General Information
Calorific Value (CV) of Waste
The calorific value (CV) of waste refers to the amount of heat released by a unit weight or unit volume of a substance during complete combustion. It is measured in units of energy per amount of material, such as kJ/kg.
The CV of waste depends on its composition. Waste with a higher proportion of PVC typically has a higher calorific value compared to waste with more paper and less PVC. To estimate the calorific value of a waste mix, you can calculate the weighted average based on the composition.
Example Calculation
To determine the average calorific value of a waste mix, consider the following fractions:
Hazardous waste: 20% of the mass, CV = 12 MJ/kg
Medical waste: 50% of the mass, CV = 19 MJ/kg
Plastics - PVC waste: 30% of the mass, CV = 35 MJ/kg
To find the average calorific value, use the formula:
Average CV = (Fraction 1 × CV 1) + (Fraction 2 × CV 2) + (Fraction 3 × CV 3)
In this case:
Average CV = 2.4 + 9.5 + 10.5
Average CV = 22.4 MJ/kg
Activated Carbon - Uses
It is used in methane and hydrogen storage, air purification, decaffeination, gold purification, metal extraction, water purification, medicine, sewage treatment, air filters in gas masks and respirators, filters in compressed air, teeth whitening, and many other applications.
More on Plastics
The word, plastic, was derived from the word ‘Plastikos’ meaning ‘to mould’ in Greek. It is a material which is largely used because of its convenience and usefulness in daily life.
Calculation of Calorific Value of Waste
| Material - Fraction | CV (MJ/kg) | % Amount | % CV Representing in Waste Mix |
|---|---|---|---|
| Hazardous Waste | 12 | 20% | 2.4 (=12 × 0.2) |
| Medical Waste | 19 | 50% | 9.5 (=19 × 0.5) |
| Plastics - PVC | 35 | 30% | 10.5 (=35 × 0.3) |
| Total: | 22.4 (=2.4 + 9.5 + 10.5) MJ/kg |
Decomposing Time for Different Waste
Cigarette Butts
10-12 years
Monofilament Fishing Line
600 years
Rubber-Boot Sole
50-80 years
Foamed Plastic Cups
50 years
Leather Shoes
25-40 years
Milk Cartons
5 years
Plywood
1-3 years
Painted Board
13 years
Cotton Glove
3 months
Cardboard
2 months
Styrofoam
Does not biodegrade
Nylon Fabric
30-40 years
Tin Can
50 years
Ropes
3-14 months
Waxed Milk Cartons
3 months
Aluminum Cans
200-250 years
Train Tickets
2 weeks
Paper Waste
2-6 weeks
Canvas Products
1 year
Batteries
100 years
Lumber
10-15 years
Sanitary Pads
500-800 years
Disposable Diapers
250-500 years
Wool Clothing
1-5 years
Tinfoil
Does not biodegrade
What is Activated Carbon?
Activated carbon, also known as activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. It is produced from carbonaceous materials like coal, coconut shells, peat, wood, and lignite through physical modification and thermal decomposition.
The large surface area and network of submicroscopic pores make it highly effective for adsorption. Activated carbon is used in a variety of applications including air purification, water treatment, medicine, and more.
Activated carbon's large surface area allows it to absorb a significant amount of particles, making it a powerful adsorbent.
Activated Carbon - Uses
Air Purification
Used in air filters and gas masks to remove contaminants and pollutants.
Water Purification
Filters out impurities and contaminants from drinking water.
Medicine
Used to treat poisonings and overdoses by adsorbing toxins.
Gold Purification
Extracts gold from ores during the mining process.
Teeth Whitening
Removes stains from teeth, improving appearance.
Sewage Treatment
Removes organic and inorganic contaminants from sewage.
More on Plastics
The term "plastic" comes from the Greek word “Plastikos,” meaning "to mould." Plastics are used extensively in daily life due to their versatility and convenience.
Well-Known Plastics and Their Uses:
| Plastic Type | Common Uses |
|---|---|
| Polyamide (Nylon) | Women's stockings, gears, car parts, toothbrush bristles |
| Polycarbonate | Bulletproof glass, compact discs, DVDs |
| Polyethylene | Tubes, bottles, shopping bags, body armor |
| Polyethylene Terephthalate (PET) | Bottles, polyester clothing |
| Polypropylene | Food containers, chairs |
| Polystyrene | CD cases, plastic cups, plastic forks and knives |
| Polyurethane | Rubber, foam, shiny coatings on wood and tile |
| Polyvinyl Chloride (PVC) | Pipes, toys, cushions |
| Material | Mould Temperature Range (℃) | Melt Temperature Range (℃) |
|---|---|---|
| ABS | 40-80 | 190-270 |
| ABS/PC Alloy | 40-80 | 245-265 |
| Acetal | 50-120 | 180-210 |
| Acrylic | 50-80 | 220-250 |
| CAB | 40-50 | 170-240 |
| HDPE | 20-60 | 210-270 |
| LDPE | 20-60 | 180-240 |
| Nylon 6 | 40-90 | 230-290 |
| Nylon 6 (30% GF) | 50-90 | 250-290 |
| Nylon 6/6 | 40-90 | 270-300 |
| Nylon 6/6 (33% GF) | 40-90 | 280-300 |
| Nylon 11 | 40-110 | 220-250 |
| Nylon 12 | 40-110 | 190-200 |
| PEEK | 120-160 | 350-390 |
| Polycarbonate | 85-120 | 280-320 |
| Polyester PBT | 60-90 | 240-275 |
| PET (Semi Crystalline) | 20-30 | 260-280 |
| PET (Amorphous) | 20-30 | 260-280 |
| Polypropylene (Copolymers) | 30-80 | 200-280 |
| Polypropylene (Homopolymers) | 30-80 | 200-280 |
| Polypropylene (30% Talc Filled) | 30-50 | 240-290 |
| Polypropylene (30% GF) | 40-80 | 250-290 |
| Polystyrene | 30-60 | 170-280 |
| Polystyrene (30% GF) | 40-80 | 250-290 |
| PVC P | 20-40 | 170-190 |
| PVC U | 20-60 | 160-210 |
| SAN | 50-85 | 200-260 |
| SAN (30% GF) | 50-70 | 250-270 |
| TPE | 40-70 | 260-320 |
Effects of Temperature on Thermoplastics
Most of the effects of temperature on thermoplastics occur at high heat levels, although excessively low temperatures can also have an impact. Mechanical properties, chemical resistance, electrical conductivity, material fatigue, and many other attributes can be affected by increased temperatures.
This is to clear and show the fact that all the materials can be toxic when they are inappropriately used and exposed.
Some polymers can emit toxic substances at 120°C and some can withstand temperatures up to 420°C with almost zero levels of emissions.
At extreme temperatures, polymers will simply burn down very quickly, leaving no toxic materials around.
