Human society produces some unwanted and discarded materials which are called wastes.
Wastes are produced from different activities such as household activities, agricultural activities industrial activities, hospitals, educational institutions, mining operations, and so on.
These sources general different types of wastes, many of which are hazardous in nature. They cause spread of many diseases.
In general, the wastes maybe categorized as follows:
The solid wastes are the useless and unwanted substances discarded by human society. These include urban wastes, industrial wastes, agricultural wastes, biomedical wastes and radioactive wastes. The term refuse is also used for solid waste.
Wastes generated from washing, flushing or manufacturing processes of industries are called liquid wastes. Such a waste is called sewage. The most common practice is to discharge it on the ground, nallahs, rivers and other water bodies, often without any treatment.
These wastes are released in the form of gases from automobiles, factories, burning of fossil fuels etc. and get mixed in the atmosphere. These gases include carbon monoxide, CO2, sulphur dioxide, nitrogen dioxide, ozone, methane, etc.
Sources of Wastes:
Wastes produced from different sources, are classified as follows:
1. Urban or Municipal wastes
2. Industrial wastes
3. Commercial wastes
4. Agricultural wastes
Municipal Solid Waste:
The wastes, collected from the residential houses, markets, streets and other places mostly in the urban areas and disposed of by municipal bodies are called municipal solid wastes (MSW). In general, the urban solid wastes are called refuse. The Municipal solid wastes are a mixture of paper, plastic, clothes, metals, glass, organic matter etc. generated from households, commercial establishments and markets.
The proportions of different constituents vary from season to season and place to place depending on the life style, food habits, standard of living and the extent of commercial and industrial activities in the area. Municipal solid wastes are collected locally and the amount collected depends upon the size and consumption of the population. The municipal wastes, their contents and sources are summarized in the Table 17.1 & 17.2.
Industrial wastes are released from chemical plants, paint industries, cement factories, power plants, metallurgical plants, mining operations, textile industries, food processing industries petroleum industries and thermal power plants. These industries produce different types of waste products (Table 17.3). Industrial solid wastes can be classified into two groups.
These wastes are produced from food processing plants, cotton mills, paper mills, sugar mills and textile industries.
Hazardous wastes are generated by nearly every industry. Metals, chemical, drugs, lather, pulp, electroplating, dye, rubber are some of important examples. Liquid Industrial waste that runs into a stream from a factory can kill the aquatic fauna and also cause health problems for humans.
Agricultural areas produce plants and animals wastes. Excess use of fertilizer, pesticides and other chemicals used in agriculture and the wastes formed from these cause land and water pollution. They also contaminate the soil. Among pesticides chlorinated hydrocarbons, DDT, BHC, endrin, dieldrin, lindane, parathion, malathion and endosulphon are important which are absorbed by the soil and contaminate crops grown in the soil. Other agriculture wastes are produced from sugar factories, tobacco processing units, slaughter houses, livestock, poultry etc.
With the advancement of modem cities, industries and automobiles, huge amount of wastes are generated daily. These include markets, roads, buildings, hotels, commercial complexes, hostels, auto workshops, printing press etc. Hospitals, nursing homes and medical institutes also release tremendous amount of wastes which are hazardous and are much toxic in nature.
Many chemicals and disposable items are also produced from these units. These wastes are dumped in inhabited areas which pose much danger to human health and life and cause several types of infectious diseases. Apart from wastes, generated from the above sources, there are certain wastes produced from mining activities and radioactive substances that cause much damage to the society and environment.
The wastes generated by mining activities disturb the physical, chemical and biological features of the land and atmosphere. The wastes include the overburden material, mine tailings (the waste left after ore has been extracted from rock), harmful gases released by blasting etc.
Although every precaution is taken in the functioning and maintenance of nuclear reactors, yet it has been observed that measurable amount of radioactive waste material escapes into the environment. Other sources of radioactive wastes are from mining of radioactive substances and atomic explosion etc.
Wastes, which are produced from the hospitals, medical centres and nursing homes are called bio-medical wastes. These wastes are highly infectious which include used bandages, infected needles, animal remains, cultures, amputated body organs, dead human foetuses, wastes of surgery and other materials from biological research centres. Pharmacies discard out-dated and unused drugs; testing laboratories dispose of chemical wastes which are hazardous in the environment.
Classification of Wastes:
In general, the wastes are classified on the basis of their biological, chemical and physical properties and also on the basis of nature.
These wastes are natural organic compounds which are degraded or decomposed by biological or microbial action. Biodegradable wastes are generated in food processing units, cotton mills, paper mills, sugar mills, textile factories and sewage Waste of slaughterhouses is biodegradable and some part of it is used, for example, skin is used to make shoes. Most of the wastes from these industries are reused. When these wastes are in excess they act as pollutants and are not easily decomposed and they take much time for their decomposition.
These are not decomposed by microbes but are oxidized and dissociated automatically. Coal stone, metal scraps, sludge are generated from colliery operations Refineries produce inert dry solids and varieties of sludge containing oil. Fly, ash is the major solid waste from thermal power plants. Generally, these wastes are not reused and accumulate in the ecosystem and some of it move through biogeochemical cycles. Non-biodegradable wastes also include DDT, pesticides, lead, plastics, mercuric salts etc.
