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UNIT-4ENVIRONMENTAL POLLUTION Q1) What is Air pollution? State its causes and effects.A1) Air pollution is the contamination of the atmosphere by gaseous, liquid, or solid wastes or by-products that can endanger human, animal, and plant health or can attack materials, reduce visibility and produce undesirable odors.(a) Causes of air pollution: Major air pollutants are • Carbon monoxide• Carbon dioxide• Ozone• Chlorofluorocarbons (CFCs)• Sulfur compounds: Sulphur dioxide, Hydrogen sulfide.• Nitrogen oxides: Nitrous oxide, Nitric oxide, Nitrogen dioxide, Acid rains(b) Effects of air pollutions:Air pollution affects the vegetation, human health, and materials in different ways as described belowEffect on vegetation: • The most damage caused by air pollution to vegetation is on leaf structure.• Nitrogen dioxide is highly injurious to plants. It suppresses growth when plants are exposed to 0.3 to 0.5 ppm for 10 to 20 days.• Sulfur dioxide causes reduced enzymatic activity, suppression of photosynthesis, and other metabolic activities; chorus injury causes reduced crop yield and death of plants.• Acid rain washes away essential nutrients that the plants in need. It makes the soil acidic and helps the release of aluminum and copper ions, harmful to plants.Effects on human health: A person can survive for five weeks without food, five days without water, and only five minutes without air hence, the air we breathe must be of good quality.• Carbon monoxide (Co) is a poisonous gas on account of having an affinity of hemoglobin, the red pigment that carries oxygen in the blood.• Sulfur dioxide irritates the respiratory system.• Nitrogen dioxide penetrates smaller airways and lung parenchyma.• Hydrocarbons may cause cancer in human beings.• Hydrogen sulfide causes headaches, conjunctivitis, sleeplessness, and pain in the eyes. High concentration can lead to blockage of O2 transfer and damaged nerve tissues.• Mercury emitted from mining and refining of mercury causes profuse diarrhea, kidney lesions, a disorder of cardiac function, and neurological function.• Ethylene with nitrogen oxide and ozone causes eye irritation. Ethylene is found in the emission of motor vehicles, chemical industries, and growing plants.• Chlorine is also irritating to the eye, nose, and throat. It is sometimes used in swimming pools as a disinfectant.• Boron causes damage to the central nervous system and death.Effect on materials: Air pollution damage the property of metals such as corrosion of metals, soiling and eroding of building surfaces, fading of dyed materials, wooden cracking, etc. Q2) State effects of water pollution and measures to control it.A2) Polluted water will affect human health, soil health, and plant health or growth, quality of water, etc.Effect on soil health: Use of polluted water as irrigation, resulted in deterioration of soil health like microorganisms in soil decreases in number, it also affects adversely on soil Physical and chemical properties which reduce crop yield.Effect on human health: Water sustains life. It carries many microorganisms, parasites, and dust, which are taken up by human beings and animals; nitrate in drinking water can cause death to children (infants). Polluted drinking water carries organisms of many diseases of human beings.Effects on plant health: • Eutrophication occurs when lake water becomes artificially enriched with nutrients causing abnormal plant growth.• Run-off of chemical fertilizer from cultivated fields may decrease plant health.• The process of eutrophication can produce esthetic problems (bad taste and smell), oxygen depletion in deeper waters, and other chemical changes that affect badly on plant growth.Effects on water quality:• The contamination of water supplies with sewage caused major epidemics of typhoid and cholera in Britain and Europe.• Organic compounds can adversely affect the taste of water.• Most of the disease-causing bacteria enter the body of animals and human being through water and develop serious diseases.• Water pollution by domestic sewage and discharges from hospitals and slaughterhouses are the sources of pathogens causing infectious diseases. The various ways/techniques for prevention and control of water pollution are:• Stabilization of ecosystem• Reutilization of wastes• Recycling of wastes• Removal of pollutants• Enforcement of rules strictly• Treatment of sewage water with physical, chemical, or biological processes for organic matter. Q3) What are the causes and effects of soil pollution? Give measures to control soil pollution.A3) Causes of soil pollution:A wide range of agrochemicals (fertilizers and pesticides) is currently used by farmers to sustain food production. Today, over one lakh chemicals including insecticides, pesticides, fungicides, herbicides, acaricides, and rodenticides are