Journal of Microbiology and Biotechnology Research
Scholars Research Library
J. Microbiol. Biotech. Res., 2016, 6 (3):10-13
(http://scholarsresearchlibrary.com/archive.html)
ISSN : 2231 –3168
CODEN (USA) : JMBRB4
The efficiency of phosphate ion removal from waste water effluent using
microalgae in the laboratory scale
Najmeh Ahmad pour1, Mohammad Hossein Sayadi2*, Maryam Fallahi Capoorchali3 and
Mohammad Reza Rezaei4
1
Department of Environmental Sciences, University of Birjand, Iran
Department of Environmental Sciences, University of Birjand, Iran
3
The Researching Centre of the Inland Waters Aquaculture, Anzali Port, Iran
4
Department of Environmental Sciences, University of Birjand, Iran
2
Corresponding Email: [email protected]
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ABSTRACT
Human activities and urbanization have led to increase in the discharge of phosphorus in municipal wastewater
systems. The purpose of this study is to investigate the ability of Chlorella vulgaris to remove phosphate from waste
water. Therefore microalgae were cultured in laboratory conditionwith the volume of 350 ml of wastewater in order
to investigate the refining effects during 8-day period. Based on the results, the removal rates were found to be
40.65%, 38.02%, 24.42% and 72.20 % for days 1 to 4, 4 to 6, 6 to 8 and 1 to 8 respectively. It can be concluded that
the algae are able to remove phosphorus from aqueous solutions and Chlorella vulgaris has a high potential for
reducing phosphate from aqueous solutions. Therefore itcould be used to remove phosphorus from effluent,
althoughmore research is needed at different climatic conditions.
Keywords: Aqueous solution; Chlorellavulgaris; Effluent; Microalgae; Phosphorus removal
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INTRODUCTION
The wastewater resulting from human activities play a major role in environmental pollution [1]. Richnutrient or
eutrophication may result in changes in structure andfunction of the aqueous ecosystems. Water accumulation has
become a major problem in water quality management [2,3]. During the last 70 years, different of processes
including nitrification, Denitrification, and ion exchange have been utilized to remove nutrients from water and
Wastewater. These methods are expensive and require addition of chemicals as well as having certain practical
limitations and problems. Therefore, the use of phytoremediation can be considered as a substitute for these
methods. Microalgae have a high potential for wastewater treatment [4,5]. Wastewater treatment by algal cultures in
addition to not produce excessive pollution, but also effective recycling food, and efficient tool for removal of
nutrients and contaminant metals, specifically heavy metals, which in can result in the ecological safety of aqueous
ecosystems [6,7]. The advantage of using algae in wastewatertreatment systems is that, due to recycling and
consumption of nutrients by the algae, the probability of an eutrophication decreases or other and other ecological
damage [8]. The purpose of this study is to remove biological phosphate from wastewater using the microalgae
Chlorella vulgaris.
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Mohammad Hossein Sayadi et al
J. Microbiol. Biotech. Res., 2016, 6 (3):10-13
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MATERIALS AND METHODS
1- Preparation of themicroalgae
The microalgae used in this study was obtained from the Research Institute of Aquaculture of Bandar Anzali Bandar
Anzali and cultured in Erlenmeyer's of size 2000 mL with a volume of 1000 mL at temperature 22
in a solution
of 7 mg NaCl, 4 mg CaCl2; 2 mg of MgSO4.7H2O, 21.7 mg K2HPO4, 8.5 mg KH2PO4, 33.4 mg Na2HPO, 10 mg
NH4CL, 30 mg Zncl2, 30 mg Hbo3, 1.2 mg FeCl3.4H2O, 18 mg CuCl2.2H2O, 6 mg EDTA, and 3 mg MnCl2.4H2O.
Two florescent lamps with of 3500 lux light intensity were used in the Erlenmeyer'sfor lighting purposes. After the
microalgae reached their maximum level of growth, the microalgae cells were counted using a Thomas slideand
abinocular microscope. The dry weight per liter of the microalgae was calculated. The biomass cellular dry weight
of the microalgae was determined using the following method:
50 mL of the sample was taken and centrifuged with arotational speed of 3000 (rpm) rounds per minute for 15
minutes. The centrifuged sample was dried in an oven and the biomass was then computed using the following
equation (). [6]:
In which Cb and Cb0are the biomass densities at timest and start time t0, respectively.
2- Procurement of municipal wastewater
The Wastewater used in this study were obtained from the treatment of Birjand University. Wastewater contains
high levels of materials such as toxins and microbes. In order to scrutiny and prevent the interference of other
microorganisms, wastewater are filtered through a 0.45 micrometer filter paper [9]. To ensure the absence of any
contamination such as fungal and bacterial infections in the autoclave at 121 ° C for 20 minutessterilized and then
added two species are totally sterile environment .The initialconcentration of chlorella vulgaris in the wastewater
samplehad a weight of 0.026 grams. First the pH level, temperature, and concentration of the phosphate was
specified.Then, 50 ml cell samples were harvested from each Erlenmeyer duringof 4, 6 and 8 day intervalsand the
phosphate content was measured using a Bio spec-1601 spectrophotometer[10,11]. By sulfuric acid phosphate
detection was performed. The wavelength of 690 nm was used for phosphate.
