BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND

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BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND

TABLE OF CONTENTS vi

ABSTRACT xii

CHAPTER ONE

Introduction 1
1. Background of Study 1
1. Aims and Objectives 5

CHAPTER TWO

Literature Review 6
- Introduction 6
- Biodegradation 6
- Types of Biodegradation 7
  - Aerobic Biodegradation 7
  - Anaerobic Biodegradation 7
- Microorganisms Involved in Biodegradation 8
- Requirements for Biodegradation 9

2.6. Factors Affecting Contaminants Biodegradation	10
2.6.1. Biological Factors	10
2.6.1.1. Rates of Contaminant Degradation	10
2.6.1.2. Extent of Contaminant Degradation	19
2.6.1.3. General Indicators and Microbial Physiology	10
2.6.1.3.1. Carbon: Nitrogen: Phosphorus (C:N:P)	10
2.6.1.3.2. Nutrient Availability	11
2.6.1.3.3. Terminal Electron Acceptors	11
2.6.1.3.4. Soil Respirometry	12
2.6.1.4. Temperature	13
2.6.1.5. Moisture	13
2.6.1.6. pH	14
2.6.2. Environmental Factors	14
2.6.2.1. Geologic and Hydrologic Factors	14
2.6.2.1.1. Adsorption and Absorption	14
2.6.2.1.2. Contaminant Migration in Groundwater	14
2.6.2.2. Bioavailability	15
2.6.2.3. Soil Matric Potential	16
2.6.2.4. Redox Potential	16
2.7. Cyanide	18
2.8. Biodegradation Mechanism of Cyanide	19

2.8.1. Factors Affecting Cyanide Biodegradation in the Environment 20

Effects of Cyanide on the Ecosystem 21
- Cyanide Toxicity to A Living Environment 21
- Cassava Production 23
  - Classification and Description of Cassava 25
  - Origin of Cassava 26
    - Agricultural origin 26
  - Geographical Distribution of Cassava 27
- Ecological Requirements for Cassava Production 28
  - Soil 28
  - Rainfall 28
  - Altitude 28
- Cassava Harvesting and Processing 28
  - Cassava Harvesting 28
  - Cassava Processing 28
- Cassava Processing Industry (Cassava Mill) 29
  - Microorganisms and Chemical Compounds Present In Cassava Mill Effluent 30
- Importance of Cassava 31
  - Nutritional Improvements on Cassava 31

CHAPTER THREE

Materials and Methods 33
- Description of the Study Area 33
- Collection of Sample 33

3.3 Sterilization of Equipment and Media 33

Determination of Physicochemical Parameters 34
- Effluent Heavy Metals and Cation Analysis 34
- Microbiological Analysis of Sample 34
  - Media Used and Their Preparations 34
  - Determination of Total Heterotrophic Bacterial Count 35
    - Serial dilution of Cassava Mill Effluent Samples 35
    - Inoculation and Enumeration 35
    - Characterization and Identification of Bacterial isolates 35
  - Determination of Total Heterotrophic Fungal Counts 35
    - Inoculation and enumeration 35
    - Characterization and identification of fungal isolates 36
- Utilization of Cassava Mill Effluent by Microbial Isolates 36
  - Isolation of Cyanide Degrading Microbes 36
- Cyanide Degradation Experiment 37
  - Effect of Substrate Concentration (Cyanide) 37
  - Effect of pH 37
  - Effect of Inoculum Size 38
  - Effect of Phenol 38
- Analytical Methods 38
  - Growth Determination 38
  - Degradation Efficiency 38

CHAPTER FOUR

4.0. Results 40

CHAPTER FIVE

Discussion 51
- Conclusion/Recommendation 53

REFERENCES 54

APPENDICES 63

LIST OF TABLES

Table 2.1: Compounds (Organic and Inorganic) that can be utilized as terminal electron acceptors by microorganisms 12

Table 4.1: Physiochemical Properties of Cassava Mill Effluents 42

Table 4.2: Enumeration of Bacterial and Fungal Counts (x 10⁸ cfu/ml) 43

Table 4.3: Cultural, Morphological and Biochemical Characteristics of Bacterial

Isolates 44

Table 4.4: Microscopic and Macroscopic Characteristics of Fungal Isolates 45

Table 4.5: Isolation of the Cyanide Degrading Microbes with mineral salt medium containing 1% Cyanide 73

