Unit 2
Overview of Solid Waste Segregation and Management

Learning Outcomes

Prerequisites

Key words

Solid waste management, Zero waste, Microplastics, Incineration, Land filling, Composting.

Discussion

Have a closer look at our surrounding and see the different types of waste generated. Have you ever wondered how these wastes are managed?

4.2.1 Solid waste management

Solid waste refers to the range of garbage materials arising from plant, animal and human activities that are discarded as unwanted and useless. Solid waste is generated from industrial, residential, and commercial activities in a given area. The effective measures on how the solid waste will be managed is called as Solid Waste Management system or processes.

4.2.2 Functional Elements of the Waste Management System

There are six functional components of the waste management system, as outlined below:

1. Waste generation: This encompasses any activity involved in identifying materials that are no longer usable and are either gathered for systematic disposal or thrown away.

2. Onsite handling, storage, and processing: Storage is a system for keeping materials after they have been discarded and prior to collection and final disposal. This relates to activities at the point of waste generation, which facilitate easier collection. Improved storage facilities include:

• Small containers: household containers, plastic bins, etc.
• Large containers: communal bins, oil drums, etc.
• Shallow pits

3. Waste collection: This includes activities such as placing waste collection bins, collecting waste from those bins, and accumulating trash in the location where the collection vehicles are emptied. Although the collection phase involves transportation, this is typically not the main stage of waste transportation Any collection system should be carefully planned to ensure that storage facilities do not become overloaded. Collection intervals and volumes of collected waste must be estimated carefully.

4. Waste transfer and transport: These are the activities involved in moving waste from the local waste collection locations to the regional waste disposal site in large waste trans-port vehicles. This is the stage when solid waste is transported to the final disposal site. There are various modes of transport which may be adopted and the chosen method de-pends upon local availability and the volume of waste to be transported. The types of transportation can be divided in to 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

5. Waste processing and recovery: This refers to the facilities, equipment, and techniques employed to recover reusable or recyclable materials from the waste stream and to improve the effectiveness of other functional elements of waste management.

6. Disposal: This 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. This includes safe disposal, where associated risks are minimised. There are four main methods for the disposal of solid waste:

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

4.2.3 On-site disposal
On-site disposal is the handling of waste in the site of its production itself. These may be adapted for the particular site and situation in question.

1. Communal pit disposal
   The simplest solid waste management system is where consumers dispose of waste directly into a communal pit. The size of this pit will depend on the number of people it serves. The recommended size or dimension is six cubic metres per fifty people. The pit should be fenced off to prevent small children falling in and should generally not be more than100 m from the dwellings. Ideally, waste should be covered at least weekly with a thin layer of soil to minimise flies and other pests.
2. Family pit disposal
   Family pits may provide a better long-term option where there is adequate space. These should be fairly shallow (up to 1m deep) and families should be encouraged to regularly cover waste preventing oil from sweeping or ash from firewood used for cooking. This method is best suited where families have large plots and where organic food wastes are the main component of domestic refuse.
3. Communal bins
   Communal bins or containers are designed to collect waste. Here, it will not be dispersed by wind or animals, and it can easily be removed for transportation and disposal. Plastic containers are generally inappropriate since these may be blown over by the wind, can easily be removed and may be desirable for alternative uses. A popular solution is to provide oil drum cut in half. The bases of these should be perforated to allow liquid to pass out and to prevent their use for other purposes. A lid and handles can be provided if necessary.

4.2.4 Off-site disposal options

The technology choices are general options for the final disposal of waste off-site.

1. Land filling
   Once solid waste is transported off-site, it is normally taken to fill a site. Here the waste is placed in a large (pit/ trench) in the ground, which is back-filled with excavated soil each day waste is tipped. Ideally, about 0.5 m of soil should cover the deposited refuse at the end of each day to prevent animals from digging up the waste and flies from breeding.
   The location of landfill sites should be decided upon through consultation with the local authorities and the affected population. Sites should preferably be fenced.
2. Incineration
   Burning or incineration is often used for the disposal of combustible waste. This take place off-site or a considerable distance downwind of dwellings. Burning refuse within dwelling areas may create a significant smoke or fire hazard, especially if several fires are lit simultaneously. Burning may be used to re-duce the volume of waste and maybe appropriate where there is limited space for burial or landfill. Waste should be ignited within pits and covered with soil once incinerated, in the same manner as land filling.
3. Composting
   Simple composting of vegetables and other organic waste can be applied in many situations. Where people have their own gardens or vegetable plots, organic waste can be dug into the soil to add humus and fibre. This makes the waste perfectly safe and also assists the growth of plants. Properly managed composting requires careful monitoring of decomposing waste to control moisture and chemical levels and to promote microbial activity. This is designed to produce compost which is safe to handle and which acts as a good fertiliser. Such systems require considerable knowledge and experience and are best managed centrally. In general, they are unlikely to be appropriate in emergencies.
4. Recycling
   Complex recycling systems are unlikely to be appropriate but the recycling of some waste items may be possible on occasions. Plastic bags, containers, tins and glass will often be automatically recycled since they are likely to be scarce commodities in many situations. In most developing countries there exists a strong tradition of recycling leading to lower volumes of waste than in many more developed societies.

