Life Cycle Environmental and Cost Impacts of Using an Algal Turf Scrubber to Treat Dairy Wastewater
Article first published online: 5 MAR 2012
© 2012 by Yale University
Journal of Industrial Ecology
Volume 16, Issue 3, pages 436–447, June 2012
How to Cite
Higgins, B. T. and Kendall, A. (2012), Life Cycle Environmental and Cost Impacts of Using an Algal Turf Scrubber to Treat Dairy Wastewater. Journal of Industrial Ecology, 16: 436–447. doi: 10.1111/j.1530-9290.2011.00427.x
- Issue published online: 1 JUN 2012
- Article first published online: 5 MAR 2012
- anaerobic digestion;
- industrial ecology;
- life cycle assessment (LCA);
- nutrient trading
Using algae to simultaneously treat wastewater and produce energy products has potential environmental and economic benefits. This study evaluates the life cycle energy, greenhouse gas (GHG) emissions, eutrophication potential, and cost impacts of incorporating an algal turf scrubber (ATS) into a treatment process for dairy wastewater. A life cycle inventory and cost model was developed to simulate an ATS treatment system where harvested algae would be used to generate biogas for process heat and electricity generation.
Modeling results show that using an ATS significantly reduces eutrophication impacts by reducing chemical oxygen demand, nitrogen, and phosphorus in the wastewater. With low water recirculation rates through the ATS and high algae productivity, inclusion of the ATS results in net energy displacement and a reduction of GHG emissions compared to a system with no ATS. However, if high water recirculation rates are used or if algae biosolids from the digester are dried, the system results in a net increase in energy consumption and GHG emissions.
The life cycle treatment cost was estimated to be $1.42 USD per cubic meter of treated wastewater. At this cost, using an ATS would only be cost effective for dairies if they received monetary credits for improved water quality on the order of $3.83 per kilogram of nitrogen and $9.57 per kilogram of phosphorus through, for example, nutrient trading programs.