Enhanced microalgae cultivation using wastewater nutrients extracted by a microbial electrochemical system

Zixuan Wang, Christopher J. Hartline, Fuzhong Zhang, Zhen He

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Cultivating algae using wastewater nutrients is a potential approach to realize resource recovery that can contribute to circular economy. However, growing algae directly in a wastewater has problems such as bacterial contamination and a low biomass density. To address those problems, we investigated microalgal cultivation in a photobioreactor (PBR) fed with the nutrients extracted from wastewater by a microbial nutrient recovery cell (MNRC). With an external voltage of 0.3 V, the MNRC-PBR system removed 96% of COD and recovered 44% of NH4+-N and 39% of PO43−-P at a hydraulic retention time of 7.2 h. Microalgae cultivated in the nutrient recovery medium from the MNRC had 8.3-fold biomass density and 1.4-fold lipid contents, versus that cultivated in a food wastewater containing more nutrients. More significantly, 90% of biomass yielded from the MNRC-PBR system was microalgae, much higher than ∼30% in the food wastewater. A liquid exchange ratio of 30% achieved the highest microalgal density of 0.61 ± 0.06 g L−1, comparable to that in a standard BG11 medium. There was a tradeoff between recycling PBR medium and microalgal growth. The accumulated salinity was observed in the extended operation of the MNRC-PBR system treating an actual food wastewater. The results of this study have demonstrated an effective approach to extract nutrients from wastewater for enhanced microalgal growth and improved biomass quality.

Original languageEnglish
Article number117722
JournalWater Research
Volume206
DOIs
StatePublished - Nov 1 2021

Keywords

  • Microalgae
  • Microbial electrochemical
  • Nutrient removal and recovery
  • Resource recovery
  • Wastewater treatment

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