in use thought the world for pest-weed control.a) Agrochemicals: (1) Pesticides, (2) Insecticides, (3) Herbicides, (4) Fungicides, (5) Fertilizersb) Industrial wastes: (1) Effluents, (2) Dust and other waste (3) Radioactive wastes, (4) Heavy metals (5) Acid precipitationc) Urban wastes: (1) Municipal solid waste, (2) Municipal Sewage (3) Vehicular exhaustd) Rural wastes: (1) Home wastes (2) Litter (3) Livestock wastes (4) Plant residues (5) SedimentsEffects of soil pollution: Pollution of soil reduces soil quality, fertility, and water holding capacity. A large proportion of acid soils have arisen from the indiscriminate use of fertilizers. The use of pesticides causes the death of useful and beneficial microorganisms and soil organisms, making the soil hard and infertile. Application of N fertilizers such as urea and ammonium sulfate to soils produces acid.Control of soil pollution: Eco-friendly farming systems is the only approach to control soil pollution. There are several approaches to these systems, they are; organic farming; biological farming, natural farming, alternate agriculture, regenerative agriculture, perm culture, ecological agriculture, ecological farming system, integrated intensive farming system (IIFS), low external input supply agriculture (LEISA). Q4) What are the causes of marine pollution?A4) There are many ways in which pollution enters the ocean. Some of them are: • SewagePollution can enter the ocean directly. Polluting substances flow through sewage lines, rivers, or drainages which are dumped directly into the ocean. This is often how minerals and substances from mining camps find their way into the ocean. The release of other chemical nutrients into the ocean’s ecosystem leads to reductions in oxygen levels, the decay of plant life, and a severe decline in the quality of the seawater itself. As a result, all levels of oceanic life, plants, and animals are highly affected. • Toxic Chemicals from IndustriesIndustrial and agricultural waste is another most common form of wastes that is directly released into the oceans, thus polluting the ocean. When toxic liquids are dumped in the ocean directly, it affects marine life. They are hazardous and they raise the temperature of the ocean, a phenomenon known as thermal pollution, as the temperature of these liquids is quite high. Animals and plants that cannot survive at higher temperatures eventually perish. • Land RunoffLand runoff is another source of pollution in the ocean. This occurs when water infiltrates the soil to its maximum extent. The excess water from rain, flooding, or melting flows over the land and meets the ocean. Often, this water picks up man-made, harmful contaminants that pollute the ocean, including fertilizers, petroleum, pesticides, and other forms of soil contaminants. Fertilizers and waste from land animals and humans can cause damage to the ocean by creating dead zones. • Large Scale Oil SpillsShip pollution is a huge source of ocean pollution, the most devastating effect of which is oil spills. Crude oil may float on the sea for years and it is extremely toxic to marine life, often suffocating marine animals to death once it entraps them. Crude oil is also extremely difficult to clean up. This means that when it is spilled, it is usually there to stay. Thousands of crates are lost each year from ships due to storms, emergencies, and accidents. This results in noise pollution (excessive, unexpected noise that interrupts the balance of life, most often caused by modes of transportation), excessive algae, and ballast water. Often, other species can also invade an ecosystem and harm it by interrupting the life cycles of other organisms, causing a clash of nature that has already been damaged by the overflow of pollution. • Ocean MiningOcean mining in the deep sea is another source of ocean pollution. Ocean mining sites are drilled for silver, gold, copper, cobalt, and zinc, etc. These create sulfide deposits up to three and a half thousand meters down into the ocean. While we yet to have the gathering of scientific evidence to fully explain the harsh environmental impacts of deep-sea mining, we do have a general idea that deep-sea mining causes damage to the lowest levels of the ocean and increases the toxicity of the region. The permanent damage incurred also result in leakage, corrosion, and oil spills that only drastically further hinder the ecosystem of the region. Q5) What are the effects of marine pollution and how can it be prevented?A5) Some major effects of marine pollution are:• Effect of Toxic Wastes on Marine AnimalsAn oil spill is very dangerous for marine life. The oil spilled in the ocean could get on the gills and fins of marine animals, which makes it difficult for them to move properly or feed their children. The long-term effect on marine life can include cancer, failure in the reproductive