Sustainability of an Ecological Treatment System Evaluated with Emergy
Advisor:Martin, Jay F.
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Industrial and Systems Engineering Honors Theses; 2005
Agricultural waste management is a difficult challenge facing animal producers. New technologies are needed to address problems such as increasing costs, stronger environmental standards, and negative social perceptions of agricultural waste management. Conventional methods of animal waste treatment lead to undesirable odors and contamination of local waters. As urban society encroaches on the rural landscape, on-site treatment of animal wastes, rather than current dilution and land application, will become increasingly important. New technologies must be sustainable and cost-effective to address the needs of animal producers. Wetlands and other ecological treatment systems (ETS) offer waste treatment solutions that use renewable energy and natural processes to metabolize wastes and provide valuable products in addition to purified water. The goal of this study was to quantify and compare the sustainability and resource use of an ETS with other waste treatment technologies. This study compares an ETS treating liquid manure to Italian, Swedish, and Mexican waste treatment systems. Emergy analysis was used for this comparison to provide a holistic metric to evaluate the sustainability, resource use and environmental impact of an ETS. Emergy quantifies system inputs and outputs on a common basis. The benefit of this is that a diverse array of flows can be compared on an equal basis. The Waterman Ecological Treatment System (WETS) analyzed in this study was 75% more sustainable than conventional municipal waste water treatment plants because the WETS relies more on natural processes, rather than chemical and mechanical inputs, to treat waste water. Three factors contributed to more emergy input per gram of treated water required for waste treatment by the WETS when compared with other systems: the WETS is a research facility that is not optimized for efficiency, the WETS is treating high strength animal waste, and the WETS is not treating its maximum capacity for waste. Results from the emergy analysis show that sustainability of the WETS can be improved by reducing the electricity inputs and increasing the volume of waste treated. Sensitivity analyses revealed that increasing the quantity of waste treated by the system to the design treatment capacity would improve the sustainability of the system by 400%. These results demonstrate potential for ETS to provide sustainable solutions to agricultural waste treatment problems.
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