4.2.5 Zero Waste

Isn’t it good if there were no waste at all? How can we do that?
“Zero Waste” is a philosophy of eliminating the generation of materials that have no viable option for end-of-use management. Zero Waste is a goal that is ethical, economical, efficient and visionary, to guide people in changing their lifestyles and practices for sustainable natural cycles, where all discarded materials are designed to become resources for others to use. Zero Waste means designing and managing products and processes to systematically avoid and eliminate the volume and toxicity of waste conserve and recover all resources, and not burn or bury them. A zero waste approach conserves natural resources and reduces pollution from extraction, manufacturing and disposal. Reducing and reusing means fewer products are made, as people buy less and as products are made to last. Recycling keeps waste out of landfills and incinerators and provides manufacturers with recycled instead of raw materials to make new goods. Effective zero waste programmes also include many different kinds of people such as waste worker cooperatives/ local neighbourhood groups/ universities and governments.

4.2.6 Plastics and micro plastics in the environment

Look around you and find different types of plastics. Are you able to categorise those plastics?
Plastic is an umbrella term that encompasses a wide range of materials made of semi-synthetic or synthetic organic compounds. They are-long chains of polymers comprised of linked repeated units, named “monomers”. The International Union of Pure and Applied Chemistry(IUPAC) defines plastics as“ polymeric materials that may contain other substances to improve performance and/or reduce costs. Due to their ease of manufacture, low cost, impermeability, and the resistance to chemicals, temperature and light, plastics are used in a wide range of products and have replaced many other materials, such as wood, paper, stone, leather ,metal, glass and ceramic. In the modern world, plastics can be found in components ranging from stationery items to space ships. The smaller particles, frequently classified as particles<5mm, are known as micro plastics, also colloquially referred to as“mermaid`stears” due to their size and the vast array of colours they show. Microplastics come from a variety of sources, including from larger plastic debris that degrades into smaller and smaller pieces. In addition, microbeads, a type of microplastic, are very tiny pieces of manufactured polyethylene plastic that are added as exfoliants to health and beauty products, such as some cleansers and toothpastes. They have become a source of increasing concern both for scientists and the general public because they are a threat to the environment. These tiny particles easily pass-through water filtration systems and end up in the ocean and Great Lakes, posing a potential threat to aquatic life. The health effects of microplastics are yet to be understood fully.

Micro plastics may be classified as primary or secondary, depending on their source.
Primary micro plastics are deliberately manufactured within the millimetric or submillimetric size, and can be found in numerous household items, including personal hygiene products, such as facial cleansers, tooth paste and exfoliating creams. These products are of special concern, as it has been estimated that approximately 6% of all liquid skin-cleaning products sold in the EU, Switzerland and Norway contain micro plastics, of which more than 93% consist of polyethylene (PE).An-other key source of primary micro plastics are the raw materials used in the manufacture of plastic items. Inadequate handling, accidental loss, run-off from processing facilities and residues from the production process can lead to the accumulation of primary micro plastics. Micro plastics are also used, to a smaller degree, in medicine, namely as drug vectors. After their use, micro plastics are discharged in domestic waste waters and may reach the environment.
Secondary micro plastics result from the breakdown of larger plastic particles. When exposed to the elements, physical, chemical and biological processes can lead to reduction of the structural integrity of these plastics, leading to their fragmentation. However, this breakdown can also take place before these materials enter the environment, as is the case of synthetic fibres from clothes released during washing cycles or the wear-and-tear of car tyres, which generates minute polymeric fragments.

Micro plastics have been identified across the globe, including in remote locations, from the Arctic, the Antarctic and throughout the water column, from surface to the depths (benthos). Micro plastics are also found in rivers and lakes in agricultural soils, sediments and even in the atmosphere, both in indoor and outdoor environments. Once in the environment, plastics can undergo degradation through abiotic and/ or biotic processes.

4.2.7 Effects of plastics

The interaction of organisms with plastic de-bris results in a wide range of consequences, both direct and indirect, including the potential occurrence of sub- lethal effects, may be of considerable concern. Broadly, the presence of larger plastic materials in the ocean may result in entanglement and ingestion, potential creation of new habitats, and dispersal via rafting, including transport of invasive species. Entanglement and ingestion frequently cause harm or death. Gathered data appear to suggest that entanglement is far more fatal (79% of all cases) than ingestion (4% of all cases).

Although the increased awareness and focus of research has led to significant advances in the understanding of the behaviour of micro plastics in the environment, there is still much that is undetermined with regard to the ability to accurately forecast the exposure scenarios and predict exposure hot spots. Owing to its small size, micro plastics may be ingested by multiple organisms, such as planktonic and higher organisms, including mammals, birds and fish. Although the exact mechanisms of toxicity of these materials are still not under-stood, the effects are potentially due to either (1) ingestion-induced stress such as physical blockage, energy expenditure; (2) leakage of chemicals, such as additives, from plastics and; (3) exposure to contaminants adsorbed (and subsequently released) by micro plastics such as persistent organic pollutants (POPs). The direct consequences of the ingestion of micro plastics include obstruction of the digestive tract and internal injury, frequently leading to reduced food consumption and concomitant decreased nutrition. This potentially results in starvation and death. In air -breathing organisms, micro plastics have been de-scribed to lodge in gills, which may translate into reduced respiration rates.

Recap

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Answer to Objective type questions

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Reference