PURPOSE
The first purpose of this experiment was to compare the water clarity (total suspended solids) before and after wastewater treatment.
The second purpose of this experiment was to compare the treated water clarity (total suspended solids) after treatment to that of the river water it would flow into.
I became interested in this idea when I learned of the different amounts of inorganic and organic solids that flow from every household into a sewer. I was interested in how the clarity of the water changed from the initial discharge of washing machines, dishwashers, and toilets as compared to what goes into the river.
The information gained from this experiment could help people understand that wastewater treatment must be carefully monitored to avoid negative impact in the river it flows into.
My first hypothesis was the percent reduction of the total suspended solids of untreated wastewater to that of the treated wastewater would be 85% or greater.
I based my first hypothesis on the City of Selah Wastewater Treatment Plant N.P.D.E.S. permit issued by the Washington State Department of Ecology. Specifically, the percentage of reduction must be 85% or greater. In addition the weekly average for suspended solids cannot exceed 45 mg/L and the monthly average cannot exceed 30 mg/L.
My second hypothesis was that the treated wastewater would have a total suspended solids content that was no more than 50% greater than the Yakima River upstream of the wastewater entry point.
I based this hypothesis on the fact that the clarification process within the Selah Wastewater Treatment plant was designed to produce total suspended solids content close to that of the Yakima River just upstream of the wastewater entry point via the Selah ditch. It is also known that both river water and treatment plant effluent vary quite a bit from week to week due to rain, run-off from the mountains, and numerous other events.
The constants in this study were:
v
The untreated (Influent) sampling point.
v
The treated (Effluent) sampling point.
v
The River (upstream) sampling point.
v
The testing equipment
v
The testing procedures
v
The Drying oven temperature (103 – 105 degrees C)
v
The muffle furnace (505 degrees C)
v
The grab samples collection time.
v
The volume of grab sample collected at each point. (1 Liter)
v Quality
Control standard for total suspended solids which will be run with each set
of tests
- Celite 521.
- Weight Scale for solids.
- Filters – Whatman 934 AH 55mm
diameter
- Distilled water for rinse.
The manipulated variable was location of sampling.
- Influent
- Effluent
- Upstream
The responding variable was the total suspended solids.
To measure the responding variable: I used the equipment at the Selah Wastewater treatment plant Lab along with procedures found in the Book of Standard Methods 20th Edition to determine the mass of suspended solids in each sample.
MATERIALS
QUANTITY
|
ITEM DESCRIPTION
|
3
gallons
|
Distilled water
|
1
|
10 ml. pipette for
Influent sample
|
1
|
Vacuum pump
|
1
|
100 ml. cylinder for
effluent sample
|
1
|
100 ml. cylinder for
River sample
|
1
|
Suction flask
|
11
|
Filters – Whatman 934 AH
|
11
|
Aluminum weight dishes
|
1
|
Desiccator with desiccant
containing color
Indicator for moisture concentration |
1
|
Filter holder and adapter
|
1
|
Drying oven 103 – 105
degrees C
|
1
|
Muffle furnace 550
degrees C
|
3
|
Calibration Weights
|
1
|
Wax paper
|
1
|
Tweezers
|
1
|
100 ml. cylinder for
standard Celite 521
|
1
|
50 ml. cylinder
|
1
|
1 liter flask for
standard Celite 521
|
1
|
100 ml. cylinder for
reagent grade water check
|
1
|
Safety glasses
|
3
|
1 liter sample containers
|
12
pair
|
Pair of nitrile gloves
|
1
|
Scale 0.1-mg capability
|
300mg
|
Celite 521 Total
suspended solids standard
|
1
|
Lab coat
|
1
|
Wash area with soap and
antibacterial lotion
|
1
|
Clean work area
|
A. Make sure safety items are in place and being used.
B. Prepare 11 glass fiber filters (whatman 934 AH) 1 filter for distilled water check, 3 filters for Influent replicates, 3 filters for Effluent replicates, 3 filters for River replicates, 1 filter for Quality control check.
