What is the difference between TDS and TSS?

Total Dissolved Solids (TDS) represents the inorganic and organic matter dissolved in water that passes through a standard glass fiber filter. Total Suspended Solids (TSS) represents the particles retained by the glass fiber filter.

How is Volatile Suspended Solids (VSS) determined?

VSS is determined by igniting the residue retained on a glass fiber filter at 550°C. The weight loss represent the volatile (mostly organic) fraction of the suspended solids.

Total Solids calculation step by step

Total solids, total volatile solids, total suspended solids, total dissolved solids

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STEP 1 : Gather data
STEP 2 : Calculate the total solid
STEP 3 : Calculate volatile and suspended solids concentrations
STEP 4 : Total dissolved solids calculation
Interactive Online Calculator
Total Solids in Water Excel calculator

The knowledge of the total solids amount in a water stream is basic data for all environmental engineering calculations such as the design of wastewater systems. This page explains how to calculate the total solids and total dissolved solids from water analysis data.

1. STEP 1 : Gather data

In order to calculate the total solids of a water stream, it is necessary to take a sample of the water and deliver it to a laboratory for gravimetric analysis. The engineer must gather the following data from the laboratory reports:

\(V_{\text{sample}}\) = the sample size, in liters (L)
\(m_{\text{dish}}\) = tare mass of evaporating dish (g)
\(m_1\) = mass of evaporating dish + residue after evaporation and drying at 105°C (g)
\(m_2\) = mass of evaporating dish + residue after ignition at 550°C (g)
\(m_{\text{filter}}\) = tare mass of glass fiber filter (Whatman GF/C or equivalent) after drying at 105°C (g)
\(m_3\) = mass of filter + residue after drying at 105°C (g)
\(m_4\) = mass of filter + residue after ignition at 550°C (g)

2. STEP 2 : Calculate the total solid

The total solids (TS) in the water can be calculated with the following formula from the analysis results:

\[TS = \frac{m_1 - m_{\text{dish}}}{V_{\text{sample}}}\]

TS = (m₁ - m_dish) / V_sample

Where:

\(TS\) = total solids (g/L)
It is standard practice to express the total solids in mg/L by multiplying the result by \(1000\text{ mg/g}\).

3. STEP 3 : Calculate volatile and suspended solids concentrations

The analysis from the evaporating dish and the filter yields other critical indicators of wastewater quality.

Total Volatile Solids (TVS) calculation:

\[TVS = \frac{m_1 - m_2}{V_{\text{sample}}}\]

TVS = (m₁ - m₂) / V_sample

Where: \(TVS\) = total volatile solids (g/L) (representing volatile organic compounds burned off at 550°C).

Total Suspended Solids (TSS) calculation:

\[TSS = \frac{m_3 - m_{\text{filter}}}{V_{\text{sample}}}\]

TSS = (m₃ - m_filter) / V_sample

Where: \(TSS\) = total suspended solids (g/L) (retained by standard filtration).

Volatile Suspended Solids (VSS) calculation:

\[VSS = \frac{m_3 - m_4}{V_{\text{sample}}}\]

VSS = (m₃ - m₄) / V_sample

Where: \(VSS\) = volatile suspended solids (g/L).

⚠️ ENGINEERING NOTICE & EDUCATIONAL DISCLAIMER: This interactive calculator is provided exclusively for preliminary estimation and educational purposes. It is not intended for detailed design or equipment procurement without certified vendor rating. No warranty, expressed or implied, is provided, and no liability is assumed.

Total Solids Analyzer (SI & Imperial)

Sample Size (\(V_{\text{sample}}\))

Dish Tare Mass (\(m_{\text{dish}}\))

Dish + Dry Residue @105°C (\(m_1\))

Dish + Ignited Residue @550°C (\(m_2\))

Filter Tare Mass (\(m_{\text{filter}}\))

Filter + Dry Residue @105°C (\(m_3\))

Filter + Ignited Residue @550°C (\(m_4\))

Parameter Name	Acronym	Value	Unit
Total Solids	TS	0.722	g/L
Total Volatile Solids	TVS	0.338	g/L
Total Suspended Solids	TSS	0.242	g/L
Volatile Suspended Solids	VSS	0.156	g/L
Total Dissolved Solids	TDS	0.480	g/L
Volatile Dissolved Solids	VDS	0.182	g/L

💡 Plant Engineering Best Practices & Rules of Thumb

Temperature Discipline: Ensure drying at exactly 103°C to 105°C. Excessive temperatures can volatilize ammonium bicarbonate and some organic fractions prematurely.
Ignition Verification: Heavy chemical wastewater might require longer than 15-20 minutes in a 550°C muffle furnace to achieve complete carbon burn-off.
Desiccator Storage: Always cool warm crucibles and filters inside a dry desiccator. Ambient humidity absorption can ruin accurate sub-milligram weighings.
TDS Guidance: Generally, TDS levels below 500 mg/L are acceptable for municipal drinking systems. Levels above 1000 mg/L indicate high mineral content requiring treatment (RO/EDR).

4. STEP 4 : Total dissolved solids calculation

The concentrations calculated above allow process engineers to determine two other major indicators in wastewater treatment design: total dissolved solids (TDS) and volatile dissolved solids (VDS).

Total Dissolved Solids (TDS) calculation:

\[TDS = TS - TSS\]

TDS = TS - TSS

Where:

\(TDS\) = total dissolved solids (mg/L)
\(TS\) = total solids (mg/L)
\(TSS\) = total suspended solids (mg/L)

Volatile Dissolved Solids (VDS) calculation:

\[VDS = TVS - VSS\]

VDS = TVS - VSS

Where:

\(VDS\) = volatile dissolved solids (mg/L)
\(TVS\) = total volatile solids (mg/L)
\(VSS\) = volatile suspended solids (mg/L)

5. Total Solids in Water calculator Excel

MyEngineeringTools.com has developed a free Excel workbook template that allows you to calculate the distinct total solids parameters defined above directly from analytical measurements: Total Solids in Water calculator Excel Download

Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.

Sources

[Chopey] Handbook of Chemical Engineering calculations, Chopey et al, McGraw Hill, 2004