Pilot-scale microalgae cultivation and wastewater treatment using high-rate ponds: a meta-analysis

• Published in: Environmental science and pollution research international Vol. 31; no. 34; pp. 46994 - 47021
• Main Authors: Velásquez-Orta, Sharon B., Yáñez-Noguez, Isaura, Ramírez, Ignacio Monje, Ledesma, María Teresa Orta
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2024; Springer Nature B.V
• Subjects: Algae; Aquatic microorganisms; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biomass; Cultivation; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Irradiation; Microalgae; Multivariate analysis; Nutrient concentrations; Nutrient content; Parameter identification; Pilot Projects; Ponds; Productivity; Research Article; Retention time; Solar radiation; Waste Disposal, Fluid - methods; Waste Water Technology; Wastewater; Wastewater analysis; Wastewater treatment; Water Management; Water Pollution Control; Water Purification - methods; Water treatment; High-rate algal pond; Microalgae; Pilot scale; Wastewater; Outdoor cultivation; Meta-analysis
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-024-34000-7

Microalgae cultivation in wastewater has been widely researched under laboratory conditions as per its potential to couple treatment with biomass production. Currently, only a limited number of published articles consider outdoor and long-term microalgae-bacteria cultivations in real wastewater environmental systems. The scope of this work is to describe microalgal cultivation steps towards high-rate algal pond (HRAP) scalability and identify key parameters that play a major role for biomass productivity under outdoor conditions and long-term cultivations. Reviewed pilot-scale HRAP literature is analysed using multivariate analysis to highlight key productivity parameters within environmental and operational factors. Wastewater treatment analysis indicated that HRAP can effectively remove 90% of NH 4 + , 70% of COD, and 50% of PO 4 3− . Mean reference values of 210 W m −2 for irradiation, 18 °C for temperature, pH of 8.2, and HRT of 7.7 are derived from pilot-scale cultivations. Microalgae biomass productivity at a large scale is governed by solar radiation and NH 4 + concentration, which are more important than retention time variations within investigated studies. Hence, selecting the correct type of location and a minimum of 70 mg L −1 of NH 4 + in wastewater will have the greatest effect in microalgae productivity. A high nutrient wastewater content increases final biomass concentrations but not necessarily biomass productivity. Pilot-scale growth rates (~ 0.54 day −1 ) are half those observed in lab experiments, indicating a scaling-up bottleneck. Microalgae cultivation in wastewater enables a circular bioeconomy framework by unlocking microalgal biomass for the delivery of an array of products. Graphical Abstract