Businesses, communities, managers, politicians and others face difficult management and operational decisions due to escalating energy prices and heightened awareness of the social and ecological impacts of industrial activities. The development and application of EcoFlow™, a material flow optimization tool, represents a novel use of operations research and network theory to facilitate such decision making by synthesizing financial, environmental and technical material processing data. This tool provides a general framework to solve a broad variety of resource and waste management problems.
EcoFlow™ has been utilized to model municipal solid waste management systems, university waste management operations and complex industrial waste reuse networks. The primary application developed here is the City of Columbus network of municipal biosolids treatment and disposal processes. Due to both economic and environmental concerns, the City of Columbus is closely analyzing the resource efficiency of its operations in order to deliver sustainable, cost-effective solutions to improve wastewater treatment. The City has partnered with the Center for Resilience at The Ohio State University (OSU) to apply advanced analytical tools for improved management of biosolids generated from wastewater treatment plants (WWTP) using a material flow optimization decision framework that accounts for financial and environmental impacts when analyzing operational policies and capital investments.
A systems model was developed in EcoFlow™ for the City of Columbus to analyze three main objectives associated with biosolids operations management: cost reduction, energy conservation and greenhouse gas (GHG) reduction. A systems analysis was performed for the current operations of the City’s two WWTPs and Compost Facility to compare baseline operations against model optimized solutions.
Modeling results indicated that operational costs, energy consumption and GHG emissions can each be reduced by at least 10% and potentially over 50%. Current analysis shows that the most cost effective solution is to incinerate all of the sludge generated by Southerly and to land apply the solids generated at Jackson Pike. Landfill disposal consumes the least amount of energy, but is the most costly. In order to lower GHG emissions the model suggests a combination of land application, composting, and landfilling. Tradeoff analyses were conducted to understand the cost efficiency of operational scenarios that minimize energy consumption and GHG emissions. Results from these analyses show potential savings of $1.6 to $3.5 million dollars, up to 19,678 MT eCO2 and 65 to 254 TJ of energy annually. Sensitivity and scenario analyses show the network solutions to be resilient in a variety of market conditions including the increase in energy costs and the price of carbon credits.