Abstract: An improved bioretention system and color removal method combines Water Treatment Residuals (WTRs) with biochar, to provide a color removal effect, especially one beyond what could be achieved with the WTRs or biochar alone. WTRs are commonly used in drinking water treatment plants and can include the material both in its fresh or aged form. Biochar is formed by the pyrolysis of organic material. Water, such as stormwater or surface water can be directed to flow over a color removal media of WTRs and biochar to remove the color, especially color caused by tannins from the water.

Abstract: An improved bioretention system and method combines Water Treatment Residuals with biochar, to provide a synergistic phosphorus retention effect beyond what could be achieved with the WTRs or biochar alone. WTRs are commonly used in drinking water treatment plants and can include the material both in its fresh or aged form. Biochar is formed by the pyrolysis of organic material. Water can be directed to flow through a P retention media of WTRs and biochar to synergistically retain the phosphorus from the water beyond WTR or biochar alone.