A non-sterile heterotrophic microalgal process for dual biomass production and carbon removal from swine wastewater

This study addresses the development of a non-sterile heterotrophic microalgae process, mainly using Scenedesmus sp., for the treatment of wastewater with high concentration of organic matter and biomass production. Urban and swine wastewaters were used as source of organic carbon. A C:N ratio of 3.4:1 provided a maximum biomass concentration of 1.22 g/L on day 13 using autotrophic conditions. Using the same C:N ratio under dark conditions a maximum biomass concentration of 1.1 g/L was measured on day 14. Heterotrophic growth removed 81.6% of the total organic carbon (TOC), 83.7% of the chemical oxygen demand (COD) and 85.1% of the biochemical oxygen demand (BOD5). Results indicated that the application of a non-sterile heterotrophic process contributed to the removal of organic matter with the advantage of biomass generation, and although more detailed analysis is needed, it is likely due to the microalgae-bacteria association. (C) 2021 Elsevier Ltd. All rights reserved.