Microalgae-Based Technologies for Wastewater Treatment, Resource Recovery, and High-Value Bioproducts

Dear Colleagues,

Microalgae-based technologies are gaining increasing attention as sustainable solutions to global challenges in wastewater treatment, resource recovery, CO₂ mitigation, and the development of value-added bioproducts. Microalgae exhibit exceptional capabilities in nutrient removal, CO₂ fixation, the biosorption of pollutants, and the biotransformation of organic wastes. Moreover, their biomass can be further valorized into biofuels, feed additives, bioactive compounds, pigments, polysaccharides, and other high-value products.

This Special Issue aims to bring together cutting-edge research on microalgae–wastewater systems, spanning fundamental mechanisms, rational design and engineering of algal strains, bioprocess engineering, and industrial applications. We welcome submissions that explore innovative technologies for water pollution control, nutrient recovery, algal–bacterial interactions, and integrated biorefineries, as well as interdisciplinary approaches linking environmental engineering, biotechnology, and marine bioresources.

Topics of interest include, but are not limited to, the following:

• Microalgae-based wastewater treatment (nutrient removal, ammonia/organic-rich wastewater treatment, biogas slurry treatment, pollutant degradation);
• Algal–bacterial consortia systems;
• Biological nitrogen and carbon removal processes (autotrophic nitrogen removal, anaerobic systems, carbon capture using microalgae);
• Resource recovery and circular bioeconomy (valorization of waste streams into lipids, H₂, pigments, polysaccharides, proteins, biofertilizers);
• Heterotrophic and mixotrophic microalgae cultivation;
• Metabolic regulation and synthetic biology for improved bioproduct accumulation;
• Bioprocess engineering and scale-up (photobioreactors, outdoor cultivation, bioreactor design, magnetic harvesting, co-culture strategies);
• Marine microalgae and marine bioactive compounds (functional ingredients, antioxidant/antitumor activities, bioactive polysaccharides);
• Life-cycle assessment, techno-economic analysis, and large-scale demonstration practices.

We particularly encourage contributions demonstrating pilot- or engineering-scale applications, innovative process integration, and strategies that advance microalgae-based technologies toward practical deployment.

We believe that this Special Issue will serve as an inspiring platform to promote interdisciplinary collaboration and accelerate the transition toward sustainable water treatment and resource recovery using microalgae.

Dr. Yuansheng Hu
Prof. Dr. Hui Chen
Prof. Dr. Liqin Sun
Dr. Zhongliang Sun
Topic Editors