Multidisciplinary thinking to increase sustainability in engineering : a case study in sanitation

Abstract

This dissertation uses a case study in sanitation that illustrates the need for interdisciplinary analysis of sustainable solutions to engineering problems. This case study also suggests that one nontechnical factor that might be critical for increasing sustainability is consumer willingness to use the technology, which, along with factors such as cost, will drive technology adoption rates. By developing the ability and willingness to recognize needs for this type of interdisciplinary work and by collaborating with experts in other fields, engineers can more successfully create sustainable solutions to the problems they tackle. The work of this dissertation is in three stages. The first comprises a life cycle cost and cost-effectiveness analysis for a suite of household sanitation technologies. Results of this stage suggest that decentralized technologies are lower cost and more cost-effective for nitrogen management than conventional centralized wastewater treatment in the given case study location; composting and urine-diversion toilets proved the best performers on these metrics. The second stage of research expands the analysis to examine adoption of decentralized sanitation technologies as a two-party decision, with the individual discount rate used as a proxy for factors influencing homeowners’ adoption decisions. Results in two case study locations emphasize the dependence of analysis on case-specific details; in one case, monetary incentives are expected to be successful at bringing municipal and individual decision-makers into agreement to adopt decentralized sanitation systems under many cost scenarios, while monetary incentives are not expected to succeed at bringing about agreement between parties in the other case. The third stage of research uses a survey to examine non-monetary factors influencing homeowners’ adoption decisions surrounding composting and urine-diversion toilets. Results suggest that educational efforts are likely to be important in influencing adoption decisions, although not all homeowners will be swayed by additional information. Together, the three stages of this research illustrate how understanding of technologies as potential solutions to problems of sustainability changes as the analysis expands to incorporate methods from more disciplines. While true assessment of “sustainability” is difficult at best, movement toward increasingly sustainable technologies can be facilitated by broader analyses that lead to more thorough understanding.