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United States Department of Agriculture

Agricultural Research Service

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Research Project: Algal-based Water Treatment Technologies for Sustainable Horticultural Crop Production

Location: Subtropical Insects and Horticulture Research

Project Number: 6618-13000-005-00-D
Project Type: In-House Appropriated

Start Date: Jan 1, 2014
End Date: Jun 4, 2014

1. Evaluate performance and benefit of an Algal Turf Scrubber (ATS) for management of runoff from nursery production systems. 1.A. Determine the performance of an ATS system for remediating nursery runoff of excess nutrients for purposes of irrigation water reuse (i.e. recycling) or offsite discharge; and for assessing the impact of nutrients on ATS health and productivity. 1.B. Determine the utility of ATS-treated water as an irrigation water source for producing floral and nursery crops. 2. Develop value-added products from harvested algae for horticultural crop production. 2.A. Determine the physical and chemical properties of composted algae (CA) and mixes (i.e. blends) of CA with traditional substrate amendments. 2.B. Determine the utility of composted algae as an alternative substrate or substrate amendment for producing floral and nursery crops.

The overarching goal of the research is to gain an applied understanding of how several of the major drivers of degraded runoff water affect periphyton community health and algal productivity for remediating nutrients. Of particular significance is to establish the relationship between water flow rate [over an algal turf scrubber (ATS)] with nutrient load [in runoff], and how changes in rate and flow affect ATS efficiency. Water quality improvement potentials for ATS system subjected to horticultural crop production degraded water runoff will be quantified. The water source for this study is the research farm’s surface retention canal. The array of chemical, physical, and biological data collected in this study will: 1) determine the capacity of ATS to remove nutrients, 2) determine the quality of ATS effluent for irrigation, and 3) determine the quality of ATS effluent for offsite of nursery discharge. ATS-treated water chemistry values will be compared against irrigation water-quality standards for horticultural crop production for an initial assessment on the suitability of an ATS to serve as an irrigation water source. Floral and nursery crops will be irrigated with ATS-treated water to identify if there are any unanticipated benefits or consequences of this water source on plant growth, health, and/or aesthetics. Of particular interest, and undefined as an irrigation water-quality criterion, is the effects of detached and suspended periphyton in irrigation water coming into contact with foliage and substrate/rhizosphere. An applied and fundamental understanding will be gained on the chemical and physical properties of composted algae and how the product can be engineered for use as an alternative substrate and/or fertilizer for the production of containerized horticultural crops. Algae from two ATS systems are available for this study. The growth, health and physical appearance of floral and nursery crops grown in algal-based or peat-based substrates will be assessed. The potential will be evaluated of composted algae as a nutrient source for nursery crops, including if composted algae can be blended with traditional substrates to extend supplies.

Last Modified: 10/16/2017
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