The global increase in municipal and industrial wastewater generation has intensified the need for ecologically resilient and technologically advanced treatment systems. Although traditional biological treatment technologies are effective for organic load reduction, they often fail to remove recalcitrant xenobiotics such as pharmaceuticals, synthetic dyes, endocrine disruptors (EDCs), and microplastics (MPs). Engineered microbial consortia offer a promising and sustainable alternative owing to their metabolic flexibility, ecological resilience, and capacity for syntrophic degradation of complex pollutants. This review critically examines emerging strategies for enhancing microbial bioremediation in wastewater treatment systems (WWTS), focusing on co-digestion, biofilm engineering, targeted bioaugmentation, and incorporation of conductive materials to stimulate direct interspecies electron transfer (DIET). This review highlights how multi-omics platforms, including metagenomics, transcriptomics, and metabolomics, enable high-resolution community profiling and pathway reconstructions. The integration of artificial intelligence (AI) and machine learning (ML) algorithms into bioprocess diagnostics facilitates real-time system optimization, predictive modeling of antibiotic resistance gene (ARG) dynamics, and intelligent bioreactor control. Persistent challenges, such as microbial instability, ARG dissemination, reactor fouling, and the absence of region-specific microbial reference databases, are critically analyzed. This review concludes with a translational pathway for the development of next-generation WWTS that integrate synthetic microbial consortia, AI-mediated biosensors, and modular bioreactors within the One Health and Circular Economy framework.

The projected global population is expected to reach 9.7 billion by 2050, necessitating a significant increase in food production. Malnutrition remains a global health challenge that contributes to over 3.5 million deaths annually and accounts for 45% of all child mortalities. Microalgae, including cyanobacteria, are a promising solution because of their rich composition of bioactive compounds such as polyunsaturated fatty acids, carotenoids, proteins, vitamins, and minerals. These biomolecules provide various health benefits, including antioxidant, antidiabetic, anticancer, anti-inflammatory, and cardioprotective properties, making microalgal biomass a valuable ingredient in functional food formulations. However, the large-scale adoption of microalgae for food production faces several challenges, including species-specific variations in biochemical composition, inconsistencies in biomass yield, structural alterations during extraction and purification, sensory issues, and bioprocessing inefficiencies. Furthermore, regulatory challenges and concerns regarding bioavailability and safety continue to limit their widespread acceptance. Despite these limitations, microalgal bioactives have significant potential for the development of next-generation nutraceuticals and functional foods. This review examines the bioactive compounds found in microalgae, detailing their biological activities and functional applications in the food industry. Additionally, it explores the key challenges preventing their integration into food products and proposes strategies to overcome these challenges, ultimately facilitating the commercialization of microalgae as a sustainable and health-promoting food source.

The global population is expected to reach 9.5 billion, which means that crop productivity needs to double to meet the growing population’s food demand. Soil degradation and environmental factors, such as climate events, significantly threaten crop production and global food security. Furthermore, rapid urbanization has led to 55% of the world’s population migrating to cities, and this proportion is expected to increase to 75% by 2050, which presents significant challenges in producing staple foods through conventional hinterland farming. Numerous studies have proposed various sustainable farming techniques to combat the shortage of farmable land and increase food security in urban areas. Soilless farming techniques such as hydroponics have gained worldwide popularity due to their resource efficiency and production of superior-quality fresh products. However, using chemical nutrients in a conventional hydroponic system can have significant environmental impacts, including eutrophication and resource depletion. Incorporating microalgae into hydroponic systems as biostimulants offers a sustainable and ecofriendly approach toward circular bioeconomy strategies. The present review summarizes the plant growth-promoting activity of microalgae as biostimulants and their mechanisms of action. We discuss their effects on plant growth parameters under different applications, emphasizing the significance of integrating microalgae into a closed-loop circular economy model to sustainably meet global food demands.

The increasing global population has raised concerns about meeting growing food demand. Consequently, the agricultural sector relies heavily on chemical fertilizers to enhance crop production. However, the extensive use of chemical fertilizers can disrupt the natural balance of the soil, causing structural damage and changes in the soil microbiota, as well as affecting crop yield and quality. Biofertilizers and biostimulants derived from microalgae and cyanobacteria are promising sustainable alternatives that significantly influence plant growth and soil health owing to the production of diverse biomolecules, such as N-fixing enzymes, phytohormones, polysaccharides, and soluble amino acids. Despite these benefits, naturally producing high-quality microalgal biomass is challenging owing to various environmental factors. Controlled settings, such as artificial lighting and photobioreactors, allow continuous biomass production, but high capital and energy costs impede large-scale production of microalgal biomass. Sustainable methods, such as wastewater bioremediation and biorefinery strategies, are potential opportunities to overcome these challenges. This review comprehensively summarizes the plant growth-promoting activities of microalgae and elucidates the mechanisms by which various microalgal metabolites serve as biostimulants and their effects on plants, using distinct application methods. Furthermore, it addresses the challenges of biomass production in wastewater and explores biorefinery strategies for enhancing the sustainability of biofertilizers.

The projected global population of 9.22 billion by 2075 necessitates sustainable food sources that provide health benefits beyond essential nutrition, as the relationship between food biochemistry and human well-being is becoming increasingly significant. Microalgae are simple microscopic organisms rich in various bioactive compounds, such as pigments, vitamins, polyunsaturated fatty acids, polysaccharides, bioactive peptides, and polyphenols, which can be used to develop novel foods with potential health benefits. Bioactive substances offer numerous health benefits, including anti-inflammatory, anticancer, antioxidant, anti-obesity, and heart-protective effects. However, incorporating microalgal biomass into functional food products presents several challenges, including species diversity, fluctuations in biomass production, factors affecting cultivation, suboptimal bioprocessing methods, inconclusive evidence regarding bioavailability and safety, and undesirable flavors and aromas in food formulations. Despite these challenges, significant opportunities exist for the future development of microalgae-derived functional food products. Extensive investigations are essential to overcome these challenges and enable the large-scale commercialization of nutritious microalgae-based food products. This review aims to examine the potential of microalgae as natural ingredients in functional food production, explore the factors limiting their industrial acceptance and utilization, and assess the safety issues associated with human consumption.

Wastewater treatment plants (WWTPs) function as engineered ecosystems in which microbial consortia mediate nutrient cycling, xenobiotic degradation, and heavy metal detoxification. This review discusses a forward-looking roadmap that integrates microbial ecology, multi-omics diagnostics, and artificial intelligence (AI) for next-generation treatments. Meta-analyses suggest that a globally conserved core microbiome indicates sludge functions, with high predictive value for treatment stability. Multi-omics approaches, including metagenomics, metatranscriptomics, and environmental DNA (eDNA) profiling, have integrated microbial composition with greenhouse gas (GHG) emissions, showing that WWTPs contribute 2–5% of anthropogenic nitrous oxide (N₂O) emissions. Emerging AI-enhanced eDNA models have achieved >90% predictive accuracy for effluent quality and antibiotic resistance gene (ARG) prevalence, facilitating near-real-time monitoring and adaptive control of effluent quality. Key advances include microbial strategies for degrading organic pollutants, pesticides, and heavy metals and monitoring industrial effluents. This review highlights both translational opportunities, including engineered microbial consortia, AI-driven digital twins and molecular indices, and persistent barriers, including ARG dissemination, resilience under environmental stress and regulatory integration. Future WWTPs are envisioned as adaptive, climate-conscious biorefineries that recover resources, mitigate ecological risks, and reduce their carbon footprint.