Investigation Of Anaerobic Processes In Septic Tank As A Wastewater Treatment Option

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This project, aimed at investigating the anaerobic processes in septic tank as a waste water treatment option using waste water from septic tank and Soakaway as sample A and B respectively. It was observed that after the  analysis, sample A (septic tank which has fresh waste water) has higher value in conductivity =1708us/ cm3,  Total slid = 17490mg/l, Dissolved solid (16420mg/l), COD = (106mg/l), DO = (0.6883mg/l) and BOD = (106.6883mg/l) compared to sample B (Soakaway which contains waste water that has under gone anaerobic treatment) with values in conductivity =1170us/cm3, total solid = 14870mg/l dissolved solid = 12310mg/l COD = 68mg/l BOD = 68.4917mg/l. This is presented table 4.1. This indicates that there are more contaminant is septic tank than in the soakoway which has under gone anaerobic waste water treatment. From this present study, it was observed that septic tank is a rehable waste water treatment plant. 



Title Page                                                                                 i

Certification                                                                             ii

Approval Page                                                                          iii

Dedication                                                                               iv

Acknowledgement                                                                    v

Abstract                                                                                   vi

Table of Contents                                                                     vii


1.1    Background of the study                                                               1       

1.1.2    Waste water quality indicators                                                  3

1.2         Objectives of the study                                                              5

1.3         Significance of the study                                                           6

1.4         Scope of the study                                                                     6


2.1   sewage                                                                             8

2.2   septic tank                                                                       10

2.3   Waste Water                                                                     13

2.3.1What is wastewater and what is it made up of                              13

2.3.2What is Wastewater Treatment                                                       14

2.3.3Deciding which treatment option to use.                                       14

2.4   General Parameters to Measure Organic Pollution.          15

2.5 Levels of Wastewater Treatment                                                 16

2.6   Anaerobic and Aero.bic Digestion                                    20

2.6.1        Aerobic Digestion                                                             24

2.6.2        Aerobic Decomposition                                                    25

2.7   Anoxic Decomposition                                                     26

2.8   Sludge Accumulation                                                       26

2.9           Elimination of Phosphorus                                      27

2.10         Elimination of Toxic Substances                             27

2.11         Removal of Pathogens                                              28

2.12         Biogas Production                                                    29

2.13         Direct Discharge of Sewage                                      30

2.14         Pollution                                                                  33

2.15         Wastewater Management                                         35

2.16 Unit Process In Wastewater Treatment                            38

2.17    Estimating Wastewater Quantities                                        39

2.18   Sources And Variability In Wastewater Flow                  39

2.19Sedimentation                                                                 41

2.20Biological Treatment                                                                42

2.21Nutrient Removal                                                             44

2.22Disinfection                                                                     45

2.23Wastewater Management                                                 45




3.1    Experiment                                                                                      47

3.2   Field Experience                                                              48

3.3   Laboratory Experiment                                                    49

3.4           Experimental Procedure                                          54


4.1   Analysis Required:                                           69

4.2   Discussion                                                               70

4.3   Copper Content of the Parameter                             72

4.4   Iron Content                                                            72

4.5   Magnesium Content                                                72

4.6   Lead Content                                                           72

4.7   Chlorine Content                                                     73

4.8   Sulphate Content                                                    73

4.9   Chemical Oxygen Demand (Cod)                              73

4.10Dissolved Oxygen (DO)                                             74

4.11Biochemical Oxygen Demand (BOD)                                74

4.12 Total Solid                                                              74


5.1 Conclusion                                                                        75

5.2   Recommendation                                                     76

References                                                               77

        Appendix                                                                 78




1.1   Background of the Study

Human waste or more technically referred to as ‘excreta’ is defined by Chamber’s Concise 20th Century Dictionary as “useless matter discharged by animal alimentary”, animals being humans in this context. Excreta is made up of a solid matter, feces, and a liquid matter, urine and is essentially an organic compound. The constituents making up the compound are carbon, nitrogen, phosphorous, sulphur and hydrogen. Also present are fats, carbohydrates, enzymes, proteins, trace elements, pathogens and many different bacteria.

Sewage is a type of wastewater that comprises domestic wastewater and is therefore contaminated with feces or urine from people's toilets, but the word sewage is also used to mean any type of waste water.Sewage is the physical infrastructure, including pipes, pumps, and screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal. Wastewater can come from (indicates likely inclusions or contaminants)

·           Human waste (feces, used toilet paper, urine or other bodily fluids) also known as black water usually from lavatories.

