Bulletin of Environment, Pharmacology and Life Sciences

Bull. Env. Pharmacol. Life Sci., Vol 4 [1] December 2014: 55-60
©2014 Academy for Environment and Life Sciences, India
Online ISSN 2277-1808
Journal’s URL:http://www.bepls.com
CODEN: BEPLAD
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ORIGINAL ARTICLE

Cost/Benefit Evaluation Of Wastewater Treatment Plant Types

( SBR, MLE, Oxidation Ditch), Case Study: khouzestan, Iran
Reza Jalil Zadeh Yengejeh1,2, Kamal Davideh1.2, Ahmad Baqeri3,4
1. Department of Environmental Engineering, Khouzestan Science and Research Branch, Islamic Azad
University, Ahvaz, Iran.
2. Environmental Engineering Department, ,Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
3. Department of Agricultural Management, Khouzestan Science and Research Branch, Islamic Azad
University, Ahvaz, Iran .
4. Department of Agricultural Management, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
Email: ahmadbagheri53@gmail.com

ABSTRACT
In respect to the change of climatic conditions and global warming, the position of water sources in many countries is in
crisis. Therefore, constructing sewage treatment plants is of the first priorities of developmental plans aiming at
preventing from the pollution of water sources and reusing the sewage , but owing to investors’ insufficient awareness of
the economic interests of these plans and the lack of calculation of their cost and benefit indices (CBI) investment in this
sector is limited to the governmental capital. To solve this problem, the selection of the best and most economic choice is
a vital issue and wrong choice increases cost and does not bring about desired results. In this research, a comparison of a
number of sewage treatment methods and their costs has been made to optimize using financial resources and creating
an appropriate managerial view in this regard. In this direction, the calculation of per capita cost in different processes
and the drawing of comparative diagrams as well as the economic benefits of the plans have been determined in order to
determine CBI and break-even points for the use of private sector’s investors. Furthermore, for a more suitable utilization
of the research’s results and the decrease of the effect of the price fluctuations, financial calculations are made based on
Euro foreign exchange. While the examination of different methods of sewage treatment , appropriate method with
population in the hot and dry climate are determined.
Keywords: Financial Resources, Sewage Treatment Plant, CBI, MLE, SBR

Received 28.07.2014 Revised 10.10.2014 Accepted 29.10.2014

INTRODUCTION
The increase of the public awareness of water pollution problems in recent years has made to enact new
and strict laws of the environment concerning sewage draw.[1] This issue has increased the speed of
constructing and installing sewage treatment plants particularly in the developing countries and similar
to the all developmental plans, on of the most important issues regarding designing and constructing
sewage treatment plants is selecting the best and most economic choice according to the existing
conditions and future perspective[2] so the wrong choice can have an intense effect in increasing costs as
well as the lack of achievement of desired result So while other research’s has examined such as
“Economics of wastewater treatment cost-effectiveness, social gains and environmental standards"[3] ,
"Economic feasibility study for intensive and extensive wastewater treatment considering greenhouse
gases emissions"[4] , "Wastewater reuse in the absence of water scarcity and a market: A case study from
Beaconsfield Tasmania "[5] , the cost of construction of wastewater treatment also has been studied in
various methods. and calculating their construction cost to optimize financial resources of urban Water
and Wastewater Company. According to the limitation of developmental credits of the administrative
organizations as one of the major reasons of inaccessibility to the qualitative objectives of the projects
and incompleteness of a major number of the mentioned plans, in this research, while technical and
economic comparison of a number of sewage treatment methods and quantifying working values and
construction costs of sewage treatment plants in the form of case, the required credit for constructing
them is calculated as per capita (in lieu of each person). Compiling comparative table of costs

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substantially contribute to the selection of the most appropriate methods. The construction of urban
sewage treatment plants not only develops and promotes regional hygienic indices, but also s among the
most necessary developmental plans f the country owing to the global water crises as well as significant
growth of population that have doubled the harmfulness of the occurred drought. According to the fact
that investment of the governmental and private sectors requires accurate study of costs and incomes of
the plans, the lack of accurate and case researches in this regard, seriously has challenged attracting
capita and constructing sewage treatment plants. Therefore, in this research, it is attempted that while
comparing designing sewage treatment plants in different methods, their construction costs and financial
benefits of the plan, break-even points of the investment are determined.

