This document reviews the use of microalgae to biodegrade phenolic compounds in wastewater. It discusses how microalgae can remove over 70% of phenol from wastewater in a few days through metabolic pathways. The document also examines factors that affect microalgal growth, different culturing techniques like open and closed photobioreactor systems, and mechanisms by which microalgae degrade pollutants like phenol through the meta cleavage pathway. The conclusion emphasizes that microalgae significantly impact wastewater treatment and that understanding microorganism kinetics and mechanisms can further develop uses of microalgae for bioremediation.

1. Republic of Iraq
Ministry of Higher Education and
Scientific Research
University of Technology
Building and Constructions Department
By
Lec.Dr.Afaf Jadaan Obeid Al-Saned
Biodegradation of Phenolic Components in
Waste Water by Micro algae -A Review

2. Introduction
Pollution of surface water has become a
standout problem among the most
imperative environmental issues. Two sorts
of substantial and long-lasting pollution
dangers can be perceived at the worldwide
level.

3. One of the most important pollutants
from this point of view is phenol
Phenol can be removed from the
environment and industrial effluents by
different physicochemical method
but these types of treatments are limited
because they are usually expensive ,
complex and produce hazardous
end-products (waste sludge).

4. • For these reasons the interest in the use of
the process of photo remediation reduce the
formation of this environmentally hazardous
sludge .
• photo remediation, is the process of using
algae which can fix carbon dioxide by
photosynthesis and removing excess
nutrients effectively at minimal cost for
improving water quality.

5. •Microalgae
•Microalgae are microscopic. Photosynthetic
microorganisms. They are a type of eukaryotic cells
and they contain similar organelles such as
chloroplasts, nucleus, etc. Microalgae are generally,
more efficient than land. plants in utilizing sun light,
CO2, water and other nutrients which translated to
higher biomass yields and higher growth rates.

6. Algae Growth Requirements
• Microalgae have a particular set of
requirements for growth identical to that of
other photosynthetic plants. Basic inputs for
microalgae growth include water, sunlight,
nutrients and an acceptable range of
environmental conditions particular to the
algal species.

7. Factors Affecting Micro algal
Growth
• Successful treatments of wastewater
with microalgae require a good
growth, and understanding of the
factors that influence growth is
therefore essential. The growth rate of
algae and cyanobacteria is affected by
physical chemical and biological
factors as follow:

8. Factors Affecting
Micro algal Growth
Environmental
requirements
Nutrient
requirements
Light “photo”
requirements

9. Microalgae
Culturing Techniqu
Enclosed
Systems
Open
Systms

10. •The open systems, i.e., raceway
ponds and lakes, are usually
illuminated naturally (outdoors)
and open to the environment.

11. •The enclosed systems.
• usually called photo bioreactors (PBR) have
numerous possible photobioreactor (PBR)
configurations (e.g., tubular, panel, internally
illuminated, airlift bubble column reactors)

12. Different tubular photo bioreactor
systems
CO2Supply
Light
supply
method
and
illuminatio
nflux
Circulating
mechanis
m
pH
T[oc]
Approxima
tecapacity
volume[1]
Algae
Tubular
Photo
bioreactor
CO2 added to
the air at a
rate of 0.3
wm for 15
min every 2h
during the
12h light
period
A 12h
dark/light
photo
period with
3200 lux of
illumination
provided by
40 W daylight
type
fluorescent
lamp
Agitation and
aeration using
air from a
compressor
and a sintered
sparger
Determined by a
digital pH-meter
30-
Spirulina sp.
Scenedesmus
obliquus
Indoor
Solar
illumination
Airlift device200
p.
tricornutum
Outdoor:
consisting of
4m tall airlift
section with a
degassed zone
Air of
different co2
concentration
Continuous
cool white
fluorescent
illumination
Directly
determined by an
ISFET pH
26±1Chlorella
Semi-
continuous

13. Chlorella
vulgaris
Cyanobium
sp.
Scenedesm
us obliquus
Chlorella
minutissima,
D.tertiolecta
Thermosynech
ococcussp
Chorella
vulgaris
Species
Fresh
water
Fresh
water
freshwater
Cyanobacte-
rium
Type
Diluted
Manure
BG11Jaworski
Modified Bold
3N
Fitzgerald
media
Artificial
Waste
water
Media
11.85003-612Working Vol.(L)
1.7gL-1d-1Blomass
Productivity
1.381.22.5-3.50.726
1.72(batch)
0.28-0.89
(cont.)
Blomassconcentr
ateon
(g/L)
4L flasksTubular
Fence+
Tank
CSTRTubularTubularPBR Design
Fluorescent
lamp
SunlightCircular LEDLight source
25±2302530Tem.(oC)
2(for pH
control)
To control
pH
4%CO2
7.0±0.2
7.8
(initial)
10-11.58-10pH
SUMMARY OF CONTINUOUS AND SEMI-CONTINUOUS
CULTIVATION OF MICROALGAE

14. DEGRADATION OF PHENOLIC
COMPOUNDS BY MICRO ALGAE
• Till now, researches on phenol biodegradation
have almost exclusively concentrated on the
use of bacteria and fungi. But ,seems that there
was lack in literature of using algal in
biodegradation of phenol.

15. • Semple, K. T .et al, 1999 examined the catabolic
versatility of the microalgae Ochromonasdanica
(CCAP 933/2B) to degrade mixtures of phenols.
It was observed that after growth of algae, all
phenol had disappeared from a phenolic mixture
in the incubation media in 2 hours.
• Pinto et al. (2002) reported the removal of more
than 70% of phenol by two green microalgae,
ankistrodesmusbraunii and
scenedesmusquadricauda from olive-oil mill
wastewaters within 5 days of treatment. This was
similar to those obtained with fungi and bacteria.

16. • Ishihara and Nakajima (2003) reported the
removal of bis-phenol from a medium spiked
with 40 um of bis-phenol by two marine
microalga strains of nannochloropsis sp. And
chlorella gracilis up to a level of 34 % and
53% respectively over a period of 6 days under
light.

17. MECHANISMS FOR MICROALGAE
DEGRADATION OF POLLUTANTS
• Microalgae and cyanobacteria are able to rapid
uptake of nutrients and CO2 and possess quicker cell
growth. They have been studied for their capability
of degrading wide ranges of organic chemicals
including pesticides.
• In the case, of some microalgae, the presence of
molecular oxygen is indispensable. to initiates the
enzymatic attacked on the aromatic ring and
biodegradation of phenols only occurred under
aerobic conditions

18. Phenol biodegradation by meta cleavage pathway,
described in the microalgae Ochromonasdanica

19. Conclusions
• In the current study, biodegradation of phenolic Components
presented in wastewater by microalgae had been examined.
The significant impact of microalgae in treating contaminated
wastewater had been shown exploring the dominant factors
that affected the biomass growth. Culturing techniques were
further investigated to show the present development in such
field. Different reactors set up like tubular reactor and air left
reactor were investigated to highlight the progress and
benefits of culturing process under specific conditions. It had
been noticed that studying microorganism kinetics and
mechanisms possesses a great benefit in understanding the
whole process leading to more development in the current
field.