The following test results were obtained for a 100 ml wastewater sample taken at the inlet to wastewater treatment plant.  The tests were performed using the standard methods. Determine the concentration (mg/l) of total solids, total volatile solids, total suspended solids, fixed suspended solids, total dissolved solids and fixed dissolved solids.

Tare mass of evaporating dish     = 54.6422 g

     "+ Residue after evaporation of sample at 105°C = 54.7022 g

     "+ Residue after ignition at 550°C   = 54.6842 g  

Same volume of sample is used to determine the suspended solids also.  

Tare mass of filter     = 1.5348 g

      "+ Residue after drying at 105°C = 1.5553 g

       "+ Residue after ignition at 550°C = 1.5453 g

Ans: Volume of sample = 100 mL = 0.1 L  

Total Solids (TS) = [(54.7022- 54.6422) g *1000 mg/g ]/0.1 L  = 600 mg/l  

Total Volatile Solids (TVS) = (54.7022 - 54.6842)g *1000 mg/g ]/0.1L  = 180 mg/l  

Total Fixed Solids (TFS) = (54.6842 - 54.6422)g *1000 mg/g ]/0.1L  = 420 mg/l

It can also be estimated from TFS = TS-TVS = 600-180= 420 mg/l  

Suspended Solids (TSS or SS) = (1.5553-1.5348)g*1000 mg/g ]/0.1L= 205 mg/l  

Fixed Suspended Solids (FSS ) = (1.5453-1.5348)g*1000 mg/g ]/0.1L  = 105 mg/l  

Volatile Suspended Solids (VSS) = (1.5553-1.5453)g*1000 mg/g ]/0.1L  = 100 mg/l

Or it can also be estimated by VSS = TSS-FSS = 205- 105 = 100 mg/l  

Dissolved solids can be determined from the difference between total solids and suspended solids. However, laboratories routinely determine the dissolved solids also experimentally and verify the accuracy of the results.