1. Insert glass fiber filter disk (Whatman 934 AH) into filtration apparatus with the wrinkled side up.
2. Turn on Vacuum Pump. Rinse filter three times with each containing 20 ml. of reagent – grade distilled water.
3. Turn off Vacuum Pump and remove filter with tweezers from the filtration apparatus and place in Aluminum weight tin.
4. Place tin containing filter in the drying oven for 1 hour, at a temperature of 103 – 105 degrees C.
5. Place Tin containing filter in muffle furnace at 550 degrees C for 15 minutes.
6. Place Tin containing filter in desiccator to balance the temperature. The filter weight should be weighed a few times to ensure not more than a 4% change between previous weight. This is to make sure the filter is now ready for use.
C. Conduct the reagent grade distilled water check.
1. Calibrate scale with calibration weight
2. Weigh up 1 of the 11 filters.
3. Place filter on filtration apparatus.
4. Turn on Vacuum Pump.
5. Use 100 ml. of reagent grade distilled water and pour over filter.
6. Dry and weigh filter
a. Let run through filter fully.
b. Turn off vacuum pump.
c. Remove filter from filtration apparatus
d. Place filter in aluminum tin.
e. Place tin containing filter in drying oven for 1 hour at 103 – 105 degrees C.
f. Take out of Drying oven and place in desiccator until temperature is balanced. Usually 20 minutes.
g. Calibrate scale again with calibration weights
h. Take filter out of desiccator and remove from tin. Tare scale.
i. Place filter on scale and record weight in grams. Remove filter, tare scale, and re-weigh to ensure less than a 4% change from previous weight.
j. Place filter in desiccator between weights.
7. Filter should have same weight in grams or no change with the reagent grade-water. This is a quality check for reagent grade water, procedures, and equipment.
8. Calculation:
a. Weight of filter and residue after drying.
b. Tare weight of washed filter.
c. Sample size of 100 ml.
d. [(A-B) * 1,000,000] / C = Total suspended solids.
D. Conduct Quality Control Check using Celite 521 Total suspended solids Standard to check procedures in weight and measures.
1. Calibrate scale with calibration weights.
2. Place wax paper on scale and tare the scale.
3. Place 75mg of Celite 521 on wax paper. Weigh out on scale.
4. Transfer 75mg of Celite 521 to 1 liter flask filled halfway with reagent grade water. Fill the rest of the way with reagent grade water to the full mark on the 1liter flask.
5. Invert flask ten times. Let set for 10 minutes.
6. Weigh 1 of the 10 remaining filters on calibrated scale, noting the initial weight of the filter in grams.
7. Place the filter on filter apparatus.
8. Turn on vacuum pump.
9. Rinse filter with 20 ml. of reagent grade distilled water.
10. After 10 minutes invert flask ten more times and pour immediately into 100 ml. cylinder 100 ml. of standard from the 1-liter flask.
11. Pour the 100 ml. of standard from the cylinder over the filter and rinse inside of cylinder and filter apparatus with reagent grade water over the filter.
12. Repeat step 15 (Dry and weigh filter)
13. Filter should show a 75mg/l of total suspended solids if procedures were followed.
14. Calculation: Same as previous calculation with the variable (C) still at 100 ml.
E. Conduct Influent Sampling and Testing:
1. Collect a grab sample of 1 liter from the Influent of the Wastewater Treatment plant.
2. Set out three filters of the nine remaining filters in order to run three separate replicate tests from the 1-liter grab sample. This will ensure consistency of tests.
3. Each replicate will be a 10 ml. sample using a 10 ml. pipette rinsed with distilled water. Between each replicate shake the sample 25 times by inverting the 1 liter sample container.
4. Calibrate scale with calibration weights.
5. Weigh one of the three filters on scale for initial filter weight.
6. Set up filter on filtration apparatus.
7. Turn on vacuum pump.
8. Rinse with distilled water – 20 ml.
9. Shake by inverting 1 liter sample container 25 times.
10. Immediately pipette with a 10 ml. pipette 10 ml of sample using a suction bulb to suck up sample from the 1 liter sample container.
11. Empty pipette over filter while rinsing inside of pipette and filtration apparatus with distilled water over filter.
12. Run vacuum pump until sample and rinse water has filtered through filter.
13. Repeat step 15 (Dry and weigh filter)
14. Calculation same as previous calculations with the exception of (C) sample size being 10 ml. instead of 100 ml. This will equal 1 total suspended solids result in mg/l. for the three replicate tests to be performed.
