Long term outdoor microalgal phycoremediation of anaerobically digested abattoir effluent

• Published in: Journal of environmental management Vol. 323; p. 116322
• Main Authors: Shayesteh, Hajar, Vadiveloo, Ashiwin, Bahri, Parisa A., Moheimani, Navid R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: Biomass productivity; Nutrient removal; Reclaimed water; Red meat processors; Wastewater; Nutrient removal; Biomass productivity; Reclaimed water; Wastewater; Red meat processors
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.116322

Sufficient and reliable long-term field data on the growth, productivity and nutrient removal rates of microalgal based wastewater treatment system is essential to validate its overall techno-economic feasibility. Here, we investigated the semi-continuous microalgal cultivation of Scenedesmus sp. in anaerobically digested abattoir effluent (ADAE) for 13 months in outdoor raceway ponds operated at 20 cm depth. This study was initiated with three different cultures consisting of 1) monocultures of Chlorella sp., 2) Scenedesmus sp., and 3) an equal mixed concentration of both microalgae species. However, after 15 weeks, Scenedesmus sp. was found to be the most dominant microalgae species in all the different cultures, even completely taking over the Chlorella sp. monoculture. Over the course of summer and early autumn, the average weekly biomass productivity of Scenedesmus sp. cultures was 12.5 ± 0.6 g m−2 d−1 which was 16% and 30% higher than productivities recorded in spring and winter, respectively. All available ammoniacal nitrogen (NH3–N) was found to be exhausted during each growth period with an average 33.6% nitrogen assimilation rate. The average rate of phosphate and COD (chemical oxygen demand) removals were 85.2% and 37.5% throughout the cultivation period. No significant differences were found in carbohydrate, lipid and protein content of Scenedesmus sp. during different seasons of the year. Over 53% increase in biomass productivity can be achieved if CO2 is added to control culture pH at pH 6.5. Here, we successfully demonstrated reliability of continuous long-term cultivation of microalgae in ADAE for simultaneous wastewater treatment and algal biomass production. [Display omitted] •Scenedesmus sp. cultivated in waste effluent for 13 months in outdoor raceway ponds.•Scenedesmus sp. was the most dominant species in cultures taking over Chlorella sp.•Biomass productivity was 12.5 ± 0.6 g m−2 d−1 in summer which was 30% higher than winter.•All ammoniacal nitrogen and 85% of phosphorus were removed from the system.•34 and 26% nitrogen and phosphorus fixed into biomass during entire cultivation period.