Introduction

The exponential increase in urbanization and industrialization of the 19th century led to an increase in the amount and complexity of wastewater generated by cities. During the 19th century, untreated wastewater was disposed of into surface water bodies. This practice increased the concentration of nitrogen and phosphorus in the environment, which increased the growth of bacteria and algae. The exponential growth of bacteria and algae resulted in the utilization and subsequent depletion of oxygen, causing the death of aquatic life. As nitrogen can be fixed from the atmosphere by different organisms, phosphorus is the key nutrient to be removed in order to avoid eutrophication of water bodies. Past research had identified and proposed different microorganism capable to store phosphorus beyond its growth requirements. Biological nutrient removal treatment plants aim to remove phosphorus and nitrogen from wastewater. The chapter also presents an overview of the key concepts discussed in this book.