Sustainable Environmental Engineering (SEE) is to research, develop, design, build, operate, and maintain environmental engineering infrastructure systems (EEIS) that are economically feasible to reduce human health risk and minimize environmental damages so that man and the nature can coexist in harmony. EEIS include engineering systems of water distribution, sewer collection, water treatment plant (WTP) and wastewater treatment plant (WWTP), stormwater management gray infrastructure, and green infrastructure (GI). Twelve design principles (TDPs) have been developed to guide a designer to minimize footprint (FP) of human social and economic activities on the natural environments such as air, water, soil, and biosphere. FP on materials, energy, and water is typically quantified by life cycle assessment (LCA). In designing EEIS, a designer should apply the following TDPs: (i) integrated and interconnected alternatives, (ii) reliability on spatial scale, (iii) resiliency on temporal scales, (iv) economy of renewable materials, (v) efficiency of renewable energy, (vi) prevention strategies, (vii) recovery of materials and energy, (viii) early separation, (ix) effective treatment, (x) green retrofitting and remediation, (xi) optimization through modeling and simulation, and (xii) minimal life cycle costs and maximal benefits. The TDPs equip SEE designers with the knowledge and tools by quantifying uncertainty and sensitivity of the FP of EEIS alternatives. They provide a systematic and integrated approach to optimize the short‐term capital investments and long‐term operation cost while reducing the long‐term detrimental impacts on human and environments. It is hoped that the TDPs will guide the next generation of sustainable environmental engineers to think critically in developing innovative and sustainable alternatives of EEIS.

In the past, EEIS were not designed according to the TDPs. For example, traditional processes such as activated sludge (AS) severely violate the TDPs. In an AS process, biodegradable organic pollutants are oxidized with excessive amount of sludge produced as solid waste. The sludge has to been either dewatered mechanically or anaerobically digested. However, aeration is energy‐intensive process and consumes about one‐half energy of a WWTP, and sludge disposal consists about one‐third of WWTP operation cost. In fact, AS violates several TDPs because (i) organic pollutants in wastewater have their intrinsic energy content and should be utilized as energy resource and (ii) sludge incorporates free water into fixed cellular water, which is extremely energy intensive to be separated from the biosolids. Therefore, it should be avoided according to the fifth principle of prevention. One of retrofitting WWTP strategies is to divert biodegradable organic carbon to anaerobic digester to directly produce methane according to the seventh principle of recovery. Indeed, other tradition processes such as aluminum coagulation, lime neutralization, chlorination, and combined treatment of leachate with wastewater do not stand the test of the TDPs. After intensive research, development, and practice all over the world in the past decade, WWTP could have been retrofitted or designed as an energy‐positive recovery center (WRRF) to recover water, energy, nutrients, and materials. For example, WWTP treating 10 million gallon wastewater per day for population equivalency of 250 000 at Strass im Zillertal, Innsbruck, in Austria became energy positive after a decade‐long retrofitting effort in 2005. However, very few of 15 500 WWTPs in the United States and 4 800 WWTPs in China are currently energy neutral. The market sizes of retrofitting these WWTPs in the United States and China are estimated at 300 and 200 billion US dollars, respectively. In next three decades, paradigm will shift to design WWTPs as WRRFs at which water, energy, nutrients, and materials would be recovered to its maximal extent. It could be expected that a WRRF become energy production and material recovery center or even as a revenue generation asset rather than significant financial burden for a water utility. To successfully design WRRF, eight major design topics are covered to accelerate the paradigm shift toward new industrial trends in next decades. For example, Anammox and membrane biological reactor (MBR) are illustrated as the critical technology in designing energy‐positive WWTP. Advanced oxidation processes (AOPs) are important to replace separation processes. UV disinfection is presented as critical technology to achieve the US EPA second‐stage disinfectant/disinfection by‐product rules. Membrane filtration technologies such as microfiltration, nanofiltration, and reversed osmosis are key technologies in reclaiming water. To facilitate design of WRRF by using these technologies, Matlab codes for estimating capital and O&M costs of these technologies are presented for treatment, reclaiming, or recovery systems. As a result, life cycle cost and benefit of the design alternatives could be conducted.

