Preface

With the application of nitrate-containing fertilizers, consumption of animal products, and industrial production activities, ever more ammonia and nitrate are being discharged into rivers and lakes, which may cause eutrophication and deterioration of aquatic environ‐ ments. The maximum acceptable contamination level in drinking water is 10 mg/L nitrate nitrogen in the USA, Japan, and Korea, while the European Union countries set the stand‐ ard for nitrate nitrogen at 11.3 mg/L, and the World Health Organization recommends 11.3 mg/L nitrate nitrogen to protect against methemoglobinemia in bottle-fed infants. To pro‐ tect aquatic ecological systems, an ever more stringent limit was imposed to point source dischargers into sensitive water bodies, such as Chesapeake Bay area in the USA. Nitrifica‐ tion and denitrification are the fundamental process routes in nitrogen removal in aquatic ecosystems. They play an essential role in natural systems and engineered systems in terms of the nitrogen cycle. This book provides a state-of-the-art overview and discusses the fun‐ damental research on nitrogen removal. Some case studies of full-scale applications are al‐ so covered.

Topics will broadly include, but will not be limited to:


Nitrification and denitrification are fundamental for nutrient removal. While extensive re‐ search had been conducted, this book is oriented to innovative processes and selected appli‐ cations such as heterotrophic nitrification and anaerobic ammonia oxidation. It is anticipated that this book shed light for future research and innovation. This book is ex‐ tremely useful for design engineers, researchers, and practitioners.

Finally, during the course of editing and compiling this book, extensive support and guid‐ ance were received from Ms. Marijana Francetic, publishing process manager. The editor would like to express deep appreciation and gratefulness for her support.

> **Dr. Ivan X. Zhu** University of Toronto Toronto, Canada
