The environmental engineering discipline has focused much of its historical efforts in developing regions of the world on advancing environmental sustainability through improving provision of water, sanitation, and hygiene (WASH) services. However, the skills and expertise that reside within the discipline of environmental engineering are fundamental to achieve a much broader range of sustainable development goals, including those related to health, climate, water, energy, and food security; economic development; and reduction of social inequalities. Accordingly, this article critically reviews several focus areas where environmental engineering should assume a more active presence in the global community that seeks to achieve sustainability in developing regions of the world. The 10 environmental engineering Grand Challenges for the developing world covered are: (1) understand the historical perspective of the discipline's connection with public health as the field transitions forward; (2) integrate the differences encountered when operating over rural to urban locations; (3) address emissions of greenhouse gases and other important carbon-containing pollutants; (4) understand the link between development and health to better connect health outcomes and reduction in risk with ecosystem management and other development interventions; (5) address the complex interactions of water energy systems; (6) integrate the synergy inherent in development/sustainability goals of WASH, food security, and resource recovery; (7) transition to a green economy; (8) advance monitoring, evaluation, and assessment activities that include life cycle assessment, (9) integrate culture, perception, and behavior with advances in science and technology, and (10) educate globally competent engineers. Our hope is that this discussion leads to a better world through monumental improvements in the environment and human well-being and drives new innovations and opportunities in research, education, practice, and service.

Heat treatment, or thermal disinfection, is one of the simplest disinfection methods, and is widely used in the water, sanitation, and food sectors, especially in low resource settings. Pathogen reductions achieved during heat treatment are influenced by a combination of temperature and exposure time. The objective of this paper was to construct updated time-temperature pathogen inactivation curves to define "safety zones" for the reduction of four pathogen groups (bacteria, viruses, protozoan (oo)cysts, and helminth eggs) during heat treatment in a variety of matrices. A systematic review and meta-analysis were conducted to determine the times needed to achieve specified levels of pathogen reduction at different temperatures. Web of Science was searched using a Boolean string to target studies of heat treatment and pasteurization systems that exposed pathogens in water, wastewater, biosolids, soil, or food matrices to temperatures between 20 °C and 95 °C. Data were extracted from tables or figures and regression was used to assess the relationship between time and temperature. Our findings indicate that the temperatures and times needed to achieve a 1-log₁₀ reduction of all pathogen groups are likely higher and longer, respectively, than previously reported. The type of microorganism and the matrix significantly impact T₉₀ values reported at different temperatures. At high temperatures, the time-temperature curves are controlled by thermally stable viruses such as hepatitis A virus. Data gaps include the lack of data on protozoa, and the lack of data on all pathogen groups at low temperatures, for long exposure times, and with high log₁₀ reductions. The findings from this study can be used by engineers, food safety specialists for the planning and design of engineered water, sanitation, and food pasteurization and treatment systems.