Oryza sativa husks and peels of Musa paradisiaca were pretreated by hydrothermal and acid fermentation using cassava mill effluent, and co-digested in a laboratory scale reactor maintained at 45 ± 2 ⁰C for 42 days. Five digesters were used for the experiment and each digester contained equal proportion of Oryza sativa husks and Musa paradisiaca in the ratio of 1:1; and cow dung (the inoculum) was added across. Substrate in Digester X (Control) was not pretreated. Digester A contained Oryza sativa husks pretreated hydrothermally; Oryza sativa husks in Digester B was pretreated with cassava mill effluent only, that of Digester C was pretreated hydrothermally before cassava mill effluent was used; while Digester D contained Musa paradisiaca peels and Oryza sativa husks mixed together before the combined pretreatment was applied. Digester X (control) generated cumulative biogas of 68mL gVS-1 while Digester C produced the biogas of 209mL gVS-1. Substrates in Digester C contained microbial load of 6.31Log10CFU g-1 while the control contained load of 5.23Log10CFU g-1. Methanogens of genera Methanosarcina, Methanocorpusculum, Methanobacterium, Methanobrevibacter and Methanothrix were isolated from the digestates with Methanosarcina sp. as a predominant methanogen. Substrate C contained total solids of 6.87 mg kg⁻¹ and volatile solid of 6.12 mg kg⁻¹ while the digester C digestate contained a total solid of 5.04mg kg⁻¹ and volatile solid of 4.49mg kg ⁻¹ on average. Therefore this experiment has proven that Oryza sativa husks and peels of Musa paradisiaca are potential substrates for biogas production.

TABLEOFCONTENTS

TITLEPAGE

Certification- - - - - - - - - - i

Dedication - - - - - - - - - - ii

Acknowledgements- - - - - - - - - iii

Tableofcontents - - - - - - - - - iv

Abstract - - - - - - - - - - v

CHAPTERONE

1.1Introduction - - - - - - - - - -

1.2Objectiveofstudy - - - - - - - - -

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CHAPTERTWO(LITERATUREREVIEW)

2.1Typesoffeedstock/substratesforbiogasproduction - - - -

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2.1.1Agriculturalwasteswithmanureco-digestion - - - - -

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2.1.2Energycropswithmanureassubstrate - - - - - -

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2.1.3Foodwasteswithmanureassubstrate - - - - - -

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2.1.4Industrialwastesandby-productsassubstrates- - - - -

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2.1.5Manureassubstratesforbiogasproduction - - - - -

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2.2Processesofanaerobicdigestionandmicroorganismsinvolved- - -

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2.2.1Hydrolysis - - - - - - - - - -

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2.2.2Acidogenesis- - - - - - - - - -

2.2.3Acetogenesis- - - - - - - - - -

2.2.4Methanogenesis - - - - - - - - -

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2.2.5Typesofanaerobicdigestion - - - - - - -

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2.2.6Advantagesofanaerobicdigestion- - - - - - -

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2.3Factorsaffectinganaerobicdigestionforbiogasproduction - - -

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2.3.1Natureortypeofsubstrate/sub-layercomposition - - - -

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2.3.2Digestertemperature- - - - - - - - -

2.3.3Hydraulicretentiontime(HRT) - - - - - - -

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2.3.4pH - - - - - - - - - - -

2.3.5Workingpressureinthefermenter- - - - - - -

2.3.6 Digesterdesign- - - - - - - - - -

2.4Methodsofimprovingbiogasproduction - - - - - -

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2.4.1Pretreatment- - - - - - - - - -

2.4.2Co-digestion - - - - - - - - - -

2.4.3Microbialbioaugmentation - - - - - - - -

2.4.4Agitationofthereactionsystem - - - - - - -

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2.5Compositionandutilisationofbiogas - - - - - -

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2.6Sourcesofthesubstratesandtheirchemicalcomposition - - -

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CHAPTERTHREE(MATERIALSANDMETHODS)

3.0Equipmentandsupplies - - - - - - - -

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3.1Aseptictechniquesandsterilizationprocedure - - - - -

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3.2Samplecollectionandprocessing - - - - - - -

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3.3Experimentaldesign - - - - - - - - -

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3.3.1Digestionofsubstrate - - - - - - - -

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3.3.2Measurementofbiogas - - - - - - - -

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3.4Proximateandmineralanalysis - - - - - - -

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3.5Microbialanalysis - - - - - - - - -

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3.5.1Mediapreparation - - - - - - - - -

3.5.2Isolationofanaerobicbacteria - - - - - - -

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3.5.3Characterizationandidentificationofbacteriaisolates- - - -

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CHAPTERFOUR

4.0Results

CHAPTERFIVE

DISCUSSIONANDCONCLUSION

5.0Discussionandconclusion - - - - - - - -

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5.1Conclusion - - - - - - - - - -

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REFERENCES

LISTOFFIGURESANDTABLES

Figure1Stagesofanaerobicdigestion - - - - - - -

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Figure2Dailybiogasproductionpatternofthedifferentsamples - - -

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Figure3Quantitativecomparisonofthemicrobialloadoftheisolate - -

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Figure4Totalsolidofthesamples- - - - - - - -

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Figure5Volatilesolids - - - - - - - - -

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Table1Chemicalconstituentofsomelignocellulosicmaterials - - -

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Table2Comparisonbetweenwetanddrydigestion - - - - -

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Table3Methodsofpretreatmentoflignocellulosicmaterials- - - -

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Table4Percentagecompositionofbiogas - - - - - -

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Table5Morphologicalandbiochemicalcharacteristicsofbacteriaspeciesisolated

fromthesamples afteranaerobicdigestion-- - - - - -

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Table6Cumulativebiogasyieldofsamples - - - - - -

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Table7Culturalcharacteristicsoftheisolate - - - - -