The 5th International Conference of Recent Trends in Environmental Science and Engineering (RTESE'21) aims to become the leading annual conference in fields related to environmental science and engineering. The goal of RTESE'21 is to gather scholars from all over the world to present advances in the relevant fields and to foster an environment conducive to exchanging ideas and information. This conference will also provide an ideal environment to develop new collaborations and meet experts on the fundamentals, applications, and products of the mentioned fields.