Combined yeast and microalgal cultivation in a pilot-scale raceway pond for urban wastewater treatment and potential biodiesel production

Water Sci Technol. 2018 Feb;77(3-4):1062-1071. doi: 10.2166/wst.2017.620.

Abstract

A mixed culture of oleaginous yeast Lipomyces starkeyi and wastewater native microalgae (mostly Scenedesmus sp. and Chlorella sp.) was performed to enhance lipid and biomass production from urban wastewaters. A 400 L raceway pond, operating outdoors, was designed and used for biomass cultivation. Microalgae and yeast were inoculated into the cultivation pond with a 2:1 inoculum ratio. Their concentrations were monitored for 14 continuous days of batch cultivation. Microalgal growth presented a 3-day initial lag-phase, while yeast growth occurred in the first few days. Yeast activity during the microalgal lag-phase enhanced microalgal biomass productivity, corresponding to 31.4 mgTSS m-2 d-1. Yeast growth was limited by low concentrations in wastewater of easily assimilated organic substrates. Organic carbon was absorbed in the first 3 days with a 3.7 mgC L-1 d-1 removal rate. Complete nutrient removal occurred during microalgal linear growth with 2.9 mgN L-1 d-1 and 0.96 mgP L-1 d-1 removal rates. Microalgal photosynthetic activity induced high pH and dissolved oxygen values resulted in natural bactericidal and antifungal activity. A 15% lipid/dry weight was measured at the end of the cultivation time. Fatty acid methyl ester (FAME) analysis indicated that the lipids were mainly composed of arachidic acid.

MeSH terms

  • Biofuels
  • Biomass
  • Chlorella* / growth & development
  • Chlorella* / metabolism
  • Lipids / biosynthesis
  • Lipomyces* / growth & development
  • Lipomyces* / metabolism
  • Microalgae* / growth & development
  • Microalgae* / metabolism
  • Pilot Projects
  • Ponds
  • Scenedesmus* / growth & development
  • Scenedesmus* / metabolism
  • Waste Disposal, Fluid / methods*
  • Wastewater

Substances

  • Biofuels
  • Lipids
  • Waste Water