How to determine chemical characteristics of Solid Waste?
Understanding, how chemical compounds are categorized and how their properties relate to waste behaviour, as it passes through the waste management system, is crucial.
Chemical properties of solid waste
The following chemical traits of solid wastes, among others, must be known if they are to be used as fuel or for any other purpose:
• Natural fibres
• Synthetic organic material (Plastics)
• Heating value
• Ultimate analysis
• Proximate analysis
Determination of the chemical characteristics of solid waste
The chemicals in this category include fats, oils, and grease. Waste with high lipid content is useful for energy recovery operations, since lipids have significant calorific values (approximately 38000 kcal/kg).
Lipids add to the liquid content during waste breakdown because, they transition from the solid state to the liquid state at temperatures just a little bit higher, than ambient. Although, they are biodegradable, their pace of decomposition is somewhat sluggish, due to their limited solubility in waste.
Food and yard waste are the two main sources of carbohydrates. They comprise sugars and sugar polymers, like starch and cellulose. Carbohydrates are easily biodegraded to substances, like methane, carbon dioxide, and water.
Compounds with the elements carbon, hydrogen, oxygen, and nitrogen make up proteins, which are made up of an organic acid with a substituted amine group (NH2). They make up 5-10% of the dry solids in solid waste, and are primarily present in food and garden waste.
Proteins break down to create amino acids, but partial breakdown can also produce amines, which have incredibly foul odours.
· Natural materials
The naturally occurring substances cellulose and lignin, both of which are resistant to biodegradation, are included in this class. They are discovered in food, yard waste, paper, and paper goods. While, lignin is made up of a collection of monomers, cellulose is a bigger glucose polymer.
Products made of wood, cotton, and paper is 100%, 95%, and 40% cellulose, respectively. Solid waste with a high concentration of paper and wood products is suited for incineration, since it is highly flammable.
Due of their extreme biodegradation resistance, they are undesirable and of particular concern, in the management of solid waste. As a result, recycling plastics is receiving more attention, as a means of lowering the quantity of this waste component at disposal facilities.
Plastics are ideal for burning because of their high heating value of roughly 32,000 kJ/kg. However, it should be noted that burning polyvinyl chloride (PVC) releases dioxin and acid gas. The latter causes acid rain and speeds up corrosion in the combustion system.
This category, which makes up 12–25% of dry solids, comprises glass, ceramics, metals, dust, and ashes.
· Heating value
A waste material's heating value, defined as kilojoules per kilogramme (kJ/kg), must be determined in order to assess its potential for use as incinerator fuel. The Bomb calorimeter test, which measures the heat produced by the combustion of a dry material at a constant temperature of 25°C, is used to experimentally evaluate the heating value.
The combustion water is still liquid since the test temperature is below the boiling point of water (100°C). The generated water, however, is in the form of vapour because during burning, the temperature of the combustion gases rises over 100°C. When assessing incineration as a method of waste disposal or energy recovery, one must take the heating values of the relevant elements into account.
· Ultimate analysis
In order to do a mass balancing calculation for a chemical or thermal process, this refers to an analysis of waste to determine the amount of carbon, hydrogen, oxygen, nitrogen, and sulphur.
Besides, it is vital to measure ash percent because of its potentially detrimental environmental consequences, brought about by the presence of toxic metals such as cadmium, chromium, mercury, nickel, lead, tin and zinc. It should be noted that although additional elements, like iron, magnesium, etc. may be present, they are not toxic.
· Proximate analysis
This is crucial for analysing the combustion characteristics of wastes or a fuel, made from waste or refuse. The interest fractions are:
1: Moisture content, which increases weight without increasing the waste's ability to heat, and water evaporation, which lowers the amount of heat generated from the fuel;
2: Ash, which increases weight during combustion but doesn't produce any heat;
3: Volatile stuff, or that fraction of the waste that is burned and then transformed to gases;
4: Fixed carbon, often known as charcoal, is the carbon that is still present on the surface grate.
How can we assist?
Netsol Water offers you practical solutions for effective solid waste management. In order to manage solid waste, we manufacture a wide variety of solid waste recyclers, solid waste converters, green waste recyclers, food waste converters, and much more. Contact our experts today for additional information on how you can manage your solid waste.
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