MATERIALS AND METHODS

The methodology includes the following processes:
 Compiling initial information including quantitative and qualitative information.
 Selecting study methods.
 Initial design of the sewage treatment plants based on the intended processes.
 Calculating the initial estimation of constructing sewage treatment plants.
 Calculating cost per capita of constructing sewage treatment plants.
 Calculating CBI.
 Calculating break-even points and the ratio of benefit to cost.
Initial information including quantitative and qualitative information
Wastewater quality parameters are as follows and As you can see , all the Parameters are in the normal range
(Table 1). : Qualitative Principles and Selecting Study Methods are presented in [Table 2] and [Table 3].

Table 1: Qualitative principles

Parameter Sewage Sewage Treatment Sewage Sewage Sewage
Treatment Plant Plant B Treatment Plant C Treatment Plant Treatment Plant E
A D
BOD5 280 200 202 215 231
COD 300_500 300_500 300_500 300_500 300_500
10 million 10 million 10 million 10 million 10 million
Coliform
Input Sewage 1530 1530 1530 1530 1530
Temperature
NH3 25 25 25 25 25
TKN 35 35 35 35 35
PH 78.5 78.5 78.5 78.5 78.5

Table 2: Quantitative principles

Title Principles Year
Basis Year First modulus
Population 246330 374550
Sewage Treatment Plant
(person)
A
Capacity 46704 75060
Population 135423 176973
Sewage Treatment Plant
(person)
B
Capacity 38308 48222
Population 55768 80179
Sewage Treatment Plant C (person)
Capacity 12129 19604
Population 77100 101200
Sewage Treatment Plant
(person)
D
Capacity 18536 25013
Population 175700 252500
Sewage Treatment Plant E (person)
Capacity 40969 61731

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Table 3: Sewage treatment methods

Order Sewage Treatment Selection Process
Plant
1 A SBR
2 B MLE
3 C CAROUSEL (Oxidation ditch)
4 D MLE
5 E MLE

Brief Description of Each Process

Process Description of SBR (Sequence Batch Reactor):
SBR is a type of biological process of sewage treatment in which all biological treatment processes
including biological oxidation, secondary sedimentation, nitrification and mud digestion are carried out in
a reservoir. This method is also called Draw & Fill and is considered a suitable choice for sewage
treatment of types of industrial and hygienic sewage with a small population.
SBR reactor is a type of inconsistent reactor in which sewage current is intermittently entered into the
reactor and then after sewage treatment operations, treated sewage is existed from the reactor in a
certain period. Thus, if sewage current exists constantly, several SBRs should be used in a parallel way.
A SBR system may include one or several reservoirs. In the biological sewage treatment, each reservoir
has five separate phases. Each of these phases is named according to the work that it does.
These phases include:
1- Fill phase: the phase of the raw sewage entrance.
2- React phase: the phase of conducting biological reactions.
3- Settle phase: the phase of separation of microorganisms from treated wastewater.
4- Draw phase: the exist phase of treated sewage.
5- Idle phase: the phase after drawing and before refilling reactor.
In each complete cycle, Draw & Fill phase should be existed, but other cases may be eliminated when if
necessary in particular cases.
Process Description of MLE (Modie d Ludzack-En ger):
MLE process is a suspension growth process with a consistent current used to eliminate nitrogen
biologically. This is the modified process of Ludzack-En ger Process. In this method, to supply greater
nitrate density in anaerobic part, a return line from aerobic part is placed to the anaerobic part that
increases denitrification and completely eliminates nitrogen in relation to the state of Ludzack-En ger.
MLE system is designed in a way that not only has suitable efficiency in eliminating sewage organic and
microbial pollutions, but also has the potential to eliminate nutrients to draw wastewater to the shallow
waters based on the standard of Iran’s Environmental Conservation Organization.[6]
Process Description of CAROUSEL (Oxidation ditch):
CAROUSEL process is a type of oxidation ditches. In oxidation ditches, instead of an air-supply pool, a long
and shallow ditch in the form of a closed ring is use. Using revolving pectinal air-suppliers, sewage in
these ditches flows with low speed. Part of air supplying is provided through the mentioned air-supplying
act and the rest through superficial contact of sewage and air along the long ditch path. The current in
these ditches is of ditch-like ones.
Initial design of the Sewage Treatment Plants
Comparison of selected processes : Comparison the units used in the primary treatment and biological treatment.
In this study, among the different methods of water treatment plants,activated sludge,MLE , Carosel and SBR
methods are used [Tables 4 to 6].
Table 4: Introductory treatment
Introductory treatment
Sewage
Treatment flow sieving by manual Mechanical
Plant measurement air- garbage garbage
unit supplying separation separation
A √ √ √ √
B √ √ √ √
C √ √ √ √
D √ √ √ √
E √ √ √ √

