6th International Conference on Advances in Civil Engineering (ICACE-2022)

21-23 December 2022

CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

Activated Sludge Process Combined with Moving Bed Biofilm Reactor

(MBBR) for BOD and Nitrogen Removal
H. Saha1, U. Datta2, S.M. Farhan3, T. Shakeen4
1Graduated, B.Sc. Department of Civil Engineering, AUST, Bangladesh, email: himelsaha84@gmail.com
2Student, M.Sc. Department of Civil Engineering, MIST, Bangladesh, Graduated, B.Sc. Department of Civil Engineering
AUST, Bangladesh, email: uchhwas.mist@gmail.com
3Graduated, B.Sc. Department of Civil Engineering, AUST, Bangladesh, email: asif.farhann@gmail.com
4Student, M.Sc. Department of Water Resource Engineering, BUET, Bangladesh, Graduated, B.Sc. Department of Civil &

Environmental Engineering, IUT, Bangladesh, email: shakeen@iut-dhaka.edu

Abstract
Efficient treatment of wastewater is extremely crucial for supplying consumable water to the community and
environment. With the abundance of wastewater in surrounding environment, it has become imperative to treat
this sewerage and make it readily available producing it into a high-quality effluent. For adequate treatment of
wastewater, activated sludge process (ASP) with a combination of MBBR proves to be competent enough in
terms of transforming the wastewater into discharge of desired quality. The study verifies the design process
based on two different average temperatures of 10℃ and 30℃ to remove the efficiency of this process. Also, it
shows variation in major parameters such as solid retention time (SRT), hydraulic retention time (HRT), air
flow rate, oxygen requirement, MLVSS, MLSS, F/M ratio, sludge production, TSS, etc. concerning temperature
under activated sludge process and MBBR. The research recommends the design process is 91.05 percent
efficient for BOD removal, 90 percent efficient for reduction of TSS concentration and 94.4 percent efficient for
NH4-N reduction. Besides, nitrification was done as NO3–N (product of nitrification) can be obtained and
discharged into agricultural fields as fertilizer and irrigation purposes.

Keywords
ASP, MBBR, BOD5 & Nitrogen Removal

1. Introduction

When Municipal wastewater is a complex mixture of largely unknown substances that may be hazardous to
humans and aquatic organisms. Municipal wastewater treatment typically comprises preliminary treatment,
primary treatment, and secondary treatment. A higher degree of treatment, termed here as "advanced" or
"tertiary" treatment, may be required at specific locations to protect health or environmental quality. Primary
treatment is used as an economical means for removing few contaminants prior to secondary treatment. The
residue from primary treatment is a concentrated suspension of particles in water called "primary
sludge"(Metcalf & Eddy 1995). A sewage treatment plant with physical phase separation to remove settleable
and a biological process to remove dissolved and suspended organic compounds is known as secondary
treatment, and it is a process used to treat wastewater (or sewage) to achieve a specific level of effluent quality.
The step in the sewage treatment process known as secondary treatment removes dissolved and colloidal
components, as determined by the biochemical oxygen demand (BOD). It is usually performed by indigenous,
aquatic microorganisms in a managed aerobic habitat while reproducing to form cells of biological solids.
Tertiary treatment is used at municipal wastewater treatment plants when receiving water conditions or other
uses require higher quality effluent than that produced by secondary wastewater treatment. The concentration of
ammonia in secondary effluent can be reduced by nitrification. Tertiary treatment to remove nitrogen and
phosphorus, so as to minimize nutrient enrichment of surface waters, is common; nitrogen is usually removed
by nitrification followed by de-nitrification.
Activated sludge process (ASP) is a feasible treatment technology for municipal wastewater where limited space
restricts the use of other biological methods. In this process, the activity of microbial species under controlled
operating conditions permits the biodegradation of organic matter and nutrients from wastewater [1]. It also
ensures the recycling of wastewater. But this research is based on the ASP design combined with MBBR for
BOD and nitrogen removal.
Activated sludge process is probably the most versatile of the biological treatment processes capable of
producing an effluent with any desired BOD. This is a biological wastewater treatment process as pollutants are
used as food source by many different types of microorganisms during treatment. It is a suspended growth
process, sine the organisms are suspended in the wastewater rather than attached to a media as in the trickling
filter or rotating biological contactor processes. Better quality of effluent can be produced which is exempted
from odor or fly nuisance due to the process being conducted underwater. The high quality of effluent also
causes an immense rise in its cost of construction, operation, and maintenance.

