Determination of Bod Kinetic Parameters and Evaluation of Alternate Methods – India

Determination of Bod Kinetic Parameters and Evaluation of Alternate Methods - India
  • Determination of Bod Kinetic Parameters and Evaluation of Alternate Methods – India

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A Thesis submitted to THAPAR INSTITUTE OF ENGINEERING & TECHNOLOGY, PATIALA in partial fulfillment of the requirements for the award of degree of MASTER OF ENGINEERING in ENVIRONMENTAL ENGINEERING by BALWINDER SINGH Under the supervision of





This is to certify that the thesis entitled, “ Determination of BOD Kinetic Parameters And Evaluation of Alternate Methods” submitted by Balwinder Singh in partial fulfillment of the requirements for the award of Degree of MASTER OF ENGINEERING in ENVIRONMENTAL ENGINEERING to Thapar Institute of Engineering & Technology (Deemed University), Patiala, is a record of student’s own work carried out by him under our supervision and guidance. The report has not been submitted for the award of any other degree or certificate in this or any other university or institute.

(Dr. Anita Rajor) Department of Biotech. & Env. Sciences, Thapar Institute of Engg. & Tech., Patiala – 147004

(Dr. Sunil Khanna) Professor & Head, Department of Biotech. & Env. Sciences, Thapar Institute of Engg. & Tech., Patiala – 147004

(Dr. A. S. Reddy) Lecturer (Selection Grade) Department of Biotech. & Env. Sciences, Thapar Institute of Engg. & Tech., Patiala – 147004

(Dr. D. S. Bawa) Dean (Academic Affairs), Thapar Institute of Engg. & Tech., Patiala – 147004


I here by declare, that the thesis report entitled, “Determination of BOD Kinetic Parameters And Evaluation of Alternate Methods” written and submitted by me to Thapar Institute of Engineering & Technology (Deemed University), Patiala, in partial fulfillment of the requirements for the degree of MASTER OF ENGINEERING in ENVIRONMENTAL ENGINEERING. This is my original work & conclusions drawn are based on the material collected by me.

I further declare that this work has not been submitted to this or any other university for the award of any other degree, diploma or equivalent course.


ACKNOWLEDGEMENT I wish to express my deep gratitude to Dr. A. S. Reddy, Lecturer (Selection Grade), Department of Biotech. & Environmental Sciences, Thapar Institute of Engg. & Technology, Patiala for his invaluable guidance, inspiration, valuable suggestions, encouragement during the entire period of present study. I will not hesitate to express sincere thanks to Dr. Anita Rajor for providing the constant encouragement and making the lab work possible under her able guidance.

I am highly thankful to Dr. Sunil Khanna, Head, Department of Biotech. & Environmental Science for granting permission for the use of departmental labs.

Lastly, I am thankful to my colleagues, friends and family members for bearing with me and providing me all moral help during the entire period of my work.











List of tables


List of Figures


Chapter: 1 Introduction


1.1 Background information and objectives of the study 1.2 Overview of the contents of the report 1.3 Importance of the study Chapter: 2 Literature Review

6 – 11

Chapter: 3 Materials and Methods

12 – 33

3.1 Introduction 3.2 Sampling 3.3 Serial BOD testing 3.4 Estimation of BOD kinetic parameters 3.4.1 Method of Moments 3.4.2 Least Squares Methods 3.4.3 Thomas Graphical Method 3.4.5 Iteration Method 3.4.6 Fujimoto Method 3.5 comparison of different methods of estimation

CONTENTS Chapter: 4 Results & Discussion

PAGE. NO. 34 – 61

4.1 Introduction 4.2 Results 4.3 Evaluation of methods 4.4 Discussion 4.5 Conclusion

Chapter: 5 Conclusion

62 – 63


64 – 66




Page No.


