Sewer Science Lab Introduction
This lab demonstrated how the water treatment facilities treated sewer water before releasing it into the ocean. After treating the water, it becomes clean and safe enough to release into the ocean but not safe to drink.
The Four Tests
pH:
pH determines how acidic or basic a solution is on a scale from 0 to 14. Anything less than 7 is more acidic and anything more is more basic. 7 is neutral and is most capable of sustaining life on this planet. pH strips are used to measure the pH of the water.
Ammonia:
Ammonia (NH3) is an acidic substance that represented urine in this lab. Ammonia is highly toxic and bacteria will attack the ammonia using an action that requires oxygen. The oxygen that is used is needed in the water for the survival of other species will be used up by the bacteria and the other life that will need it will die.
Turbidity:
Turbidity is a measurement of how many suspended particles are in water. When the turbidity is high, it means that the water is murky and when the turbidity is lower, the water is clearer. This impacts the marine life that receive their oxygen from the water with gills. When fish are in water with high turbidity, the particles in the water stick onto their gills and suffocate them.
Chemical Oxygen Demand (COD):
Chemical oxygen demand (COD) measures the amount of oxygen that would be needed to destroy all the pollution in the water. The higher the COD, the more pollution there is. The dissolved oxygen reacts with the pollution, creating CO2 and H2O which leaves the marine life with less oxygen.
Treatment Steps: Pictures & Data
Raw Sewage:
Made of: Amount used: Represents this type of waste
in real waste water:
Dried coffee grounds 8g Food/Feces
Ground-up breakfast cereal 3.44g Food/Feces
Ground-up pet food 3.94g Food/Feces
Cut-up plastic 1.7g All plastics
Baking Soda 4g Cleaning products
Torn-up toilet paper pieces 4.52g Paper products
Ammonia 10mL Urine
Vegetable oil 20mL All oils
in real waste water:
Dried coffee grounds 8g Food/Feces
Ground-up breakfast cereal 3.44g Food/Feces
Ground-up pet food 3.94g Food/Feces
Cut-up plastic 1.7g All plastics
Baking Soda 4g Cleaning products
Torn-up toilet paper pieces 4.52g Paper products
Ammonia 10mL Urine
Vegetable oil 20mL All oils
Primary Treatment:
Primary treatment of water is removing the oil and large particles in the water. The two treatment processes used are sedimentation and flotation. Particles that are denser than water will sink to the bottom. Anything less dense than water, such as oil, will float to the top. Dissolved matter will stay in the middle.
Secondary Treatment:
The middle layer of dissolved matter is poured into an aeration tank in the secondary treatment. eat the dissolved ammonia & food nutrients in the waste water. Air is added for the aerobic microorganisms to survive. Microorganisms eat the dissolved ammonia, food nutrients in the waste water, and the pollutants and convert the compounds into solids.
Secondary with Flocculation:
The waste water is then moved to the secondary sedimentation tank so flocculation can occur (microbes settle to the bottom of the tank). Aluminum sulfate is added to capture the microorganisms and make them stick together sink to the bottom.
Filtration:
Filtration is the final stage of the waste water treatment. The water is transferred to a filtration column, made of sand and charcoal. The coal layer is on top of the sand layer and takes out large solids in the water. The then water travels between the sand and into the bottom of the filter. On its way to the bottom, the water leaves behind fine particles stuck in the sand and charcoal.
Data Analysis
Graphs below table
Tests
|
May 10th, 2012
Day 1 |
May 14th, 2012
Day 2 |
May 16th, 2012
Day 3 |
May 20th, 2012
Day 4 |
pH
|
8
|
7
|
7
|
7
|
Ammonia Concentration
(mg/Liter) |
6x2
12 |
6x2
12 |
3x2
6 |
2x2
4 |
Turbidity
|
292
|
79
|
48
|
11
|
Chemical Oxygen Demand
(mg/Liter) |
1088
|
1084
|
100
|
36
|
Anyalysis
The pH of the water after filtration became a neutral 7. The ammonia, turbidity, and COD levels drastically dropped throughout the lab. While the turbidity and the COD gradually declined, the ammonia levels