Page-1
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

Sludge treatment may take place in most climates, however activated sludge sewage treatment is best done in a
centralized treatment facility. However, the treatment capability is decreased in colder climates.
According to the Pennsylvania Department of Environmental Protection (DEP), the conventional activated
sludge process is susceptible to failure from shock loads. Due to its relatively low mixed liquor suspended solids
(MLSS) concentration and head-end loading, the conventional activated sludge process is best for low-strength,
domestic wastes with minimal peak load considerations.
Industrial wastewater can be effectively treated using a membrane bioreactor (MBR). In comparison to
traditional wastewater treatment methods, it has various benefits, such as increased volumetric loading, a
smaller reactor footprint, entire solids retention at all biomass concentrations, and less sludge generation.
Technology using membrane bed reactors has been used to treat a variety of industrial wastewaters, including
wastewaters from the food sector, leachate, pharmaceuticals, dyes, and oily wastewaters.

By enhancing suspended and attached growth systems, MBBR technology seeks to start a process with a high
concentration of microbial biomass. [2]. By embracing connected development innovations, for example,
biofilms, MBBRs have been demonstrated to be a dependable strategy for treating wastewater with natural
matter, particularly tertiary nitrification [3]. In the course of treating patients, MBBRs employ attached growth
concepts. [4]. This method was created using an ASP that is typically used with a fluidized bed reactor. [5]. This
innovation has the upsides of both the ASP and the biofilm reactor while utilizing free-drifting media to give the
ideal surface region [6].
Membrane separation is a physical separation technique that is frequently used in the treatment of wastewater
and drinking water. [7]. It requires less space to set up, produces less surplus sludge, has a high level of
automation, and doesn't require the addition of chemicals. Other benefits of membrane technology include a
higher removal of organic contaminants and nutrients. [8]. Membrane treatment can also be performed ahead of
biological treatments, depending on the intended outcome of the treatment. Moving bed reactors are regularly
utilized in wastewater treatment processes. They can be tuned to the application by choosing explicit
microorganisms, however, these kinds of reactors are extremely successful at nitrification, de-nitrification, and
substance oxygen interest (COD) decrease processes on the grounds that moving bed reactors are additionally
simple to construct, and simple to scale the reactor to fulfill different wastewater needs [9].

The overall objective of the research is to design an activated sludge process (ASP) and MBBR for BOD and
nitrogen removal. This research also aims to evaluate different factors affecting the ASP and MBBR for treating
municipal wastewater. It will also analyze temperature variation in BOD and nitrogen removal process of ASP
and MBBR. This study can be used in any municipal wastewater treatment plant where ASP needs to be
designed and the analysis can be used for municipal wastewater treatment plant. It can be used both in tropical
countries as well as countries with high temperature. The design process is done considering both the average
winter (10°C) and summer (30°C) temperature