Typical values of k and L0 of various waters



BOD results of River Satluj sample (SAT-7)



BOD results of East Bein River (EB-4)



BOD results of Treated Municipal Sewage



BOD results of Treated Distillery Effluents



BOD results of Treated Dairy Effluents



BOD results of Treated Textile Effluents



Duration of lag observed in serial BOD test



BOD kinetic parameters values for SAT-7



BOD kinetic parameters values for EB-4



BOD kinetic parameters values for Treated Municipal Sewage



BOD kinetic parameters values for Treated Distillery Effluents



BOD kinetic parameters values for Treated Dairy Effluents



BOD kinetic parameters values for Treated Textile Effluents



Sum of absolute differences between observed and expected BOD values



Results discarded from the method evaluation



Suitability of methods for different samples



Figure No.


Page No.


Fate of biodegradable organic matter, during BOD test



Moore’s diagram for n=7 days



Thomas method for SAT-7 (IV)



Daily Difference method for SAT-7 (IV)



Fujimoto method for SAT-7 (IV)


4.1 – 4.4

Method comparison for SAT-7 (sample I – IV)

52 – 53

4.5 – 4.8

Method comparison for EB-4 (sample I – IV)

54 – 55

4.9 – 4.11

Method comparison for Sewage (sample I – III)

56 – 57

4.12 – 4.14

Method comparison for Distillery Effluent (sample I – III)

57 – 58

4.15 – 4.17

Method comparison for Dairy Effluent (sample I – III)

59 – 60

4.18 – 4.20

Method comparison for Textile Effluent (sample I – III)

60 – 61

CHAPTER: 1 Introduction

1.1 Background information and objectives of the study: Biodegradable organic matter is one of the important pollution parameter for water and wastewater. Being heterogeneous (suspended colloidal and dissolved forms) and being composed of a wide variety of compounds, it is very difficult to have a single direct method for estimating its organic matter concentration in any water or wastewater sample. Because of this reason, indirect methods, like BOD, COD, etc. are dependent upon for the measurement of organic matter concentration. These methods measure the organic matter concentration through estimating the amount of oxygen required for its complete oxidation. Methods like COD are quite accurate and take very less time for estimating the organic matter concentration. But they cannot differentiate biodegradable organic matter from non-biodegradable organic matter. Further, COD is not capable of accurately estimating volatile organic matter and organic matter with nitrogen bases. Because of these reasons, BOD is preferred over COD. In the BOD test microorganisms are used for bio-oxidation of the organic matter in the presence of oxygen. The amount of oxygen utilized in the bio-oxidation process is measured and expressed as organic matter concentration in terms of oxygen. This method actually estimates the amount of biodegradable organic matter rather than the total organic matter present in water or wastewater sample. In this method, the sample is diluted to appropriate level, seeded with sufficiently acclimatized microbial populations, aerated and then filled in the air proof BOD bottles and incubated under favaourable conditions. Through measuring the initial and final dissolved oxygen present in the incubated sample, the amount of oxygen consumed in the bio-oxidation process is estimated. Fig.1.1 shows the fate of biodegradable organic matter during the incubation in the BOD test.


Organic Matter

Microorganism Biodegradable Organic Matter

n tio a id ox o Bi Bi os yn th es is


CO2+H2O+NH3+Metabolic Synthesized energy microbial biomass Auto oxidation by microorganisms O2

Residual biomass


Non-Biodegradable Organic Matter

CO2 + H2O + Metabolic energy


Fig. (1.1): Fate of the biodegradable organic matter, during incubation in the BOD test.

The bio-oxidation process is rather slow and complete bio-oxidation takes a quite long time (over 25 days). This necessitates incubation of the sample for quite long time for getting the total biodegradable organic matter concentration. In practice, incubating the sample, for such a long time, is not feasible and even if feasible, since the results cannot be real time measurements; their utility is very limited. To avoid this long incubation period a compromising approach is followed. In this approach the sample is incubated for relatively short period of 5 days for getting major portion of the organic matter bio-oxidized. The obtained results are extrapolated through using a mathematical model [BOD kinetics model, y = L0 (1-e-kt)]. Use of this BOD kinetics model requires prior knowledge of the BOD kinetic parameters (k & L0). The required kinetic parameters for the water or wastewater in question are obtained through laboratory experimentation (through conducting serial BOD test, wherein the BOD exerted of the incubated sample is measured at regular intervals). Results of the serial BOD test are used in estimating kinetics parameters with the help of one of the multitude methods available. Accuracy and reproducibility of BOD testing is not very satisfactory. Hence estimation of the kinetic parameters which uses serial BOD test results is prone to become much more inaccurate. For getting satisfactory results selection of appropriate method of calculation of kinetic parameters is very important. Present study is actually concerned with evaluation of the commonly used alternative methods of kinetic parameters estimation. In the present study the following six methods have actually been evaluated: 1. Method of Moments 2. Method of Least Squares 3. Thomas Graphical Method 4. Daily Difference Method 5. Iteration Method

