Wastewater Treatment and Water Treatment Processes in Civil Engineering

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CIVIL ENGINEERING
By Name
Course
Instructor
Institution
Location
Date

Civil Engineering 2
Waste Water Treatment,
Water Treatment Process, and Field Trip

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Environmental Engineering (Wastewater Treatment)
Introduction
Wastewater treatment refers to the techniques of changing water is which not recommended for
use into a form that can return to be reused or change it back to water that has least impacts on
the environment (Medema, 2011, p.198).
Typical conventional wastewater treatment process used for the removal of carbon
Primary treatment
The primary treatment involves various steps such as sedimentation, removal of grit and
screening. Grit is used in the elimination of dense material, while screening removes large
objects from the water. The water is passed through sedimentation tanks after going through
screening and removal of grits. In the sedimentation tanks, sludge settles as some of the
substances in the water rise to the surface of the water where they are skimmed off (Faust, 2013,
p.255).
Secondary treatment
Secondary treatment involves the mechanisms by which microorganisms are not removed in the
primary process are joined together to form large molecules or particles through supplying them
with chemicals and oxygen that facilitates their growth so that they can easily be removed
(Ramalho, 2012, p.167).

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Figure 1: Schematic Diagram for Wastewater Treatment Plant
Oxygen supply
Experimental Procedure
1. By keeping a ratio of nitrogen, carbon, and phosphorus at 15:100: 1, synthetic wastewater
is prepared
2. Biomass extracted from a wastewater treatment plant is mixed with the synthetic
wastewater
3. Microbial activities are kept steady and constant through sufficient supply of oxygen and
keeping the temperature at 24⁰C

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4. The concentrations of heavy metals in samples of treated drinking water and wastewater
were measured and the difference noted
5. The concentration of phosphorous, ammonia, nitrate and nitrate in samples of treated
drinking water and wastewater are measured and the difference noted
6. The amount of dissolved organic carbon in the synthetic wastewater is measured before
and after the experiment
Data, Results, and Discussion
Dissolved Oxygen (DO)
All the processes that were involved in the activation of sludge in the aeration system were
influenced by dissolved oxygen. Through appropriate aeration, there was sufficient supply of
oxygen that hindered the microorganisms from settling out of the mixed liquor (Rakness, 2011,
p.177).
A conclusion from the measurement of dissolved oxygen
The amount of dissolved oxygen was 9.4 mg/L at zero minutes which was observed to drastically
decrease to 8.6 mg/L at the time of 30 minutes. This was an illustration that the amount of carbon
dioxide as well in the system was reducing and thus the less volume of oxygen was then needed
to eliminate the traces of carbon. The change in the volume of dissolved oxygen with time is
recorded as shown in the table below

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Table 1: Dissolved Oxygen
0 5 10 15 20 25 30 35
0
2
4
6
8
10
12
time in minutes
Dissolve Oxygen mg/L
Figure 2: Amount of dissolved oxygen (mg/L) against time (min)
As can be observed from the graph, the concentration of dissolved oxygen needed in the system
is inversely proportional to the time. This illustrated that an increase in the time of contact of