Isolation And Characterization Of Microorganisms Involved In Biogas Production Using Cassa Peels

Abstract

This study was aimed at investigating microorganisms associated with biogas production using cassava peel as substrates. Cassava peels obtained after peeling cassava roots were anaerobically digested using a 5 litre capacity fermentor. The peels were blended and mixed with water, in the ratio of 1:2. Standard microbiological methods and anaerobic biodigester were used to screen the isolates and the wastes substrate for biogas production. The mean flammable biogas yield of the cassava peels was 13.7Litre/total mass of slurry. Analysis revealed that the temperature of raw substrates ranged between 26°C and 30°C while the pH varied between 4.04 and 6.86 during digestion. The results of the total heterotrophic and anaerobic microbial counts during the digestion period showed a steady variation in the anaerobic bacteria and fungal counts as fermentation progressed. The load obtained for the total heterotrophic bacteria and anaerobic bacteria were within 2.9x104cfu/ml to 9.4x104cfu/ml and 1.8x103cfu/ml to 6.9x103cfu/ml respectively. Similarly the fungal count obtained through the digestion period ranged from 1.1x10cfu/ml to 3.9x10cfu/ml. The bacterial isolates were identified as Pseudomonas sp, Escherichia coli, Bacillus sp, Clostridium sp, and Methanococcus sp, while fungi isolated were identified as Saccharomyces cerevicae, Aspergillus sp and Penicillium sp.

TABLE OF CONTENT

Title page ﾿ i

Certification ﾿ ii

Declaration ﾿ iii

Dedication ﾿ iv

Acknowledgement ﾿ v

Table of content ﾿ vi

List of Table ﾿ vii

List of Figures ﾿ viii

Abstract ﾿ ix

CHAPTER 1:

INTRODUCTION

1.1 ﾿     Introduction ﾿ 1

1.2    Aim and Objectives ﾿ 4

CHAPTER 2:

LITERATURE REVIEW

2.0      Literature Review ﾿ ﾿ 5

2.1. ﾿ Biogas ﾿ 5

2.2 ﾿ Biogas Composition ﾿ 5

2.3 ﾿ Chemical Characteristics of Biogas ﾿ 6

2.4 ﾿ Physical Characteristics of Biogas ﾿ 6

2.5 ﾿ Methane as a Component of Biogas ﾿ 6

2.6 ﾿ Collection of Biogas ﾿ 7

2.7 ﾿ Types of Biogas bioreactor ﾿ 7

2.8 ﾿ Substrate  (Cassava Peels ) ﾿ 7

2.9 ﾿ Microbial Floral Present in Production of Biogas ﾿ 8

2.10 ﾿ Microbiology and Biochemistry of Biogas Production ﾿ 8

2.10.1 ﾿ Hydrolysis ﾿ 10

2.10.2 ﾿ Acidification/Acetogenesis ﾿ 10

2.10.3 ﾿ Methane Formation ﾿ 10

2.11 ﾿ Interactions between the Various Microbial Groups ﾿ 11

2.12 ﾿ Factors Influencing Biogas Production. ﾿ 11

2.12.1 ﾿ Temperature ﾿ 11

2.12.2 ﾿ pH (Hydrogen Concentration) ﾿ 12

2.12.3 ﾿ Substrate Quality and Characterization ﾿ 13

2.12.4 ﾿ Loading Rate ﾿ 13

2.12.5 ﾿   Bioreactor  Design ﾿ 14

2.13 ﾿ Benefit of Biogas Technology ﾿ 14

2.14 ﾿ Domestic and Industrial Uses        ﾿ 15

2.15    Other Uses of Biogas ﾿ 15

CHAPTER 3:

3.0 ﾿ MATERIALS AND METHODS 

3.1 ﾿ Construction of Anaerobic Digester ﾿ 16

3.2 ﾿ Sample Collection ﾿ 16

3.3 ﾿ Pretreatment of Cassava Peels ﾿ 16

3.4 ﾿ Charging of the Digester ﾿ 16

3.5 ﾿ Determination of Quantity of Biogas Produced ﾿ 16

3.6 ﾿ Determination of Physiochemical Analysis of the Slurry in the Bioreactor. ﾿ 17

3.6.1 ﾿ Hydrogen Ion Concentration (pH) ﾿ 17

3.6.2 ﾿ Temperature ﾿ 17

3.6.3 ﾿ Dissolved Oxygen (DO) ﾿ 17

3.7 ﾿ Determination of Biogas Flammability ﾿ 17

3.9 ﾿   Collection of Sample for Isolation ﾿ 17

3.9 ﾿ Media Preparation ﾿ 18

3.10 ﾿ Isolation Of Microorganisms (Fungi And Bacteria) ﾿ 18

3.13  Isolation And Identification Of Bacterial Isolates ﾿ 19

3.14  Gram Staining ﾿ 19

3.14  Biochemical Identification of the Isolates ﾿ 19

3.14.1 Catalase test ﾿ 20

3.14.2  Coagulase Test ﾿ 20

3.14.3  Oxidase Test ﾿ 20

3.14.4   Indole Test ﾿ 20

3.14.5 Citrate Utilization Test ﾿ 21

3.14.6 Urease Test ﾿ 21

3.14.7 Methyl Red Test ﾿ 21

3.14.8 Voges- Proskauer Test ﾿ 21

3.14.9 Sugar Fermentation Test ﾿ 21

CHAPTER 4:

RESULTS

4.0    Results of Biogas Produced and microbial isolates ﾿ 23

4.1    Results ﾿ 23

CHAPTER 5:

 DISCUSSION, CONCLUSION AND RECOMMENDATION

5.1    Discussion ﾿ 29

5.2    Conclusion ﾿ 31

5.3    Recommendations ﾿ 32

REFERENCES ﾿ 47