SOLID WASTE MANAGEMENT

INTRODUCTION – SOLID WASTE MANAGEMENT

In this article let’s see about Solid waste, its Sources, Types, Impact & Solid Waste Management in detail.

What is Solid Waste?

• Solid waste is defined as the unwanted matter which is generated by the society that does not have any economic value from the point of view of first owner. Solid waste refers here to all non-liquid wastes.
• Solid waste can create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately. If not correctly disposed of, waste may provide breeding sites for insect-vectors, pests, snakes and vermin (rats) that increase the likelihood of disease transmission. It may also pollute water sources and the environment.

What is Solid Waste Management?

It 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, economics, aesthetic, engineering and also other environmental considerations.

Impact of Solid Waste – Associated risks

Disease transmission:

• Decomposing organic waste attracts animals, vermin and flies. Flies may play a major role in the transmission of faecal-oral diseases, particularly where domestic waste contains faeces (often those of children). Rodents may increase the transmission of diseases such as leptospirosis and salmonella, and attract snakes to waste heaps.
• Solid waste may also provide breeding sites for mosquitoes. Mosquitoes of the Aedes genus lay eggs in water stored in discarded items such as tins and drums; these are responsible for the spread of dengue and yellow fevers. Such conditions may also attract mosquitoes of the Anopheles genus, which transmit malaria.

Pollution:

Poor management of the collection and disposal of solid waste may lead to leachate pollution of surface water or groundwater. This may cause significant problems if the waste contains toxic substances, or if nearby water sources are used for water supplies.

Effect on morale:

The effect of living in an unhygienic and untidy environment may lead people to become demoralised and less motivated to improve conditions around them. Waste attracts more waste and leads to less hygienic behaviour in general

Categories of Solid Waste:

Different categories of solid waste include:

• Organic waste: Waste from preparation of food, market places, etc.
• Combustibles: Paper, wood, dried leaves, packaging for relief items, etc. (high organic and low moisture content)
• Non-combustibles: Metal, tin cans, bottles, stones, etc.
• Ashes/dust: Residue from fires used for cooking
• Bulky waste: Tree branches, tyres, etc.
• Dead animals: Carcasses of domestic animals and livestock
• Hazardous waste: Oil, battery acid, medical waste
• Construction waste: Roofing, rubble, broken concrete, etc.

Sources of Solid Waste

In most emergency situations the main sources of solid waste are:

• Medical centres
• Food stores
• Feeding centres
• Food distribution points
• Slaughter areas
• Warehouses
• Agency premises
• Markets
• Domestic areas

SOLID WASTE MANAGEMENT – Initial Steps

In order to establish effective solid waste management in the affected area the following process should be used:

Components Of Solid Waste Management

Solid waste management can be divided into five key components:

• Generation
• Storage
• Collection
• Transportation
• Disposal

Generation:

Generation of solid waste is the stage at which materials become valueless to the owner and since they have no use for them and require them no longer, they wish to get rid of them. Items which may be valueless to one individual may not necessarily be valueless to another. For example, waste items such as tins and cans may be highly sought after by young children.

Storage:

Storage is a system for keeping materials after they have been discarded and prior to collection and final disposal. Improved storage facilities include:

• Small containers: household containers, plastic bins, etc.
• Large containers: communal bins, oil drums, etc.
• Shallow pits
• Communal depots: walled or fenced-in areas

Collection:

Collection simply refers to how waste is collected for transportation to the final disposal site. Any collection system should be carefully planned to ensure that storage facilities do not become overloaded. Collection intervals and also volumes of collected waste must be estimated carefully

Transportation:

This is the stage when solid waste is transported to the final disposal site (see 7.6 for more details). There are various modes of transport which may be adopted and the chosen method depends upon local availability and also the volume of waste to be transported. Types of transportation can be divided into three categories:

• Human-powered: open hand-cart, hand-cart with bins, wheelbarrow, tricycle
• Animal-powered: donkey-drawn cart
• Motorised: tractor and trailer, standard truck, tipper-truck

Disposal:

The final stage of solid waste management is safe disposal where associated risks are minimised. There are four main methods for the disposal of solid waste:

