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.