Reducing Phosphates in Wastewater by Minimizing the Amount of Laundry Detergent 9 th Grade
Question How much detergent is actually needed to clean a load of laundry?
Hypothesis I believe that the amount of detergent recommended on the label is more detergent than what is needed.
Abstract My project was to reduce the amount of phosphates in wastewater by reducing the amount of detergent used in laundry. I believed that the amount of detergent recommended by the manufacturer is more than necessary to clean a load of laundry. By reducing detergent usage, less phosphates go into the environment. I first found the concentration of the detergent in a load of laundry. I then tested the turbidities of detergent concentrations up to the recommended amount on the label. Graphs of the results showed an expected upward trend and a dip and another upward trend. My conclusion is that all detergent after the dip in the graph is unnecessary because all that is happening is that the detergent is clouding up the water. I estimate that only 80% of the detergent is necessary. Using that amount will have a 20% reduction in phosphates in wastewater.
Use of Phosphates Most detergents are made up of two parts: surfactants and builders. Surfactants lift dirt off of clothes and dishes. The builder prevents minerals from interfering with the surfactants. Without builders, detergents would be more expensive. Phosphates are excellent builders, so detergent companies began to use phosphates as their builders. Phosphates are also nutrients to plants, so farmers use phosphates in their fertilizers.
Environmental Problems The growth amount of algae is dependant on the amount of phosphates in the water. When more phosphates enter the water, there is a boom in the growth of the algae. When there is a lot of algae, the river or lake turns green and can give off an unpleasant odor. The algae also takes most of the oxygen, which makes it harder for fish to live in the water. When phosphate laden water has been used, it is treated and then goes back into lakes or rivers. However, treatment does not eliminate phosphates, so the phosphates go into the river as well. This can cause eutrophication, which turns the water green and makes it less safe for drinking.
Eutrophication Eutrophication happens when water is enriched with phosphates. The phosphates fertilize the water, which causes a boom in aquatic growth.
Micelles Detergent traps dirt by using micelles. Micelles have a hydrophilic head and a hydrophobic tail. When micelles go into the water, they tend When micelles go into the water, they tend to bunch up. When the water hits the Critical Micelle Concentration, then the water becomes turbid.
Cascade Soap Turbidity 70 60 50 Turbidity (NTU) 40 30 Cascade Soap 20 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Mass (g)
Clorox 2 for Colors Turbidity 80 70 60 Turbidity (NTU) 50 40 30 Clorox 2 for Colors 20 10 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Mass (g)
Sun Burst Turbidity 12 10 8 Turbidity (NTU) 6 Sun Burst detergent 4 2 0 0 0.05 0.1 0.15 0.2 0.25 Mass (g)
Turbidimeter Calibration 80 70 60 Turbidity (NTU) 50 40 30 Expected Result 20 10 0 1 2 3 4 5 6 7 8 9 Trials
Materials Cascade detergent Sun Bounce detergent Clorox 2 for colors detergent Water 100 ml measure Stirring rods Turbidimeter Scale Plastic containers
Procedure 1. Calculate the amount of water used in a load of laundry. 2. Calculate the mass of the recommended amount of detergent for a load of laundry. 3. Find the concentration of detergent in a load by using the two values above. 4. Weigh as small of an amount of detergent as possible on the scale. Put the detergent into the plastic container. 5. Add 100 ml of water to the detergent and stir. 6. Measure the turbidity of the detergent solution and record. 7. Repeat steps 4-6 for the detergent until the detergent hits the concentration used for the recommended amount of detergent. 8. Repeat steps 2-7 for the other detergents used.
Applications By only using 80% of the manufacturer s suggestion, there would be a 20% phosphate reduction in wastewater. Less phosphate in rivers and lakes will reduce aquatic growth. There would also be a major cost savings because less detergent is being used.
Conclusion I conclude that you can use less detergent than the recommended amount on the label. I estimate that about 80% of recommended detergent is necessary per laundry load.