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Open Access Energy Return on Investment for Algal Biofuel Production Coupled with Wastewater Treatment

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This study presents a second-order energy return on investment analysis to evaluate the mutual benefits of combining an advanced wastewater treatment plant (WWTP) (with biological nutrient removal) with algal biofuel production. With conventional, independently operated systems, algae production requires significant material inputs, which require energy directly and indirectly, and the WWTP requires significant energy inputs for treatment of the waste streams. The second-order energy return on investment values for independent operation of the WWTP and the algal biofuels production facility were determined to be 0.37 and 0.42, respectively. By combining the two, energy inputs can be reduced significantly. Consequently, the integrated system can outperform the isolated system, yielding a second-order energy return on investment of 1.44. Combining these systems transforms two energy sinks to a collective (second-order) energy source. However, these results do not include capital, labor, and other required expenses, suggesting that profitable deployment will be challenging.

Keywords: algae; algal biofuel production; biofuel; biological nutrient removal; energy balance; energy return on investment; synergy; wastewater treatment

Document Type: Research Article


Affiliations: 1: The Center for Electromechanics, University of Texas at Austin, Austin, 1 University Station R7000, Austin, TX 78712 2: Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin 3: Center for International Energy and Environmental Policy, University of Texas at Austin 4: Department of Mechanical Engineering, University of Texas at Austin 5: Austin Water Utility, Environmental and Regulatory Services Division, City of Austin, Austin, Texas

Publication date: September 1, 2012

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  • Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year.

    Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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