Table 4.6: Effect of Substrate Concentration (Cyanide) 74

Table 4.7: Effect of pH 75

Table 4.8: Effect of Inoculum Size 76

Table 4.9: Effect of Phenol 77

LIST OF FIGURES

Figure 2.1: Schematic Illustration of the Effect of Cyanide on the Human Body 23

Figure 2.2: The Traditional Cassava Processing Process 29

Figure 4.1: Isolation of the Cyanide Degrading Microbes with mineral salt medium containing 1% Cyanide 46

Figure 4.2: Effect of Substrate Concentration (Cyanide) 47

Figure 4.3: Effect of pH 48

Figure 4.4: Effect of Inoculum Size` 49

Figure 4.5: Effect of Phenol 50

ABSTRACT

The cyanide component of cassava mill effluent CME is highly toxic to man and it environment. This research was assessed using various concentrations of cyanide with variable concentrations of pH values, inoculum size and phenol, an inhibitory substance. The heterotrophic bacterial and fungal counts were 6.32 x 10⁸cfu/ml and 2.87 x 10⁸cfu/ml respectively. The microorganisms isolated and characterized were: Staphylococcus aureus, Bacillus, Escherichia coli, Lactobacillus, Micrococcus, Klebsiella, Pseudomonas, Salmonella, Corynebacterium, Aspergillus niger, Penicillium, Fusarium and Saccharomyces species. The physicochemical parameters; pH (4.81), electrical conductivity (4860uS/cm), cyanide (17.13mg/l), chemical oxygen demand (2041.20mg/l), biological oxygen demand (1490.08mg/l), total dissolved solids (2478.60mg/l), cations and heavy metals such as Chromium (19.44 mg/l), Manganese (136.08mg/l), Iron (340.20 mg/l) and Nickel (121.50mg/l) were above the Federal Environmental Protection Agency standard for effluent discharge. Bacillus, Pseudomonas and Aspergillus species which had the highest turbidity were used for the batch biodegradation studies. The result revealed that cyanide concentration of about 30ppm at pH 6 with inoculum size 6.5ml gave the highest cyanide degradation ability of 32.73% using Pseudomonas sp. at a residence time of 8 days. It was also found that the same organism gave the best degradative ability in the presence of phenol, an inhibitory substance. The findings revealed that Pseudomonas sp. and Bacillus sp. can be utilized for remediating cassava mill effluent contaminated environment containing cyanide.

CHAPTER ONE

1.0 INTRODUCTION

BACKGROUND OF STUDY

Biodegradation is the breakdown of materials through the aid of bacteria, fungi, or additional biological means, Vert et al. (2012). Eskander and Saleh, (2017) defines biodegradation as the fragmentation of all organic materials carried out by life forms comprising mainly of bacteria, fungi, protozoa and other organisms. Through this biologically natural process, toxic contaminants are converted into less lethal or harmless substances. It can be described as an action leading towards a change in the chemical composition and structure of contaminant caused by biological activity leading to naturally occurring metabolite end products (Bachmann et al., 2014; Jabir and Mustafa, 2016).

Cyanide is a group of compounds which contains a C≡N group: one atom of carbon linked with one atom of nitrogen by three molecular bounds, Moradkhani et al. (2018); Nwokoro and Uju Dibua (2014); Razanamahandry et al. (2017). In the environment, cyanides can be found in many different forms (Kuyucak and Akcil, 2013; Mirizadeh et al., 2014). It is also defined as a toxic nitrogen compound produced by living organisms comprising algae, bacteria, fungi, and plants as part of a defence mechanism against predation (Maniyam et al., 2013). Nevertheless, these natural sources of cyanide are inconsequential in pollution of the environment in comparison to cyanide production through anthropogenic activities (Zohre et al., 2017). Cyanide is lethal to humans and animals (Parker-Cote et al., 2018; Tiong et al., 2015; Uzoije et al., 2011) and thus wastewater containing cyanide poses a threat to aquatic organisms and terrestrial organisms that utilise water on the mainland (Mekuto et al., 2013).

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BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND

BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND