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

  1. 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 Biodegradation10
2.6.1. Biological Factors10
2.6.1.1. Rates of Contaminant Degradation10
2.6.1.2. Extent of Contaminant Degradation19
2.6.1.3. General Indicators and Microbial Physiology10
2.6.1.3.1. Carbon: Nitrogen: Phosphorus (C:N:P)10
2.6.1.3.2. Nutrient Availability11
2.6.1.3.3. Terminal Electron Acceptors11
  2.6.1.3.4. Soil Respirometry  12
2.6.1.4. Temperature13
2.6.1.5. Moisture13
2.6.1.6. pH14
2.6.2. Environmental Factors14
2.6.2.1. Geologic and Hydrologic Factors14
2.6.2.1.1. Adsorption and Absorption14
2.6.2.1.2. Contaminant Migration in Groundwater14
2.6.2.2. Bioavailability15
2.6.2.3. Soil Matric Potential16
2.6.2.4. Redox Potential16
2.7. Cyanide18
2.8. Biodegradation Mechanism of Cyanide19

2.8.1. Factors Affecting Cyanide Biodegradation in the Environment                                  20

CHAPTER THREE

3.3 Sterilization of Equipment and Media                                                                              33

CHAPTER FOUR

4.0. Results                                                                                                                             40

CHAPTER FIVE

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

  1. 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