Human has freely harnessed air, water, and food from the Earth and energy from the Sun in the past million years. In the modern society, however, the infrastructure to deliver water and electricity is expensive due to fit‐for‐all design philosophy in the past. Some of the flaws have not been challenged in the past hundred years since the first WWTP with AS was built. To meet these challenges and capture unique opportunities, these design flaws have to be corrected. The book starts with renewable resource and human FP in Chapter 1. Common environmental engineering (EE) issues such as air, water, and soil pollution under climate change are explained. Environmental quality indexes of air, water, and soil are defined and illustrated. Human FP and environmental laws are organized from the perspective of LCA. Chapter 2 shows how Crystal Ball could be applied to quantify the uncertainty and sensitivity during human health risk assessment using Monte Carlo simulation. Health risk of disinfection by‐products (DBPs) in drinking water is used as an example. Chapter 3 defines and establishes the TDP SEE to guide the designers of EEIS. The topics covered include green chemistry, green engineering, regenerative design of WWTPs, life cycle cost and benefit analysis, and decision principles and metrics. New design challenges of SEE are explained under the context of the United Nations 17 Sustainable Development Goals (SDGs) with market size analysis of the United States and China. From Chapters 4 to 15, each design principle and the associated computer tools are explained. Chapter 4 lays the foundation of planet, people, and profit as the ultimate SEE design goals. Integrated management and best management practice (BMP) of EEIS are defined. The design hierarchy is ranked in the order of prevention, reduction, reuse, recycle, treatment, recovery, disposal, and remediation. Chapter 5 explores reliability of an EEIS on spatial scales such as residential house, community, and city. It shows how SEE design principles could be applied at different spatial scales and how laboratory and pilot data should be accurately extrapolated to full‐scale treatment plants. Since UV disinfection is expected to replace chlorination in both WTP and WWTP, virus sensitivity index (VSI) and bacteria sensitivity index (BSI) are developed to estimate the UV fluence required by any given virus or bacteria from laboratory data through statistical analysis by SPSS. Chapter 6 focuses on resiliency on temporal scales. It demonstrates that population growth is the key element as unsteady flow and how to design an equalization tank to reduce the unsteady effect. Also, chemical kinetics and catalysts are discussed in detail to reduce reaction time. Chapter 7 emphasizes the economy of material using modern reactor design theory. Matlab codes are presented to compare the hydraulic characters of batch, continuous stirred tank reactor (CSTR), and plug‐flow reactor (PFR). Chapter 8 demonstrates how to balance the embodied energy vs. the energy required for operation and maintenance. The energy auditing of WWTP for retrofitting purpose is illustrated. Six design hierarchies are presented sequentially from Chapters 9 to 14. To demonstrate the effectiveness of prevention, Chapter 9 explains why prevention is the number one priority in SEE design. For example, GI holds the key to prevent nonpoint source pollution, while rain harvest may be the most effective way to prevent contamination due to stormwater runoff and to save precious tap water from irrigation. Other GI such as green roof, bioswale, rain garden, septic tanks, and constructed wetlands are equally important in designing smart cities or communities. Chapter 10 provides unit cost and benefit analysis tools for water reclaiming systems because water is the major product of the highest market price to be recovered with huge demand in terms of irrigation, reuse, or recharge of underground aquifer. Chapter 11 critically examines precipitation as an unsustainable design because it requires large amount of chemicals, such as bases or acids. Even worse, it incorporates free water, which should have been the product, into sludge as the secondary waste. To avoid adding chemicals, a better design may be ion exchange. Ultra‐, micro‐, and nano‐membrane filtrations are illustrated as an industrial trend to replace traditional tank processes such as coagulation, flocculation, and precipitation. Chapter 12 focuses on engineering design of AOP such as UV disinfection because it is expected that more and more UV disinfection will replace chlorination. Virus sensitivity index (VSI) and Bacteria sensitivity index (BSI) during UV disinfection are introduced. Membrane biological reactor (MBR) is introduced as major treatment technology to reduce FP of WWTPs. However, the energy FP of MBR is still relative large; as a result, it might not be suitable for financial restrained rural areas. Chapter 13 fully establishes the energy benchmarks in retrofitting WWTPs to energy‐positive WRRF. For green remediation, a comprehensive software package to remediate contaminated air, water, and soil by the US EPA is presented. Chapter 14 examines the optimization of EEIS through modeling and simulation. By using Fenton treatment of leachate as an example, the optimal conditions are derived both theoretically modeled and validated experimentally. Chapter 15 offers the latest technologies in recovering N and P from wastewater. It reveals how different flow rates affect capital and operation cost of recovering N and P. It briefly introduces financing, accounting, and entrepreneurial concepts for SEE students. The information is critical for SEE designers to estimate costs of SEE alternatives according to regenerative, neutral, and negative design. Lastly, the potential of applying 3D printing, Internet of things, artificial intelligence, blockchain, big data, cloud computing, and data mining in SEE design is explored. It is to encourage SEE designers to think out of the box by defining the box and using multipliers to extend their design to exceed the physical or chemical limits.

