CVE 375 Lab 1

“Solids” are the physical, non-liquid
material present in water samples. Large
solids such as personal care items are termed
“rags,” whereas small materials such as rocks
and sand are called “grit,” and tiny particles
are called “colloids.” In environmental
engineering, Total Solids (TS) refer to the
remaining mass of material after the
evaporation of the liquid. Additionally,
Suspended Solids (TSS) refer to the mass of
material retained on a filter, while Total
Dissolved Solids (TDS) refer to the mass of
material passing through a filter.
TSS is an important concept in
wastewater treatment. Further, TSS is a water
quality parameter that can indicate the
efficiency of treatment processes and
estimate the strength of wastewater.
The testing methods of TSS consist of
membrane filtration whereby the TSS will be
physically separated from the water samples
by size exclusion. The particles larger than
the pore size of the filter will remain
unfiltered and can be measured.
The objectives of this experiment are
to measure the Total Suspended Solids (TSS)
of a water sample, compare the differences in
TSS for various water types, and understand
the importance of TSS in environmental
engineering.
dishes, an analytical balance, a filter
apparatus, a vacuum pump, forceps and an
oven.
Prior to starting the lab, the filters
were washed with the DI water and dried.
The first filter was weighed while the first
water sample was collected and the filter
apparatus was assembled. Note that the filters
were each weighed immediately before the
addition of their corresponding water sample.
The vacuum was then turned on and the filter
was sprayed with DI water. The first sample
was slowly added to the filter apparatus. The
filter was removed with forceps and placed
solids side up on a weighing dish after the
entire sample had passed. The top of the filter
apparatus was rinsed and the same steps were
repeated for the remaining three samples. The
weighing dishes were placed in the oven at
103-105 °C for 15 minutes. After removed
from the oven, the samples cooled for three
minutes and the new masses were recorded.
Materials and Methods
This experiment was performed
according to Standard Method 2540 D in
order to determine TSS of different water
samples. The materials used in this
experiment were 20 mL of DI water, four
clean filters, 100 mL of each water sample
(wastewater influent, wastewater effluent,
surface water, and saltwater), four weighing
2
Results
Table 1: TSS of Various Water Samples
Sample
Volume
(mL)
Clean
Filter W1
(mg)
Solids
Filter W2
(mg)
W3 (mg)
TSS
(mg/L)
Influent
100
133.2
134.4
1.2
12
Effluent
100
128.2
129.5
1.3
13
Surface
Water
100
114.3
114.9
0.6
6
100
127.0
141.8
14.8
1.3
1*
1000)*
0.6
14.8
!"",.$' 1.'&- = 100 ∗ (
Calculations:
Mass remaining on filter (W3):
W3 = W2 - W1
W3 (Influent)= 134.4mg - 133.2mg = 1.2mg
W3 (Effluent)= 129.5mg - 128.2mg = 1.3mg
W3 (Surface Water)= 114.9mg - 114.3mg =
0.6mg
W3 (Salt Water)= 141.8mg - 127.0mg = 14.8mg
) = 12mg/L
) = 13mg/L
1000)*
1*
1000)*
1*
)=6mg/L
)=148mg/L
TSS Percent Removal of the wastewater
process:
!""!"# − !""+##
%/0& =
∗ 100%
!""!"#
12213
12
148
Fig. 1: Graph of TSS values for different
water samples
1*
!"",%-#./& 1.'&- = 100 ∗ (
∗ 100% = -8.3%
TSS Percent Difference between the Surface
Water and WW Effluent:
5!""+## − !"",1 5
%2344 =
∗ 100%
(!""+## + !"",1 )
(
2
|1326|
%2344 = 13!6) ∗ 100% = 73.7%
(
TSS remaining of sample:
$3(&')
1000&,
!"" =
∗ (
)
)*+(&,)
1,
1000)*
!""+##$%&"' = 100 ∗ (
%/0& =
Salt
Water
1.2
!""!"#$%&"' = 100 ∗ (
2
Discussion
The results of the lab provide insight
into the importance of TSS determination.
The TSS values for the influent, effluent,
surface water, and salt water samples were
determined to be 12 mg/L, 13 mg/L, 6 mg/L,
and 148 mg/L, respectively. As shown by
Fig. 1, the salt water had significantly more
TSS than the other samples. This could be
related to the salinity and minerals present in
salt water thereby contributing to a high TSS
value. Additionally, the sources of TSS in
natural water bodies are erosion, decayed
organisms, bacteria, vehicle exhaust
emissions, vehicle parts, building and
construction material, road salt, road paint
and
pedestrian
debris,
atmospheric
deposition of particles, and rock weathering.
Several of these factors likely contributed to
the high TSS value of the salt water sample.
3
Fig. 1 also indicates that the
wastewater influent and effluent had nearly
the same TSS with the effluent actually
having a slightly greater amount of TSS than
the influent. It is very unlikely that this is the
case in that wastewater influent should in
theory have significantly more TSS than the
effluent since it has yet to undergo the
treatment process. Additionally, the typical
TSS values of raw wastewater range from
155-330 mg/L, with 250 mg/L being typical
concentration, while wastewater effluent is
typically less than 25 mg/L (Heger). The
reason for wastewater treatment plants
having such high TSS concentrations is the
BOD (Biochemical Oxygen Demand) which
can cause excessive solids generation.
As a result of the lab influent TSS
value being well below the typical influent
TSS range, it can be inferred that an error
occurred during testing. Since there is only a
1 mg/L difference between the calculated
influent and effluent TSS values, it is likely
that the effluent sample was mistakenly used
twice during this lab. This is a major source
of error that also affected calculation of the
TSS percent removal of the wastewater
process resulting in a negative percent
removal.
The TSS percent removal calculation
was intended to demonstrate how TSS can
indicate the level of efficiency of the
wastewater treatment process depending on
how large or small of a percentage the
calculation yields. As shown by the
calculation in this lab, an ineffective
wastewater treatment (little to no removal of
TSS) will yield a very small percent removal.
Since there was an error in measuring the
TSS of the influent (the effluent sample was
used twice), the percent removal was -8.3%
indicating that no TSS was removed. The
TSS percent difference calculation was used
to determine the closeness of the wastewater
effluent and surface water TSS values. This
calculation is another indicator of the
efficiency of the wastewater treatment
process. Theoretically, the percent difference
should not be too large because this would
result in contamination of the surface water
by the effluent. This lab calculated the
percent difference to be 73.7%.
As a result of the error that was made
during this lab, it cannot be concluded if this
treatment plant was efficient. However,
based on the typical values of TSS of
influents and effluents the expected TSS
percent removal should be 90% which would
therefore indicate an efficient treatment
plant. However, TSS is not necessarily the
best indicator of treatment efficiency in that
many factors can affect the TSS of samples.
These
factors
include
high
flow,
geomorphology catchment, type of soil,
wastewater and septic system effluent and
seasons.
Conclusion
Based on the results of the lab it can
be concluded that the TSS values for the
influent, effluent, surface water, and salt
water samples were determined to be 12
mg/L, 13 mg/L, 6 mg/L, and 148 mg/L,
respectively. An error occurred when
filtering the influent sample which resulted in
a much lower TSS value than anticipated.
References
Heger, S. (2017, September 23). How high
TSS can impact onsite system performance,
4
and 10 ways to reduce it. Onsite Installer.
www.onsiteinstaller.com/online_exclusives/
2017/09/an_installers_guide_to_total_suspe
nded_solids#:~:text=TSS%20is%20the%20
most%20common,less%20than%2065%20
mg%2FL.
5