Water/Wastewater Laboratory Calculations - Basic Mathematics for Water and Wastewater Operators - page 243

Biosolids sample
73.43 g (weight of biosolids and dish)
-22.28 g (weight of dish)

51.15 g (weight of biosolids sample)

Totalsolidsweight
Biosolids

2.60 g
51.15 g

%Total solids = ×= ×= 100 100 5%

sample weight

To calculate the percent volatile solids, the grams total solids and grams volatile
solids must be determined. Because the total solids value has already been calcu-
lated (above), only volatile solids must be calculated:

Volatile solids
24.88 g (weight of sample and dish before burning)
-22.98 g (weight of sample and dish after burning)
1.90 g (weight of solids lost in burning)

Volatilesolidsweight
Tot

1.90 g
2.60 g

%Volatile solids = ×= ×= 100 100 73%

al solidsweight

WASTEWATER SUSPENDED SOLIDS
AND VOLATILE SUSPENDED SOLIDS
Total suspended solids (TSS) are the amount of filterable solids in a wastewater sam-
ple. Samples are filtered through a glass fiber filter. The filters are dried and weighed
to determine the amount of total suspended solids in mg/L of sample. Volatile sus-
pended solids (VSS) are those solids lost on ignition (heating to 500°C). They are
useful to the treatment plant operator because they give a rough approximation of the
amount of organic matter present in the solid fraction of wastewater, activated bio-
solids, and industrial wastes. With the exception of the required drying time, the sus-
pended solids and volatile suspended solids tests of wastewater are similar to those
of the total and volatile solids performed for biosolids. Calculations of suspended
solids and volatile suspended solids are demonstrated in Example 16.18.
Note: The total and volatile solids of biosolids are generally expressed as percents,
by weight. The biosolids samples are 100 mL and are unfiltered.

■ Example 16.18
Problem: Given the following information regarding a primary effluent sample, cal-
culate the mg/L suspended solids and the percent volatile suspended solids of the
50-mL sample.

After Drying (Before Burning) After Burning (Ash)

Weight of sample and dish 24.6268 g 24.6232 g

Weight of dish (tare weight) 24.6222 g 24.6222 g