In order to measure phosphate content, we first procure standard contents of 0.05 – 0.2 grams and then calculate the
density of the phosphate according to the calibration graph.
In the field of wastewater treatment, mathematical models form effective tools for the process,equipment design,and
infrastructure ofwastewater treatment. Water quality enhancementand predictionare also performed by these models.
Therefore, it is necessary to describe quantitative models observed in light of the microalgae behaviors with respect
to nutrient removal. One model for absorbing phosphate is the Michaelis-Menten kinetics model:
In which SPO4is the phosphate concentration in the environment and Ks is the half-saturation constant for absorbing
phosphate.This model can, however, show increases in the phosphate absorption rate due to inter-phosphorus
insufficiency [12,13].
RESULTS AND DISCUSSION
In this study, the chlorella vulgaris present in wastewater was tested for a period of 8 days and the wastewater
phosphate contents were examined in the 4th, 6th and 8th day. Samples were taken at regular intervals and the
concentration of the remaining wastewater phosphate content, after undergoing a membrane filtration process, was
calculated using a spectrophotometric method. In the initialwastewater compounds, the phosphate content was 0.148
mg per liter with a pH level of 8.30. Phosphate contents in the chlorella vulgaris sample decreased from the first day
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Mohammad Hossein Sayadi et al
J. Microbiol. Biotech. Res., 2016, 6 (3):10-13
______________________________________________________________________________
to the 8th day. The lowest amount of phosphate was observed in the 8th day which also showed the highest change in
pH level and cellular weight. The variation trend of phosphate contents in the wastewater containing microalgae
chlorella vulgaris is shown in Table 1.
Figure 1 shows the percentage of phosphorus removal by microalgae chlorella vulgarisat different time periods. As
showed by figure 1, the removal percentages are 02.65, 38.40, 24.42, and 72.20 for periodsof 1-4 days, 4-6 days, 6-8
days and 1-8 days, respectively.
Table1: variation trend of phosphate content and pH of wastewater and the dry weight of chlorella vulgaris.
Day
Phosphate (mg per kg)
Dry weight (g)
pH
1
50.65
0.026
8.30
4
30.06
0.249
9.1
6
18.63
3.844
9.5
8
14.08
3.931
10.18
Figure 1: the percentage of phosphorus removal by microalgae chlorella vulgaris at deferent time intervals
Removal of nutrients by microalgae cells is consistent with their cellular aggregation, metabolic activity,
andenvironmental conditions. Researchers have examined the potential of microalgae in wastewater treatment of
domestic and industrial wastewaters. The Domestic sewage was procured from a polluted culture farm, and the
industrial wastewaters were procured from petro materials of a factory floor. They procured a mixed culture of
microalgae which included local samples, mostly Chlorella pyrenoidosa. The algae were able to efficiently grow
and remove 50-60 percent of the phosphorus in a period of 15 days under different environmental conditions such as
pH levels,temperatures, lightened and darkened conditions which were also consistent with the findings of the
present study [14]. Lau et al (1997) used stabilized microalgae chlorella vulgaris in carrageenan and alginate
activities for treatment waste waters. The results showed that immobilizedmicroalgae were ableof removing
orthophosphate in a period of 3 days whereas the free immobilizedcould only remove about 50 percent of these two
compounds are removed in a similar time [11]. The mono-cellular microalgae chlorella vulgaris and scenedesmus
dimorphus were able to removing 55% phosphate content related to dairy wastewaterand cultural pig farms of
Columbia [15]. Another type of scenedesmus grown in artificial wastewaters was able to remove 50 percent of
phosphate content [8,16]. So far, practically no report of able to removePO4-3from domestic sewageusing microalgae
undergoing biological treatment.
CONCLUSION
Wastewaters contain organic and mineral nutrients responsible for the pollution of water and other environmental
hazards. Use of these nutrients for microalgae growth not only leads to eutrophication control but also reduces their
contents in sewages. Microalgae strains used in this study absorbed phosphate and reduced its content in sewages.
The present study indicated that by enhancing microalgae growth and increasing pH levels, the chlorella vulgaris is
ableto further removing phosphorus. It can be concluded from thisstudy that algae have a potential for removing
phosphorus from aqueous solutions and the algae chlorella vulgaris is highly capable of reducing phosphate content
in aqueous solutions and can be used for remove phosphorus from wastewaters. However, further investigations
under different climatic conditions are still necessary.
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Mohammad Hossein Sayadi et al
J. Microbiol. Biotech. Res., 2016, 6 (3):10-13
______________________________________________________________________________
Acknowledgments
The valuable collaboration of faculty authorities of natural resources and environmental to provide Birjand
University necessary Facilities to carry out this thesis and the Mrs Ghafuri and Mr Rezai to collaborate on all Steps
of laboratory and data analysis Thanks and appreciate.
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