2021 2nd International Conference of Recent Trends in Environmental Sustainability and Green Technologies (ICRTEG 2021) will take place in Ottawa, Canada, on October 16-18, 2021. ICRTEG 2021 provides managers, academicians, scientists, and researchers in various government, public, and private sectors an in-depth look into new techniques, strategies, and technologies for achieving environmental sustainability through best business and technology practices. The conference covers topical issues including sustainable strategy and innovation, advanced technologies related to the 4th Industry Revolution, green digitalization, sustainable asset management (ILS, operation and maintenance, reliability, life cycle etc.), energy and defense efficient systems, green and sustainable transformation, as well as other topics like product usability, reverse and closed loop supply chain, environmental issues (carbon footprints, global warming, recycling and reuse systems, applied ergonomics, climate change), and all those topics related to logic, philosophy and history of science and technology from the green/sustainable point of view. This conference offers research contributions, constructive debates, and investigations on new legislations on disruptive technologies, green (sustainable) IT and processes, Industry 4.0, healthcare informatics and applications in terms of environmental, defense and social issues for both the manufacturing and service industries.