Phosphate Removal from Nursery Runoff Water Using an Iron-Based Remediation System

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.