Solid Waste Management
Overview
- Definition
- Type & Source
- Generation of Solid Waste
- Collection, Transportation & Segregation of Solid Waste
- Disposal methods
- Principles of Waste Management
Solid Waste: Any unwanted or discarded material from residential, agriculture commercial or industrial activities that causes environmental problems is called solid waste.
Solid Waste Management: Solid waste management is defined as the discipline associated with control of generation, storage, collection, transport or transfer, processing and disposal of solid waste materials in a way that best addresses the range of public health, conservation and other environmental considerations.
Every day, tones of solid waste are disposed of at various landfill sites. This waste comes from homes, offices, industries and various other agriculture related activities. These landfill sites produce foul smell if waste is not stored and treated properly. It can pollute the surrounding air and can seriously affect the health of humans, wildlife and our environment. The following are major sources of solid waste:
- Residential:
Residences and homes where people lives are some of the major sources of solid waste. Garbage from these places includes food waste, plastics, paper, yard waste, ashes, like bulky household items like electronic, tires, batteries used oil. Most homes have garbage bind where they can throw their solid wastes in and later the bin is emptied by a garbage collecting firm or person for treatment.
- Industrial: Industrial are known to be one of the biggest contributors of solid waste. They include light and heavy manufacturing industries, construction sites, fabrication plants, canning plants, power and chemical plants. These industries produce solid waste in form of housekeeping wastes, food wastes, packaging wastes, ashes, construction and demolition materials, specials wastes, medical wastes as well as other hazardous wastes.
- Commercial:
Commercial facilities and buildings are yet another source of solid waste today. Commercial building and facilities in this case refer to hotels, markets, restaurants. Some of the solid waste generated from these places include plastics, food wastes, metals, paper, glass, wood, cardboard materials, special wastes and other wastes.
- Institutional: The institutional centers like school, colleges, prisons, military barracks and other 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, electronic as well as various hazardous wastes.
- Construction and Demolition Area: Construction and demolition sites also contributes to the solid waste problem. Construction sites include new construction sites for buildings and roads, road repairs sites, building renovation sites and building demolition sites. Some of the solid wastes produced in these include steel materials, concrete, wood, plastics, rubber, copper wires, dirt and glass.
- 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.
- Treatment Plants and Sites: Heavy and light manufacturing plants also produce solid waste. They include refineries, power plants, processing plants, mineral extraction plants and chemicals plants. Among the wastes produced by these plants include, industrial process wastes, unwanted specification products, plastics, metal parts just to mention but a few.
- Agriculture: Crop farms, orchards, diaries, vineyards and feedlots are also sources of solid wastes. Among the wastes they produce include agriculture wastes, spoiled food, pesticide container and other hazardous materials.
- Biomedical: This refers to hospitals and 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 to the environment and the people in these facilities.
Types & Sources of Solid Waste
- Agriculture Solid Waste
- Domestic Solid Waste
- Industrial Solid Waste
- Institution Solid Waste
- Biomedical Solid Waste
- Commercial Solid Waste, etc.
Elements of Solid Waste Management
- Waste generation: Waste generation refers to activities involved in identifying materials which are no longer usable and are either gathered for systematic disposal or thrown away.
- Onsite handling, storage and processing are the activities at the point of waste generation which facilitate easier collection. For example, waste bins are placed at the sites which generate sufficient waste.
- Waste collection: Elements of collection, includes not only the gathering of solid waste and recyclable material, but also the transport of these materials after collection, to the location where the collection vehicles is emptied.
- Transportation to the site of disposal: Waste transfer and transport are the activities involved in moving waste from the local waste collection locations to the regional waste disposal site in large waste transport vehicles.
- Waste Segregation & Storage: Waste handling and separation involves activities associated with waste management until the waste is placed in storage containers for collection. Handling also includes the movement of loaded containers to the point of collection. Separating different types of waste components is an important step in the handling and storage of solid waste at the source.
- Disposal method: Disposal is the final stage of waste management. It involves the activities aimed at the systematic disposal of waste materials in locations such as landfills or waste-to-energy facilities. There are two types of Disposal methods: –
i. Biological method: The most frequently used waste disposal or treatment method which is the controlled aerobic decomposition of organic waste materials by the action of microorganisms.
(a) Composting (from Humus to Black Soil): Due to lack of adequate space for landfills, biodegradable yard waste is allowed to decompose in a medium designed for the purpose. Only biodegradable waste materials are used in composting. Good quality environmentally friendly manure is formed from the compost and can be used for agriculture purposes. Composting by Trenching
- Trenches 3-12 m long, 2-3 m wide and 1-2 m deep with spacing 2 m.
