Grand challenges in environmental engineering

Environmental issues such as water pollution, climate change, soil erosion, hazardous wastes, resource depletion, and biodiversity loss have been at the front of global concerns for many years. These environmental problems pose a severe threat to the quality of human life and ecosystem sustainability, and thus protecting the natural environment has become an important task for individuals, organizations, and governments. Encouragingly, environmentalists and engineers have made great achievements in the development of science, theories, and techniques for environmental remediation. As an involved interdisciplinary field, environmental engineering embraces broad scientific disciplines such as chemistry, biology, physics, geology, ecology, engineering (e.g., materials, computers, and civil engineering), mathematics, and economics to develop practical solutions for treating and controlling natural and anthropogenic contaminants across all environmental matrices (i.e., water, air, soil, and sediment), thus sustaining the health of all living things and improving the quality of the ecosystem. The Frontiers in Environmental Engineering significantly push the boundary of environmental protection to a high level. Typically, breakthroughs in wastewater management, air pollution control, soil remediation, and waste utilization have marked the improvement of humanity’s standards of living. For instance, the anaerobic ammonium oxidation technology (anammox) innovates the direct oxidation of ammonia to nitrogen gas (N2) without the generation of toxic nitrous oxide (N2O, a kind of greenhouse gas) (Dalsgaard et al., 2003; Kuypers et al., 2003; Kartal et al., 2011), which importantly regulates the nitrogen circle in the wastewater treatment process. Carbon dioxide (CO2), a major part of greenhouse gas, has been recognized as the main reason for climate change. To manage the high carbon emission in the atmosphere, the carbon capture, utilization, and storage technology (CCUS) which involves the capture of CO2 from anthropogenic sources, and distribution of captured CO2 to different utilization or storage processes has shown an important role in achieving the carbon-neutral goal (Bachu, 2016; Tapia et al., 2018). Heavy metal(loid) polluted soils attract global public attention owing to growing concerns about the security of groundwater and agricultural products. Phytoremediation has gained increasing attention for its cost-effectiveness, ecofriendliness, and good efficiency. Currently, ~ 500 plant species have been identified as hyperaccumulators of metal(loid)s and employed for soil remediation (Li et al., 2019; Gavrilescu, 2022). Also, the controllable pyrolysis of plastic wastes to form value-added carbon-based functional materials can not only help to manage hazardous solid waste but OPEN ACCESS