6. Fujimoto Method For evaluating these methods, results are obtained from serial BOD testing for 7 days, of the following samples have been used: 1. Satluj river water sample 2. East Bein river water sample 3. Treated Municipal sewage sample 4. Treated Distillery effluent 5. Treated Dairy effluent 6. Treated Textile effluent 1.2 Overview of the contents of the report: This M.E. dissertation includes five chapters. Chapter 1 is introduction. In this chapter after giving brief background information on BOD and BOD kinetics, objective of the study is introduced. This chapter also includes overview of the contents of the thesis and importance of the present study. In Chapter 2, review of published literature on BOD, BOD kinetics and methods for BOD kinetic parameters estimation is presented. In the Chapter 3, the approach followed for achieving the objective of the study is presented. In addition to this, this chapter also includes a brief overview on the commonly used methods of BOD kinetic parameters estimation. Chapter 4 includes the results of the study and discussion. The results mainly include three components, the serial BOD test results, the estimated BOD kinetic parameters, and results of evaluation of the alternate methods of kinetic parameters estimation. In the discussion, it has been shown, which of the method is most appropriate and why.

The report concludes with Chapter 5, wherein the study is summarized, limitations of the study are highlighted and scope for further study is brought forward. 1.3 Importance of the study: Design, operation and control of biological treatment units require knowledge of ultimate BOD whereas the BOD test gives 5 days BOD value or 3 days BOD value. BOD tests are usually conducted at 20ºC, whereas temperature in the biological treatment units can be different. These situations make BOD kinetics and BOD kinetic parameters estimation very important. Very few laboratories actually perform BOD kinetic parameters studies and ultimate BOD is found through thumb rules, which is undesirable. In the light of these, the present study proves very important. The study brings about the fact that all methods of kinetic parameters estimation cannot be appropriate for all conditions. One has to sensibly select appropriate methods for estimating the kinetic parameters.

CHAPTER: 2 Literature Review

An attempt has been made to review the available literature on BOD, BOD kinetics and available methods for kinetic parameters estimation. In the nineteenth century the performance of sewage treatment plants was measured mainly by the chemical analysis related to the determination of various forms of nitrogen; as an index of the state and progress of the oxidation of organic matter. Frankland, 1868 as referred by William (1971) first observed that depletion of dissolved oxygen in the wastewater containing organic matter was due to chemical reactions. He observed that depletion of oxygen was dependent on the time of storage. Dupret 1884 as referred by William (1971) recognized that oxygen depletions were due to the activity of microorganisms. The classical equation for expressing the BOD process is: Substrate + bacteria + O2 + growth factors

&22 . H2O + increased

bacteria + energy ————————————————————-(2.1) The royal commission on Sewage Disposal, 1912, chose an incubation period of five days for the BOD test because that is the longest flow time of any British river to the open sea. An incubation temperature of 20oC was chosen because the long-term average

summer temperature in Britain was 18.3oC (Nesarathnam,1998).

