To determine the total solid in water, you combine the measurements of both suspended and dissolved substances present in the water sample.
Total Solids (TS) represent the collective weight of all particulate and dissolved materials remaining after a water sample has been evaporated at a specific temperature. As defined in the reference, TS = TSS + TDS. This means the total solid content is the sum of the Total Suspended Solids (TSS) and the Total Dissolved Solids (TDS).
Understanding Total Solids (TS)
Total solids are a crucial parameter in water quality assessment, indicating the overall amount of material (other than pure water) present. This includes everything from visible sediment particles to invisible dissolved salts and organic compounds. High levels of total solids can affect water clarity, taste, and suitability for various uses, including drinking, irrigation, and industrial processes.
Components of Total Solids
Total solids are divided into two main categories:
- Total Suspended Solids (TSS): These are the solid particles that are suspended in the water and can be filtered out. They include things like silt, clay, plankton, organic debris, and other particulate matter. TSS contributes to turbidity (cloudiness) in water.
- Total Dissolved Solids (TDS): These are the solid substances that are dissolved in the water and pass through a filter. They include dissolved salts (like chlorides, sulfates, carbonates), minerals, metals, and some organic compounds. TDS affects the water's conductivity and can influence its taste and suitability for consumption.
| Component | Description | Measurement Method (Typical) | Contribution to TS |
|---|---|---|---|
| Total Suspended Solids (TSS) | Solids retained by a filter | Filtration, Drying, Weighing | Particulate Matter |
| Total Dissolved Solids (TDS) | Solids passing through a filter (in filtrate) | Evaporation of Filtrate, Drying, Weighing OR Conductivity Meter | Dissolved Substances |
The Determination Process
The standard method for determining total solids involves laboratory analysis, which measures TSS and TDS separately and then calculates the total.
1. Measuring Total Suspended Solids (TSS)
- A known volume of water sample is passed through a pre-weighed standard filter (usually fiberglass).
- The filter paper, retaining the suspended solids, is dried in an oven at a specific temperature (commonly 103-105°C) until a constant weight is achieved.
- The difference between the final weight (filter + dried residue) and the initial filter weight represents the mass of the TSS.
- TSS is typically reported in milligrams per liter (mg/L).
2. Measuring Total Dissolved Solids (TDS)
- The water that passed through the filter in the TSS measurement (the filtrate) contains the dissolved solids.
- A known volume of this filtrate is placed in a pre-weighed evaporation dish.
- The filtrate is evaporated in an oven (commonly at 180°C) until a constant weight of residue is obtained.
- The difference between the final dish weight (dish + dried residue) and the initial dish weight represents the mass of the TDS.
- TDS is typically reported in milligrams per liter (mg/L).
- Alternatively, TDS can be estimated using a conductivity meter, as dissolved salts increase water's electrical conductivity. However, the evaporation method is the definitive standard for mass measurement.
3. Calculating Total Solids (TS)
Once the concentrations of TSS and TDS in mg/L are determined, the total solids concentration is calculated using the formula provided:
TS (mg/L) = TSS (mg/L) + TDS (mg/L)
For example, if a water sample has a TSS concentration of 50 mg/L and a TDS concentration of 300 mg/L, the total solids concentration would be:
TS = 50 mg/L + 300 mg/L = 350 mg/L
This straightforward summation provides the total mass of all solid material present in the water sample, combining both the suspended and dissolved fractions.
