TSS or Total Suspended Solids
TSS (Total Suspended Solids) in Stormwater FAQs
Total suspended solids (TSS) describe particulates of varied origin, including soils, metals, organic materials and debris that are suspended in a moving body of water.
Turbidity, a related pollutant, is a measure of the optical diffraction imparted by solids in the water, with no direct relationship between TSS and turbidity units. Suspended solids are insoluble in water and will settle out of suspension with enough time.
Stormwater runoff can carry particulate debris into waterbodies creating TSS conditions. Turbulence keeps the particulates suspended in water, allowing the solids to be transported downstream.
TSS should be removed from stormwater because the effects of high TSS levels in water ingested by humans often mean higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria, which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.[i]
TSS can also make water bodies in the environment less aesthetically enjoyable and can have negative impacts on plants and wildlife. TSS reduce visibility and absorb light, which can increase stream temperatures and reduce photosynthesis.[ii] Resulting negative impacts of TSS on plant and wildlife include:
- interference with aquatic plant photosynthesis, reducing the amount of food, habitat and dissolved oxygen available for other species;[iii]
- fine particles clogging and abrading fish and insect gills and tissue and interference with egg and larval development;[iv] and
- pollutants such as pesticides and PCBs adhering to the surfaces of TSS and being transported through stormwater runoff into aquatic environments.[v]
TSS and other settleable pollutants such as settleable solids, metals, floatables and trash can be removed by gravity separation. Stormwater flows through a chambered gravity separator gradually settling finer and finer particles. Oil and grease are skimmed from the surface and retained during this process. Clara is a highly effective gravity separator for the removal of oil and grease, settleable solids, metals, floatables and trash. If a higher level of TSS removal is needed, Clara can operate upstream of the Aquip passive media filter. Find out more about the Clara gravity separator and the Aquip passive media filter.