Skip to main content
ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #304968
Title: Algal turf scrubbers: periphyton production and nutrient recovery on a South Florida citrus farm

Author
item D Aiuto, Peter
item Patt, Joseph - Joe
item ALBANO, JOSEPH - Former ARS Employee
item Shatters, Robert - Bob
item EVENS, TERRENCE - Former ARS Employee

Submitted to: Ecological Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2014
Publication Date: 1/2/2015
Citation: D Aiuto, P.E., Patt, J.M., Albano, J.P., Shatters, R.G., Evens, T.J. 2015. Algal turf scrubbers: Periphyton production and nutrient recovery on a South Florida citrus farm. Ecological Engineering 75:404-412.

Interpretive Summary: There is a strong need to develop strategies that reduce nutrient loading to Florida’s waters. The purpose of this study was to investigate the nutrient-removing ability and growth rate of algae, grown on an Algal Turf Scrubber (ATSTM) that received runoff from a citrus orchard operated by the USDA in southern Florida. ATSs consist of a downward sloping flow-way in which water is introduced in a pulsed or continuous manner. The water flows over the length of the flow-way and is then re-circulated or discharged. The ATS is either seeded or naturally colonized by algae and various other organisms such as bacteria and aquatic insects. As the algae grow, nutrients such as phosphate and nitrate are removed by the algae from water flowing over the flow-way. Our ATS received a continuous flow of water pumped from the orchard’s drainage canal. Over an 18-month period, the ATS removed phosphate, nitrate, nitrite and ammonium from the agricultural drainage water. On average, each day the ATS produced 5.5 grams of algae (dry weight) per square meter. Over half of the production occurred in the upper quarter of the flow-way. Algal growth rate increased during the summer months, when compared to winter months. The community was dominated by filamentous green algae for most of the study. The results indicated that ATSs could be an effective means of treating agricultural runoff from citrus and other fruit tree orchards while yielding algae.

Technical Abstract: There is a strong need to develop strategies that reduce nutrient loading to Florida’s waters. The purpose of this study was to investigate the nutrient-removing ability and growth rate of periphyton, grown on an Algal Turf Scrubber (ATSTM) that received runoff from a citrus orchard operated by the USDA in southern Florida. A pilot scale ATS (1.2 m wide x 234 m long; 0.5% declining grade) was constructed and received a continuous flow (227 L min-1) of water pumped from the orchard’s drainage canal. Over an 18-month period, PO4-P, NO3-N, NO2-N and NH4+ removal averaged 16%, 49%, 19% and 41%, respectively. On average, the entire flow-way yielded 5.5 g m-2 day-1 (range: 1-16 g m-2 day-1) of periphyton (dry weight). However, the upper 60 m yielded 11 g m-2 day-1 (range: 1-26 g m-2 day-1). Over 54% of production occurred in the upper 26% of the flow-way and growth rate increased 195% during the summer months (June, July, Aug.) when compared to winter months (Jan., Feb., Mar.). Harvested periphyton contained an average of 24.1% C, 3.8 % N, .38 % P, and .003% Si. During colonization, diatom chains (Aulocoseira spp.) along with various pennate diatoms dominated. However, the community was dominated by filamentous Chlorophyta for most of the study. The results indicated that ATSs could be an effective means of treating agricultural runoff from citrus and other fruit tree orchards while yielding periphyton.