Biogenic nanoparticles-the future of eco-friendly wastewater treatment: a review

Abstract Biogenic nanoparticles produced using plant and microbial sources have emerged as low cost and environmentally benign alternatives for wastewater treatment applications. This review examines the underlying mechanisms of plant and microbe mediated nanoparticle synthesis, highlighting how naturally occurring biomolecules act as reducing, stabilizing, and capping agents to regulate nanoparticle surface characteristics. The discussion outlines key practical advantageous, including lower energy inputs, avoidance of hazardous reducing agents, use of renewable biological resources, and the potential for in situ or decentralized production, while also noting constraints like variability in plant extracts or microbial cultures. Applications in the removal of organic dyes, heavy metals, and pharmaceuticals are discussed with emphasis on performance indicators such as adsorption capacity, degradation efficiency, selectivity, and nanoparticle recovery and reuse. Alongside future opportunities for advancing green nanotechnologies through improved standardization, process control, integration with existing treatment systems, and comprehensive lifecycle under techno-economic evaluations. A comparative assessment indicates that plant-based synthesis is typically rapid, scalable, and suitable for high throughput production due to its procedural simplicity and abundance of phytochemicals. In contrast microbial synthesis generally allows finer control over nanoparticles size, shape and crystallinity. Unlike existing reviews that largely describe individual synthesis approaches or application specific studies, this review offers a critical, integrative comparison of biogenic nanoparticle synthesis routes, highlighting key performance and practical limitations across systems. The analysis indicates that no single biogenic route is universally optimal; rather, application driven selection is required, balancing efficiency, scalability and environmental capability. These insights clarify current progress while identifying priority directions for advancing biogenic nanomaterials towards real-world wastewater treatment applications.