Work

Optimization of Auxenochlorella pyrenoidosa Photobioreactor Parameters for Low Carbon-to-Nitrogen Ratio Wastewater Treatment: Effects of Inoculum Density, Aeration, Light Intensity, and Photoperiod

Year: 2025

Type: article

Abstract: Treating wastewater with a low carbon-to-nitrogen (C/N) ratio remains a major challenge for conventional biological processes because insufficient organic carbon limits heterotrophic denitrification. To address this issue, microalgae-based photobioreactors offer a sustainable alternative that couples nutrient removal with biomass valorization. This study systematically evaluated the effects of four key operational parameters—initial inoculum density, aeration rate, light intensity, and photoperiod—on nutrient removal, biomass productivity, and metabolite accumulation of Auxenochlorella pyrenoidosa (A. pyrenoidosa) treating synthetic low C/N wastewater. Optimal operating conditions were identified as an initial OD680 of 0.1, aeration rate of 2 L air min−1, light intensity of 112 μmol m−2 s−1, and a 16L:8D photoperiod. Under these conditions, the photobioreactor achieved 86.35% total nitrogen and 98.43% total phosphorus removal within 11 days while producing biomass rich in proteins, polysaccharides, and lipids. Metagenomic analysis revealed a metabolic transition from denitrification-driven pathways during early operation to assimilation-dominated nitrogen metabolism under optimized conditions, emphasizing the synergistic interactions within algal–bacterial consortia. These findings demonstrate that optimized A. pyrenoidosa-based photobioreactors can effectively recover nutrients and produce valuable biomass, offering a viable and sustainable solution for the treatment of low C/N wastewater.

Source: Water

DOI: 10.3390/w17243577

Authors: Lin Zhao, Yuwei Xu, Tian Tian, Yifan Zhang, Guanqin Huang, Jun Tang

Institutions: Fuyang Normal University, Shenzhen University

Language: English

Topic: Algal biology and biofuel production

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production, Affordable and clean energy, Climate action

Open Access status: gold

Estimated APC paid: $3,137