2. Methodology

Materials and Methods

Influent wastewater characteristics data is obtained at first in order to analyze its necessary characteristics.
Effluent requirements are determined in terms of NH4-N, TSS and BOD concentrations. An appropriate
nitrification safety factor is selected for the design SRT based on expected peak/average TKN loadings. Safety
factors vary from 1.3 to 2.0. The minimum DO concentration is selected for the aeration basin mixed liquor. A
minimum DO concentration of 2.0 mg/L is recommended for nitrification. The nitrification maximum specific
growth rate (µm) is determined based on the aeration basin temperature and DO concentration and Knis
determined. The net specific growth rate µ and SRT at this growth rate is determined to meet the effluent NH4-
N concentration. The design SRT is obtained by applying the safety factors. The biomass production is
determined, and nitrogen balance was performed to determine NOx and the concentration of NH4-N oxidized.
The VSS mass and TSS mass for the aeration basin is calculated. A design MLSS concentration is selected, and
the aeration basin volume and hydraulic residence time are determined. After that, the overall sludge production
and observed yield are determined. The oxygen demand is calculated with the additional alkalinity. Secondary
clarifier and aeration oxygen transfer system is designed using these data. For MBBR process, applied BOD
flux was calculated by dividing BOD removal flux by % BOD removal (for BOD removal case) and for
Nitrification, dividing BOD removal flux by % Nitrogen removal. Media area and volume is calculated with the
measurements for reactor tank volume and hydraulic retention time. The final effluent quality is evaluated by
the values of all the parameters calculated during this experiment [10].

Page-2
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

Design process
The main design procedure involves a complete-mix activated-sludge (CMAS) process to treat 30,000 m3/d of
primary effluent to (a) meet a BOD5 concentration less than 30 g/m3 and (b) accomplish BOD removal and
Nitrification with an effluent NH4-N concentration of 0.50 g/m3.Comparison between two design conditions of
average winter temperature of 10℃ and Average summer temperature of 30℃ is shown.

Table 1: Wastewater characteristics

Concentration Constituent
BOD 100 mg/L
SBOD 60 mg/L
COD 275 mg/L
sCOD 140 mg/L
rbCOD 110 mg/L
TSS 100 mg/L
VSS 80 mg/L
TKN 15 mg/L
NH4-N 9 mg/L
TP 5 mg/L
Alkalinity 125 mg/L as CaCO3
bCOD/BOD ratio 1.6

Table 2: MBBR design parameter and condition

Design parameter Unit Design condition

Average flow m3/d 30000
BOD concentration g/m3 100
TKN concentration g/m3 15
Non-biodegradable VSS g/m3 42.4
TSS g/m3 100
VSS g/m3 80
Minimum design temperature ℃ 10(winter) and 30(summer)
Effluent NH4- N g/m3 0.5

Table 3: Design consideration/Assumption:

Design parameter Unit Design

consideration/Assumption
Fine bubble ceramic diffusers with % 35
an aeration clean water transfer
efficiency
Liquid depth for the aeration basin m 5
The point of air release for the m 0.5 m above the tank bottom
ceramic diffusers
DO in aeration basin mg/L 2.0
Site elevation (pressure = 1 kPa) m 34
Aeration  factor g/m3 0.50 for BOD removal only
 =0.65 for nitrification
β =0.95 for both conditions
Diffuser fouling factor - 0.90
SRT for BOD removal d. 5
Design MLSS XTSS concentration mg/L 3000
(values of 2000 to 3000 mg/L can be
considered)
TKN peak/average factor of safety, - 1.5
FS

