Efficacy of selected phosphorus sorbing materials (PSMs) to enhance the orthophosphate sorption capacity of filter socks

Abstract

Agricultural phosphate (PO43−) is a major cause of water quality compliance failures. Filter socks (FS) are a sediment-control method proven to be effective at removing sediment and sediment bound-P. Within the water and wastewater treatment industries phosphorous sorbing materials (PSMs) are widely used to remove reactive PO43−. Combining PSMs with FS provides an opportunity to concomitantly remove sediment, sediment bound-P and PO43− from agricultural runoff. A column experiment was undertaken to evaluate the efficacy of selected PSMs to remove PO43− across a range of PO43− concentrations (0.08, 0.26 and 1.3 mg/L) and contrasting FS fill media (PAS 100 Compost and Woodchip). The results indicate that Ca-enriched ferrihydrite removed up to 99% of PO43−, and was the only PSM to reduce PO43− to below the target value of <0.05 mg/L. An initial cost-benefit analysis indicates that PSM-enhanced FS are a viable option to remove PO43− from agricultural runoff.