system, behavioural changes, and even death. • Disruption to the Cycle of Coral ReefsOil spilled floats on the surface of the water and prevents sunlight from reaching marine plants and hampers the process of photosynthesis. Skin irritation, eye irritation, lung and liver problems can impact marine life over a long time. • Depletes Oxygen Content in WaterMost of the debris in the ocean does not decompose and remains in the ocean for years. It uses oxygen as it degrades. As a result of this, oxygen levels go down. When oxygen levels go down, the chances of survival of marine animals like whales, turtles, sharks, dolphins, penguins for a long time also goes down. • Failure in the Reproductive System of Sea AnimalsIndustrial and agricultural wastes contain various poisonous chemicals that are considered hazardous for marine life. Chemicals used in pesticides can accumulate in the fatty tissue of animals, leading to failure in their reproductive system. • Effect on Food ChainChemicals used in industries and agriculture get washed into the rivers and from there are carried into the oceans. These chemicals do not get dissolved and sink at the bottom of the ocean. Small animals consume these chemicals and are later eaten by large animals, which in turn affects the whole food chain. • Effects on Human HealthAnimals from the impacted food chain are then eaten by humans, which affects their health as toxins from these contaminated animals get deposited in the tissues of people and can lead to cancer, birth defects, or long-term health problems. Solutions to Ocean PollutionOcean pollution is a very big problem and it needs to be solved as early as possible. With the world’s oceans getting polluted, the marine ecosystems are getting severely disturbed. The world’s water reserves are also becoming limited. In these situations, we must find ways of solving ocean pollution. Some of the ways are as follows: • Reducing the Use of Plastic ProductsPlastic wastes form the largest portion of ocean pollutants. Out of the 260 million tons of plastic produced each year globally, approximately 10% ends up in the oceans.These plastics then take thousands of years to decompose, during which time they possess a terrible threat to life in the oceans. Thus, a reduction in the use of plastic products could help in significantly reducing the rates of ocean pollution. • Use Reusable Bottles and CutleryUse and throw bottles and cutlery are large contributors to causing ocean pollution. Most of the non-reusable bottles and cutlery are made out of either plastic or Styrofoam. Both these materials require a few hundred or thousand years to decompose. A plastic bottle would require about 450 years to decompose completely. In the meanwhile, it would remain inside the ocean, releasing toxins that would poison the marine life. • Recycle Whatever You CanThe 3 R’s are the saviour of ocean health. With the increase in population, the waste produced has also increased significantly. As finding dumping grounds becomes difficult, a lot of the wastes are dumped in ocean beds. These wastes that are dumped in the ocean remain there for a long time, affecting marine life.One should check if something is recyclable before throwing it away. Then the products that can be recycled can be taken to the recycling centre nearby. • Stop Littering the Beach, and Start Cleaning ItThe beach is undoubtedly one of the loveliest places to visit and hang out in. As a result of this, there is a lot of littering around as well. The first and foremost thing that needs to stop is this. Abundant dustbins should be placed on the beaches. If someone is seen littering, they must be reprimanded immediately, and strict rules and regulations must be followed at all times. If the beach seems untidy, we could pick up the wastes and throw it in the dustbin. • Reducing the Use of Chemical FertilizersRunoffs, too, pollute the oceans immensely. To prevent this, the usage of chemical fertilizers must be controlled. It must be kept in mind that excessive use of chemical fertilizers harms the soil, the water bodies nearby, and, ultimately, the ocean. These runoffs are so toxic that they can very easily kill marine life. • Reducing the Energy UseAs the population increases, the energy demand also increases. A major amount of energy is produced from petroleum. This petroleum is obtained by the drilling of the ocean beds. Any spillage during the procedure could harm marine life. Not only that, but the procedure itself also violates the marine ecological balance. So, by controlling our energy use, we could also solve the problem of ocean pollution. Q6) What are the effects of noise pollution?Hypertension is, in this case, a direct result of noise pollution caused by elevated blood levels for a longer time. Hearing loss can be directly caused by noise pollution, whether listening to loud