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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICAL TREATMENT OF MANURE AND ORGANIC RESIDUALS TO CAPTURE NUTRIENTS AND TRANSFORM CONTAMINANTS

Location: Sustainable Agricultural Systems Laboratory

Title: Algal turf scrubbing: cleaning surface waters with solar energy while producing a biofuel

Authors
item Adey, Walter
item Kangas, Patrick
item Mulbry, Walter

Submitted to: Bioscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 2, 2011
Publication Date: June 1, 2011
Repository URL: http://handle.nal.usda.gov/10113/56651
Citation: Adey, W., Kangas, P., Mulbry Iii, W.W. 2011. Algal turf scrubbing: cleaning surface waters with solar energy while producing a biofuel. Bioscience. 61:434-441.

Interpretive Summary: Algal Turf Scrubbing (ATS) is an engineered system for growing attached, lawn-like, filamentous algae on sloping surfaces over which wastewaters of many types can be pulsed. Algae grows using the nutrients in the wastewater and are removed from the system by weekly harvesting. Compared to conventional municipal wastewater treatment processes, ATS systems have relatively low capital and operational costs, but do require large land areas and people onsite to harvest the algae. Previous reports have estimated that the cost for nutrient capture using ATS was comparable to other manure-management practices-around $5 to $6 for each pound of recovered nitrogen and around $25 for each pound of recovered phosphorus. Beyond the benefit of nutrient removal, algae from ATS systems has potential use a biofuel feedstock and/or organic fertilizer.

Technical Abstract: Throughout the long period of human expansion across the earth, the atmosphere and the earth’s natural waters have been used as low cost sinks or dumps for our human, agricultural and industrial wastes. Despite significant investment, the methods employed for the last half century have largely failed to achieve the needed nutrient reductions. Not only are surface waters in many watersheds increasingly eutrophic, but large semi-enclosed coastal water bodies, such as the Chesapeake Bay and the Gulf of Mexico have also become hypoxic over large areas. Algal Turf Scrubbing (ATS) is an engineered system for growing attached, lawn-like, filamentous algae on sloping surfaces over which wastewaters of many types can be pulsed. During the last decade, ATS has been demonstrated for tertiary sewage treatment and nutrient removal from farm wastes and streams and lakes; treatment rates of 40-80 million liters per day (lpd) are routine and entire river cleaning systems of 12 billion lpd are under design. Since the algal biomass is quite amenable to fermentation processes, several laboratories are now engaged in research & development on the potential of producing biofuels such as ethanol and butanol. Unlike the algal photobioreactor systems currently under development, the costs for producing a biofuel from the cleaning of wastewaters by ATS could be very low, essentially that of the refining cost.

Last Modified: 12/18/2014
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