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Environmental Science waste (Jamnabai Narsee School (JNS), Mumbai)

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ENVIRONMENTAL SCIENCE (GRADE 10) CHAPTER: WASTE 1. What is SOLID WASTE? Municipal solid waste (MSW), commonly known as trash or garbage, refuse or rubbish is a waste type consisting of everyday items that are discarded by the public. Waste can be classified in several ways: o Biodegradable waste: food and kitchen waste, green waste, paper (can also be recycled). o Recyclable material: paper, glass, bottles, cans, metals, certain plastics, fabrics, clothes, batteries etc. o Inert waste: construction and demolition waste, dirt, rocks, debris. o Electrical and electronic waste (E-waste) - electrical appliances, TVs, computers, screens, etc. o Composite wastes: waste clothing, Tetra Packs, waste plastics such as toys. o Hazardous waste including most paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and containers o Toxic waste including pesticide, herbicides, fungicides o Medical waste. 2. Differentiate between BIODEGRADABLE AND NON-BIODEGRADABLE MATERIALS. Biodegradable o Biodegradable items are things that can easily break, dissolve and fade away in time. o Like soil and other micro-organism or bacteria, they undergo natural process in a quick or slow time but not a threat to the environment. o Some of the wastes that decompose into soil are garden wastes, egg shells, and kitchen food scraps. o They are destroyed and dissembled by natural or biological elements, which include oxygen or air, ultraviolet light from the sun, and nitric acid that comes from the rain. Others also include microscopic elements or critters and soil. Non-Biodegradable o Things that are non-biodegradable cannot break down or dissolve for many years. o They become useful once more that s why we call them recyclable. o So, any wastes that are thrown in the garbage can be dumped in a recycling center or factor that can make them useful for other things. o Take the papers and thin boards as examples. They do not usually dissolve and vanish although they shrink. Yet, they can remain as debris on holes, water, etc. which may eventually damage the environment. That s why they are collected to be trimmed into pieces until they form again as new pieces of paper. o Non-biodegradable materials simply cannot be affected by natural process. o They do not react and dissolve easily on the soil. o Some of these items that are very common to use again at homes are aluminum cans, glasses, bottles, plastic products, metal scraps, grocery bags or other plastic bags, and even Styrofoam (polystyrene). o These and other non-biodegradable items must be stored properly after use so they can be recycled. Generally, the difference between non-biodegradable and biodegradable items is based their effects to both health and environment. Nevertheless, we can help our own government and other organizations 1 in saving the Earth against air and water pollutions. First, we recycle and reuse materials that are nonbiodegradable. Secondly, we separate biodegradable ones from non-biodegradable. 3. What are the diverse WAYS in which SOLID WASTES CAN BE DISPOSED? Landfill: o Sanitary landfill is the cheapest satisfactory means of disposal, but only if suitable land is within economic range of the source of the wastes; typically, collection and transportation account for 75 percent of the total cost of solid waste management. o In a modern landfill, refuse is spread in thin layers, each of which is compacted by a bulldozer before the next is spread. When about 3 m (about 10 ft.) of refuse has been laid down, it is covered by a thin layer of clean earth, which also is compacted. o Pollution of surface and groundwater is minimized by lining and contouring the fill, compacting and planting the cover, selecting proper soil, diverting upland drainage, and placing wastes in sites not subject to flooding or high groundwater levels. o Gases are generated in landfills through anaerobic decomposition of organic solid waste. If a significant amount of methane is present, it may be explosive; proper venting eliminates this problem. Methods to Reduce Waste: o Traditional waste management strategies include reusing materials, recovering materials through recycling, incineration and landfills. In recent years recycling has become the preferred choice of waste disposal for many industries. o On the commercial level, government regulation usually works to the advantage of big firms and to the disadvantage of small ones. Resource Recovery: o Numerous thermal processes, now in various stages of development, recover energy in one form or another from solid waste. These systems fall into two groups: combustion processes and pyrolysis processes. o Many companies burn in-plant wastes in conventional incinerators to produce steam. o A few municipalities produce steam in incinerators in which the walls of the combustion chamber are lined with boiler tubes; the water circulated through the tubes absorbs heat generated in the combustion chamber and produces steam. Recycling: o The practice of recycling solid waste is an ancient one. o Metal implements were melted down and recast in prehistoric times. o Today, recyclable materials are recovered from municipal refuse by many methods, including shredding, magnetic separation of metals, air classification that separates light and heavy fractions, screening, and washing. o Another method of recovery is the wet pulping process: Incoming refuse is mixed with water and ground into a slurry in the wet pulper, which resembles a large kitchen disposal unit. o Large pieces of metal and other non-pulpable materials are pulled out by a magnetic device before the slurry from the pulper is loaded into a centrifuge called a liquid cyclone. o Here the heavier non-combustibles, such as glass, metals, and ceramics, are separated out and sent on to a glass- and metal-recovery system; other, lighter materials go to a paper-fibrerecovery system. The final residue is either incinerated or is used as landfill. o Increasingly, municipalities and private refuse-collection organizations are requiring those who generate solid waste to keep bottles, cans, newspapers, cardboard, and other recyclable items separate from other waste. Special trucks pick up this waste and cart it to transfer stations or directly to recycling facilities, thus lessening the load at incinerators and landfills. Composting: o Composting is nature's process of recycling decomposed organic materials into a rich soil known as compost. o Anything that was once living will decompose. 