Page-3
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

3. Result & Discussions

Complete mix activated sludge process design

Average BOD loading was 3000 kg/d and remained same with the increase in temperature from 10°C to 30°C.
As the flow rate or discharge was found same, the average BOD loading also remained same with the increase
in temperature. Besides, average TKN load was found 450 kg/d and remained same with the increase in
temperature. Average TKN load is mainly dependent on the flow rate. The flow rate was found 30000 m3/d and
remained same throughout the design process. Design solid retention time (SRT) was found 18.18 days (d) at
10°C and 9.1days at 30°C in the case of BOD removal with nitrification. Solid retention time (SRT) is inversely
proportional to specific growth rate (n). As the specific growth rate (n) decreased with increase in
temperature, the solid retention time (SRT) also decreased.
In case of BOD removal only, aeration tank volume was found 5926.93 m3 at 10°C and with the increase in
temperature to 30°C, it was found 5368.52 m3 .On the case of BOD removal with nitrification, aeration tank
volume was found 18225.75 m3 at 10°C and with the increase in temperature to 30°C it was found 8992.77
m3 .It shows that, aeration tank volume decreases with the increase of temperature although temperature is not
directly related with tank volume. Aeration tank volume is generally related to the mass of MLSS and the flow
rate. In this study, the flow rate remained constant throughout the design process and the value of the aeration
tank volume also decreased relatively with the change of temperature. Besides, number of aeration tank was
taken 3 for both BOD removal only and BOD removal with nitrification cases and 1 tank was considered extra
when maintenance of the treatment process is necessary.
Hydraulic retention time (HRT) was found 4.74 hours (hr) at 10°C and 4.29 hr at 30°C in the case of BOD
removal only. For the case of BOD removal with nitrification, hydraulic detention time (HRT) was found 14.58
hr at 10°C and 7.19 hr at 30°C. Aeration tank volume is proportional to hydraulic retention time. The value of
aeration tank volume is decreased relatively. Besides, Hydraulic retention time is also decreased. Air flow rate
was found 49.18 m3 /min at 10°C and 53.47 m3 /min at 30°C. For the case of BOD removal with nitrification, air
flow rate was found 62.58 m3 /min at 10°C and 69.22 m3 /min at 30°C. Air flow rate is increased relatively with
the change of temperature. Air flow rate is related to oxygen requirement. Oxygen requirement was found
112.81 kg/hr at 10°C and 131.33 kg/hr at 30°C for the case of BOD removal only. Again, for BOD removal with
nitrification, oxygen requirement was found 199.33 kg/hr at 10°C and at 30°C, it was found about 202.82 kg/hr.
More oxygen requirement leads to more air flow rate. Solubility of water reduces with increasing temperature
from 10°C to 30°C, more oxygen is required to add to wastewater resulting in increased air flow rate.
MLVSS was found 2280 g/m3 at 10°C and 2250 g/m3 at 30°C for the case of BOD removal only. For the case
of BOD removal with nitrification, MLVSS was found 2232 g/m3 at 10°C and 2226 g/m3 at 30°C. Itis clarified
that MLVSS increases as the temperature increases. MLVSS has a direct relation with SRT. At low temperature,
the SRT is high, so the microorganism growth rate is higher and biomass production is also high. Due to high
biomass production, the MLVSS is also high. On the other hand, the SRT is low in high temperature that results
in low biomass production. So, the MLVSS is low at low SRT. Besides, for both BOD removal and BOD
removal with nitrification cases, MLSS was found 3000 g/m3 at both 10°C and 30°C. The concentration of
MLSS was kelp constant in this project. F/M ratio was found 0.22 at 10°C and 0.25 at 30°C for the case of BOD
removal only. For the case of BOD removal with nitrification, F/M ratio was found 0.074 at 10°C and 0.15 at
30°C.So it can be said that F/M ratio increases as the temperature increases. F/M ratio refers to the measure of
food provided to bacteria in an aeration tank. In high temperature, the growth rate of microorganisms increases,
which results in higher population of microorganisms. As microorganisms’ increase, the food consumption or
degradation of organic matters also increases. So, F/M increases with increasing in temperature.
BOD loading was found 0.51 at 10°C and 0.56 at 30°C for the case of BOD removal only. In other case of BOD
removal with nitrification, BOD loading was found at 0.16 at 10°C and 0.33 at 30°C. So, it can be said that
BOD loading increases as the temperature increases. In case of BOD removal only, sludge production was
found 3556 kg/day at 10°C and with increasing temperature at 30°C, it was found 3221 kg/d. In case of BOD
removal with nitrification, sludge production was 3008 kg/day at 10°C and with the increase in temperature to
30°C, it was 2965 kg/d. It shows that, sludge production decreases as the temperature increases.
Based on TSS, observed yield was found 1.2 kg TSS/kg bCOD at 10°C and 1.07 kg TSS/kg bCOD at 30°C for
the case of BOD removal only. For the other case of BOD removal with nitrification, observed yield based on
TSS was found 1 kg TSS/kg bCOD at 10°C and 0.99 kg TSS/kg bCOD at 30°C. Based on VSS, observed yield
was found 0.91 kg VSS/kg BOD at 10°C and 0.80 kg VSS/kg BOD at 30°C for the case of BOD removal only.
For the other case of BOD removal with nitrification, observed yield based on VSS was found 0.77 kg VSS/kg
BOD at 10°C and 0.74 kg VSS/kg BOD at 30°C. So observed yield (both based on TSS and VSS) decreases as
the temperature increases.
Oxygen requirement was found 112.81 kg/hr at 10°C and increased to 131.33 kg/hr at 30°C for the case of BOD
removal only. In the other case of BOD removal with nitrification, oxygen requirement was found 199.33 kg/hr

Page-4
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

at 10°C and as the temperature increased to 30°C, it increased to 202.82 kg/hr. Oxygen requirement depends on
solubility. At low temperature, the solubility of O2 is high. So, the transfer of oxygen into water is easier and the
amount of oxygen loss is lower. At high temperature, the solubility of O2 is low. So, the transfer of oxygen into
water is harder which results in higher oxygen demand. So, it can be said that oxygen requirement increases as
the temperature increases. As the reactor is an open reactor, excess oxygen will have to be provided as there is a
tendency of loss by up flow.
Air flowrate was found 49.18 m3 /min at 10°C and 53.47 m3 /min at 30°C. For the case of BOD removal with
nitrification, air flow rate was found 62.58 m3 /min at 10°C and 69.22 m3 /min at 30°C. As oxygen is one of the
basic components of air, more oxygen requirement leads to more air flowrate. With temperature increase oxygen
requirement increases and as a result, air flowrate is also high. RAS ratio found 0.60 remained constant with
temperature increase from 10°C to 30°C. Clarifier hydraulic application rate is found 22 m3 /m2 .d for both BOD
removal and BOD removal with nitrification which did not change with the change in temperature from 10°C to
30°C. Number of clarifier is taken 3 for all cases each having diameter of 21m. Alkalinity to be added as
Na(HCO3 ) is found to be 1560.69 kg/d and it was increased to 1614.82 kg/d as the temperature increased from
10°C to 30°C. So, alkalinity requirement is increased with the increase in temperature.
Effluent BOD concentration is found 8.95 g/m3 for both BOD removal and BOD removal with nitrification it
didn’t change with increase in temperature from 10°C to 30°C. Effluent TSS concentration is found 10 g/m3 for
both BOD removal only and BOD removal with nitrification and it also didn’t change with the increase in
temperature from 10°C to 30°C. Effluent NH4 -N concentration is found 0.5 g/m3 for both BOD removal only
and BOD removal with nitrification and also it didn’t change with the increase in temperature from 10°C to
30°C.

MBBR
The value of applied BOD flux for BOD removal is 12.24 g/m2. d at 10°C and 12.12 g/m2. d at 30°C. The BOD
flux is generally related to the BOD removal and % BOD removal. The concentration of BOD removal flux
remains same in both 10°C and 30°C and the percentage of BOD removal is also nearly same in both 10°C and
30°C. That’s why the value of BOD flux for BOD removal is quite same in different season. The value of
applied flux for nitrification is found 0.93 g/m2. d. Applied flux for nitrification is related to the value of %
nitrogen removal and nitrogen removal flux.
The value of media area for BOD removal at 10°C and 30°C was found 245098.04 m2 and 24724.75 m2
respectively. Media area was found different at different temperature. This happens because media area value is
related to the applied flux value for BOD removal. For 30°C, the applied BOD flux value is found lower than
that of at 10°C. For this reason, it results in higher media area in lower BOD flux value. Besides, media area for
nitrification is found 483870.97 m2 This media area is related to the value of nitrogen application rate and
applied flux. Media volume for BOD removal at 10°C and 30°C is found 490.2 m3and 495.05 m3 respectively.
The media volume is found higher for higher media area. Media volume for nitrification was found 967.74 m3.
Reactor tank volume for BOD removal at 10°C and 30°C was found 980.4 m3 and 990.1 m3 respectively. The
reactor tank volume is found higher for higher media volume and the reactor tank volume is related to the media
volume. Besides, the reactor tank volume for nitrification was found 1612.9 m3.
The hydraulic retention time for BOD removal in 10°C and 30°C is found 0.78h and 0.79h respectively. The
hydraulic retention time is related to the reactor tank volume. The hydraulic retention time is found higher for
higher reactor tank volume. Besides, the hydraulic retention time for nitrification was found 1.29h.
The overall result is shown in the following tables: -

Table 4: Design summary prepared for activated sludge process

BOD removal and

BOD removal only (Part A)
Design Parameter Unit nitrification (Part B)
10℃ 30℃ 10℃ 30℃
Average wastewater
m3/d 30000 30000 30000 30000
Row
Average BOD load kg/d 3000 3000 3000 3000
Average TKN load kg/d 3000 3000 3000 3000
Aerobic SRT Days 5 5 18.18 9.1
Aeration tanks Number 3 3 3 3
Aeration tank
m3 5926.93 5368.52 18225.75 8992.77
volume, all

Page-5
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

BOD removal and

BOD removal only (Part A)
Design Parameter Unit nitrification (Part B)
10℃ 30℃ 10℃ 30℃
Hydraulic detention
Hr 4.74 4.29 14.58 7.19
time, 
3
MLSS g/m 3000 3000 3000 3000
MLVSS g/m3 2280 2250 2232 2226
F/M g/g.d 0.22 0.25 0.074 0.15
BOD loading kg BOD/m3. d 0.51 0.56 0.16 0.33
Sludge production kg/d 3556 3221 3008 2965
kg TSS/kg
bCOD
Observed yield 1.2 1.07 1 0.99
kg VSS/kg
BOD
Oxygen required kg/h 112.81 131.33 199.33 202.82
Air flowrate at
average wastewater sm3/min 49.18 53.47 62.58 69.22
Row
RAS ratio Unitless 0.60 0.60 0.60 0.60
Clarifier hydraulic 3 2
m /m . d 22 22 22 22
application rate
Number 3 3 3 3
Clarifiers
Diameter, m 21 21 21 21
Alkalinity addition
kg/d 1560.89 1614.82
as Na (HCO3)
Effluent BOD g/m3 8.95 8.95 8,95 8.95
TSSe g/m3 10 10 10 10
Not Not
Effluent NH4+-N g/m4 0.5 0.5
calculated calculated

Table 5: Design summary prepared for MBBR

Function Unit BOD removal Nitrification

10℃ 30℃
Applied flux g/m2. d 12.24 12.12 0.93
Media area m2 245098.04 247524.75 483870.97
Media volume m3 490.2 495.05 967.74
Reactor tank volume m3 980.4 990.1 1612.9
Hydraulic retention time, h 0.78 0.79 1.29

4. Conclusion of the Results

There are certain disadvantages that traditional ASP has such as, instability under large load variations,
comparatively more manpower, land area, energy requirement. Along with the benefit of allowing the capacity
of the current plant to be increased by adding more media to the MBBR Tank, the MBBR process emerges as
offering better performance in several areas. Additionally, due to their small size and ability to fit in small
spaces, both the maintenance and installation costs are lower than with ASP. [11]. In order to bring on better
performance this research has been carried out using a method of ASP combined with MBBR for BOD and
Nitrogen removal. This research focused on variation of characteristics of the parameters with temperature
fluctuation.

Analysis shows that the factors affecting the design process, have significant impact on the result. Solid
retention time (SRT) was higher at low temperature. Hydraulic retention time (HRT) was also found higher for
low temperature. HRT was found 4.74hr at 10°C and 4.29hr at 30°C in the case of BOD removal only and for

