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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #366019
Research Project: Integrated Strategies for Managing Pests and Nutrients in Vegetable and Ornamental Production Systems

Location: Citrus and Other Subtropical Products Research

Title: Phosphate removal from nursery runoff waterusing an iron-based remediation system

Author
item ORDONEZ HINZ, FRANCISCA - University Of Florida
item Albano, Joseph
item WILSON, P. CHRIS - University Of Florida

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2019
Publication Date: 4/17/2019
Citation: Ordonez Hinz, F., Albano, J.P., Wilson, P. 2019. Phosphate removal from nursery runoff waterusing an iron-based remediation system. Water. 11:795-805. DOI:https://10.3390/w11040795.
DOI: https://doi.org/10.3390/w11040795

Interpretive Summary: A tank system to remove phosphorous from nursery runoff water was tested. Phosphorous, a fertilizer component, easily moves through container potting mix with water from irrigation and rainfall. Phosphorous is not toxic living organisms directly, but indirectly, phosphorous can change the aquatic environment to cause shifts in diversity of plants and animals, cause harmful algal blooms that produce toxic chemicals, and often both, occur simultaneously. Therefore, to balance the plants need for this fertilizer component with the need to protect aquatic ecosystems from becoming nutrient-rich in phosphorous, best management practices and nutrient removal systems are needed. In this test, inorganic chemistry comes into play, exploiting the chemical reaction of iron and phosphorous in water that is highly oxygenated (often by bubbling air through the water). Under these conditions, iron-phosphate, an insoluble chemical compound is form and as such, drops out of solution where it can then be physically removed by mechanical process, like filtration. The test showed that depending on the ratio of iron to phosphate in the water, that this system and chemistry, had the capacity or removing in excess of eighty percent of the phosphorous with the highest iron to phosphorous concentration approaching one hundred percent phosphorous removal.

Technical Abstract: Phosphorous (P) losses from containerized plant production nurseries can be significant due to the low nutrient retention capacities of the media components. As environmental regulators establish, refine, and enforce nutrient criteria, effective methods are needed to reduce amounts of P in runoff and drainage water. This study investigated the use of a small scale flow-through ferrous iron (Fe(II))-based remediation system for chemically precipitating P. This system consisted of four inter-connected tanks, with the first two maintained under anaerobic conditions and the last two maintained under aerobic conditions. FeSO4 was introduced into the first of the aerobic tanks at different rates to achieve Fe:P ratios of 0, 9.0, 16.3, and 21.2. Water samples were collected from the systems, and P removal was monitored by ion chromatography. Phosphorus removal efficiencies of 78, 95, and 99% were observed for each respective treatment, indicating great potential for this conceptual system at Fe:P dosing ratios =16.3 and phosphorus concentrations between 3 and 5 mg/L. This type of system may especially be useful for nurseries with space limitations.