2 o Basically, backyard composting is an acceleration of the same process nature uses. o By composting your organic waste, you are returning nutrients back into the soil for the cycle of life to continue. o Finished compost looks like soil deep brown, crumbly and smells like a forest floor. o Types of composting: Backyard composting If you have a yard and a balance of browns (fallen leaves or straw) and greens (grass clippings and food scraps), you have all you need to make compost. Worm composting (vermicomposting) If you have a tiny yard or live in an apartment or have an abundance of food scraps, this type of composting is for you. Grass cycling: If you have grass clippings and don't want to use them in a compost pile you can leave them on the lawn to decompose. Read about grass cycling for tips, techniques and benefits. Vermiculture: It is also known as worm farming, is the utilization of some species of earthworm such as Eisenia fetida (commonly known as red wiggler, brandling, or manure worm), E. foetida, and Lumbricus rubellus to make Vermi-compost, which is a nutrient-rich, natural fertilizer and soil conditioner, which is the end-product of the breakdown of organic matter. Unlike composting, worm farming can be carried out on the balcony of an apartment, in the basement of a house, or in a heated garage if the bin is suitable and it is well maintained to avoid odors. o Worm bins also: can speed up the process by month are often much smaller than compost bins can take pure kitchen waste, without needing garden waste or soil once the colony has been established can handle paper (e.g. paper with food on it, which can't be put out with paper recycling) o Vermiculture can be an especially useful practice in developing countries where fertilizer is harder to obtain. It can be used to convert animal waste, food scraps, and other dead organic matter into a nutrient rich fertilizer. This can ultimately be used to fertilize a home garden and produce a greater quality and quantity of food for the family. Biotechnology o The application of microbes or other living organisms for waste management/treatment whether it's solid waste or wastewater - or even what are called "chemical wastes". o Environmental biotechnology is the used in waste treatment and pollution prevention. o Environmental biotechnology can more efficiently clean up many wastes than conventional methods and greatly reduce our dependence on methods for land-based disposal. o Environmental engineers use bioremediation, the broadest application of environmental biotechnology, in two basic ways. o They introduce nutrients to stimulate the activity of bacteria already present in the soil at a waste site, or add new bacteria to the soil. o The bacteria digest the waste at the site and turn it into harmless by-products. o After the bacteria consume the waste materials, they die off or return to their normal population levels in the environment. o Through application of biotechnical methods, enzyme bioreactors are being developed that will pre-treat some industrial waste and food waste components and allow their removal through the sewage system rather than through solid waste disposal mechanisms. o Waste can also be converted to biofuel to run generators. Microbes can be induced to produce enzymes needed to convert plant and vegetable materials into building blocks for biodegradable plastics. 4. Mention the different TYPE OF WASTES. 3 Liquid type: Waste can come in non-solid form. Some solid waste can also be converted to a liquid waste form for disposal. It includes point source and non-point source discharges such as storm water and wastewater. Examples of liquid waste include wash water from homes, liquids used for cleaning in industries and waste detergents. Solid type: Solid waste predominantly, is any garbage, refuse or rubbish that we make in our homes and other places. These include old car tires, old newspapers, broken furniture and even food waste. They may include any waste that is non-liquid. Hazardous type: Hazardous or harmful waste are those that potentially threaten public health or the environment. Such waste could be inflammable (can easily catch fire), reactive (can easily explode), corrosive (can easily eat through metal) or toxic (poisonous to human and animals). In many countries, it is required by law to involve the appropriate authority to supervise the disposal of such hazardous waste. Examples include fire extinguishers, old propane tanks, pesticides, mercury-containing equipment (e.g., thermostats) and lamps (e.g. fluorescent bulbs) and batteries. Organic type: Organic waste comes from plant or animal sources. Commonly, they include food waste, fruit and vegetable peels, flower trimmings and even dog poop can be classified as organic waste. They are biodegradable (this means they are easily broken down by other organisms over time and turned into manure). Many people turn their organic waste into compost and use them in their gardens. Recyclable type: Recycling is processing used materials (waste) into new, useful products. This is done to reduce the use of raw materials that would have been used. Waste that can be potentially recycled is termed "Recyclable waste". Aluminum products (like soda, milk and tomato cans), Plastics (grocery shopping bags, plastic bottles), Glass products (like wine and beer bottles, broken glass), Paper products (used envelopes, newspapers and magazines, cardboard boxes) can be recycled and fall into this category. 