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
2.13.1……………………………………………………………………………………… Types of carbide 59
2.13.2……………………………………………………………………………………… Calcium 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
CHAPTER ONE
INTRODUCTION
- Background of Study
Air, water and land pollution brought about by sewage is one of the major problems face by most cities around the world. As the world population increases and cities expand, human waste production consequently increases. These wastes, nonetheless, could be a major source of harmful heavy metals, organics pollutants, pathogenic agents and disease causing vectors. Getting rid and/or managing these wastes without causing undesirable impact on the environment and the health of human remains a huge challenge to the environmental engineers.
Despite the challenges posed, if sewage is properly treated, it can prove to be beneficial; sewage sludge could be used to improve the physical, chemical and biological characteristics of agricultural soils as well as supply growing plants with essential macro elements such as Nitrogen(N), Phosphorus(P), Sulphur(S) and micro nutrients such as Copper(Cu), Iron(Fe), Molybdenum(Mb), and Zinc(Zn) which can increase crop yield (Katterman and Day, 1989).
There are traditional sewage disposal practices which are inimical to the environment and man’s health. In rural areas, pit latrines constructed for the deposition of human excreta are discharged into the streams and rivers without treatment. In cities, septic tanks constructed to receive human effluents could indiscriminately be disposed in an event of tank being filled up. This could lead to an increase in the loading of organics to the nearby surface water with its attendant health challenge. Furthermore, careless disposal of sewage could lead to creation of a chain of problems like spread of diseases, eutrophication, increase in Biological Oxygen Demand (BOD), etc., and consequently, results to environmental degradation.
Generally, there are various types of liquid waste generated in urban centers: human excreta, domestic wastes produced in households, hospital wastes, industrial effluents, agricultural liquid wastes and nuclear wastes. When improperly handled and discharged, liquid wastes pose a serious threat to human health and the environment because of their ability to enter watersheds, pollute ground water and drinking water (US EPA, 2009).
Cities in developing countries like Nigeria lack the resources to treat wastewater before disposal. Even where expensive wastewater treatment plants are installed, only a small percentage of the total wastewater volume is treated before discharge resulting in rivers, lakes and aquifers becoming severely contaminated (Sanamdikar and Harne, 2012). Poverty, lack of awareness and general apathy make sewage treatment a hydra-headed challenge in Nigeria. Institutional support and legislation for pollution control are therefore needed.
However, there are many technics available that can render the sewage harmless and safely dischargeable to the environment. But, these may be uneconomical as they could also be sophisticated in use. This gives credence to the research work. The addition of calcium carbide to sewage treatment has been in use but ratio to be used is unknown.
The research therefore seeks to ascertain the appropriate mass of calcium carbide that will impact significantly on certain quantity of sewage. This therefore could provide a reliable treatment model for use. Hence, the research work would be beneficial to the civil/environmental engineering students, the practising engineers and municipal waste treatment agencies.
1.2 Statement of Problem
Indiscriminate discharge of sewage in rivers and on the environment is high in Nigeria. There is concern that if urgent measures are not taken to treat this sewage before discharging it, this could result to human health, water, air, and soil quality and plants risks. This project will seek answers to what extent liquid sewage treated with calcium carbide helps reduces its harmful effect to the environment when discharged.
- Objective of Study
The objective of this project is to investigate the effect of addition of carbide on sewage degradation.
1.4 Significance of Study
The significance of this project is that it will address the urgent need of treating sewage before discharging it into the environment and rivers in order to reduce its harmful effect on the receiving bodies and make for a safe and healthy environment. It will also guide the civil/environmental engineers and students how calcium carbide could be used to treat sewage.
1.5 Scope of Study
This project is limited to the investigation of the strength of sewage when treated with calcium carbide.
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