This document summarizes wastewater treatment processes and evaluates the efficiency of wastewater methods in Cameroon using the case of Buea. It describes primary, secondary, and tertiary wastewater treatment processes. For Buea, it outlines the design of a semi-centralized wastewater treatment plant including grit removal, primary sedimentation, biofiltration, oxidation ponds, and disinfection. Analysis shows the plant meets national wastewater discharge standards through significant reductions in BOD, nitrogen, and phosphorus levels. The proposed system is preferred by local residents over autonomous systems and could help Cameroon improve wastewater management.

1. WASTEWATER
ENGINEERING
WASTEWATER TREAMENT PLANT OF
CAMEROON
Written by:
WADJOU Christian (瓦朱)
M202261018
October 2022

2. 2
CONTENTS
Introduction
Wastewater processes
Efficiency of wastewater methods in
Cameroon: Case Of Buea
Conclusion
References

3. INTRODUCTION 3
 Wastewater treatment is the set of processes aimed at depolluting waste water before
returning it to the natural environment or reusing it. Wastewater is water which, following
its domestic, commercial or industrial use, is likely to pollute the environments into
which it would be discharged. This is why, with a view to protecting the receiving
environments, treatments are carried out on these effluents collected by the urban or
private sanitation network. The objective of the treatments is to minimize the impact of
wastewater on the environment. When treated water is reused, it is called wastewater
recycling.
 In recent years, there has been increasing concerns with regards to the management of
sewage in many parts of the world and Africa in particular. Water scarcity and water
pollution phenomena pose a critical challenge in many developing countries and
especially in urban areas where the authorities increasingly face difficulties in managing
water supply and the generated wastewater.

4. WASTEWATER PROCESSES 4
Primary treatment
o Filtration: The wastewater is passed through bar screen. Large objects, like rags, sticks,
plastic bags, cans, etc. are removed in this process.
o Grit and Sand Removal: The wastewater is slowly passed through the sedimentation
tank. Grit, sand and pebbles settle down at the bottom.
o Sedimentation: Water is then sent to the sedimentation tank. Solids, like faeces settle at
the bottom. Floatable impurities, like oil and grease float on the surface. A scraper removes
the faeces from the water. The impurity thus collected is called sludge, which is sent to the
sludge tank. The sludge can be used to produce biogas or to produce manure. A skimmer
removes the floatable impurities. Now, the water is called clarified water.

5. WASTEWATER PROCESSES 5
Secondary treatment
o Biofiltration
This method of secondary treatment of wastewater employs sand filters, contact filters, or
trickling filters to ensure that additional sediment is removed from wastewater. Of the three
filters, trickling filters are typically the most effective for small-batch wastewater treatment.
o Oxidation pond
Oxidation ponds, also called lagoons or stabilization ponds, are large, shallow ponds designed to treat
wastewater through the interaction of sunlight, bacteria, and algae. Algae grow using energy from the
sun and carbon dioxide and inorganic compounds released by bacteria in water. During the process
of photosynthesis, the algae release oxygen needed by aerobic bacteria. Mechanical aerators are
sometimes installed to supply yet more oxygen, thereby reducing the required size of the pond. Sludge
deposits in the pond must eventually be removed by dredging. Algae remaining in the pond effluent can
be removed by filtration or by a combination of chemical treatment and settling.

6. WASTEWATER PROCESSES 6
Secondary treatment
Figure 1: Aeration treatment

7. WASTEWATER PROCESSES 7
Tertiary treatment
Tertiary treatment is the next wastewater treatment process after secondary treatment.
o This step removes stubborn contaminants that secondary treatment was not able to clean
up. Wastewater effluent becomes even cleaner in this treatment process through the use of
stronger and more advanced treatment systems.
o Tertiary treatment technologies can be the extensions of conventional secondary biological
treatment to further stabilize oxygen-demanding substances in the wastewater or to remove
nitrogen and phosphorus.
o Tertiary treatment may also involve physical-chemical separation techniques such
as carbon adsorption, flocculation/precipitation, membranes for advanced filtration, ion
exchange, dechlorination, and reverse osmosis.

8. WASTEWATER PROCESSES 8
Figure 2: Tertiary treatment of wastewater

9. WASTEWATER PROCESSES 9
Figure 3: Example of a conventional treatment process in a municipal WWTP.

10. EFFICIENCY OF WASTEWATER METHODS
IN CAMEROON: Case Of Buea
10
Figure 4: Map showing location of study area.

11. EFFICIENCY OF WASTEWATER METHODS
IN CAMEROON: Case Of Buea
11
Figure 5: Layout of wastewater treatment pant for Municipality of BUEA

12. 12
Designed treatment units for the wastewater treatment plant
EFFICIENCY OF WASTEWATER METHODS IN
CAMEROON: Case Of Buea
Table 2: Dimension of the treatment units for the wastewater

13. EFFICIENCY OF WASTEWATER METHODS
IN CAMEROON: Case Of Buea
13
Theoretical performance of the designed wastewater treatment plant (continued)
• The theoretical performance of the design proposed is as seen below (Table 2). A
comparison of the performance is done with the national discharge standard for wastewater,
to see if environmental norms are met.
• From the table we can observe BOD reduction from 222 mg/l to 16.3 mg/L, Total Kjeldahl
Nitrogen reduction 55 mg/L to 22.5 mg/L and total phosphorus reduces from 15mg/L to 9.7
mg/L. The pollution reduction is capable of meeting the national discharge standard as seen
in (Table 2) above.
Table 2: Pollutant reduction by the treatment plant

14. CONCLUSION 14
 The semi-centralized sanitation system for the municipality of Buea, in view of
improving the management of wastewater of domestic origin.
 The system being proposed is able to meet the national discharge standards for
wastewater.
 The system proposed is accepted by 70% of the respondents and is preferred by them
relative to the autonomous sanitation system.
 Thus in the years to come Cameroon will be able to do much better with the appropriate
means and appropriate technology.

15. REFERENCES 15
 David et al., J Pollut 2018, 1:2, Design of a Semi-Centralized Wastewater Treatment System
for Developing Cities: The Case of Buea Municipality, Cameroon.
 1Auguste Landry Kamegne Kamtoh; 2Celestin Defo; 3Victor Dang Mvongo, International
PKFokam Conference on Science & Technology ; 30 – 31 March 2021, Yaoundé-Cameroon.
Anji Reddy Mareddy, Technology in Environmental Impact Assessment, 2017
 https://www.britannica.com/technology/wastewater-treatment/Flow-rates
 https://fr.wikipedia.org/wiki/Traitement_des_eaux_us%C3%A9es; 05/10/22; 23h07

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