5. Mention different SOURCES of WASTE. Municipal sources of waste: This includes trash or garbage from households, schools, offices, market places, restaurants and other public places. They include everyday items like food debris, used plastic bags, soda cans and plastic water bottles, broken furniture, grass clippings, product packaging, broken home appliances and clothing. Medical/Clinical sources of waste: Medical/clinical waste, normally refers to waste produced from health care facilities, such as hospitals, clinics, surgical theaters, veterinary hospitals and labs. They tend to be classified as hazard waste rather than general waste. Items in this group include surgical items, pharmaceuticals, blood, body parts, wound dressing materials, needles and syringes Agricultural sources of waste: Typically, this is waste generated by agricultural activities. These include horticulture, fruit growing, seed growing, livestock breeding, market gardens and seedling nurseries. Waste items in this group include empty pesticide containers, old silage wrap, out of date medicines and wormers, used tires, surplus milk, cocoa pods and corn husks. Industrial sources of waste: Since the industrial revolution, the rise in the number of industries manufacturing glass, leather, textile, food, electronics, plastic and metal products has significantly contributed to waste production. Look at the things in your home, every item there was probably manufactured and possibly, waste was produced as a result. Construction/demolition sources of waste: Construction waste is that resulting from the construction of roads and building. Sometimes old buildings and structures are pulled down (demolished) to make space for new ones. This is particularly common in old cities that are modernizing. This is called demolition waste. Waste items include concrete debris, wood, earth, huge package boxes and plastics from the building materials and the like. Electronic sources of waste: This is waste from electronic and electrical devices. Think of DVD and music players, TV, Telephones, computers, vacuum cleaners and all the other electrical stuff in your home. These are also called e-waste, e-scrap, or waste electrical and electronic equipment (WEEE). Some e-waste (like TV) contains lead, mercury, cadmium, and brominated flame retardants. These are 4 harmful to humans and the environment. It is therefore important that the right authorities ensure the proper disposal of such waste. 6. State the DISADVANTAGES OF LANDFILL. The site will look ugly whilst 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 site. Once the site has been filled it might not be able to be used for redevelopment as it might be too polluted. The jobs created in the local area are likely to be low paid jobs. The trucks delivering the waste to the site are very big and noisy. They will spoil the peace and quiet in the area and could also contribute to traffic congestion (traffic jams) in the local area. The gases given off from the site as the waste begins to decompose (break down) will cause the air in the local area to be smelly. 7. List the ADVANTAGES AND DISADVANTAGES OF INCINERATORS. Advantages: o Incineration is a practical method of disposal that saves a lot of money on transport of waste to landfills and thus also the carbon footprint that such transport leaves behind. o The sheer reduction in the space required to dispose of the 10 percent of waste that it does produce relieves pressure on land, which in urban areas can constitute a big saving. o Landfills have never been a pretty site and give rise to a lot of pests and insects. An incinerating plant will look like any other industrial structure. o Waste to Energy (WTE) incinerating plants have a huge advantage that they can produce electricity which in the long run can help to reduce costs. A 250 ton per day incinerator can produce 6.5 megawatts of electricity per day and this itself can save about $3 million per year. o Some cold countries also use the heat from incinerators for heating of offices and houses in locations near the plant. o Gases and leachates that are produced in landfills by waste are eliminated and the waste that is produced in the incineration is totally free of any environmental risk. o In fact, there are efforts to convert even this waste to other materials Disadvantages: o The prohibitive cost of incineration plant has been a turnoff of for municipal authorities and is only now being addressed with the introduction of WTE plants. o The need for huge waste to incinerate has led to abandonment of other plans for recycling and reuse of waste. o Dioxins are produced in the treatment and is a cancer forming chemical. These are produced in the smoke stack. o The plants require skilled personnel for operation and continuous maintenance. 8. EXPLAIN THE FOLLOWING TERMS. Bio-remediation: is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site. According to the EPA, bioremediation is a treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or nontoxic substances . Technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site, while ex situ involves the removal of the contaminated material to be treated elsewhere. Bio-fertilizers: is a substance which contains living microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Bio-fertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant 5 growth through the synthesis of growth-promoting substances. Bio-fertilizers can be expected to reduce the use of chemical fertilizers and pesticides. The microorganisms in bio-fertilizers restore the soil's natural nutrient cycle and build soil organic matter. Using bio-fertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil. Since they play several roles, a preferred scientific term for such beneficial bacteria is "plant-growth promoting rhizobacteria" (PGPR). Therefore, they are extremely advantageous in enriching soil fertility and fulfilling plant nutrient requirements by supplying the organic nutrients through microorganism and their byproducts. Hence, bio-fertilizers do not contain any chemicals which are harmful to the living soil. Bio-pesticides: Bio-pesticides (also known as biological pesticides) are pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered bio-pesticides. o Microbial pesticides consist of a microorganism (e.g., a bacterium, fungus, virus or protozoan) as the active ingredient. Microbial pesticides can control many kinds of pests, although each separate active ingredient is relatively specific for its target pest[s]. For example, there are fungi that control certain weeds, and other fungi that kill specific insects. o Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest. Bio-mining: is an approach to the extraction of desired minerals from ores. Microorganisms are used to leach out the minerals, rather than the traditional methods of extreme heat or toxic chemicals, which have a deleterious effect on the environment. -------------------------------------************************************-------------------------------------- 6

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