Abstract
Photoautotrophic algal systems have been investigated as potentially greener and more sustainable alternatives to the traditional bacteria-based wastewater treatment (WWT) systems. This paper presents mixotrophic algal systems as better suited for WWT. Since the literature is void of mixotrophic WWT systems, a brief review of the laboratory results from the literature comparing the different types of algal metabolisms is presented first. Details of a mixotrophic WWT system driven by an extremophilic alga, Galdieria sulphuraria (pH = 1 to 4; temperature = 25 to 56 °C) are presented next. Results from pilot scale version of this mixotrophic system (700 L) are summarized to show that it can reduce biochemical oxygen demand (BOD) and nutrients in primary-settled wastewater in a single step to yield discharge-ready effluent in <3 days of fed-batch processing. Average volumetric removal rates of BOD5 (16.5 ± 3.6 mg L−1 d−1) and ammoniacal nitrogen (6.09 ± 0.92 mg L−1 d−1) in this mixotrophic system were found to be not different from those reported for the photoautotrophic high rate algal ponds (significance level of 0.05); but, that of phosphates (1.40 ± 0.57 mg L−1 d−1) is greater than that reported for the photoautotrophic high rate algal ponds (significance level of 0.05). Additionally, the extreme culture conditions in this particular mixotrophic system enabled concurrent reductions of E. coli (>5 log) and other pathogenic bacteria.
| Original language | English (US) |
|---|---|
| Article number | 101569 |
| Journal | Algal Research |
| Volume | 41 |
| DOIs | |
| State | Published - Aug 1 2019 |
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Keywords
- Autotrophy
- BOD removal
- Galdieria sulphuraria
- Heterotrophy
- Mixotrophy
- Nutrient removal
- Pathogen removal
ASJC Scopus subject areas
- Agronomy and Crop Science
Cite this
Algal wastewater treatment : Photoautotrophic vs. mixotrophic processes. / Nirmalakhandan, N.; Selvaratnam, T.; Henkanatte-Gedera, S. M.; Tchinda, D.; Abeysiriwardana-Arachchige, I. S.A.; Delanka-Pedige, H. M.K.; Munasinghe-Arachchige, S. P.; Zhang, Y.; Holguin, F. O.; Lammers, Peter.
In: Algal Research, Vol. 41, 101569, 01.08.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Algal wastewater treatment
T2 - Photoautotrophic vs. mixotrophic processes
AU - Nirmalakhandan, N.
AU - Selvaratnam, T.
AU - Henkanatte-Gedera, S. M.
AU - Tchinda, D.
AU - Abeysiriwardana-Arachchige, I. S.A.
AU - Delanka-Pedige, H. M.K.
AU - Munasinghe-Arachchige, S. P.
AU - Zhang, Y.
AU - Holguin, F. O.
AU - Lammers, Peter
PY - 2019/8/1
Y1 - 2019/8/1
N2 - Photoautotrophic algal systems have been investigated as potentially greener and more sustainable alternatives to the traditional bacteria-based wastewater treatment (WWT) systems. This paper presents mixotrophic algal systems as better suited for WWT. Since the literature is void of mixotrophic WWT systems, a brief review of the laboratory results from the literature comparing the different types of algal metabolisms is presented first. Details of a mixotrophic WWT system driven by an extremophilic alga, Galdieria sulphuraria (pH = 1 to 4; temperature = 25 to 56 °C) are presented next. Results from pilot scale version of this mixotrophic system (700 L) are summarized to show that it can reduce biochemical oxygen demand (BOD) and nutrients in primary-settled wastewater in a single step to yield discharge-ready effluent in <3 days of fed-batch processing. Average volumetric removal rates of BOD5 (16.5 ± 3.6 mg L−1 d−1) and ammoniacal nitrogen (6.09 ± 0.92 mg L−1 d−1) in this mixotrophic system were found to be not different from those reported for the photoautotrophic high rate algal ponds (significance level of 0.05); but, that of phosphates (1.40 ± 0.57 mg L−1 d−1) is greater than that reported for the photoautotrophic high rate algal ponds (significance level of 0.05). Additionally, the extreme culture conditions in this particular mixotrophic system enabled concurrent reductions of E. coli (>5 log) and other pathogenic bacteria.
AB - Photoautotrophic algal systems have been investigated as potentially greener and more sustainable alternatives to the traditional bacteria-based wastewater treatment (WWT) systems. This paper presents mixotrophic algal systems as better suited for WWT. Since the literature is void of mixotrophic WWT systems, a brief review of the laboratory results from the literature comparing the different types of algal metabolisms is presented first. Details of a mixotrophic WWT system driven by an extremophilic alga, Galdieria sulphuraria (pH = 1 to 4; temperature = 25 to 56 °C) are presented next. Results from pilot scale version of this mixotrophic system (700 L) are summarized to show that it can reduce biochemical oxygen demand (BOD) and nutrients in primary-settled wastewater in a single step to yield discharge-ready effluent in <3 days of fed-batch processing. Average volumetric removal rates of BOD5 (16.5 ± 3.6 mg L−1 d−1) and ammoniacal nitrogen (6.09 ± 0.92 mg L−1 d−1) in this mixotrophic system were found to be not different from those reported for the photoautotrophic high rate algal ponds (significance level of 0.05); but, that of phosphates (1.40 ± 0.57 mg L−1 d−1) is greater than that reported for the photoautotrophic high rate algal ponds (significance level of 0.05). Additionally, the extreme culture conditions in this particular mixotrophic system enabled concurrent reductions of E. coli (>5 log) and other pathogenic bacteria.
KW - Autotrophy
KW - BOD removal
KW - Galdieria sulphuraria
KW - Heterotrophy
KW - Mixotrophy
KW - Nutrient removal
KW - Pathogen removal
UR - http://www.scopus.com/inward/record.url?scp=85067000654&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85067000654&partnerID=8YFLogxK
U2 - 10.1016/j.algal.2019.101569
DO - 10.1016/j.algal.2019.101569
M3 - Article
VL - 41
JO - Algal Research
JF - Algal Research
SN - 2211-9264
M1 - 101569
ER -