The total solids (TS) contents of sludge are used in the design and process control of wastewater treatment facilities. Total dissolved solids (TDS) are used to evaluate the suitability of water for both domestic supplies and industrial purposes. The total suspended solids (TSS), including the volatile fraction (VSS), are commonly monitored to evaluate the degree of pollution in natural waters and serves as a key process control parameter for wastewater treatment operation.

The measurement of solids is by means of the gravimetric procedure. The various forms of solids are determined by weighing after the appropriate handling procedures.

1. Placing a clean porcelain crucible for 60 min at 550 °C in the muffle then is passed to a desiccator to cool and then weighed (noted as weight of the crucible).

2. Add with a blunt pipette 10 mL of anaerobics sludge. In a warming rack remove all the water possible. Go to the muffle furnace at 100 °C within 2 h; after this time is cooled and weighed (weight recorded as 100 °C).

3. Place the crucible in the muffle at 550 °C for 1 h and pass it to the desiccator and record the weight of the crucible (as weight at 550 °C).

4. Finally returned to the desiccator. After obtaining the three weights, and proceeded to determine the total solids, volatile and fixed as follows: [35]

Weight to 100oC — Weight of the crucible g

total suspendedsolids TSS :—— — ——————— — — ————— [=] (6)

Sample volume L

Fixed solids FS : Weightt° 55°°C — Weight of thecrucible [ (7)

Sample volume L