SOLID WASTE MANAGEMENT

 SOLID WASTE MANAGEMENT

• Solid Waste Management is a term that is used to refer to the process of collecting and treating solid wastes.
• Solid waste is the unwanted or useless solid materials generated from human activities in residential, industrial or commercial areas.
• Solid Waste Management reduces or eliminates the toxic pollutants on the environment & human health. 

SOURCES OF SOLID WASTES

1) Residential Solid Waste

• Residences and Homes where people live are some of the major sources of solid waste.
• The Garbage from these places includes Food wastes, Plastics, Paper, Glass, Leather, Cardboard, Metals, Yard wastes, Ashes and Special wastes like bulky household items such as Electronics, Tires, Batteries, Old mattresses and used Oil.

2) Industrial Solid Waste

• Industries are known to be one of the biggest contributors to solid waste.
• Industrial Solid Waste include Light and Heavy manufacturing industries, Construction sites, Fabrication plants, Canning plants, Power and chemical plants.
• Industries produce solid waste in the form of Housekeeping wastes, Food wastes, Packaging wastes, Ashes, Construction and Demolition materials, Special wastes, Medical wastes as well as other Hazardous wastes.

3) Commercial Solid Waste

• Commercial facilities and buildings are yet another source of solid waste today.
• Commercial buildings and facilities refer to Hotels, Markets, Restaurants, Godowns, Stores and Office buildings.
• Some of the Solid wastes generated from these places include Plastics, Food wastes, Metals, Paper, Glass, Wood, Cardboard materials, Special wastes and other Hazardous wastes.

4) Institutional Solid Waste

• The institutional centers like Schools, Colleges, Prisons, Military barracks and other Government centers also produce solid waste.
• Some of the common solid wastes obtained from these places include Glass, Rubber waste, Plastics, Food wastes, Wood, Paper, Metals, Cardboard materials, Electronics as well as various Hazardous wastes.

5) Construction and Demolition areas

• Construction and Demolition sites contribute to the Solid waste problem. Construction sites include New construction sites for Buildings and Roads, Road repair sites, Building renovation sites and Building demolition sites.
• Some of the solid wastes produced in these places include Steel materials, Concrete, Wood, Plastics, Rubber, Copper wires, Dirt and Glass.

6) Municipal services

• The urban centers also contribute immensely to the solid waste crisis in most countries today.
• Some of the solid waste brought about by the Municipal services include Street cleaning, Wastes from Parks and Beaches, Wastewater treatment plants, Landscaping wastes and Wastes from Recreational areas, including Sludge.

7) Treatment plants and sites

• Heavy and light manufacturing plants also produce solid waste. They include Refineries, Power plants, Processing plants, Mineral extraction plants and Chemical plants.
• Among the wastes produced by these plants, there are industrial process wastes, unwanted specification products, plastics, metal parts, just to mention a few.

8) Agricultural wastes

• Crop farms, Orchards, Dairies, Vineyards and feedlots are also sources of solid wastes.
• Among the wastes they produce are Agricultural wastes, Spoiled food, Pesticide containers and other Hazardous materials.

9) Biomedical wastes

• Biomedical wastes refer to Hospitals & Biomedical equipment and Chemical manufacturing firms.
• In hospitals, there are different types of solid wastes produced. Some of these solid wastes include Syringes, Bandages, Used gloves, Drugs, paper, Plastics, Food wastes and Chemicals.
• All these require proper disposal or else they will cause a huge problem for the environment and the people in these facilities.

Approximate time taken to degrade Solid wastes

EFFECTS OF IMPROPER SOLID WASTE DISPOSAL

1. Litter surrounding.
2. Impact on Human health - Skin irritations, Respiratory problems, Blood infections, Growth problems and even Reproductive issues.
3. Disease causing Insect pests.
4. Unpleasant foul smell.
5. Environmental problems.
6. Soil and Ground water pollution.
7. Emission of Toxic gases.
8. Toxic impact on Land and Aquatic animals

METHODS OF SOLID WASTE MANAGEMENT

·       Methods for treating Solid wastes are

1)    Incineration

2)    Composting

3)    Sanitary Landfills

4)    Recovery and Reuse

5)    Pyrolysis

6)    Gasification

1) Incineration

• Incineration is the combustion of waste in the presence of oxygen, so that the waste is converted into Carbon-di-oxide, Water vapour and Ash.
• The equipment used for the Incineration process is Incinerator.
• Incinerators are used in Small scale incineration (Laboratory incinerators) and Large scale incineration (Waste-to-energy plants).
• Incinerators that recycle heat energy through Furnace and Boiler are called “Waste-to-energy plants”.
• Waste-to-energy systems are more expensive to set up and operate compared to Plain incinerators because they require

ü  Special equipment and controls

ü  Highly skilled technical personnel

ü  Auxiliary fuel systems.

·      Most Incinerators operate at higher temperatures than the Ignition temperature, which is a Minimum temperature. Thermal destruction of most organic compounds occurs between 590 °C and 650 °C. Most hazardous waste Incinerators are operated at 980°C to 1200°C to ensure nearly complete destruction of the organics in the waste.