music in your headphones or being exposed to loud drilling noises at work, heavy air or land traffic, or separate incidents in which noise levels reach dangerous intervals, such as around140 dB for adult or 120 dB for children. Sleep disturbances are usually caused by constant air or land traffic at night, and they are a serious condition in that they can affect everyday performance and lead to serious diseases. Child development. Children appear to be more sensitive to noise pollution, and many noise-pollution-related diseases and dysfunctions are known to affect children, from hearing impairment to psychological and physical effects. Also, children who regularly use music players at high volumes are at risk of developing hearing dysfunctions. In 2001, it was estimated that 12.5% of American children between the ages of 6 to 19 years had impaired hearing in one or both ears Various cardiovascular dysfunctions. An increase in blood pressure level caused by noise pollution, especially during the night, can lead to various cardiovascular diseases. Dementia isn’t necessarily caused by noise pollution, but its onset can be favoured or compounded by noise pollution. Psychological dysfunctions and noise annoyance. Noise annoyance is a recognized name for an emotional reaction that can have an immediate impact. Effects of Noise Pollution on Wildlife and Marine LifeOur oceans are no longer quiet. Thousands of oil drills, sonars, seismic survey devices, and shipping vessels are now seen on our waters, and this is a serious cause of noise pollution for marine life. The most affected amongst them are whales, as their hearing helps them orient themselves, feed, and communicate. Noise pollution thus interferes with cetaceans’ (whales and dolphins) feeding habits, reproductive patterns, and migration routes, and can even cause haemorrhage and death.Other than marine life, the effects of noise pollution are also seen on land animals. They are affected by noise pollution in the form of traffic, firecrackers, etc., and birds are especially affected by the increased air traffic.Social and Economic Costs of Noise PollutionThe World Health Organization estimates that one out of three people in Europe is harmed by traffic noise. Other than the medical effects of noise pollution on humans, there is a significant social and economic impact. Since noise pollution leads to sleep disturbance, it affects the work performance of an individual during the day. This may lead to hypertension and cardiovascular disease and cost additional time and money, and it negatively affects school performance in children.Q7) State causes and effects of radioactive pollution.A7) Causes of Radioactive Pollution • Nuclear Accidents from Nuclear Energy Generation PlantsIn the postmodern world, various forms of energy are being discovered. Among these, nuclear energy is said to be the most potent source due to its high latent power. Reports indicate that the high latent power is due to its high level of radiation. Therefore, using nuclear energy is prohibited. However, research is underway to determine its environmental safety and to put in place the most appropriate precautionary measures for its use. In some cases, and countries, however, nuclear power plant accidents like the Fukushima Daiichi nuclear disaster (2011), Chernobyl disaster (1986), and Three Mile Island accident (1979) left many dead and even many more affected by the radiation released. • The Use of Nuclear Weapons as Weapons of Mass Destruction (WMD) The use of nuclear missiles and atomic bombs, a form of nuclear energy, in the Second World War shows the damaging nature of radioactive pollution or contamination.The effects of the two strikes in Hiroshima and Nagasaki that prompted the end of the war in 1945 have been seen to date with children born with complications such as mental retardation as well as conditions like autism and other disorders. The number of cancer cases present in the two towns is more than those of the rest of Japan.• Use of RadioisotopesRadioisotopes are utilized in making detectors and in other industrial activities. Isotopes such as uranium have high concentrations of radiation. Common Isotopes such as carbon-containing radioactive material are easily found in waterways through sewage lines. Since most of the raw sewage is untreated before release, once released, the isotope combines with other compounds and elements present in water. This water is utilized by people for domestic purposes. Fishes use the same water to survive. Consumption of these fishes and from contaminated water sources means the potential intake of radiation. • MiningMining involves the excavation of mineral ores from the mines, which are then broken into smaller, manageable pieces. Radium and Uranium are naturally occurring in the environment and are equally radioactive.Hence, mining