Methodological considerations from a wastewater treatment case study in Kenya

Emergy methodology questions were raised during a case study where a Sugar factory effluent were treated in a pond system in the Lake Victoria watershed, and evaluated from a performance, cost and resource use perspective. This paper focus on the methodological questions, which were the following: (1) how should the emergy systems diagram be drawn when dealing with a system that is in the recycle loop? Is the wastewater on top in the energy hierarchy (highest transformity) or should the treatment system be located somewhere between the sugar factory on the energy hierarchy top and the dispersed nutrients low down in the energy hierarchy? (2) Rain emergy dominated the local renewable inputs. But how do rain contribute to the wastewater treatment in a pond system, other than as minor dilution? And is evapotranspiration a relevant measure of rain emergy in an aquatic system? (3) Since the case study had a microeconomic focus, is the historical ecosystem work behind lime a relevant item to include from the company's perspective? (4) the wastewater can be considered as a treatment problem, but also as a nutrient and water resource for e.g. irrigation. How does emergy accounting deal with the dualism of a get-ridof-view and a get-use-of-view? (5) Is the, among some people, controversial maximum empower theory needed for the evaluation of the system, or is the less controversial energy hierarchy theory sufficient for the interpretation? (6) Does the emergy evaluation add any information regarding the sustainability of the pond system? i This manuscript was originally submitted in January 2008 to the proceedings of the conference Emergy Synthesis 5: Theory and Applications of the Emergy Methodology. Fifth Biennial Emergy Research Conference, at the Center for Environmental Policy, University of Florida, Gainesville, Florida, USA, January, 2008. It was, however, lost in the peer review process due to unclear reasons. Since it contained some interesting diagrams not published afterwards it is here published as a working paper, planned for further refinement. The manuscript was based on an abstract submission and a poster presentation at the conference. Author to whom correspondence should be addressed. Current affiliation: Department of Ecotechnology and Sustainable Building Engineering, , Mid Sweden University, 83125 Östersund, Sweden; E-Mail: [email protected] . Grönlund et al., Dept. of Ecotechnology and Sustainable Building Engineering, Mid Sweden University Ecotechnology working paper 2018-1a 2