Ecosystems as unit operations for local techno‐ecological synergy: Integrated process design with treatment wetlands

Abstract

Despite the critical importance of ecological systems for sustaining all chemical and manufacturing processes, process design has kept nature outside its system boundary. Recent efforts for sustainable process design aim to reduce environmental impact, but no design method considers the capacity of ecosystems to supply the goods and services that are needed to sustain a process. Overcoming this deficiency of conventional process design is essential to transform the chemical industry into an activity that respects ecological constraints and results in a net positive societal impact. As an important step toward meeting this goal, this work expands the boundary of process design to include ecosystems as unit operations in traditional design. Similar to tasks performed by conventional unit operations, ecological processes perform ecosystem functions resulting in goods and services required by the technological system. The goal behind designing integrated techno‐ecological process flowsheets is to balance the ecosystem service demand of technological systems with the ecosystem service supply of ecological systems. Systems are optimized to balance the demand and supply subject to unit operation level constraints of technological and ecological systems, and interactions between detailed process level variables and ecological variables are explored. The Techno‐Ecological Synergy (TES) Design method is developed and applied to a biofuel production system, considering ecosystem services like water provisioning and water quality regulation provided by wetland ecosystems. Comparing the integrated TES design with conventional techno‐centric design shows that TES design can result in net positive impact manufacturing: a case where the ecosystem service supply is equal to or exceeds the demand, with little or no compromises in process profitability. These results should encourage close integration between technological and ecological systems while designing sustainable processes, and identify many challenges for developing TES of individual processes and across the life cycle. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2390–2407, 2018

Accounting for nature's intermittency and growth while mitigating NO2 emissions by technoecological synergistic design—Application to a chloralkali process

“…We demonstrate that a TES methodology of abatement with reforestation is an economically and ecologically viable solution, even after accounting for seasonal and growth dynamics of the forest ecosystem. These results provide further validation to the idea of including ecosystems as unit operations in process design . This work conveys that, with appropriate policy planning, one can take advantage of seasonal intermittency and establishment time of forest‐based ecosystems.…”

“…Realizing the importance and urgency of sustainable development, chemical engineering has been making efforts toward contributing to this goal . Manufacturing processes have been reducing their energy and resource use by improving process efficiency with the help of approaches such as heat integration, mass exchange network synthesis, and waste minimization .…”

Life Cycle Assessment for the Design of Chemical Processes, Products, and Supply Chains

“…The capability of this approach has been shown for a biodiesel production facility that can operate sustainably with only small economic losses. Later, Gopalakrishnan et al (97) extended this work by including the ecosystem as a unit operation to design both process and ecosystem in biodiesel production.…”

A perspective on the role of uncertainty in sustainability science and engineering

“…The goal of this framework is to determine the extent of ecological overshoot from specific activities for each ecosystem service and to encourage mutually beneficial designs of technological and ecological systems. Several case studies indicate the potential environmental and economic benefits of establishing such synergies ( Bakshi, 2019 ; Hanes et al., 2017 ; R.J. 2018 ; Gopalakrishnan et al., 2016 , 2017 ; Gopalakrishnan and Bakshi, 2018 ; Martinez-Hernandez et al., 2017 ; Hernandez et al., 2019 ). However, these studies are based on simplified models that do not account for the dynamics of technological and ecological systems, which can be quite different.…”