·       Incineration method of Solid waste management can be done by

ü  Individuals

ü  Municipalities

ü  Institutions

ü  Industries

ü  Hospitals

·     Incineration is an excellent method for safely destroying materials such as contaminated cloth, animal carcasses and pathological materials.

·       Advantages of Incineration include

ü  Waste volume reduction (up to 20 or 30 % of the original volume)

ü  Cutback on transportation costs

ü  Reduction of Greenhouse gas emissions.

ü  When garbage is burned, pollutants such as mercury, lead, dioxins may be released into the atmosphere, and cause health issues. This type of pollution is controlled by Incineration process.

·       Disadvantage of Incineration include

ü  High operating cost

ü  Causes Smokes or Fire hazards

ü  Emits Gaseous pollutants

2) Composting

• Composting is the controlled aerobic biological decomposition of organic matter into a stable, humus like product called Compost.
• Composting is a biological process in which microorganisms, specifically fungi and bacteria, convert degradable organic waste into substances like Humus. This finished product, which looks like soil, is high in Carbon and Nitrogen.
• The final product of Composting is a uniform, black mass of rotten, nutrient rich manure.
• Composting making is one of the most effective processes for recycling organic wastes intended for use in agriculture. It is a natural process that turns the waste material into a valuable natural fertilizer.
• Good quality environmentally friendly manure is formed from the compost that is an excellent medium for growing plants and can be used for agricultural purposes.

Advantages of Composting

• Environmentally friendly in nature.
• Supplies nutrients.
• Improves microbial activity, which helps release soil nutrients for use by plants.
• Reduces the need for chemical fertilizers which are costly and potentially damaging to the environment.
• Increases the amount of organic carbon and nitrogen, improving physical properties of soil and allowing higher response to chemical fertilizers and higher crop yields.
• Improves soil structure, improving drainage and making tillage easier.
• Increases the water-holding capacity of soil.
• Helps check wind erosion by improving soil structure.

Disadvantages of Composting

• Requires intensive management and experienced personnel for large scale operation.

3) Sanitary Landfills

• Sanitary landfills are a method of waste disposal where the waste is buried either underground or in large piles. This method of waste disposal is controlled and monitored very closely.
• The method was introduced in England in 1912 (where it is called Controlled tipping).
• Once the Landfill is set up, waste can then be added to the Landfill. Instead of simply filling the Landfill completely with waste, the Landfill is organized in layers. The layers alternate between waste and soil. This alternation of materials reduces odors and allows for more rapid decomposition, which is the breakdown of materials. When a landfill is full, it is sealed and covered in a thick layer of clay.
• Modern Landfills are designed in such a way that the bottom of the landfill is covered with an impervious liner, which is usually made of several layers of thick plastic and sand. This liner protects the groundwater from being contaminated because of Leachates.
• Leachates is the term used to describe liquids that leach or leak from the Landfill.
• When the Landfill is full, it is covered with layers of Sand, Clay, Topsoil and Gravel to prevent leakage of water.

·       Advantages of Sanitary Landfills are

ü  If Landfills are managed efficiently, it is an ensured sanitary waste disposal method.

·       Disadvantages of Sanitary Landfills are

ü  With the absence of any kind of monitoring and no Leachate collection system, this leads to the Contamination of both land and water resources.

ü  Risk of Pollution.

ü  Requires reasonably large area.

4) Recovery and Recycling

• Recycling or Recovery of resources is the process of taking useful but discarded items for the next use.
• Plastic bags, tins, glass and containers are often recycled automatically since, in many situations, they are likely to be scarce commodities. Traditionally, these items are processed and cleaned before they are recycled.
• The process Recycling or Recovery aims at

ü  Reducing energy loss

ü  Consumption of new material

ü  Reduction of landfills.

•      The most developed countries follow a strong tradition of recycling to lower volumes of waste.

·       Advantages of Recovery and Recycling is

ü  Recycling is environmentally friendly

·       Disadvantages of Recovery and Recycling are

ü  It is expensive to set up

ü  In most emergencies, there is limited potential.

5) Pyrolysis

• Pyrolysis is a method of solid waste management whereby solid wastes are chemically decomposed by heat without the presence of oxygen.
• It usually occurs under pressure and at temperatures of up to 200 °C - 760 °C.
• In this method, the solid wastes are changed into gasses, solid residue of carbon and ash and small quantities of liquid.

·       Advantage of Pyrolysis is

ü  Keep the environment clean and reduce health and settlement problems.

·       Disadvantage of Pyrolysis is

ü  Destroy chlorinated organic molecules by heat may create incomplete combustion products, including dioxins and furans. These compounds are highly toxic in the parts per trillion ranges.

ü  The residue it generates may be hazardous wastes, requiring proper treatment, storage, and disposal.

6) Gasification

• Gasification converts Municipal Solid Wastes to a usable Synthesis gas, or Syngas.
• Gasification occurs in a higher temperature range of 480 °C – 1650 °C with very little Oxygen.
• Gasification is a unique process that transforms a carbon-based material, such as MSW or biomass, into other forms of energy without actually burning it. Instead, gasification converts the solid and liquid waste materials into a gas through a chemical reaction.
• Gasification reaction combines those carbon-based materials with small amounts of air or oxygen, breaking them down into simple molecules, primarily a mixture of Carbon monoxide and Hydrogen.