15. Place this same filter into the aluminum tin.
16. Place tin containing filter in muffle furnace at 550 degrees C for twenty minutes.
17. After twenty minutes, place the tin containing the filter into desiccator until filter temperature has stabilized, usually thirty minutes.
18. Calibrate scale with calibration weights.
19. Take filter out of desiccator and remove from tin. Tare scale.
20. Place filter on scale and record weight in grams. Remove filter, tare scale, and re-weigh to ensure less than 4% change from previous weight. Place filter in desiccator between weights.
21. Calculation for volatile suspended solids.
a. Weight of filter plus residue after drying.
b. Weight of filter plus ash after ignition.
c. Sample size (10 ml.)
d. [(A – B) x 1,000,000] / C = volatile suspended solids in mg/l.
22. Repeat this procedure for the two remaining filters for the Influent grab suspended solids test/volatile suspended solids testing.
23. This will end up with three total suspended solids results that can be averaged together for one result measured in mg/l.
24. This also will have three volatile suspended solids results that can be averaged together for one result measured in mg/l.
25. This will result in the total suspended solids make of organic and inorganic solids in one 1 liter influent grab sample.
F. Conduct Effluent Sampling and Testing:
1. Collect pick up a grab sample of 1 liter from the Effluent outfall of the Wastewater Treatment plant, which empties into the Selah ditch.
2. Set out three filters of the six remaining filters in order to run the separate replicate tests from the 1 liter grab sample. This will ensure consistency of tests.
3. Each replicate will be 100 ml. sample using a 100 ml. cylinder rinsed with distilled water. Between each replicate shake the sample 25 times by inverting the 1 liter sample container.
4. Use the same procedures as the Influent grab sampling and test. *Exception: 100 ml. of sample use. Remember this in the calculations.
5. The result will show the average of three Total suspends solids tests with a result measured in mg/l. I will also have an average of three volatile suspended solids tests with a result measured in mg/l.
6. To prove the first hypothesis use a percent reduction formula.
7. Average Total suspended solids (Influent).
8. Average Total suspended solids (Effluent).
9. [(A – B)/A] x 100 =% Total suspended solids reduction.
10. This will help prove that the wastewater Treatment clarification process is adequate and functioning properly.
G. Conduct Yakima River testing upstream of the Selah ditch discharge.
1. Collect a grab sample of 1 liter from the Yakima River upstream of the Selah ditch discharge.
2. Set out the three remaining filters in order to run three separate tests from the 1 liter grab sample. This will ensure consistency of tests.
3. Each replicate will be a 100 ml. sample using a 100 ml. cylinder rinsed with distilled water. Between each replicate I will shake the sample 25 times by inverting the 1 liter container.
4. Use the same procedures as the Effluent sampling and testing.
5. 100 ml. will also be used for sample size in calculation.
H. The result will show the average of three Total suspends solids tests with a result measured in mg/l. I will also have an average of three volatile suspended solids tests with a result measured in mg/l.
I. To prove the second hypothesis I will compare the Selah Wastewater Treatment Plant Effluent outfall data to the data obtained from the Yakima River test data.
The first original purpose of this experiment was to compare the water clarity (total suspended solids) before and after wastewater treatment.
The second original purpose of this experiment was to compare the treated water clarity (total suspended solids) after treatment to that of the river water it would flow into.
The results showed that the average total suspended solids of the influent water (before treatment) was 177.8 milligrams/liter. The average total suspended solids of the effluent water (after treatment) was 7.1 milligrams/liter. The average percentage reduction in suspended solids was 96.0%. The average total suspended solids of the upstream water (natural river) was 5.2 milligrams/liter.
My first hypothesis was the percent reduction of the total suspended solids of untreated wastewater to that of the treated wastewater would be 85% or greater.
The results indicate that this hypothesis should be accepted, because the average reduction was 96%.
My second hypothesis was that the treated wastewater would have a total suspended solids content that was no more than 50% greater than the Yakima River upstream of the wastewater entry point.
The results indicate that this hypothesis should be accepted, because the effluent was 37% higher than the river water.
After thinking about the results of this experiment, I wonder if testing during spring, summer, or fall would provide similar results to my winter tests. I also wonder how the temperature of the effluent compares with the river.
If I were to conduct this project again there would be a change in the upstream river location. I would have started my experiment a little earlier to get more weeks of data.
Researched ---- Megan L
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