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Table 5: Biological characteristics :

Biological treatment
Sewage surplus
Treatment secondary final Air
Oxidation Anoxic mud SBR
Plant sedimentation gathering upplying
channel pools pumping tanks
pools little pool pools
station
A - - - - - √ √
B - √ √ √ √ √ -
C √ √ √ - - √ -
D - √ √ √ √ √ -
E - √ √ √ √ √ -

Table 6: Disinfection Units & Mud condensation and dehydration

Disinfection Units & Mud condensation and dehydration
Sewage mechanical
Aerobic digestives
Treatment UV condensation unit Mud saving Chlorination
and Mechanical
Plant sterilization and mud tanks Unit
dehydration
dehydration
A - - √ √ √
B √ √ - - -
C - √ √ √ -
D √ √ - - -
E √ √ - - -

Plan Technical Specifications

1. Covered population in the horizon of the plan: 985000 persons (for the sum of the first modulus of
sewage treatment plants).
2. Sewage per capita production: 220 liters per day.
3. Sewage medium quantity: 229630 cubic meters per day for the sum of the first modulus of sewage
treatment plants).
4. Sewage treatment plant A process, SBR with the capacity of 75060 cubic meters per day.
5. Sewage treatment plant B process, MLE with the capacity of 48222 cubic meters per day.
6. Sewage treatment plant C process, CAS with the capacity of 19604 cubic meters per day.
7. Sewage treatment plant D process, MLE with the capacity of 25013 cubic meters per day.
8. Sewage treatment plant E process, MLE with the capacity of 61731 cubic meters per day.
Quantitative and Qualitative Plan Objectives:
1. Annual sewage treating approximately 83 million cubic meters and preventing from its entrance into
shallow and underground water sources.
2. Supplying hygienic sewage through sewage treatment for different consumptions such as agriculture.
3. Preserving environment and preventing from the destruction of biological sources.
4. Reducing remedial costs and optimizing environment as well as improving social welfare.

RESULTS AND DISCUSSION

According to the method described in the Materials and Methods, Calculation of costs and benefits and
was brought out in the following tables:
Cost Estimation
Generalities
In the estimation calculation of costs, owing to the foreign exchange fluctuations as well as the effect of
these fluctuations on the cost of work implementation, Euro is used as the reference for calculating prices
and using conversion rate of Rial into Euro anytime, the calculation of costs is possible anytime.
Considered costs in the initial estimation include following cases:
Separated Summary of Costs are presented in [Table 7] And Separated Summary of Costs are listed in
[Table 8].

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1. Engineering Services and Design

2. Product Providence Including:
Mechanical equipments and installations – electrical equipments and installations – instrumentation
equipments and installations – spare parts.
3. Building and Administrative Operations Including:
Processing buildings – lateral buildings – enclosure-building – enclosing with a fence and green space.
Point: Building materials providence, loading, deliverance, and implementation are considered in the
costs.
4. One-year utilization
Personnel costs - chemical materials consumption – electricity consumption – sampling and
experiments – other costs.