Many chemical, biological, explosive or radioactive wastes, which are highly reactive and toxic, pose a severe danger to human, plants or animal life and are called hazardous wastes. They are highly toxic in nature. Hazardous wastes, when improperly handled, can cause substantial harm to human health and to the environment. Hazardous wastes may be in the form of solids, liquids, sludge’s or gases.
They are generated primarily by chemical production, manufacturing and other industrial activities. The important hazardous wastes are lead, mercury, cadmium, chromium, many drugs leather, pesticides, dye, rubber and effluents from different industries. They may cause danger during inadequate storage, transportation, treatment or disposal operations. The hazardous waste materials may be toxic, reactive, ignitable, explosive, corrosive, infectious or radioactive.
These are wastes that easily catch fire with a flash point less than 60°C. Such fires not only present immediate dangers but can spread harmful particles over wide areas.
These comprise mostly acidic or alkaline wastes that corrode other materials. These require special containers for disposal and should be separated from other wastes as they release toxic contaminants.
These are explosive or highly reactive wastes. These undergo violent chemical reactions and are exploded to generate heat and toxic gases.
These wastes release toxins or poisonous substances and pose hazards to human health and the environment.
Impacts of Waste Accumulation:
Industrialization on a massive scale, increasing urbanization, advance technology in agriculture and changing life pattern have resulted in the production of huge amount of wastes. The improper waste disposal creates many ecological and social problems, for instance, accumulation of wastes in the densely populated areas, disposal of urban sewage and industrial wastes discharged into rivers etc. affect soil, air and water ecosystem. Chemical, biological and explosive wastes pose immediate or long run danger to the life of man, plants and animals.
The dumping of solid wastes is hazardous to human health. It has been estimated that about twenty-five human diseases are associated with solid waste. There is an increase in the number of rats and flies due to dumping of wastes in open places and they are the carriers of other organisms responsible for several dreaded diseases.
The flies which carry pathogenic organisms are spreading diseases like dysentery, diarrhoea etc. It is estimated that about 70,000 flies are produced in one cubic foot of garbage. Dumping of solid wastes has a number of adverse effects on all the components of an ecosystem and they also affect the aesthetic sense as well.
Spoilage of Landscape:
It is a common practice to dump plastic bags, containers, vegetables, fruit peels, cans etc. in the open area without thinking about its consequences (Fig. 17.1). We need to be fully aware that improper disposal of waste spoils the beauty of the landscape.
Dumping of wastes in a haphazard and unscientific manner has serious environmental impact.
Most of the wastes contain organic compounds a number of inorganic minerals and other harmful matter which contaminate the environment and lead to:
1. Degradation of land,
2. Pollution of drinking water,
3. Destruction of aquatic life,
4. Degradation of ground and surface water used for irrigation and industries, and
5. Improper disposal of wastes cause soil, air and water pollution.
Human health is directly concerned with the overall quality of the environment. However, in the last few decades, due to human’s desire for rapid advancement in industrialisation, agriculture and other activities, much damage has been done to the environment. Large-scale deforestation, drastic climatic changes and pollutants on land, air and water are some of the unpleasant consequences that ultimately affect the human health.
It is a well-known fact that an adult healthy man is exposed everyday to polluted air through breathing and to food and water through oral intake. Our skin is also exposed to the environmental chemicals which lead to many health problems immediately or after sometime.
Health hazards due to air pollution:
Hazardous air pollutants present in the atmosphere affect human health both directly and indirectly. It may be a short-term or long-term effect.
The following are the adverse effects on human health:
1. Toxic gas carbon monoxide reduces the blood oxygen and formation of haemoglobin, causing injury to heart and central nervous system.
2. Sulphur dioxide and sulphuric acid both cause irritation in the respiratory tracts of humans and high concentrations of sulphur dioxide leads to severe heart and lung diseases like bronchitis, asthma, etc.
3. Nitrogen oxide at higher concentration affects respiratory organs, liver and kidneys.
4. Ozone can seriously affect the pulmonary functions.
5. Lead can cause injury in blood-formation organs and nervous system, especially impairing of brain functions of new-born babies.
6. Pesticides and radiations are other toxic air pollutants which are very dangerous for human health.
7. Metal, dusts, asbestos and hydrocarbons shorten the life span and cause deterioration of nervous system and there is additional risk of cancer.
8. In mining operation, silica and dust cause pneumoconiosis (common disease in mine workers).
9. Petroleum components can affect the blood forming organs, brain, teeth bones etc.
10. Mercury and cadmium are known to damage the kidneys and brain.
Water is said to be polluted when its quality or composition is changed either naturally or as a result of human activities. Nearly 80% of the human diseases in developing countries are due to polluted water alone.
The well-known impacts of water pollutants are as follows:
1. A large numbers of industrial pollutants that come to human body through drinking water and contaminated food threaten the life and health. The famous MINAMATA and ITAI-ITAI diseases took a big toll of human life in Japan due to mercury and cadmium from the industrial effluents in the aquatic ecosystem.
