title: Application of nitrogen sufficiency conversion strategy for microalgae-based ammonium-rich wastewater treatment.
abstract: Ammonium ([Formula: see text]-N)-rich wastewater, a main cause for eutrophication, can serve as a promising medium for fast microalgae cultivation with efficient [Formula: see text]-N removal. To achieve this goal, a well-controlled three-stage treatment process was developed. Two trophic modes (mixotrophy and heterotrophy) in Stage 1 and Stage 2, with two nitrogen availability conditions (N sufficient and N deprived) in Stage 2, and different [Formula: see text]-N concentrations in Stage 3 were compared to investigate the effects of nitrogen sufficiency conversion on indigenous strain UMN266 for [Formula: see text]-N removal. Results showed that mixotrophic cultures in the first two stages with N deprivation in Stage 2 was the optimum treatment strategy, and higher [Formula: see text]-N concentration in Stage 3 facilitated both microalgal growth and [Formula: see text]-N removal, with average and maximum biomass productivity of 55.3 and 161.0 mg L(-1) d(-1), and corresponding removal rates of 4.2 and 15.0 mg L(-1) d(-1), respectively, superior to previously published results. Observations of intracellular compositions confirmed the optimum treatment strategy, discovering excellent starch accumulating property of strain UMN266 as well. Combination of bioethanol production with the proposed three-stage process using various real wastewater streams at corresponding stages was suggested for future application.
authors.affiliation: a Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment , Tsinghua University , Beijing , People's Republic of China.|b Bioproducts and Biosystems Engineering Department , Center for Biorefining, University of Minnesota , Saint Paul , MN , USA.|c College of Environmental Science & Engineering , Research Institute of Environmental Planning and Management, Tongji University , Shanghai , People's Republic of China.
authors.forename: Jinghan
authors.initials: J
authors.lastname: Wang
authors.affiliation: b Bioproducts and Biosystems Engineering Department , Center for Biorefining, University of Minnesota , Saint Paul , MN , USA.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Zhou
authors.affiliation: c College of Environmental Science & Engineering , Research Institute of Environmental Planning and Management, Tongji University , Shanghai , People's Republic of China.
authors.forename: Haizhen
authors.initials: H
authors.lastname: Yang
authors.affiliation: b Bioproducts and Biosystems Engineering Department , Center for Biorefining, University of Minnesota , Saint Paul , MN , USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Ruan
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry / Q000378:metabolism*; D056804:Biofuels; D058086:Microalgae / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D064751:Ammonium Compounds; D056804:Biofuels; D009584:Nitrogen; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Nitrogen sufficiency conversion; ammonium-rich wastewater; microalgae; mixotrophic cultivation; three-stage process