increases the natural geological processes by moving these materials from underneath the earth to the surface. Other minerals with contain radiation are thorium, plutonium, carbon, radon, potassium, and phosphorus. • Spillage of Radioactive ChemicalsSpillages over oceans have occurred when ships hit glaciers or coral reefs and release chemicals on waterways and in the atmosphere. The majority of these chemicals, including petroleum products, have a significant level of radiation, which can be detrimental to the environment. • Tests on RadiationRadiation is said to have shown a lot of interesting properties, which encouraged scientists to conduct tests to learn more about it. It is one of the key elements in the cure and treatment of cancer.Chemotherapy, a cancer curative health initiative, uses radiation to prevent further growth of the cancer cells as well as to keep the immune system strong. Many scientists have been exposed to radiation leading to their deaths or other complications.As per the report to the UN General Assembly in 2000, nuclear testing is the main reason for human exposure to radioactivity caused by man. • Cosmic Rays and Other Natural SourcesThese come from the outer space to our planet with intense radiation as their nature, therefore, causing radioactive pollution. Gamma rays are said to have the highest level of radiation but some are not visible to the human eye. The quantity with which the rays hit the earth depends on the altitude of the earth and the geographical location. There may be terrestrial radiations from radioactive elements present in the earth’s crust. There can also be unstable radio-nuclides split into smaller parts emitting energetic radiation that can enter into the body of organisms through the air during respiration. • Nuclear Waste Handling and DisposalThe radioactive wastes are of three categories- high level, low level, and transuranic. They mainly comprise of the disposal from nuclear weapons, the cleaning materials from nuclear plants, military installations, emitted from plutonium processing, and other radioisotopes from hospitals and laboratories. The handling and disposal of nuclear waste may generate low to medium radiation over a long period. The effects of radiation are hard to predict and are not easily distinguishable as the radioactivity may contaminate and propagate through air, water, and soil as well. Also, identifying locations of some nuclear waste is not easy. The main concern is that the radiation waste cannot be degraded or treated chemically or biologically. The only options are either to contain the waste by storage in tightly closed containers shielded with radiation-protective materials (such as Pb) or dilution. It can also be contained by storage in remote areas with little or no life like remote caves or abandoned salt mines. However, natural or artificial whatever shields are used may get damaged over time. Moreover, waste disposal practices in the past may not have used appropriate measures to isolate the radiation. Therefore, those areas need to be identified carefully, and restrictions promptly imposed. • Defensive Weapon ProductionThe production of defensive weapons that may release radioactive materials has high health risks. However, the current standards will not allow the release of any significant amount of radiation unless an accident occurs. Effects of Radioactive Pollution1. Genetic MutationsRadiation has adverse effects when it comes to genetics. It leads to damage to DNA strands leading to the genetic break up over time. The degree of genetic mutation leading to changes in DNA composition varies for the level of radiation one has been exposed to and the kind of exposure. If a human or an animal is exposed to too much radiation from the atmosphere, the food consumed, and even water used then, the chances are that their bodies have already absorbed the radiation. Once in the body, it remains active because energy cannot be destroyed.The resulting mutation makes one highly prone to cancer. For pregnant women, kids are born with adverse defects caused by genetic mutations like low weight during birth. Effects such as disfigured births and impairment like blindness in children have also been seen. Infertility has also been mentioned as an effect of radiation. 2. DiseasesCancer is the most dominant radiation-related disease. It has developed over the years and poses a great risk in global health. Other forms include leukaemia, anaemia, haemorrhage, a reduction in the life span leading to premature aging and premature deaths as well as others such as cardiovascular complications. Leukaemia, for instance, is caused by radiation in the bone marrow. 