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CE 170: Water Quality and Supply Engineering
Lab 3: Measurement of Total
Suspended Solids
Purpose of Lab
The purpose of this lab is become familiar with the standard
measurement of total suspended solids (TSS) and the relative
precision of that measurement.
Procedures
- The filters you will be using have been washed and dried. You
are going to weigh them on the analytical balance, so handle them
with tongs or tweezers at all times.
- Remove three aluminum boats and three filters from the
desiccater. Note the markings on the boats.
- Using the analytical balance, weight the aluminum boats and
filters. Record those weights.
- Place the filter on the suction apparatus as directed by the
instructor. Wet filter with a small amount of deionized water to
seat it.
- Filter 50 mL of the sample (or another volume as directed by
the instructor). Use care that you deliver exactly the volume
specified and that your sample is well-mixed.
- Wash the filter with three successive 10 mL washings of
distilled water while continuing suction. Wait 3 min. between
washings. (If some solids have been caught in your glassware,
rinse them out with these washings.)
- Turn off the suction and, using tweezers, place the filter in
its boat.
- Repeat steps 4-7 for the other two filters.
- Place the all the aluminum boats and filters in the drying
oven for at least one hour.
- Remove the aluminum boats and filters from the oven and place
in the desiccater for at least 15 minutes.
- Weight the aluminum boats and filters. Record those values.
Data Analysis
- Calculate the TSS values for your samples in mg/L.
- Exchange data with the other groups and record all the TSS
values.
- For the complete class data set, calculate the mean, sample
standard deviation, coefficient of variation, and 95% confidence
interval about the mean.
Discussion Questions
- Compare the precision of the suspended solids data with that
of the volume measurements of the previous week's lab. (Use the
COV as your measure of precision.) Comment on possible reasons for
the difference.
- Why are there no calculations or discussions of relative error
or accuracy in this lab?