This document describes an experiment to determine the biochemical oxygen demand (BOD) of a lake water sample. BOD measures the amount of dissolved oxygen needed by microorganisms to break down organic matter in water over 5 days. The results show increasing BOD readings over time. There are two types of BOD tests - seeded and unseeded. Seeded tests add microorganisms, while unseeded rely on microorganisms already present. High BOD effluent discharged into rivers can reduce oxygen levels and harm aquatic life. BOD testing helps evaluate sewage treatment plant performance and water quality.

1. Jordan University of Science and Technology
Faculty of Engineering
Civil Engineering Department
CE 453
“Environmental lab”
“Biological Oxygen Demand”
Experiment (6)
Student Name: Anas Mohammad Maghayreh.
Student ID: 20120023117.
Section #:1
Submission Date: 3/8/2015.
Submitted to: Dr. Hani Abu Qdais

2. Abstract:
BOD is the principle test to give an idea of the biodegradability of any
sample and strength of the waste. Hence the amount of pollution can be
easily measured by it. Efficiency of any treatment plant can be judged by
considering influent BOD and the effluent BOD and so also the organic
loading on the unit. Application of the test to organic waste discharges allows
calculation of the effect of the discharges on the oxygen resources of the
receiving water. Data from BOD tests are used for the development of
engineering criteria for the design of wastewater treatment plants.
In this experiment, determination of (BOD) of sample waste water from a
lake
Introduction
The biochemical oxygen demand determination is a chemical procedure for
determining the amount of dissolved oxygen needed by aerobic organisms in
a water body to break the organic materials present in the given water sample
at certain temperature over a specific period of time. BOD of water or
polluted water is the amount of oxygen required for the biological
decomposition of dissolved organic matter to occur under standard condition
at a standardized time and temperature. Usually, the time is taken as 5 days
and the temperature is 20°C. The test measures the molecular oxygen utilized
during a specified incubation period for the biochemical degradation of
organic material (carbonaceous demand) and the oxygen used to oxidize
inorganic material such as sulfides and ferrous ion. It also may measure the
amount of oxygen used to oxidize reduced forms of nitrogen (nitrogenous
demand).
:Objective
To become familiar with the concept of the standard BOD test and its
measurement in water and wastewater

3. Apparatus:
 BOD bottles.
 Pipet.
 BOD Sensors.
 BOD Incubator
Procedure:
1-Make a standard sample of 300 ml of each sample adding to it
distilled water recorded the dilution.
2-Put each sample in BOD bottles.
3-Put the bottles in the incubator at 20 (+/-) 1 C.
4-After 2 days read the BOD from the BOD meter direct for each
sample.
5-After 5 days read the BOD from the BOD meter direct for each
sample.
6-Then calculate the BOD for each sample.
and Results:Data
BOD Sensor readingDay (time)
171
182
213
214
245
Picture (2): BOD SensorsPicture(1):BOD Incubator
Table(1): BOD readings from sensor

4. Discussion:
About the trend , it is clear above that the bod consumed is not linearly related to
the time , since the organic matter consumption is a first order reaction and hence it
would produce an exponential time dependent function .
There is two types of tests ; seeded test and unseeded test
In unseeded test , bacteria ( microorganism is already there ) , all u need to add is
the dilution water + nutrient for them to work .
So that when u find C of O2 consumed all u have is to divide by the dilution factor
to take in to consideration the effect of the dilution water .(that the concentration of
organic matter has been diluted too .)
Conclusion:
On the basis of the BOD values, the characteristics of the water and the
biological activity of the incubated microflora can be determined. Effluent
with high BOD levels is discharged into a stream or river; it will accelerate
bacterial growth in the river and consume the oxygen levels in the river. The
oxygen may diminish to levels that are lethal for most fish and many aquatic
insects. As the river re-aerates due to atmospheric mixing and as algal
photosynthesis adds oxygen to the water, the oxygen levels will slowly
increase downstream. The biological capacity of a sewage treatment plant can
be tested by comparing the BOD value of a known control solution with the
BOD derived from the treatment plant. BOD detects only the destructible
proportion of organic substances and as a general principle is therefore lower
than the COD value, which also includes inorganic materials and those
materials which cannot be biologically, oxidized.

5. Picture(2) : BOD curve
Appendix: