Journal of Environmental Protection, 2011, 2, 996-1001
doi:10.4236/jep.2011.27114 Published Online September2011 (http://www.SciRP.org/journal/jep)
The New Methods for Purifying the Industrial
Effluents by Submerged Biofilm Reactors
Seyed Alireza Mousavi Shirazi
Department of Physics, South Tehran Branch, Islamic Azad University, Tehran, Iran.
Received June 12th, 2011; revised July 18th, 2011; accepted August 27th, 2011.
ABSTRACT
Life on the earth is dependent on dynamic interactions between its physical, chemical and biological components. In
fact, all the individual processes are responsible for regulating the environmental equilibrium which can provide bio-
sphere for multiple forms o f human life. In order to overcome on shortcomings, the use of immob ilized cell bioreactor
technology which provides a valuable effective for treatment of waste water is discussed. An immobilized system which
in this matter is applied is about absorbed or captured microorganisms in a solid substratum to retain them in a reactor
or analytical system. The multiply of these immobilized cells is done when by nutrients be supplied and then migrate to
the surfaces which are referred to biofilms. The biofilms can be developed on various support systems such as polypro-
pylene pall, rocks, sands, charcoal, ceramics, and glass beads. The controllable reaction vessels which are used for
these colonized surfaces are referred to bioreactors. Bioreactors in both up flows and down flows mode which use of
either batch or continuous processes principle can be operated. Synchronic with development in biotechnology, there is
also an extensive development in the field of bioreactors like: pumped tower loop reactor (PTLR), liquid impelled loop
reactor (LILR), multipurpose tower bioreactor (MTB), fluidized-bed and packed-bed bioreactor, that in this a rticle are
discussed them.
Keywords: Biofilm, Bioreactor, Effluent, Environment, Liquid, Waste Water
1. Introduction
These facts that increasing the human population and
excessive agricultural activities and modern industriali-
zation can damage environment and biosphere, as an
important and serious problem are enumerated. The
deleterious effects of human activities on the biosphere
are collectively known as pollution. The pollution pre-
vention and its controlling have been caused a major
problem in present century. Waste waters management
and environment protection is commensurate with social
and economical relations and public health of society.
The waste water of various industries is including the
complex mixtures of solid materials and dissolved parti-
cles which have either high biological oxygen demand
(BOD) or chemical oxygen demand (COD) values and it
indicates their toxic effects on the plankton. Heretofore
abundant researches that deal on activities for elimination,
conversion the toxic pollution on industrial waste waters
have been reported. There is a similar problem which is
related to sewages produced due nutrients and beverage
industries [1].
The influence of the ratio carbon-nitrogen and phos-
phorus concentration on the performance of a biofilm
fluidized bed reactor has already bee used for denitrifica-
tion [2]. The thickness and the density of the biofilms
were related mainly with the shear stress in the reactor
and the composition of biofilms was dependent on the
composition of the medium and related with higher ac-
tivities of the microorganisms. Th e surface concentration
depended on the surface characteristics of the biofilms.
The biofilm is a dynamical structure, in which formation
of cracks and fissures is taking place continuously [3].
There are two process configurations based on the
BAS reactors, for nitrogen removal from wastewater by
integration of nitrification in biofilms and denitrification
in suspension. The first setup consists of a conventional
nitrifying BAS reactor coupled with a suspended biomass
reactor. The second process configuration is a single
BAS reactor which is sequentially aerated and non-aer-
ated, by cyclically recirculation the off gas [4].
A wake model is used to predict the liquid holdup,
while the solids holdup is obtained by iteration based on

The New Methods for Purifying the Industrial Effluents by Submerged Biofilm Reactors997
material balance [5].
The numerous numbers of both biodegradable organic
particles and dissolved substances in the waste waters
have high BOD value which must be reduced before
disposal of them into sewerage [6]. BOD is the amount
of dissolved oxygen which is consumed by a diluted
waste water sample and is kept for a specified time (5
days) at 20˚C. The COD is an indicator of the overall
parameter which by a hot and acidic solution of K2Cr2O7
can be chemically oxidized [7].
2. Materials and Methods
In primary stage of waste water treatment usually the sol id
sediments such as grits, soils, the suspended large particles
through grid and firm oil by suction are rem oved.
The secondary treatment is based on biological oxida-
tion that its aim is reduction of effluent’s BOD by using
the activated sludge, trickling filters, lagoons and anaero-
bic digesters individual l y or i n combinational form at s.
These treatment methods are slow and occupy a large
space and generate a large amount of sludge that is
caused disposal problems. In biological activity on waste
water treatment, free and suspended microorganisms
such as activated sludge and fixed biofilm such as trick-
ling filter are used [8]. The problem of activated slud ge is
production of a large amount of sludge and thereby bar-
ring the trickling filter. These shortcomings by using the
bioreactors are eliminated in which the immobilized cells
for treatment have been used.
An immobilized system is a system in which the mi-
croorganisms in a solid substratum either are superficial-
ity absorbed or captured for maintenance in bioreactor. It
is shown in the Figure 1.
These immobilized cells when be fed by nutrient ma-
terials then are multiplied and steadied on the surfaces
which are entitled biofilm. Biofilms by various mainte-
nance systems such as polypropylene pall rings, rocks,
sand, charcoal, ceramics and glass beads can be devel-
oped [7]. The biofilm rectors have reaction ability. The
bioreactors can be applied either up flow or down flow
mode which use either batch principle or continuous
process that these are shown in Figures 2-5 [9].
The volumes of bioreactors for various usages are as
Table 1 [9].
Gel Entrapment Adsorption
 Biocatalyst
Figure 1. Approaches of immobilized biocatalysts.
Table 1. The volumes of used bioreactors in biotechnological processes.
Product groups Bioreactor volume (m3)
Beer, wine
Cheese, bread, sauerkraut
Organic acids (citric acid, acetic acid)
Vitamins (Vit C, Vit E, VitB2)
Enzymes (amylase, lactase, protease)
Antibiotics (penicillin)
Pharmaceuticals (insulin, interferon)
Biomass (bakers/brewers yeast)
Single cell protein
Cheese industry
Milk processing
Wine distillery
Enzyme production
Jam manufacture
Cane molasses distillery
Yeast production
1000
200
100
10 - 50
10 - 50
200
10
200
1500 (continuous)
110
4150
5600
2000
430
1700
1280

The New Methods for Purifying the Industrial Effluents by Submerged Biofilm Reactors 998
Figure 2. Batch reactor (Type 1 of bioreactor).
Figure 3. Continuous reactor (Type 2 of bioreactor).
Figure 4. Up-flow reactor (Type 3 of bioreactor).
Figure 5. Down-flow reactor (Type 4 of bioreactor).
Figure 6. Pumped tower loop reactor (PTLR).
The PTLR reactor for batch production of Xanthan has
specially been developed and it eliminates the posed
problems in treatment by high viscosity and plastically
behavior of polysaccharide.
These achievements by helping a specially designed-
pump are afforded that this pump for keeping the liquid
in kinetic movement and shorter time of fermentation
and more concentration is applied. The LILR bioreactor
for some instances among applications for biocatalyst in
organic solvents is developed. This bioreactor consists of
two parallel tubes connected at the top and bottom.
The bioreactors which have newly been developed are
illustrated as Figures 6-12 [9].
In the LILR bioreactor the organic solvent which has
low density into a continuous non organic fluid with high
density from bottom is distributed and through difference
between densities, the fluid with continuous phase is cir-
culated. The MTB bioreactor uses of the air lift principle
and for cells of sensitive to shear can be used. Both mi-
crobe flocculating and microorganisms culturing in three
different modes can be performed: 1) bubble column. 2)
Bioreactor with inner loop that this loop has relevancy to
airlift which by riser pipe its activity is performed. 3)
Bioreactor with inner loop dependent on airlift which by
down comer pipe its activity is performed [8]. The ad-
vantage of the MTB bioreactor is that in this bioreactor
the modular design is causer for preparation of a system
based on biological processes requirements. The fluid-
ized bed and packed bed reactors which are as samples of
bioreactors, for decrement of related processes fees and
prevention of biocatalysts have been developed. In the
fluidized bed reactors, the immobilized catalyst floated in
water exists freely around airlift source while in the
packed bed reactors the catalyst along with oxygen is
almost saturated.
These bioreactors including biofilm reactors have ei-
ther round or flat drum.

The New Methods for Purifying the Industrial Effluents by Submerged Biofilm Reactors 999
Figure 7. Liquid impelled loop reactor (LILR).
Figure 8. As a bubble column.
Figure 9. Airlift loop reactor with draft tube as riser.
Figure 10. Airlift loop reactor with draft tube as down
comer.
Figure 11. Fluidized bed reactor.

The New Methods for Purifying the Industrial Effluents by Submerged Biofilm Reactors 1000
Figure 12. Packed bed reactor.
Dairy industries usually generate a large amount of
waste water. According to Internationa l Dairy Federation
for generation of milk and Milk Products, 10.7 million
ton cheese has been used and 88.34 million ton whey is
annually generated [10].
Anyway in forthcoming view, pouring the waste water
of dairy industries like whey and cheese industries to
either rivers or seas is one of the most important prob-
lems from the environmental pollution aspects. This
problem concerns and must accurately be considered
because these waste waters have high BOD with 32,000
ppm - 60,000 ppm that these amounts depend on proc-
esses of manufactory of waste water’s producer. One of
the usage instances of produced waste water in cheese
industry is pro duct i o n o f or ganic gases [11].
3. Disscusion
There are several applications of this technology in
treatment processes of industrial waste waters according
to Table 2 [1].
The wastewaters due various industries are including a
mixture of solids complex and solved particles with high
BOD (according to table2). The BOD before disposal in
common sewerage may reduce. The various chemical
and physical processes like steam stripping, ion ex-
changing and solvent extraction for separation toxic par-
ticles of waste waters can be used. The environmental
refinement of waste water might able to use live micro-
organisms in a free state to either suspended biofilm or
fixed forms. In this state a lot of produced sewerage or
wastewaters by using the immobilized cell bioreactor
technology under aerobic or anaerobic conditions can be
refined [12,13]. There is an economical and feasible de-
vised method to treat cheese whey. This method is for-
mulated of 1% glucose, 1% extracted yeast in laboratory.
4. Conclusions
At all two main aims are deduced: 1) preparing a method
for practical and economic applications of submerged
biofilm reactor in refinement of industrial wastewaters. 2)
Developing a batch of processes relating immobilized
submerged biofilm reactors for treatment of wastewaters
due dairy industries. Cheese whey is compounded of
lactose, nitrogenous compounds, vitamins and minerals
which by microorganisms to growth can be used. The
microorganisms which don’t use of lactose can be
growth through consuming other components of cheese
whey. There is a major problem for usage of cheese
whey to growth the yeast and this problem is that some
of the yeasts are relatively able to ferment the lactose.
There are several methods such as hydrolyze of cheese
whey, yeast adaptation and pressure selection which are
attempted to overcome on this problem [7,14]. A sub-
merged fixed biofilm reactor by using the culture in
Table 2. Strong effluents from food and beve rage industr ie s.
Type of waste Main pollutants
Abattoir
Beet sugar
Cannery (meat)
Distillery
Domestic sewage
Dairy
Grain washing
Fermentation industry
Starch reduction of flour
Suspended solids, protein
Suspended solids, fat, protein
Suspended solids, carbohydrates, protein
Suspended solids, oil-grease
Carbohydrates, protein
Carbohydrates, fat, protein
Suspended solids, carbohydrates
Suspended solids, carbohydrates, protein
Suspended solids, carbohydrates, protein

The New Methods for Purifying the Industrial Effluents by Submerged Biofilm Reactors 1001
laboratory can be applied to treat cheese whey and all
dairy effluents for reducing BOD. At all one of the fast-
est environment to growth the microorganisms are both
slimy and effluent where the various types of extracted
wastewaters exist.
REFERENCES
[1] J. Bailey and D. Ollis, “Biochemical Engineering Fun-
damentals,” 2nd Edition, McGraw-Hill, New Delhi, 1986.
[2] C. F. Alves, L. F. Melo and M. J. Vieira, “Influence of
Medium Composition on the Characteristics of a Denitri-
fying Biofilm,” Process Biochemistry, Vol. 37, No. 8,
2002, pp. 837-845. doi:10.1016/S0032-9592(01)00282-5
[3] W. A. J. Benthum, M. C. Loosdrecht, L. Tijhuis and J. J.
Heijnen, “Solids Retention Time in Heterotrophic and
Nitrifying Biofilms in a Biofilm Airlift Suspension Re-
actor,” Water Science and Technology, Vol. 32, No. 8,
1995, pp. 53-60. doi:10.1016/0273-1223(96)00007-8
[4] W. A. J. Benthum, M. C. Loosdrecht and J. J. Heijnen,
“Process Design for Nitrogen Removal Using Nitrifying
Biofilm and Denitrifying Suspended Growth in a Biofilm
Airlift Suspension Reactor,” Water Science and Tech-
nology, Vol. 36, No. 1, 1997, pp. 119-128.
doi:10.1016/S0273-1223(97)00344-2
[5] Y. Haibo and E. Rittmann, “Predicting Bed Expansion
and Phase Holdups for Three-Phase Fluidized-Bed Reac-
tors with and without Biofilm,” Water Research, Vol . 31,
No. 10, 1997, pp. 2604-2616.
doi:10.1016/S0043-1354(97)00102-4
[6] M. J. Abraham and R. A. Srinivasan, “Lipid and Fatty
Acid Composition of Selected Fungi Grown on Whey
Medium,” Journal of Food Science, Vol. 49, No. 3, 1984,
pp. 950-951. doi:10.1111/j.1365-2621.1984.tb13249.x
[7] C. Nicolella, M. C. Loosdrecht and J. J. Heijnen,
“Biofilm Reactors,” Journal of Biotechnology, Vol. 80,
No. 1, 2000, pp. 1-33.
doi:10.1016/S0168-1656(00)00229-7
[8] R. Ramakrishnan, “Use of a Submerged Biofilm Reactor
in the Treatment of Industrial Effluent,” Bombay Univer-
sity, Bombay, 1995.
[9] G. Mijnbeak, “Operational Modes of Bioreactors,” But-
terworth-Heinemann Ltd, Oxford, 1992.
[10] V. Kapil, A. K. Dodeja and S. C. Sarma, “Manufacture of
Lactose-Effect of Processing Parameters on Yield and
Purity,” Journal of Food Science, Vol. 28, No. 3, 1990,
pp. 167-170.
[11] R. Salvetti, A. Azzellino, R. Canziani and L. Bonomo,
“Effects of Temperature on Tertiary Nitrification in Mov-
ing-Bed Biofilm Reactors,” Water Research, Vol. 40, No.
15, 2006, pp. 2981-2993.
doi:10.1016/j.watres.2006.05.013
[12] P. Wilderer, “Technology of Membrane Biofilm Reactors
Operated under Periodically Changing Process Condi-
tions,” Water Science and Technology, Vol. 31, No. 1,
1995, pp. 173-183. doi:10.1016/0273-1223(95)00165-J
[13] Z. Zhang, J. Zhou, J. Wang, H. Guo and J. Tong, “Inte-
gration of Nitrification and Denitrifying Dephosphatation
in Airlift Loop Sequencing Batch Biofilm Reactor,”
Process Biochemistry, Vol. 41, No. 3, 2006, pp. 599-608.
doi:10.1016/j.procbio.2005.08.005
[14] C. Nicolella, M. C. Loosdrecht and J. J. Heijnen,
“Wastewater Treatment with Particulate Biofilm Reac-
tor,” Biotechnology, Vol. 80, No. 1, 2000, pp. 1-33.