ABSTRACT

This study was carried out to investigate the microorganisms associated with the co-digestion of cassava peel, pig dung and cow rumen fluid for the production of biogas. These wastes were collected between July and August 2018 while the experimental studies were carried out between September and October 2018. The animal wastes were used as collected without further treatment. The blending ratio was 1:1:1 (10kg of each) and was initially mixed with water in the ratio of 1:2 (10kg of waste 20kg of water) and fed into a 15 liters laboratory scale anaerobic digester using improved rubber water dispensers (35cm diameter, 55cm high). The anaerobic digestion process was batch operated for 30 days under room temperature conditions. In order to achieve homogeneity of the slurry and discourage scum formation in the system, daily stirring was carried out using the inbuilt manual stirring mechanism in the digester. The physicochemical and microbial parameters of the slurry samples analyzed using prescribed equipments and standard methods. Daily biogas production was monitored and volume of gas measured using downward displacement method. The maximum biogas production was 1.90 Ld-1 for total anaerobic count of 3.61 x 106 cfu/mL and mean fungal count of 2.11 x 106 cfu/mL observed at the 16th day of biodigestion. The  results  indicate the incidence of Clostridium sp; Streptococcus sp, Lactobacillus sp; Bacillus sp, Micrococcus sp, Pseudomonas sp, Enterobacter sp, Fusarium sp, Aspergillus sp and Mucor sp were  isolated and identified in slurry of the codigestion of a cassava peel, pig dung and cow rumen fluid. 

TABLE OF CONTENTS

Title Page i

Certification ii

Dedication iii

Acknowledgements iv

Table of Contents v

List of Tables vii

List of figures viii

Abstract ix

CHAPTER 1

INTRODUCTION

1.1 Aim and Objectives of the Study 3

CHAPTER 2

LITERATURE REVIEW

2.1 History of Anaerobic Digestion (AD)  5

2.2 Anaerobic Co-digestion of Organic Wastes 7

2.3 Anaerobic Digestion Technology 8

2.3.1 Types of anaerobic digesters 9

2.3.2 System of anaerobic digesters 9

2.3.3 Modes of anaerobic digester  10

2.4 Maximizing Biogas Production through Co-digestion 11

2.4.1 Factors Affecting Anaerobic Digestion Efficiency 13

2.4.1.1 pH Level  13

2.4.1.2 Temperature  13

2.4.1.3 Mixing  14

2.4.1.3 Total Solid (TS)  15

2.4.1.4 Carbon to Nitrogen Ratio (C/N)  15

2.4.2 Advantages of Anaerobic Digestion to the Society    16

2.4.2.1 Odour Control  16

2.5 Literature Study on Various Feedstock 16

CHAPTER 3

MATERIALS AND METHODS

3.1 Study Area and Sample Collection 19

3.2 Materials 19

3.3 Methods 19

3.4 Microbial Analysis 20

3.4.1 Biochemical Tests 21

3.5 Physicochemical Analysis 23

3.6 Determination of Biogas Production 26

3.7 Data Analysis and Confirmation of Results 27

CHAPTER 4

RESULTS AND DISCUSSION

4.1 RESULTS 28

4.2 DISCUSSION 33

CHAPTER 5

5.1 CONCLUSION 35

REFERENCE

APPENDIX I

APPENDIX II

LIST OF TABLES

Table 4.1 Substrate and Microbial Composition 29

Table 4.2 Mean Anaerobic and Fungal Count 30

Table 4.3 Physicochemical Characteristics of Slurry For 30 Days 31

Table 4.4: Mean Volume Of The Biogas Produced 32