Additives
A number of granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. amendments have been demonstrated to improve nutrient removal from discharge water in BMPs such as bioretention systems, stormwater planters, absorbent landscapes, sand filters or green roofs.
There are two primary processes involved, chemical precipitationAny form of rain or snow. and adsorptionThe attachment of gas, vapour or dissolved matter onto the surface of solid materials.. Both mechanisms are ultimately finite, but have been shown in come cases to make significant improvements on the discharged water quality over several years.
In our effort to make this guide as functional as possible, we have decided to include proprietary systems and links to manufacturers websites.
Inclusion of such links does not constitute endorsement by the Sustainable Technologies Evaluation Program.
Lists are ordered alphabetically; link updates are welcomed using the form below.
| Material | Benefits | Potential concerns |
|---|---|---|
| Biochar | Renewable Enhances soil aggregation, water holding capacity and organic carbon content |
Currently expensive Energy intensive to produce Some sources say ineffective for phosphorus removal |
| Bold & GoldTM | Documented total phosphorus removal of up to 71%[1] | Proprietary |
| Fly ash | ||
| Iron filings (ZVI) | Proven phosphorus retention Retained phosphorus is stable |
May harm plants[2] Removal efficiency declines with increased concentration of incoming phosphorus |
| Red sand | Proven phosphorus removal Also removes TSSTotal suspended solids |
Poor orthophosphate removal in hypoxic or anoxic conditions |
| Smart SpongeTM | Removes phosphorus, as well as TSSTotal suspended solids, fecal coliform bacteria and heavy metals Non-leaching |
1-3 year lifespan, after which the product is removed as solid waste Proprietary |
| Sorbtive mediaTM | High phosphorus removal efficiency | Proprietary |
| Water treatment residuals | Waste product reuse | Quality control (capabilities depend on source, treatment methods, storage time, etc of WTR) |
- ↑ Hood A, Chopra M, Wanielista M. Assessment of Biosorption Activated Media Under Roadside Swales for the Removal of Phosphorus from Stormwater. Water. 2013;5(1):53-66. doi:10.3390/w5010053.
- ↑ Logsdon SD, Sauer PA. Iron Filings Cement Engineered Soil Mix. Agron J. 2016;108(4):1753. doi:10.2134/agronj2015.0427.