Table 7: Separated Summary of Costs

Title Costs
Engineering Services Product Building Operations Utilization
Providence
Sewage Treatment Plant A 408,480 4,329,490 5,568,691 621,098
Sewage Treatment Plant B 61,960 ,017,474 ,953,472 471,646
Sewage Treatment Plant C 99,800 ,490,886 ,229,796 349,707
Sewage Treatment Plant D 22,000 3,653,690 5,568,691 322,315
Sewage Treatment Plant E 32,206 3,681,860 7,887,466 541,328

Table 8: Sum Total of Costs

Order Title Sum Total of Construction Costs
1 Sewage Treatment Plant A €10,927,758
2 Sewage Treatment Plant B €8,704,551
3 Sewage Treatment Plant C €7,270,188
4 Sewage Treatment Plant D €9,766,697
5 Sewage Treatment Plant E €12,442,859

Calculation of Incomes of the Plan

According to the fact that plan period is considered fifteen years and the amount of input sewage to the
sewage treatment plant and consequently, the amount of productive wastewater and mud are increasing,
the incomes of the plan are determined as follows and the general results are outlined in [Table 9].
Unit Rate of the Incomes of Sewage Treatment:
1. Selling wastewater for 0.058 € for each cubic meter.
2. Selling productive fertilizer for 0.015 € for each kilogram.
3. Sewage disposal wage 0.132 € for each cubic meter.
4. Subscription fee 182 € for each subscriber.

Table 9: Summary of the Incomes of the Plan

Number of Obtained Incomes Number of Utilization Obtained Incomes
Utilization Year (€) Year (€)
First 18394777 Ninth 11066744
Second 9017653 Tenth 11370049
Third 9302575 Eleventh 11676052
Fourth 9590050 Twelfth 11984827
Fifth 9880079 Thirteenth 12280327
Sixth 10172806 Fourteenth 12583777
Seventh 10468087 Fifteenth 13021519
Eighth 10766066 Sum Total 357755635

Cost-Benefit Analysis
Cost-Benefit Analysis (CBA) is a relatively simple and common technique for decision-making concerning
an attempt and making a change. As its name implies, the value of the obtained incomes of an attempt are
merely added and are subtracted from the relevant costs.[7],[8] Costs are incurred altogether or it might
be incurred gradually, but benefits are reaped after a period. We have expressed and brought this time
factor with the calculation of a period of income return in our analysis. This is the very time that should
be spent for the return of obtained incomes of a change in lieu of its costs.[9]

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Analyze the results of the study show that benefits arising from the construction of wastewater treatment
brought back the initial investments. According to the tables treatment plant. construction costs, and
summary of Revenue projects, ten years is a long return on investment. General analysis results are
shown in [table10]

Table 10: CBA

Order Title Result
1 Capital Return Duration 10 Years
2 Break-even Point 97.9 of Capacity
3 Cost-Benefit Ratio 1.64
4 Direct Employment 75 Persons
5 Indirect Employment 110 Persons

CONCLUSION
In order to develop sewage treatment plants and with the objective of preventing from polluting water
sources, appropriate methods of biological treatment should be chosen and the capital of private sector
should be attracted through identifying CBI and incomes of such plans as well as reforming laws can
provide utilization of the private sector’s sewage treatment plants. In this paper, according to Table 5, the
construction cost of sewage treatment plant is more economic by MLE method and this process not only
eliminates organic and microbial materials, but also has the potential to eliminate nutrients to draw
wastewater to the shallow waters based on the standard of Iran’s Environmental Conservation
Organization.[10] Furthermore, this method has the other advantages of the study methods such as SBR
and CAROUSEL and is less sensitive to seasonal changes and environment temperature. The required
ground for this method is small like the other systems of active mud. In addition, it requires lesser energy
in relation to CAROUSEL and SBR methods and has a higher efficiency in accepting incoming organic
shock to sewage treatment plant. Thus, this method is recommended as the optimum one.

ACKNOWLEDGEMENT
This Article derived from M.Sc degree thesis of Mr. kamal davideh which was performed under
supervision of Dr. Reza Jalilzadeh (Ph.D) and Mr. Ahmad Bagheri at Department of Environmental
Engineering, College of Engineering, Ahvaz Branch, Islamic Azad University, Iran. We would like to thank
Khouzestan Water and Wastewater Company that provided the required information.

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CITATION OF THIS ARTICLE

Reza JalilZ Y, Kamal D, Ahmad B. Cost/Benefit Evaluation Of Wastewater Treatment Plant Types ( SBR, MLE,
Oxidation Ditch), Case Study: khouzestan, Iran . Bull. Env. Pharmacol. Life Sci., Vol 4[1] December 2014: 55-60

BEPLS Vol 4 [1] December 2014 60 | P a g e ©2014 AELS, INDIA