Page-6
 6th International Conference on Advances in Civil Engineering (ICACE-2022)
21-23 December 2022
CUET, Chattogram, Bangladesh
www.cuet.ac.bd/icace

the case of BOD removal with nitrification, HRT was found 14.58hr at 10°C and 7.19hr at 30°C. Aeration tank
volume is proportional to hydraulic retention time. As the value of aeration tank volume is decreased, hydraulic
retention time is also decreased. MLVSS increases as the temperature increases. MLVSS has a direct relation
with SRT. At low temperature, the SRT is high, so the microorganism growth rate is higher and biomass
production is also high.
Oxygen requirement found higher at 30°C. It depends on solubility. With rise in temperature, the solubility of
O2 reduces, thus hindering the transfer of oxygen into water which results in higher oxygen demand. So, it can
be said that oxygen requirement increases as the temperature increases. Sludge production was found higher at
30°C. Higher temperature leads to the drastic increase in microorganism activity, resulting in higher sludge
production. In the MBBR process, HRT was found higher at 30°C. The hydraulic retention time is found higher
for higher tank volume.
Finally, it can be said that the activated sludge process is one of the most satisfactory systems for wastewater
treatment. This system is combined with MBBR process which makes the project more feasible.

5. Acknowledgement

At first, the research members recall the gratefulness to Almighty. Then they express their sincere gratitude and
deep indebtedness to their supervisor Dr. Fahim Hossain, Assistant Professor, Department of Civil Engineering,
AUST, who offered knowledge and experience that significantly aided the research. His careful reading of the
draft, valuable comments, criticism and constructive suggestions immensely contributed to the improvement of
this paper. We would also like to show our gratitude to Khondker Nabil Mahmood, M.Sc. Student, Technical
University of Munich for sharing his numerous wisdoms with us during this paperwork.

References
1. Yildiz BS (2012) Water and wastewater treatment: Biological processes. In: Metropolitan Sustainability:
Understanding and Improving the Urban Environment. Elsevier Ltd., pp 406–428
2. Bassin JP, Dezotti M (2017) Moving bed biofilm reactor (MBBR). In: Advanced Biological Processes
for Wastewater Treatment: Emerging, Consolidated Technologies and Introduction to Molecular
Techniques. Springer International Publishing, pp 37–74
3. di Biase A, Kowalski MS, Devlin TR, Oleszkiewicz JA (2019) Moving bed biofilm reactor technology
in municipal wastewater treatment: A review. J. Environ. Manage. 247:849–866
4. Leyva-Díaz JC, Martín-Pascual J, Muñío MM, González-López J, Hontoria E, Poyatos JM (2014)
Comparative kinetics of hybrid and pure moving bed reactor-membrane bioreactors. Ecol Eng 70:227–
234. https://doi.org/10.1016/j.ecoleng.2014.05.017
5. Santos AD, Martins RC, Quinta-Ferreira RM, Castro LM (2020) Moving bed biofilm reactor (MBBR)
for dairy wastewater treatment. Energy Reports 6:340–344. https://doi.org/10.1016/j.egyr.2020.11.158
6. Rodgers M, Zhan X-M Moving-medium biofilm reactors
7. Fakhru’l-Razi A, Pendashteh A, Abdullah LC, Biak DRA, Madaeni SS, Abidin ZZ (2009) Review of
technologies for oil and gas produced water treatment. J. Hazard. Mater. 170:530–551
8. Abu Bakar SNH, Abu Hasan H, Mohammad AW, Sheikh Abdullah SR, Haan TY, Ngteni R, Yusof
KMM (2018) A review of moving-bed biofilm reactor technology for palm oil mill effluent treatment. J.
Clean. Prod. 171:1532–1545
9. Barwal A, Chaudhary R (2014) To study the performance of biocarriers in moving bed biofilm reactor
(MBBR) technology and kinetics of biofilm for retrofitting the existing aerobic treatment systems: A
review. Rev. Environ. Sci. Biotechnol. 13:285–299
10. Rusten B, Eikebrokk B, Ulgenes Y, Lygren E (2006) Design and operations of the Kaldnes moving bed
biofilm reactors. Aquac Eng 34:322–331. https://doi.org/10.1016/j.aquaeng.2005.04.002
11. Sharmila D (2017) Comparative Analysis of Activated Sludge Process and Moving Bed Bio-Reactor
( MBBR ) Technology of Nesapakkam Sewage Treatment. 7:3985–3989

Page-7