The textbook materials are presented from simple to complicated, easy to difficult, and component to system. Fundamental sciences are presented in a simple and easy approach. For example, calculus is intentionally used as minimal as possible to inspire students with chemistry, biology, ecology, and physics to pursue their career in SEE. Critical information such as unit energy content, sustainable metrics, and benchmark rubrics are provided for students to make their own judgment in their engineering design. Starting from Chapter 4, each chapter illustrates one SEE design principle and presents step‐by‐step methods of its implementation. To make the TDPs practically and easily to be implemented in engineering design, connection between traditional three‐phase submittals such as 30, 60, and 100% is established. Experiential learning is embedded in open‐ended problems for students who could select their hometown. Students are encouraged to identify and prioritize EE issues in their hometown and communicate with its stakeholders to develop design alternatives through three steps. First, local air, water, and soil quality data have to be calculated to prioritize environmental issues by quantifying the corresponding quality indices. Second, these indices should be compared with governmental standards to prioritize the major environmental problems. Third, the local EE problems should be critically analyzed according to the TDPs by using tools presented in the book. Assessment rubrics are given to rank students’ best sustainable design to serve their community‐based and open‐ended projects. By applying the TDPs together with innovative technologies, regenerative EE infrastructure can be designed by avoiding unsustainable design such as chlorination and leachate treatment with wastewater by AS. During the whole course project design, experiential teaching, critical thinking, entrepreneurial skills, and community involvement are intervened with traditional learning modules such as homework and assignments. As a result, students will be able to design sustainable EEIS adapted to the climate change in the next 20, 50, and 100 years.

Connecting dots of the human suffering as well as environmental damage due to unsustainable design in the past, we dream to empower new generations of SEE designers to help the less fortunate become healthier, richer, and better by designing and building sustainable communities across cities, states, countries, and the globe. As a result, we can hand a better world to our children and grandchildren. This book presents systematic design method of EEIS to achieve sustainable development by decoupling economic prosperity from environmental degradation. We hope that this book serves as a catalyst to transform EE education and practice for decades to come.

We would like to thank Mr. Jinze Li, who devoted his time and effort in developing part of the MatLab codes, figures and diagrams and Dr. Rena Chen for her contribution to part of Chapter 2. Students who took the courses of advanced treatment system, reactor design, open channel hydraulics and hydraulic engineering at Florida International University (FIU) are greatly appreciated. These students include Mrs. Angela Pierotti, Claudia Cardona, Natalie Duque, Annie Barahona, Katheline Tabuteau, and Mr. Carlos Fomoros. Also, original research projects have been carried out at FIU, Lappeenranta University of Technology (LUT), and Tallinn University of Technology (TUT) by our postdoctors include Dr. Shrawan Singh and Dr. Jean‐Marie Fontmorin, Dr. Feiping Zhao, and Dr. Evgenia Iakovleva. WZT would like to thank the unwavering support from Dr. Kenneth Furton, Provost at FIU; Dr. John Volakis, Dean of the College of Engineering and Computing at FIU; Dr. Mark Weiss, Dr. Osama, Mohammed, and Dr. Anthony McGoron, Associate Deans of the College of Engineering and Computing at FIU; Dr. Atorod Azizinamini, the Chairman of Department of Civil and Environmental Engineering at FIU; and Professor Enn Loigu, Chairman of Department of Environmental Engineering at TUT, Tallinn, Estonia. We would also like to thank our editors, Mr. Michael Leventhal and Mrs. Grace Paulin and Shalisha Sukanya, for their excellent editing skills and timely professional service.

This book is dedicated to WZT’s former advisor, Professor Pao‐Chiu Hsu, of Tsinghua University, Beijing, China, on his 100th birthday anniversary in 2017 because this book is a continuation of his vision of water industry by educating the next generation of environmental engineers in China. Professor Hsu is the father of water treatment in modern China. After earned his Ph.D. in the United States in 1951, Dr. Hsu returned to Tsinghua University in 1955. Professor Hsu’s third edition of textbook, Water Treatment Engineering, offered the best theoretical and engineering design of WTP in China. He catalyzed the transformation of water and wastewater engineering to water industry after he defined “water industry” as borrowing and returning clean water to nature scientifically in 1997. Since then, China integrated water and wastewater departments as water bureaus across the country. As a result, wastewater is treated and returned to the nature through about 4800 WWTPs in China.

Full‐hearted appreciation goes to the FIU president, Dr. Mark Rosenberg, for his global vision and championship in protecting academic freedom. In 2005, WZT was going to add a hard copy of WZT’s first book, Physicochemical Treatment of Hazardous Wastes, to his book collections authored by the FIU professors. WZT was not able to deliver a hard copy because Dr. Rosenberg was the Chancellor of Florida State University System in Tallahassee, Florida, from 2005 to 2008. Now, WZT will fulfill the promise by delivering the first hard copy of this book to his Ronald Reagan Presidential House at FIU. Under the president’s leadership, FIU is ranked at 362 from 1000 best universities in the world by the U.S. News & World Report in 2017. Last, but not the least, this book is dedicated to our families. Their sacrifices and unconditional love made this period of life journey completed and fulfilled!