum growth response of water hyacinth exposed to Cd and Zn 12

Table 2.2: Chromium uptake by water hyacinths during a period of 17 days from Keith

et al., 2006 13
Table 2.3: copper uptake by water hyacinth during a period of 17 days.from Keith et

al., 2006 14
Table 2.4: Arsenic uptake by water hyacinth during a period of 17 days from Keith et

al., 2006 14

Table 4.1: variations on bioconcentration factor of zinc 31

Table 4.2: variations on bioconcentration factor of chromium 31

Table 4.3: Variability in zinc uptake compared to initial concentration & exposure time.


Table 4.4: variability in uptake of chromium 37

Table 4.5: Translocation ability of chromium by the plant 40

Table 4.6: variations in translocation ability of zinc 41

List of figures

Figure 2.1: Common aquatic plants (source: Aquatics, 2005) 6

Figure 2.2: Morphology of water hyacinth plant (source: Aquatics, 2005) 8

Figure 3.1: Topographic map showing the location of Nyabugogo swamp and its

influents 15

Figure 3.2: Plan view of experimental set up. 18

Figure 3.3: steps in lab experiment. 18

Figure 4.1: Relative growth of water hyacinth plants vs exposure time for different Zn

and Cr concentrations 23

Figure 4.2: Correlation between Relative Growth of plants and Final Fresh Weight 24

Figure 4.3: variations of pH in blank samples 24

Figure 4.4: Zinc conc. remaining in blank water samples over time 25

Figure 4.5: Chromium conc. remaining in blank water samples over time 26

Figure 4.6: pH variations in plant water samples over time 27

Figure 4.7: Zinc conc. remaining in water samples with water hyacinth plants over time


Figure 4.8: Chromium conc. remaining in water samples with water hyacinth plants 29

Figure 4.9: Bioconcentration factor of Zinc 30

Figure 4.10: Bioconcentration factor of Chromium 31

Figure 4.11: Desorption of Zinc after 1 week 33

Figure 4.12: Desorption of Zinc after 2 weeks 33

Figure 4.13: Desorption of Zinc after 4 weeks 33

Figure 4.14: Total desorption of Zinc 34

Figure 4.15: Desorption of Chromium 34

Figure 4.16: Variations of uptake for zinc by the plants 35

Figure 4.17: Uptake of chromium in plant tissues for different initial concentrations 36

Figure 4.18: Translocation ability for Zinc by water hyacinth plants 38

Figure 4.19: Translocation ability for 1 week 38

Figure 4.20: Translocation ability for 2 weeks 39

Figure 4.21: Translocation ability for 4 weeks 39

Figure 4.22: Comparison of roots and shoots in translocation ability 40

Figure 4.23: Correlation of roots vs. shoots 40

List of symbols and abbreviations

AAS: Atomic Absorption Spectrometer

ANOVA: Analysis of variance

APHA: American Public Health Association

AWWA: American Water Works Association

BCF: Bioconcentration factor

BOD5: Biological oxygen demand during 5 days

CGIS: Geographic Information System and Remote Sensing Center.

Cr: Chromium

EDTA-Na2: Ethylen diethyl tetracetate disodium

et al.: Et alii

FFW: Final fresh weight

IFW: Initial fresh weight

ppm: Part per million

RG: Relative growth

SPSS: Statistical Package for the Social Sciences

TA: Translocation ability

US.EPA: United States Environment Protection Agency

WEF: Water Environment Federation

Zn: Zinc


To my beloved family.


The achievement of this research was possible with the contribution of several persons with their continued remarks, comments, encouragement, their financial and moral supports, etc. to whom I would like to thank you.

First of all, I am very grateful to the Almighty God for his mercy during my studies and research. I'm also grateful to Rwandan Government for the financial support to complete this Master's Programme.

In particular, my heartfelt thanks to my supervisor PhD. candidate SEKOMO BIRAME Christian and my co-supervisor Dr. Innocent Nhapi, for their acceptance to supervise this research, their particular remarks, scientific discussions, critical comments, their availability and their encouragement. My thanks go also to all UNESCO-IHE and NUR staffs who had direct and indirect contributed to my studies at this juncture. I am also indebted to the laboratory personnel of National University of Rwanda, especially Jean Nepomuscene and Dominic of the Department of Chemistry from the Faculty of Sciences, NUR.

I can not close my acknowledgements without to thank all WREM colleagues cohort for their individual contribution, their sharing ideas through certain modules, their scientific discussions during some hard moments, for their cooperation and team spirit.

Furthermore, I greatly acknowledge my family, for being always with me in every single steps of this thesis with their encouragement.

To everyone concerned by this research, please found your place in my grateful thanks.

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