Adeney 1928 as referred by Jenkins (1960) defined the absolute strength of sewage as the amount of dissolved oxygen required for its complete biochemical oxidation. Winkler’s method was mostly used to determine the dissolved oxygen content in water (Standard Method 1995). Bruce, (1993) suggested headspace biochemical oxygen demand (HBOD) test having three main advantages: the test does not require sample dilution, oxygen demand determined with in a shorter period of time (2436hrs) that can be used predict 5-day BOD value and the experimental conditions used in the HBOD test, more accurately reproduce the hydrodynamic and culture

conditions. Booki, (2004) suggested the use of fibre optic probe to obtain oxygen demands in 2 or 3 days in respirometric tests, and then 5-day BOD can be predicted from the results. While a standard BOD test procedure developed for certain effluents has been widely accepted, disagreements regarding the basic mechanisms and kinetics of the test continue to persist. In fact, a review of the history of the BOD test and the related mathematical procedures leads to the conclusion that the only universally accepted concept is that the basic reactions involved are biochemical in nature. The controversies about BOD kinetics arises largely due to the fact that the distinction between BOD as a test and BOD as a microbial metabolic process is frequently overlooked. (The term process is used to refer to the series of cellular enzymatic reactions, which bring about the conversion of given reactants to final products under the constraints of the prevalent environmental constraints and factors)(William E.1971). Phelps (1953) has presented the developmental history of BOD test and its kinetics. He after studying the simplified reaction system associated with eq. 2.1 suggested that the velocity of the reaction varied directly as the concentration of the bacterial food supply (substrate). The concentration of the substrate was rated in terms of oxygen equivalents as indicated by the test. Nonetheless, Phelps realized the limitations of his empirical monomolecular law and delineated them quite clearly. In essence, he concluded that though there was no actual reason why BOD reaction should be monomolecular, the approximation was sufficient for practical applications. He also noted that there were instances where the approach was not applicable. Despite its stochastic nature, the first order approach has been applicable under some circumstances, and it is apparently an acceptable approximation of a more general deterministic expression or expressions. The BOD test is designed to determine the quantity of oxygen required by the biota of the system to completely oxidize the biologically available organic material William, (1971). The quantity of oxygen required is the sum of oxygen consumed by:

1. The bacteria of the ecosystem with in the confines of the BOD bottle as they utilize the organic material (substrate) to support synthesis and respiration. 2. The consumers (protozoa) as they ingest the bacteria as a food source to support their growth and respiration. 3. The process of auto destruction of bacterial and protozoan biomass produced as a result of the preceding two processes. During the initial phase of the BOD process, substrate is assimilated by bacteria under aerobic conditions and a major portion of the substrate is converted to biomass. When bacterial production has reached a maximum, i.e. when the substrate concentration has been reduced to essentially zero concentration, the bacteria will either enter the auto destruction phase, or if protozoa are present, they will start utilizing the bacteria as a food source. When essentially all the bacteria have been so consumed the protozoa will enter an auto destruction phase. Conceptually then, the BOD test is terminated when the concentration of bacteria and protozoa have returned to their respective concentration which prevailed at the start of the test. Gaudy (1972), Le Blanc (1974), Stones (1981) and Shrivastava (1982) have also reviewed the BOD test. Studies of streeter and Phelps, 1925 as referred by Gaudy (1972) led to the following first order equation (BOD kinetic model). dL/dt =

– kL

In integrated form Lt


In other form BODt

L0 e-kt =

L0(1 – e-kt) ——————————————-(2.2)

Where, BODt =

BOD exerted in ‘t’ days of incubation.


BOD exerted at any time ‘t’




Oxygen demand yet to be exerted at t=0 i.e. ultimate BOD.



BOD reaction rate constant and its units are time-1.



Time of incubation.

Analysis of the above first order equation indicates two variables, rate constant k and ultimate BOD, L0 are dependent on each other. If the rate of biochemical oxidation is very high, the value BOD5 is essentially equal to the ultimate BOD. (Ramallho, 1983). Maity and Ganguly (2002) observed that experimental ‘k’ value is always greater than the theoretical ‘k’ value by 18% and 24%, when the sample is tested at 20oC and at 27oC respectively. Shrivastava (2000) studied the effect of sewage and indigenous seed on BOD exertion and found that with indigenous seed the BOD values are observed more and kinetic study revealed that with indigenous seed the ultimate BOD is more and value of rate constant is higher in both first order and second order equations with sewage seed. Typical values of k and L0 are listed in table 2.1 (Peavy, 1985) Table: 2.1

Typical values of k & L0 for various waters. K (Day-1)

L0 (mg/l)