• Land application: burial or landfilling
• Composting
• Burning or incineration
• Recycling (resource recovery)

SOLID WASTE MANAGEMENT -Important Steps

Important steps involved in solid waste management

• Reduce, Reuse and Recycle of Raw Materials

• Discarding wastes

Reduce: If usage of raw materials is reduced, the generation of waste also gets reduced

Reuse: Plastic bottles, metal containers, clothes and many other household items can be reused many times before discarding them. Rubber rings, and other useful items can be made from discarded cycle tubes

Recycling

• Recycling is the reprocessing of discarded materials like glass, old paper cans, newspapers, tin, plastic, rubber, into new useful products.
• Old aluminium cans and also glass bottles can be recycles to produce new ones
• Waste paper can be recycled to make fresh paper
• Metals like steel and aluminium can be easily recycled. Lead is widely recycled.

Reduce, Reuse & Recycle (3R’s) help in saving money, energy, raw materials and thereby help in reducing pollution.

Discarding

The following methods are adopted for discarding wastes:

• Landfill
• Incineration and
• Composting

Landfills

In sanitary landfills waste in dumped in many layers of 80 cm thick refuse which is covered with soil of 20 cm thickness. The decomposition of solid wastes generates toxic gases. Solid waste volume shrinks by 25-30% after 2-3 years. This is the most common and cheapest method of waste disposal and also it is mostly employed in big cities.

Advantages

• It is simple and economical
• Segregation of wastes is not required
• Landfilled areas can be reclaimed and used for other purposes
• Converts low-lying waste-land into useful areas

Hazardous waste

It is solid waste that has hazardous waste characteristics or is a listed hazardous waste. Hazardous substance may exhibit one or more of the following hazardous characteristics:

• Ignitability, or something flammable.
• Corrosivity, or something that can rust or decompose.
• Reactivity, or something explosive.
• Toxicity, or something poisonous. Examples
• Batteries containing toxic metals (zinc, lead or mercury)
• Radioactive materials
• Wastes from hospitals & pathology Labs
• Toxic Chemicals

Incineration

It is a hygienic way of disposing solid waste. It is suitable if waste contains more hazardous material and organic content. This process is the most effective process for completely destroying plastic waste and also pathogenic medical waste. It is expensive process, compared to other methods of waste disposal.

What is an Incineration?

• Municipal solid wastes are burnt at high temperature in big furnaces called incinerators. Combustible substances such as plastic materials, rubbish, garbage, dead organisms are separated for burning in incinerators. The non-combustible materials can be left out for recycling and reuse. About 10 % solid material and also ash remains after combustion which can be disposed off by other means.
• The heat produced in the incinerator during burning of refuse is used for generation of electricity through turbines.

Advantages

• It reduces the waste volume by 90 per cent
• Requires very little space
• Safest from hygienic point of view
• The only method available for safe and complete decomposition/destruction of plastic waste
• An incinerator plant of 3000 tonnes per day capacity can generate 3MW of power.

Disadvantages

• Its capital and operating cost is very high
• Operation needs skilled personnel
• Formation of smoke, dust and ashes needs further disposal and that may cause air pollution.
• During incineration high levels of dioxins, furans, lead and cadmium may be emitted with the fly ash of incinerator.

Composting:

• It is a popular method used for the disposal of biodegradable wastes. During composting microorganisms like bacteria and fungi decompose the plant and animal waste into organic manure. Waste needs to be separated into biodegradable and non- biodegradable wastes before composing.
• Biodegradable wastes is dumped in underground trenches and covered with earth/old manure and also left for decomposition. Organic matter is decomposed by bacteria and the refuse is finally converted into powdery brown coloured mass called compost which can be used in agriculture.

Advantages

• Waste is converted into useful manure which enhances the productivity of soil.
• Industrial solid wastes which are biodegradable, can be composted.
• Manure can be sold easily, thereby reducing cost of waste disposal Disadvantages
• Non-biodegradable waste must be separated collected.
• Non-biodegradable waste must be disposed off separately.
• The technology still not widely used due to problems in implementation.

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