2011 Issue

45 T hE gLobAL PoPULATIon is currently approaching 7 billion and is pro- jected to peak in the latter part of the 21st century at between 9 and 10 billion. Southeast Asian economies are growing at a rate of 8 percent annually. China has eclipsed the U.S. in primary resource consumption and is projected to exceed U.S. per capita consumption in the next 20 years. As the population grows in combination with an increased standard of living, the strain on natural resources is evident. The socio-economic strain on those resources has resulted in human conflict over fossil fuels and water. Environmental degradation and resource depletion in combination with climate change and rising sea levels resulting in retracting livable land mass in some of the most populated areas is compel- ling policy makers worldwide to make comprehensive and sustainable natural resource management changes. Many recent journal articles and reports have emphasized the importance of sustainability in wastewater practices and management. Thus, the trend of decision-making in the wastewater indus- try is shifting from compliance-driven to resource-recovery-driven, as well as from linear waste and treat to closed-loop re- cover and reuse. Moreover, the focus of the industry is trending from strictly eco- nomically driven to value driven systems. Economics are and will be an important part of the fiduciary responsibility of public utility management; however, in addition to economics, constituents expect public utilities to make deci- sions based on social and environmental well-being. Also, the time horizon for decision-making is much different than that of businesses. For example, public Sustainable Wastewater Management: Energy and Nutrient Resource Recovery GLEN DAIGGER , DRURY WHITLOCK AND TANIA DATTA Climate change; population growth; per capita resource consumption; sanitation; environmental degradation; and the depletion of natural resources leading to energy, food, and water shortages can be listed among the major socio-economic and political issues worldwide. utilities are charged with managing assets that may be in use for hundreds of years. Hence, making decisions through the lens of sustainability using tools such as use of triple-bottom-line (economic, social, and environmental) approaches are becoming more common place. Energy efficiency improvements will also be an integral part of any energy recov- ery program. For a goal of achieving net zero or net positive energy balance, a concerted effort for reducing the demand for energy as well as incorporating tech- nologies and practices that allow energy recovery needs to be made. Considering a typical wastewater treat- ment plant, these efforts focus on vari- ous areas that require specific attention to achieve the resource recovery goals. The currently available and emerging technologies and practices under the two broad categories of energy recovery, and nutrient recovery, with focus on the liquid and solids treatment are as follows: Daigger Whitlock Datta • Energy Recovery from Municipal Wastewater Treatment Plants • Biogas Enhancing Technologies • Biogas-fueled Energy Recovery Sys- tems • Thermal Processing of Biosolids with Energy Recovery • Energy Recovery from Liquid Streams • Nutrient Recovery from Municipal Wastewater Treatment Plants • Phosphorus Recovery • Nitrogen Recovery • Carbon Recovery Mr. Daigger, P.E., Ph.D, is a Professional Engineer, Wastewater Remediation Specialist – Senior Vice President and Chief Technology Officer at CH2M HILL. Mr. Whitlock, P.E., MBA, is a Professional Engineer and Water and Wastewater Technologist with CH2M HILL. Ms. Datta, ME, is a Water and Wastewater Technologist at CH2M HILL