            Cesspit leakage

            Septic tank discharge

            Sewage treatment plant discharge

            Wasting water (personal, clothes, floors, dishes etc) also known as greywater or sludge.

            The home Rainfall   collected   on   roofs,   yards,   hard-sandugsetc (generally clean with traces of oils and fuel).   

            A Groundwater infiltrated into sewage.

            Industrial waste.

            Toxic waste (metal plating, cyanide production, pesticide manufacturing; etc)

The composition of wastewater varies widely. This is a partial list of what it may contain.

·        Water  (more than 95  percent),  which is  often  added during flushing to carry waste down a drain

·        Pathogens    such   as   bacteria,   viruses,   proteins   and parasitic worms.

·        Non pathogenic bacteria.

·        Organic   particles   such   as   feces,   hairs, food, vomit, paper, fibers, plant materials, humans etc,

·        Inorganic particles such as sand, grit, metal particles, ceramics, etc.

·        Gases    such    as   hydrogen    sulfide,    carbon    dioxide, methane etc.

·        Pharmaceuticals  and  hormones 


1.1.2        Waste Water Quality Indicators

Anti-oxidizable material present in a natural waterway or in an industrial wastewater will be oxidized both by biochemical (bacterial) or chemical processes. The result is that the oxygen content of the water will be decreased. Basically, the reaction for biochemical oxidation may be written as.

Oxidizable material + bacteria +nutrient + O    CO2 +H20 +

Oxidized   inorganic   such   as   NO3   or   SO2.

Oxygen consumption by reducing chemicals such as sulfides and nitrites is typified as follows:

S2 + 202           SO42-

NO2- + I/202        NO3-

Since all natural waterways contain bacteria and nutrients, almost any waste compounds introduced into such waterways will initiate biochemical reactions (such as shown above).

Those biochemical reactions create what is measured in the laboratory as the biochemical oxygen demand (BOD). Such chemicals are also liable to be broken down using strong oxidizing agents and these chemical reactions create what is measured in the laboratory as the chemical oxygen demand (COD). Both the BOD and, COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as a measure of pollution effect.

The BOD test measures the oxygen demand of biodegradable pollutants whereas the COD test measures the oxygen demand of oxidizable  pollutants.

Wastewater treatments are numerous processes that can be used to clean up wastewaters depending on the type and extent of contamination. Wastewater can be treated in wastewater treatment plants which include. Physical, chemical and biological treatment processes. Municipal wastewater is treated in sewage treatment plant (which may also be referred to as wastewater treatment plant), Agricultural wastewater may be treated in agricultural wastewater treatment processes, whereas industrial wastewater is treated in industrial wastewater   treatment processes.

Treated wastewater can be reused as drinking water in industry (cooling towers), in artificial recharge of aquifers, in agriculture and in the rehabilitation of natural ecosystems (for example in Florida's everglades).

There are numerous benefits of using recycled water for irrigation, including the low cost when compared to other-sources, particularly in an urban area, consistency of supply (regardless of season, climatic conditions and associated, water restrictions) and general consistency of quality. Irrigation of recycled wastewater is also considered as a means for plant   fertilization and particularly nutrients supplementation. (CSL London Olympics waste preview).

1.2 Objectives of the study

The main objective of this study includes the following;

1.     Determination of acidity, alkalinity and pH contents in a waste water

2.     Determination of biochemical oxygen demand (BOD) in wastewater

3.     Determination of chemical oxygen demand (COD) in


4.     Determination of chemical constituents in a wastewater

5.     Modern management of wastewater


1.3   Significance of the study

This project aims at determining the anaerobic processes taking place in the septic tank as a wastewater treatment option. Also to determine if septic tank is a reliable waste water treatment plant.


1.4   Scope of the Study

This project is based on the determination of the anaerobic processes taking place in the septic tank. Also to determine if the waste water treatment is really treating the waste water well. And also to check the level of contaminants present in the septic tank and soakaway pit on the following parameters through physical and chemical analysis. Physical analysis: temperature, pH, Conductivity and Turbidity. Chemical analysis: biochemical oxygen demand (B.O.D), chemical oxygen demand (C.O.D), acidity, alkalinity,  Total Solid, Dissolved solid, Suspended Solid, Total Hardness, Copper, Iron, Lead, Chloride, Sulphate, Calcium/ magnesium and Phosphorus present in wastewater.


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