- Dry wastes are filled up in 15 cm. On top of each layer 5 cm thick sandwiching layer of animal dung is sprayed in semi liquid form.
- Biological action starts in 2-3 days and decomposition starts.
- Solid waste stabilizes in 4-6 months and changed into brown colored odorless powdery form known as Humus.
(b) Sanitary Landfill:
This is the most popular solid waste disposal method used today. Garbage is basically spread out in thin layers, compressed and covered with soil or plastic foal. 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 ground water from being contaminated (water pollution) because of leaching or percolation. When the landfill is full, it is covered with layers of sand, clay, topsoil and gravel to prevent seepage of water.
OR
- It is the most traditional method of waste disposal.
- Waste is directly dumped into discussed quarries, mining voids or borrow pits.
- Disposed waste is compacted and covered with soil.
- Gases generated by the decomposing waste materials are often burnt to generate power.
- It is generally used for domestic waste.
Advantages:
- Landfill site is a cheap waste disposal option for the local council.
- Jobs will be created for local people.
- Lots of different types of waste can be disposed of by landfill in comparison to other waste disposal methods.
- The gases given off by the landfill site could be collected and used for generating power.
Disadvantages:
- The site will look ugly while it is being used for landfill.
- Dangerous gases are given off from landfill sites that cause local air pollution and contribute to global warming.
- Local streams could become polluted with toxins seeping through the ground from the landfill.
- Once the site has been filled it might not be able to be used for redevelopment as it might be too polluted.
ii. Thermal method: The waste treatment technology that involves high temperatures in the processing of the waste feedstock. Commonly this involves the combustion of waste materials.
(a) Incineration (10000C in excess of O2): This method involves burning of solid wastes at high temperatures until the wastes are turned into ashes. Incinerators are made in such a way that they do not give off extreme amounts of heat when burning solid wastes. This method of solid waste management can be done by individuals, municipalities and even institutions. The good thing about this method is the fact that it reduces the volume of waste up to 20 or 30 % of the original volume.
OR
- Incineration is a waste treatment process that involves the combustion of solid waste at 10000C.
- Waste materials are converted into ash, flue gas and heat.
- The ash is mostly formed by the inorganic constituents of the waste and gases due to organic waste.
- The heat generated by incineration is used to generate electric power.
Advantages
· Minimum of land is needed compared to other disposal methods.
· The weight of the waste is reduced to 25% of the initial value.
· No risk of polluting local streams and ground waters as in landfills.
· Incineration plants can be located close to residential areas.
· Gases are used to generate power.
Disadvantages
· Expensive.
· Required skilled labor.
· The chemicals that would be released into the air could be strong pollutants and may destroy ozone layer (major disadvantage).
· High energy requirement.
(b) Pyrolysis: This is method of solid waste management whereby solid wastes are chemically decomposed by heat without presence of oxygen. This usually occurs under pressure and at temperatures of up to 430°C. The solid wastes are changed into gases, solid residue and small quantities of liquid. (500-1000°C without O2, releases char, gases, flue gases).
OR
· Heating of the solid waste at very high temperature in absence of air.
· Carried out at temperature between 500°C – 1000°C.
· Gas, liquid and chars are the byproducts.
Segregation of Waste: Waste can be segregated into the following streams: –
(i) Recycle waste.
Eg: paper, glass, plastic & waste materials.
(ii) Toxic waste
Eg: medicines, chemicals sprays, fertilizers, pesticides container, batteries.
(iii) Soiled waste Hospital waste such as soiled with blood and body fluids.
Laws Under Min of Environment, Forest and Climate Change,
- Municipal Solid Waste Management Rule, 2000. This rule was amended in 2016,
- Solid Waste Management Rule, 2016
As per Govt. Policy
Color of Bins Type of Waste
1. Green waste Organic
2. White waste Paper
3. Yellow waste Glass
4. Grey waste Metal
5. Blue waste Plastic
6. Red waste Hazardous
Principles of Solid Waste Management – 4 “R’s”
- Reduce
- Reuse
- Recycle
- Recover
Impact of Solid Waste on Public Health & Environment
- Nausea, Vomiting
- Air borne diseases
- Cancer of different types
- Global Warming (through Land Fill method)
- Ground Water pollution (through Land Fill method)