Shujuan Zhang

Semiconductor–biological hybrid systems (SBHS) have emerged as a disruptive technology for solar-driven chemical manufacturing, effectively bypassing the thermodynamic bottlenecks of natural photosynthesis. However, the aggressive pursuit of record-breaking solar-to-chemical conversion efficiencies has inadvertently fostered an efficiency trap. A profound interdisciplinary schism exists wherein the acute environmental toxicity and long-term interfacial instability of these hybrid architectures are frequently overlooked. This review provides a critical appraisal of the oft-ignored environmental risks inherent in current SBHS designs. We systematically dissect the heavy metal leaching toxicity of first-generation inorganic photosensitizers and unveil the complex, bidirectional degradation mechanisms at the abiotic–biotic interface. Specifically, we highlight the dual threats of photogenerated reactive oxygen species inducing cellular oxidative stress and active, microbially induced material dismantling via reductive dissolution driven by extracellular electron transfer. To navigate beyond this purely performance-driven paradigm, we propose a multidimensional, standardized evaluation matrix that systematically balances catalytic efficiency with biological safety and life-cycle sustainability. Ultimately, this review offers a comprehensive roadmap to transition biohybrid platforms from fragile laboratory concepts into robust, scalable, and ecologically benign negative-emission technologies.

The management and control of harmful cyanobacterial blooms remain a persistent global environmental challenge. This study evaluated the algicidal efficacy and ecological impacts of butanedione (BD), a naturally occurring agent, in aquatic microcosms that simulate real-world conditions. Special attention was given to the distinct roles of its two main photolytic products, peroxyacetyl radical (CH₃C(O)OO^•) and acetate (Ac). The results demonstrated that Ac exerted minimal short-term impact on cyanobacterial proliferation. In contrast, BD-derived radicals induced rapid cyanobacterial suppression, improving key water quality parameters in the early phase and subsequently supporting the recovery of eukaryotic algae. These radicals also markedly altered aquatic community structure, enriched beneficial photoheterotrophic bacteria, and suppressed functional pathways related to cell envelope biosynthesis. Notably, BD treatment reduced the abundance of antibiotic resistance genes (ARGs) and virulence factor genes, as well as the total relative abundance of potential bacterial hosts carrying both types of genes to 1/5 of that observed in the Ac-treated group. These results underscore BD's dual functionality as an effective cyanocide with application potential, providing a scientifically grounded strategy for the sustainable management of harmful cyanobacteria-affected aquatic ecosystems.

Collectively, these six articles do more than mark an anniversary; they chart a testament to the journal's vision of fostering a collaborative, global community of environmental engineers dedicated to solving the planet's most pressing ecological challenges. They demonstrate that the future of environmental engineering lies in integrating advanced materials and biological processes, embracing systemic assessment tools, and finding value in what was once considered waste. As the journal enters its next phase, we look forward to building on this foundation, welcoming innovative research, and continuing to serve as a vital platform for sharing knowledge that empowers the environmental engineering community to protect and restore natural ecosystems for future generations.We extend our gratitude to all the contributing authors, the journal's editorial boards, and the Frontiers team for their support in making this anniversary Research Topic possible. It is our hope that these works inspire further inquiry, collaboration, and action-core tenets of Frontiers in Environmental Engineering as we move forward in our mission to advance environmental engineering for a sustainable world.