Effects of Addition of Carbide on Sewage Degradation

ABSTRACT 

The objective of this research is to investigate the effect of addition of carbide on sewage degradation. To provide answers to the above objective, some laboratory tests were conducted which include Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total coliform, pH and Suspended Solids (SS) tests. Six experimental set ups of 5liters of sewage were constructed in the laboratory under anaerobic condition. Each of the sewage contained 0g (which served as control), 1g, 2g, 5g, 8g and 10g of fresh calcium carbide. Samples were collected twice per week for two months for the laboratory tests. The results from the tests showed that there was a gradual increase in the percentage of COD and BOD efficiency removal as the quantity of carbide added increased with time. Also, the number of positive coliform bacteria decreased as the quantity of carbide added increased with time. There was also a gradual increase in suspended solid as the quantity of carbide added increased. pH value increased as the quantity of carbide added increased with time. This could be due to the assumed calcium hydroxide produced from the reaction of sewage with calcium carbide since calcium hydroxide is a base. Calcium carbide can therefore be used in the reduction of BOD, COD and coliform bacteria in sewage.

TABLE OF CONTENTS

Title page .................................................................................................... i

Approval ..................................................................................................... ii

Certification..............................................................................................iii

Dedication ................................................................................................iv

Acknowledgement ...................................................................................v

Abstract ...................................................................................................vi

Table of contents ......................................................................................vii

List of tables .............................................................................................xi

List of figures ...........................................................................................xii

List of symbols ........................................................................................xiii

CHAPTER ONE: INTRODUCTION

1.1 Background of Study ......................................................................1

1.2 Statement of Problem......................................................................3

1.3 Objectives of Study.........................................................................4

1.4 Significance of Study......................................................................4

1.5 Scope of Study................................................................................4

CHAPTER TWO: LITERATURE REVIEW

2.1 Effects of Chemicals on Sewage Treatment ....................................5

2.2 Sewage ...........................................................................................23

2.3 Origin of Sewage ............................................................................23

2.3.1 Composition of Sewage .................................................................24

2.3.2 Nutrients in Sewage ........................................................................25

2.4 Characteristics of Wastewater.........................................................26

2.5 Chemical Characteristics of Wastewater.........................................27

2.5.1 Biological Oxygen Demand (BOD) ...............................................27

2.5.2 Chemical Oxygen Demand (COD) .................................................28

2.5.3 Dissolve Oxygen (DO) ...................................................................29

2.5.4 pH...................................................................................................30

2.5.5 Total Coliform (MPN) Test..............................................................31

2.6. Physical Characteristics of Sewage ...................................................31

2.6.2 Solids:..............................................................................................31

2.6.3 Odour:..............................................................................................32

2.6.4. Temperature:...................................................................................32

2.6.4.1 Importance of temperature: ...........................................................32

2.6.5 Color:...............................................................................................33

2.6.6 Turbidity:.........................................................................................33

2.7 Objectives of Wastewater Treatment (Agunwamba, 2001) .................33

2.8 Waste-Water Treatment Technologies ................................................34

2.9 Waste-Water Treatment Methods.......................................................34

2.9.1 Waste-Water Treatment Physical Processes.....................................34

2.9.1.1 Screening ......................................................................................35

2.9.1.2 Comminution ................................................................................36

2.9.1.3 Flow Equalization ......................................................................36

2.9.1.4 Sedimentation ......................................................................37

2.9.1.5 Horizontal flow .............................................................................37

2.9.1.6 Solid contact clarifiers...................................................................38

2.9.1.7 Inclined Surface Basins.................................................................38

2.9.1.8 Flotation........................................................................................38

2.9.1.9 Granular Medium Filtration ..........................................................39

2.9.2 Wastewater Chemical Treatment Processes......................................40

2.9.2.1 Chemical Precipitation ..................................................................40

2.9.2.2 Chemical Coagulation...................................................................41

2.9.2.3 Chemical Oxidation and Advanced Oxidation...............................43

2.9.2.4 Ion Exchange .................................................................................................... 43

2.9.2.5 Disinfection...................................................................................44

2.9.2.6 Dechlorination...............................................................................45

2.9.3 Biological unit processes..................................................................45

2.9.3.1 Activated-sludge process...............................................................46

2.9.3.2 Aerated Lagoons ...........................................................................48

2.9.3.3 Trickling Filters ............................................................................48

2.9.3.4 Rotating Biological Contactors .....................................................49

2.9.3.5 Stabilization Ponds........................................................................50

2.9.3.6 Completely Mixed Anaerobic Digestion .......................................51

2.9.3.7 Biological Nutrient Removal.........................................................53

2.9.3.7.1 Nitrification-Denitrification........................................................53

2.9.3.7.2 Phosphorus Removal..................................................................55

2.10 Application of Treatment Methods....................................................56

2.10.1 Preliminary Treatment....................................................................56

2.10.2 Primary Treatment .........................................................................57

2.10.3 Secondary Treatment .....................................................................57

2.10.4 Tertiary/Advanced Waste-Water Treatment...................................57

2.11 Natural Treatment Systems ...............................................................58

2.12 Degradation of Organic Matter .......................................................58

2.13 Carbide ...........................................................................................59

2.13.1Types of carbide .............................................................................59

2.13.2Calcium Carbide .............................................................................59

2.13.3 Effect of Calcium Carbide on Microorganisms ..............................60

CHAPTER THREE: METHODOLOGY

3.1 Collection of Samples and Description of Experimental Set Up .....62

3.2 Methods of Analysis. .....................................................................63

3.3 Laboratory Determination...................................................................63

3.2.1 Suspended Solids (SS) .....................................................................63

3.2.2 Dissolved Oxygen............................................................................64

3.2.3 Biochemical Oxygen Demand (BOD)..............................................64

3.2.4 Coliform tests...................................................................................65

3.2.5 Chemical Oxygen Demand (COD) .................................................65

3.2.6 pH value...........................................................................................66

3.3 Statistical Analysis using ANOVA .................................................66

CHAPTER FOUR: RESULTS ANALYSIS AND PRESENTATION

4.1 Biochemical Oxygen Demand (BOD).................................................69

4.2 Chemical Oxygen Demand (COD)......................................................69

4.3 Coliform .............................................................................................70

4.4 Suspended Solid (SS)..........................................................................70

4.5 pH.......................................................................................................70

4.6 Effect of Varying Percentages of Carbide on Waste Degradation........71

4.6.1 Biochemical Oxygen Demand (BOD)..............................................71

4.6.2 Chemical Oxygen Demand (COD) ..................................................72

4.6.3 Coliform Bacteria.............................................................................72

4.6.4 pH Value..........................................................................................73

CHAPTER FIVE: CONCLUSION AND RECOMMENDATION

5.1 Conclusion..........................................................................................81

5.2 Recommendation ................................................................................81

REFERENCES .......................................................................................82

APPENDIX .............................................................................................88