Environmental microbiology and biotechnology are crucial in the modern society. They influence human health, environment and serve as a source of energy and provider of novel bioproducts. The key areas of interest are bioremediation, microbial communities, pathogen detection, waste water treatment, energy generation, bioprocesses and natural product discovery. Environmental microbiology must interact with hydrology, biogeochemistry, limnology, oceanography and numerical modeling. Environmental biotechnology is a stream in science which deals with microorganisms for environmental improvements. it primarily focuses on improving biological systems. It is a cross disciplinary where the experts focus on creating new products, analyze them and their relationships which helps in development. Microbes are organisms that are too small to be seen unaided eye. They include bacteria, fungi, protozoa, microalgae and viruses. Microbes live in familiar settings such as soil, water, food, and animal intestines, as well as in more extreme settings such as rocks, glaciers, hot springs, and deep sea vents. The wide variety of microbial habitats reflects an enormous diversity of biochemical and metabolic traits that have arisen by genetic variation and natural selection in microbial populations. Wastewater treatment is the process of converting wastewater water that is no longer needed or is no longer suitable for use into bilge water that can be discharged back into the environment. It's formed by a number of activities including bathing, washing, using the toilet, and rainwater runoff. Wastewater is full of contaminants including bacteria, chemicals and other toxins. Its treatment aims at reducing the contaminants to acceptable levels to male the water safe for discharge back in to the environment. This book provides general information in the areas of Environmental Science, Microbiology and Biotechnology. Keeping in view the recent advances in these discipline, this book aims to focus on the application of Microbiology and Biotechnology in tackling the environmental issues.