3. Soil InfertilityExposure of radiation to the atmosphere means it is present even in soils. Radioactive substances in the soil react together with various nutrients leading to their destruction, thus rendering the soil infertile and highly toxic. Such soil leads to the harvest of crops that are riddled with radiation and thus, unfit for consumption by both humans and animals. Plants that grow from such soil are also genetically modified. Since these are at the base of the food chain, the herbivores consume them and retain the radiation levels. The carnivores such as lions, vultures end up consuming them and increasing their levels of radiation – explained through the concept of Bio magnification. 4. Cell DestructionRadioactive pollution has diverse effects, such as the alteration of cells. The bodies of living organisms are unique as within it, there are millions of cells in one single body, where each has its purpose to fulfil. Radiation distorts the cells present, leading to permanent damage of the various organs and organ systems. In the face of too much radiation, permanent illnesses and death are inevitable. 5. BurnsRadiation is not easy to feel, but it is easy to realize that you have been affected by it. The immediate presence of burns, red lesions, and sores is evidence. To make it worse, this can lead to skin cancer. 6. Effects on WildlifeThe animals at different levels suffer differently. The higher-level organisms get more affected than insects and flies. Herbivores, such as cattle, when grazing the contaminated land, the deposited Ce-13 and I-131 get accumulated on the animal tissues in a large amount. These radionuclides enter their metabolic cycles and affect their DNAs (mentioned above; ionizing). 7. Effects on PlantsThe plants are also exposed to radiation, and the damage is mostly done due to the increased Ultraviolet waves. Different plants get affected differently. The stomata stop evaporating during the increase of radiation. When the radiation hits the chromosomes, the reproduction gets hampered. It results in altered shapes, sizes, and health in plants. Exposure in high amounts destroys the affected plants. When we eat these plants, we ingest nuclides. 8. Effects on Marine lifeThe power plants, which are the sources of nuclear energy and chemical processing, have been releasing radioisotopes into the water for decades. Cesium, Radon, Crypton, Ruthenium, Zinc, and Copper are a few of them. Though the waste is released in a “permissible” amount, it does not mean safe. Q8) What are the methods of solid wastes disposal?A8)
A6) Whether we realize it or not, noise pollution can be hazardous to our health in various ways.
Diseases in humans due to noise pollution.
Methods of Solid Wastes Disposal:i. Sanitary Landfillii. Incinerationiii. Compostingiv. Pyrolysisi. Sanitary Land Filling:In a sanitary landfill, garbage is spread out in thin layers, compacted, and covered with clay or plastic foam. In modern landfills the bottom is covered with an impermeable liner, usually several layers of clay, thick plastic, and sand. The liner protects the groundwater from being contaminated due to the percolation of leachate.Leachate from the bottom is pumped and sent for treatment. When the landfill is full it is covered with clay, sand, gravel, and topsoil to prevent seepage of water. Several wells are drilled near the landfill site to monitor if any leakage is contaminating groundwater. Methane produced by anaerobic decomposition is collected and burnt to produce electricity or heat. Sanitary Landfills Site Selection: Should be above the water table, to minimize interaction with groundwater. Preferably located in clay or silt. Do not want to place in a rock quarry, as water can leech through the cracks inherent in rocks into a water fracture system. Do not want to locate in sand or gravel pits, as these have high leaching. Unfortunately, most of Long Island is sand or gravel, and many landfills are located in gravel pits after they were no longer being used. Do not want to locate in a flood plain. Most garbage tends to be less dense than water, so if the area of the landfill floods, the garbage will float to the top and wash away downstream. A large number of adverse impacts may occur from landfill operations. These impacts can vary:• Fatal accidents (e.g., scavengers buried under waste piles).• Infrastructure damage (e.g., damage to access roads by heavy vehicles).• Pollution of the local environment (such as contamination of groundwater and/or aquifers by leakage and residual soil contamination during landfill usage, as well as after landfill closure).• Off-gassing of methane generated by decaying organic wastes (methane is a greenhouse gas many times more potent than carbon dioxide, and can itself be a danger to inhabitants of an area).