Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens
The microalgal strain <i>Chlorella sorokiniana</i> isolated from a waste stabilization pond was used for tertiary treatment of municipal wastewater. Three light:dark (L:D) regimes of 12:12, 16:8, and 24:0 were used for treating wastewater in microalga (A), microalga + sludge (A + S), and...
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doaj-c27f79c1bc794e299a4402bb260a59462021-09-09T13:57:27ZengMDPI AGSustainability2071-10502021-08-01139554955410.3390/su13179554Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and PathogensSwati Rani0Raja Chowdhury1Wendong Tao2Linda Nedbalová3Department of Biotechnology, B.R. Ambedkar National Institute of Technology, Jalandhar 144011, IndiaDepartment of Civil Engineering, Indian Institute of Technology, Roorkee 247667, IndiaDepartment of Environmental Resources Engineering, State University of New York, Syracuse, NY 13210, USADepartment of Ecology, Faculty of Science, Charles University, Viničná 7, 128 44 Prague, Czech RepublicThe microalgal strain <i>Chlorella sorokiniana</i> isolated from a waste stabilization pond was used for tertiary treatment of municipal wastewater. Three light:dark (L:D) regimes of 12:12, 16:8, and 24:0 were used for treating wastewater in microalga (A), microalga + sludge (A + S), and sludge (S) reactors. The removal of nutrients (N and P) was found to be the highest in the microalga-based reactor, with more than 80% removal of biochemical oxygen demand (BOD) and 1.2–5.6 log unit removal of pathogens. The addition of sludge improved chemical oxygen demand (COD) removal. Nitrifiers were found to be predominant in the A + S reactor. Algal biomass productivity was more than 280 mg/L/d in all the L:D regimes. The increase in light regime improved nutrient removal and biomass productivity in the algal reactor. Results of the kinetic study showed that (i) nitrifiers had more affinity for ammonium than microalga, and hence, most of the ammonia was oxidized to nitrate, (ii) microalga assimilated nitrate as the primary nitrogen source in the A + S reactor, and (iii) solubilization of particulate organic nitrogen originated from dead cells reduced the nitrogen removal efficiency. However, in the microalga-based reactor, the ammonium uptake was higher than nitrate uptake. Among pathogens, the removal of <i>Salmonella</i> and <i>Shigella</i> was better in the A + S reactor than in the other two reactors (microalga and sludge reactor). Additionally, the heterotrophic plate count was drastically reduced in the presence of microalga. No such drastic reduction was observed in the stand-alone sludge reactor. Kinetic modeling revealed that microalga–pathogen competition and pH-induced die-off were the two predominant factors for pathogen inactivation.https://www.mdpi.com/2071-1050/13/17/9554municipal wastewatermicroalganutrientpathogen<i>Salmonella</i><i>Shigella</i> |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Swati Rani Raja Chowdhury Wendong Tao Linda Nedbalová |
spellingShingle |
Swati Rani Raja Chowdhury Wendong Tao Linda Nedbalová Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens Sustainability municipal wastewater microalga nutrient pathogen <i>Salmonella</i> <i>Shigella</i> |
author_facet |
Swati Rani Raja Chowdhury Wendong Tao Linda Nedbalová |
author_sort |
Swati Rani |
title |
Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens |
title_short |
Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens |
title_full |
Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens |
title_fullStr |
Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens |
title_full_unstemmed |
Microalga-Mediated Tertiary Treatment of Municipal Wastewater: Removal of Nutrients and Pathogens |
title_sort |
microalga-mediated tertiary treatment of municipal wastewater: removal of nutrients and pathogens |
publisher |
MDPI AG |
series |
Sustainability |
issn |
2071-1050 |
publishDate |
2021-08-01 |
description |
The microalgal strain <i>Chlorella sorokiniana</i> isolated from a waste stabilization pond was used for tertiary treatment of municipal wastewater. Three light:dark (L:D) regimes of 12:12, 16:8, and 24:0 were used for treating wastewater in microalga (A), microalga + sludge (A + S), and sludge (S) reactors. The removal of nutrients (N and P) was found to be the highest in the microalga-based reactor, with more than 80% removal of biochemical oxygen demand (BOD) and 1.2–5.6 log unit removal of pathogens. The addition of sludge improved chemical oxygen demand (COD) removal. Nitrifiers were found to be predominant in the A + S reactor. Algal biomass productivity was more than 280 mg/L/d in all the L:D regimes. The increase in light regime improved nutrient removal and biomass productivity in the algal reactor. Results of the kinetic study showed that (i) nitrifiers had more affinity for ammonium than microalga, and hence, most of the ammonia was oxidized to nitrate, (ii) microalga assimilated nitrate as the primary nitrogen source in the A + S reactor, and (iii) solubilization of particulate organic nitrogen originated from dead cells reduced the nitrogen removal efficiency. However, in the microalga-based reactor, the ammonium uptake was higher than nitrate uptake. Among pathogens, the removal of <i>Salmonella</i> and <i>Shigella</i> was better in the A + S reactor than in the other two reactors (microalga and sludge reactor). Additionally, the heterotrophic plate count was drastically reduced in the presence of microalga. No such drastic reduction was observed in the stand-alone sludge reactor. Kinetic modeling revealed that microalga–pathogen competition and pH-induced die-off were the two predominant factors for pathogen inactivation. |
topic |
municipal wastewater microalga nutrient pathogen <i>Salmonella</i> <i>Shigella</i> |
url |
https://www.mdpi.com/2071-1050/13/17/9554 |
work_keys_str_mv |
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