2. Some agrochemicals like chlorinated pesticides disposed in water accumulate in the aquatic food chains and enter the human body causing heavy infection. In coastal Karnataka, several people died by consuming crabs contaminated with pesticides.
3. Changes in water quality due to deficiency of iodine lead to goitre which has been found to be endemic in many parts of India.
4. Many water borne diseases prevalent in the Indian population, like cholera, typhoid, gastroenteritis and hepatitis are due to polluted water.
5. Excess fluorine in drinking water has caused bone and teeth diseases (fluorosis), the most severe disease is the KNOCK-KNEE syndrome in Andhra Pradesh.
Health Hazards due to Soil or Land Pollution:
The accumulation of toxic chemical compounds, salts, disease-causing organisms and radioactive materials in the soil cause various health problems.
The impact of waste accumulation in soil/land has shown the following major health effects:
1. The impact of land pollution on human health is indirect. The pollutants added in the soil enter the human body through water or air through the food chain.
2. Several agrochemicals like DDT, fluorine, arsenic, lead compounds and organ phosphorus compounds are super toxic and cause symptoms like nausea, vomiting, diarrhea, sweating, salivation and muscular tremors.
3. Some rodenticides as strychnine, sodium fluoro-acetate etc.. are blood coagulants.
4. Ethylene dichloride, ethylene dibromide and methyl dibromide accumulate in liver, kidney, heart, spleen and cause degenerative lesions.
Impact of Waste Accumulation on Terrestrial Life:
Hazardous wastes may pollute soil, air, surface water and underground water. The oil pollutants may affect man, plants and animals. These toxic substances are transferred to different organisms through the food chain and cause a number of complications in living organisms.
Some of these are as follows:
1. Many toxic chemicals, pesticides, other agricultural wastes released into the environment that are taken up by the plants from air, water and soil. Plants growing under such conditions are severely affected by these toxic chemicals.
2. Exposure to high concentration of pollutants may cause acute injuries like chlorosis, discolouration and even the death of plants.
3. Crops show reduced productivity and yield. The quality of plant nutrients is also decreased.
4. Sulphur dioxide is a most toxic pollutant which damage the crops.
5. In recent years, the losses to agriculture and animal life due to fluoride content have greatly increased.
6. Besides morphological changes, biochemical and physiological changes have also been observed in many mammals including man.
7. Too much accumulation of wastes disturb the behaviour of wild and domestic animals and also cause health problems.
8. Some highly toxic chemicals lead to genetic disorders in animals.
9. Several domestic animals like cow, buffalo, goat etc. often eat polythene and plastics bags along with food material which ultimately reach to their alimentary canal causing many disorders and even their death.
Impact of Waste Accumulation on Fresh Water:
Large amount of wastes of human society are disposed of in the rivers, lakes, ponds and other aquatic bodies making the water polluted which is not fit for drinking and other domestic purposes.
The impacts of waste dumping on aquatic life are as follows:
1. The toxic wastes reaching the water bodies badly disturb the aquatic life.
2. The sewage of cities is often drained into the rivers, which is dangerous to flora, fauna and human life.
3. Due to heavy accumulation of wastes into the canals, lakes and rivers, oxygen concentration is reduced considerably thus affecting the life of fishes and other aquatic populations. In extreme deficiency of oxygen most of the fishes die.
4. Sewage from municipalities, sanatoria and tanneries discharged into the rivers, canals and lakes etc. carry many species of bacteria and other microbes which cause diseases in human and animals.
5. Some pollutants for example heavy metals, cyanides and several other organic and inorganic compounds are harmful to aquatic organisms. Many of them especially non-biodegradable ones accumulate in the body of organisms and cause long-term effects.
6. Biodiversity decreases in highly polluted aquatic habitats.
7. The DDT and other pesticides present in very low concentrations in water may accumulate to higher concentration within algae, insects and fishes. The birds or people that feed on these fishes are then exposed to very high levels of hazardous substances. In birds, these substances can affect the egg production and bone formation.
Impact of Waste Accumulation on Marine Life:
One of the least known but most significant uses of the sea is as an enormous dumpsite. In the past, the oceans were able to assimilate the wastes of the civilization without noticeable adverse effects. However, industrialization and other associated developments along with sharp increase in global population have given rise to huge amounts of wastes that are now taxing the capacity of the oceans to absorb them. Human wastes ranging from the raw sewage of urban centres to junked appliances and automobiles have heavily polluted the sea shores.
The impacts of waste dumping on marine life are as follows:
1. The growth of marine algae is affected.
2. Massive oil spills not only spoil innumerable beaches and estuaries but also cause widespread damage to marine life.
3. Herbicides and pesticides (especially the organ chlorides) reach the oceans via the wind and rivers and contaminate marine water.
4. It is a matter of great concern that mangrove forests are being damaged at an alarming rate due to disposal of wastes along sea shores.
5. Thermal and radioactive pollution have disturbed the life of fishes in estuaries and coastal ecosystems. Their breeding is also affected adversely.