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Issue 9, 2019
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Seasonal treatment and economic evaluation of an algal wastewater system for energy and nutrient recovery

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Abstract

Algal systems have been proposed for treating wastewater while simultaneously recovering energy and nutrients. In this study, an integrated system with algal treatment of municipal wastewater followed by hydrothermal liquefaction (HTL) conversion and upgrading steps was evaluated. Pilot-scale treatment of primary clarified municipal wastewater effluent was evaluated in different seasons (cold, warm, and a transitional period in between) with different strains of algae selected for each season, and the warm season strain successfully met all local discharge regulations. The collected wastewater algae biomass was subjected to HTL at 300 and 350 °C and both energy and nutrient recoveries were much improved at the higher temperature. The transitional batch was found to have the highest biocrude oil yields, and its co-products had the highest nutrient (nitrogen and phosphorus) contents. Economic analysis of conversion processes informed by the observed HTL product yields was conducted. While this revealed that targeting biofuel products alone was not profitable, adding nutrient co-products (e.g., ammonium sulfate fertilizer), adjusting algae harvesting time, and incorporating component-specific conversion processes could substantially improve system economics. Overall, this study highlights connections between treatment and conversion processes, and demonstrates how these connections can be leveraged for more efficient resource recovery without compromising treatment operations.

Graphical abstract: Seasonal treatment and economic evaluation of an algal wastewater system for energy and nutrient recovery

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Publication details

The article was received on 21 Mar 2019, accepted on 01 Jul 2019 and first published on 02 Jul 2019


Article type: Paper
DOI: 10.1039/C9EW00242A
Environ. Sci.: Water Res. Technol., 2019,5, 1545-1557

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    Seasonal treatment and economic evaluation of an algal wastewater system for energy and nutrient recovery

    Y. Li, S. A. Slouka, S. M. Henkanatte-Gedera, N. Nirmalakhandan and T. J. Strathmann, Environ. Sci.: Water Res. Technol., 2019, 5, 1545
    DOI: 10.1039/C9EW00242A

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