• Harbouring of disease vectors such as rats and flies, particularly from improperly operated landfills.ii. Incineration:The term incinerates means to burn something until nothing is left but ashes. An incinerator is a unit or facility used to burn trash and other types of waste until it is reduced to ash. An incinerator is constructed of heavy, well-insulated materials so that it does not give off extreme amounts of external heat.The high levels of heat are kept inside the furnace or unit so that the waste is burned quickly and efficiently. If the heat were allowed to escape, the waste would not burn as completely or as rapidly. Incineration is a disposal method in which solid organic wastes are subjected to combustion to convert them into residue and gaseous products. This method is useful for the disposal of residue of both solid waste management and solid residue from wastewater management. This process reduces the volumes of solid waste to 20 to 30 percent of the original volume.Incineration and other high-temperature waste treatment systems are sometimes described as “thermal treatment”. Incinerators convert waste materials into heat, gas, steam, and ash. Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used to dispose of solid, liquid, and gaseous waste. It is recognized as a practical method of disposing of certain hazardous waste materials. Incineration is a controversial method of waste disposal, due to issues such as the emission of gaseous pollutants.iii. Composting:Due to a shortage of space for a landfill in bigger cities, the biodegradable yard waste (kept separate from the municipal waste) is allowed to degrade or decompose in a medium. A good quality nutrient-rich and environmental-friendly manure are formed which improves the soil conditions and fertility.Organic matter constitutes 35%-40% of the municipal solid waste generated in India. This waste can be recycled by the method of composting, one of the oldest forms of disposal. It is the natural process of decomposition of organic waste that yields manure or compost, which is very rich in nutrients.Composting is a biological process in which micro-organisms, mainly fungi, and bacteria, convert degradable organic waste into humus like substance. This finished product, which looks like soil, is high in carbon and nitrogen and is an excellent medium for growing plants.The process of composting ensures the waste that is produced in the kitchens is not carelessly thrown and left to rot. It recycles the nutrients and returns them to the soil as nutrients. Apart from being clean, cheap, and safe, composting can significantly reduce the amount of disposable garbage. Organic fertilizer can be used instead of chemical fertilizers and is better especially when used for vegetables. It increases the soil’s ability to hold water and makes the soil easier to cultivate. It helped the soil retain more of the plant nutrients.To make a compost pit, you have to select a cool, shaded corner of the garden or the school compound and dig a pit, which ideally should be 3 feet deep. This depth is convenient for aerobic composting as the compost has to be turned at regular intervals in this process.Preferably the pit should be lined with granite or brick to prevent nitrate pollution of the subsoil water, which is known to be highly toxic. Each time the organic matter is added to the pit it should be covered with a layer of dried leaves or a thin layer of soil which allows air to enter the pit thereby preventing bad odour. At the end of 45 days, the rich pure organic matter is ready to be used. Composting: some benefits• Compost allows the soil to retain more plant nutrients over a longer period.• It supplies part of the 16 essential elements needed by the plants.• It helps reduce the adverse effects of excessive alkalinity, acidity, or the excessive use of chemical fertilizer.• It makes soil easier to cultivate.• It helps keep the soil cool in summer and warm in winter.• It aids in preventing soil erosion by keeping the soil covered.• It helps in controlling the growth of weeds in the garden.iv. Pyrolysis:A pyrolysis is a form of incineration that chemically decomposes organic materials by heat in the absence of oxygen. Pyrolysis typically occurs under pressure and at operating temperatures above 430 °C (800 °F).In practice, it is not possible to achieve a completely oxygen-free atmosphere. Because some oxygen is present in any pyrolysis system, a small amount of oxidation occurs. If volatile or semi-volatile materials are present in the waste, thermal desorption will also occur.Organic materials are transformed into gases, small quantities of liquid, and a solid residue containing carbon and ash. The off-gases may also be treated in a second thermal oxidation unit. Particulate removal equipment is also required. Several types of pyrolysis units are available, including the rotary kiln, rotary hearth furnace, and fluidized bed furnace. These units are similar to incinerators except that they operate at lower temperatures and with less air supply.
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