Microalgae Oil Production Using Wastewater in Japan—Introducing Operational Cost Function for Sustainable Management of WWTP

Riaru Ishizaki, Agusta Samodra Putra, Sosaku Ichikawa, Tofael Ahamed, Makoto M. Watanabe and Ryozo Noguchi
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Riaru Ishizaki: Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
Agusta Samodra Putra: Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
Sosaku Ichikawa: Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
Tofael Ahamed: Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
Makoto M. Watanabe: Algae Biomass and Energy System R&D Center, University of Tsukuba, Ibaraki 305-8572, Japan
Ryozo Noguchi: Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan

Energies, 2020, vol. 13, issue 20, 1-19

Abstract: A comparative evaluation of economic efficiency was performed for native polyculture microalgae oil production in an oxidation ditch (OD) process wastewater treatment plant (WWTP). A cost function was developed for the process. The operational cost per 1 m 3 of wastewater (w.w.) was 1.34 $/m 3 -w.w. in the existing scenario, 1.29 $/m 3 -w.w. in algal scenario A (no cost for CO 2 and waste heat) and 1.36 $/m 3 -w.w. in algal scenario B (no cost for CO 2 ). The conditions were set as follows: hydraulic retention time (HRT): 4 days, microalgal productivity: 0.148 g/L and daily treatment volume: 81.6 m 3 -w.w./d. The cost differences were related to the increase in polymer flocculants for algae separation (+0.23 $/m 3 -w.w), carbon credits from CO 2 absorption (−0.01 $/m 3 -w.w), the sales of biocrude (−0.04 $/m 3 -w.w) and sludge disposal (−0.18 $/m 3 -w.w). Hence, the introduction of the algae scenario was the same cost-effective as the existing scenario. Microalgae oil production in an OD process WWTP can serve as a new energy system and reduce the environmental load in a society with a declining population.

Keywords: microalgae; biocrude; oxidation ditch; economic efficiency; wastewater treatment (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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