| Complexity level: | 6 |
| Project cost ($): | 40 |
| Time required: | 1 day to prepare, 10 days for observation |
| Material availability: | Enzymes may be purchased at a DIY store or some of the larger supermarkets. |
| Safety concerns: | Basic safety requirements |
Hypothesis
Liquid enzymes will be the quickest to break down the fat, oil and grease.
Overview
Grease trap
With a rising number of restaurants, fast food chains, diners and other food outlets in cities, increasing amounts of fat, oil and grease are being discharged into the city sewer systems. These discharges solidify when cooled. They then combine with other solid materials that are discharged into the sewer pipes and cause blockages.
Grease traps are part of a plumbing system and are used to intercept most fat, oil and grease before they go through wastewater treatment. Wastewater usually contains small amounts of oil which floats in a septic tank. This layer of scum is slowly digested by microorganisms via anaerobic digestion. However, large amounts of discharge can overwhelm this system and result in untreated waste being released into the environment.
Introducing bacteria into grease traps will help in breaking down fat, oil and grease. Introducing bleach, ammonia or enzymes should be avoided because they will affect the bacteria digesting the waste. Smaller grease traps should be cleaned at least once a month.
Scientific Terms
Materials
The materials required for this science fair project:
- 300ml of FOG (fat, oil and grease) from a grease trap
- A measuring cylinder
- 600ml of distilled water
- 50ml of liquid enzyme, your should acquire at least 3 different brands
- 50mg of powder enzyme, your should acquire at least 3 different brands
- 50mg of solid enzyme, your should acquire at least 3 different brands
- An assistant
- A plastic bag
- A pair of PVC gloves
- A black marker pen
Procedure
1. For this science fair project, the independent variable is the form of enzyme used to dissolve and breakdown the FOG waste, - namely, liquid, powder and solid enzymes. The dependent variable is the number of days taken for the FOG waste to breakdown. This is determined by observing the beaker everyday. The constants (control variables) are the amount of enzyme, water and FOG waste used.
2. A visit to a nearby restaurant is made and permission obtained from the owner to open their grease trap to obtain some FOG waste samples. With the help of the assistant, the cover of the grease trap is opened. Wearing the PVC gloves, collect about 300ml of greasy waste from the trap. The waste from the grease trap is brought back to the lab for testing.
3. 9 beakers are labeled “liquid”,” powder” and “solid”. Distinguish between all the "liquid"beakers by labelling them 1 to 3. Do the same for powder and solid enzymes. Each of the 9 beakers are filled with 200ml of distilled water. Place 50ml of each of the three types of liquid enzyme, 50mg of each of the three types of powdered enzyme and 50mg of each of the three types of solid enzyme into the beakers according to the labels. 100ml of the greasy waste from the grease trap is extracted and poured into the beakers.
4. The beakers are observed everyday to see if the enzymes have completely broken down the greasy waste. The observations made are recorded in the table below.
Results
It is observed that the solid enzyme broke down the greasy waste the fastest and the liquid enzyme was the slowest acting enzyme.
| Type of enzyme | ||||||||||
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 | Day 8 | Day 9 | Day 10 | |
| Liquid 1 | X | X | X | X | X | X | X | X | Y | Y |
| Powder 1 | X | X | X | X | X | X | X | Y | Y | Y |
| Solid 1 | X | X | X | X | X | Y | Y | Y | Y | Y |
| Liquid 2 | X | X | X | X | X | X | X | X | X | Y |
| Powder 2 | X | X | X | X | X | X | Y | Y | Y | Y |
| Solid 2 | X | X | X | X | Y | Y | Y | Y | Y | Y |
| Liquid 3 | X | X | X | X | X | X | X | X | Y | Y |
| Powder 3 | X | X | X | X | X | X | X | Y | Y | Y |
| Solid 3 | X | X | X | X | X | Y | Y | Y | Y | Y |
Y - waste material broken down completely, X – waste material breakdown not completed
Conclusion
The hypothesis that liquid enzymes will be the quickest enzyme to break down fat, oil and grease is incorrect.
Grease traps are normally installed in restaurants, hospitals, hotels and schools to prevent fat, oil and grease discharge from reaching water treatment facilities and overwhelming treatment systems. If their release is uncontrolled , they will accumulate and coat the walls of sewage pipes and eventually result in blockages, which are difficult to fix. It is therefore useful and important to know what sort of enzyme works most effectively and efficiently on FOG.
Also consider
Will the enzymes work more quickly at higher temperatures? Try using warm water and see if it makes a difference.
Does the hardness of the water have an effect on the rate at which these enzymes work?
References
How does a grease trap work? - http://www.ehow.com/how-does_4886521_grease-trap-work.html
Grease trap treatment products - http://www.rex-bac-t.com/c-51-grease-traps.aspx
Grease interceptor - http://en.wikipedia.org/wiki/Grease_interceptor
