Total suspended solids

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Total suspended solids (TSS) is the

wastewater treatment plant. It is listed as a conventional pollutant in the U.S. Clean Water Act.[1] Total dissolved solids
is another parameter acquired through a separate analysis which is also used to determine water quality based on the total substances that are fully dissolved within the water, rather than undissolved suspended particles.

TSS is also referred to using the terms total suspended matter (TSM) and suspended particulate matter (SPM). All three terms describe the same essential measurement. TSS was previously called non-filterable residue (NFR), but was changed to TSS because of ambiguity in other scientific disciplines.

Measurement

TSS of a water or

The gain in weight is a dry weight measure of the particulates present in the water sample expressed in units derived or calculated from the volume of water filtered (typically milligrams per litre or mg/L).

If the water contains an appreciable amount of dissolved substances (as certainly would be the case when measuring TSS in

deionized water
after filtering the sample and before drying the filter. Failure to add this step is a fairly common mistake made by inexperienced laboratory technicians working with sea water samples, and will completely invalidate the results as the weight of salts left on the filter during drying can easily exceed that of the suspended particulate matter.

Although

stream current
or wave action) can produce higher values of TSS not necessarily accompanied by a corresponding increase in turbidity. This is because particles above a certain size (essentially anything larger than silt) are not measured by a bench turbidity meter (they settle out before the reading is taken), but contribute substantially to the TSS value.

Definition problems

Although TSS appears to be a straightforward measure of particulate weight obtained by separating particles from a water sample using a filter, it suffers as a defined quantity from the fact that particles occur in nature in essentially a continuum of sizes. At the lower end, TSS relies on a cut-off established by properties of the filter being used. At the upper end, the cut-off should be the exclusion of all particulates too large to be "suspended" in water. However, this is not a fixed particle size but is dependent upon the energetics of the situation at the time of sampling: moving water suspends larger particles than does still water. Usually it is the case that the additional suspended material caused by the movement of the water is of interest.

These problems in no way invalidate the use of TSS; consistency in method and technique can overcome short-comings in most cases. But comparisons between studies may require a careful review of the methodologies used to establish that the studies are in fact measuring the same thing.

TSS in mg/L can be calculated as:

(dry weight of residue and filter − dry weight of filter alone, in grams)/ mL of sample * 1,000,000

See also

  • Bed load – Particles in a flowing fluid that are transported along the bed
  • Settleable solids
     – Process by which particulates move towards the bottom of a liquid and form a sediment
  • Turbidity – Cloudiness of a fluid
  • Volatile suspended solids – water quality measure
  • Water pollution – Contamination of water bodies
  • Water quality – Assessment against standards for use

References

  1. ^ United States. Clean Water Act, sec. 304(a)(4), 33 U.S.C. § 1314(a)(4).
  2. ^ Michaud, Joy P. (1994). "Measuring Total Suspended Solids and Turbidity in lakes and streams." Archived 2010-07-30 at the Wayback Machine A Citizen's Guide to Understanding and Monitoring Lakes and Streams. State of Washington, Department of Ecology.
  • Moran, Joseph M.; Morgan, Michael D., & Wiersma, James H. (1980). Introduction to Environmental Science (2nd ed.). New York: W.H. Freeman.
  • Eaton, Andrew D.; Greenberg, Arnold E.; Rice, Eugene W.; Clesceri, Lenore S.; Franson, Mary Ann H., eds. (2005). Standard Methods For the Examination of Water and Wastewater (21 ed.). American Public Health Association.
    ISBN 978-0-87553-047-5. Also available on CD-ROM and online
    by subscription.
  • Ramsey, Justin. 2001. Design of septic tanks design summary series.
  • National Association of Wastewater Transporters. Scandia, MN (1998). Introduction to Proper Onsite Sewage Treatment.