BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND
TABLE OF CONTENTS vi
ABSTRACT xii
CHAPTER ONE
- Introduction 1
- Background of Study 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
- Geographical Distribution of Cassava 27
- Ecological Requirements for Cassava Production 28
- Cassava Processing Industry (Cassava Mill) 29
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
- Determination of Total Heterotrophic Bacterial Count 35
- Serial dilution of Cassava Mill Effluent Samples 35
- Characterization and Identification of Bacterial isolates 35
- Determination of Total Heterotrophic Bacterial Count 35
- Utilization of Cassava Mill Effluent by Microbial Isolates 36
- Discussion 51
- Conclusion/Recommendation 53
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).
BIODEGRADATION OF CYANIDE FROM CASSAVA MILL EFFLUENT IN EBELLE COMMUNITY OF ESAN LAND