Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater

This study evaluated the physicochemical properties and phosphorus adsorption capacities for oyster shell (OS), broken bricks, volcanics, and zeolite when used as substrates for swine wastewater treatment. All substrates, with the exception of volcanics, proved to be appropriate for microorganism and plant growth enrichment within water treatment systems. Meanwhile, phosphorus adsorption tests indicated that OS was most effective in phosphorus removal. Significant phosphorus removal was achieved in pilot tests when OS was used as a substrate in vertical-flow wetlands treating swine wastewater from an anaerobic tank. The pilot tests also indicated that both soluble reactive phosphorus (SRP) and total phosphorus (TP) removal rates increased when the HRT was prolonged. Overall, the study results showed that OS could be used for phosphorus removal in constructed wetlands, and such use carries the added benefits of reuse of a by-product that promotes sustainability.

► Oyster shell was chosen as substrate in wetlands treating swine wastewater.
► Oyster shell was suitable for the growth of plants and microorganisms.
► Oyster shell had high capacity of phosphorus removal.
► Significant phosphorus removal was achieved when wetlands packed with oyster shell.