Unit – 5
WATER POLLUTION
Environmental Pollution can be defined as any undesirable change in physical, chemical, or biological characteristics of any component of the environment i.e. air, water, soil which can cause harmful effects on various forms of life or property. The term pollution can be defined as influence of any substance causing nuisance, harmful effects, and uneasiness to the organisms. Any substance causing Nuisance or harmful effects or uneasiness to the organisms, then that particular substance may be called as the pollutant.
Water Pollution
Water pollution can be defined as the contamination of water bodies. Water pollution is caused when water bodies such as rivers, lakes, oceans, groundwater, and aquifers get contaminated with industrial and agricultural effluents.
When water gets polluted, it adversely affects all life forms that directly or indirectly depend on this source. The effects of water contamination can be felt for years to come.
Types of Water Pollution
- Chemical pollution: The most common type of water pollution, chemicals can infiltrate both underground water sources and those sitting on the Earth's surface.
- Groundwater pollution : agriculture is a key source of water pollution, especially for groundwater. Fertilisers and pesticides applied to crops can seep into the ground and contaminate underwater rivers and waterbeds, thus compromising the quality of wells, boreholes and other places from which groundwater is extracted for human use.
- Microbiological pollution : Unlike most others on this list, microbiological pollution is a naturally occurring form of water contamination. Microorganisms such as bacteria, protozoa and viruses can infiltrate water supplies, causing diseases such as bilharzia and cholera. Humans are most susceptible to this kind of pollution in places where adequate water treatment systems are not yet in place.
- Nutrient pollution : While they’re vital for underwater flora and fauna to flourish, an excess of nutrients can upset the delicate imbalance of water-based ecosystems. Fertilisers contain a high concentration of nutrients which, if they contaminate rivers, lakes and coastal areas, can cause algal blooming that can block out sunlight and inhibit the growth of other organisms.
- Oxygen-depletion pollution : Another consequence of algal blooms is their consumption of oxygen supplies. This means that those species which depend upon oxygen to survive are killed off, while anaerobic ones thrive. Some anaerobic microorganisms are capable of producing ammonia, sulphides and other harmful toxins, which can make the water even more dangerous to animals (and humans, too).
- Surface water pollution : which can lead to poor water quality, while accidental oil spills and negligent industries emptying waste into water bodies are also key contributors. Suspended matter, Improperly discarded waste, such as fragments of plastic, rubber or other manmade materials, can find themselves into water sources and persist for a long time. Because they are too robust to dissolve in the water and too big to mix effectively with the molecules, they simply float on its surface and prevent oxygen and sunlight from penetrating below.
Causes of Water Pollution
The main causes of water pollution are attributed to
- Industrial activities
- Urbanization
- Religious and social practices
- Agricultural runoff
- Accidents (such as oil spills, nuclear fallouts etc)
Effects of Water Pollution
The effect of water pollution depends upon the type of pollutants and its concentration. Also, the location of water bodies is an important factor to determine the levels of pollution.
- Water bodies in the vicinity of urban areas are extremely polluted. This is the result of dumping garbage and toxic chemicals by industrial and commercial establishments.
- Water pollution drastically affects aquatic life. It affects their metabolism, behaviour, causes illness and eventual death. Dioxin is a chemical that causes a lot of problems from reproduction to uncontrolled cell growth or cancer. This chemical is bio accumulated in fish, chicken and meat. Chemicals such as this travel up the food chain before entering the human body.
- The effect of water pollution can have a huge impact on the food chain. It disrupts the food-chain. Cadmium and lead are some toxic substances, these pollutants upon entering the food chain through animals (fish when consumed by animals, humans) can continue to disrupt at higher levels.
- Humans are affected by pollution and can contract diseases such as hepatitis through faecal matter in water sources. Poor drinking water treatment and unfit water can always cause an outbreak of infectious diseases such as cholera etc.
- The ecosystem can be critically affected, modified and destructured because of water pollution
Control Measures
Water pollution, to a larger extent, can be controlled by a variety of methods. Rather than releasing sewage waste into water bodies, it is better to treat them before discharge. Practising this can reduce the initial toxicity and the remaining substances can be degraded and rendered harmless by the water body itself. If the secondary treatment of water has been carried out, then this can be reused in sanitary systems and agricultural fields.
A very special plant, the Water Hyacinth can absorb dissolved toxic chemicals such as cadmium and other such elements. Establishing these in regions prone to such kinds of pollutants will reduce the adverse effects to a large extent.
Some chemical methods that help in the control of water pollution are precipitation, the ion exchange process, reverse osmosis, and coagulation. As an individual, reusing, reducing, and recycling wherever possible will advance a long way in overcoming the effects of water pollution.
Noise Pollution
Noise is the unpleasant and undesirable sound which leads to discomfort to human beings. The intensity of sound is measured in decibels (dB). The faintest sound which can be heard by the Human ear is 1 Db. Due to increasing noise around the civilizations; noise pollution has become a matter of concern. Some of its major causes are vehicles, aircraft, industrial machines, loudspeakers, crackers, etc. Some other appliances also contribute to noise pollution like television, transistor, radio, etc. when used at high volume.
Types of Noise Pollution
Following are the three types of pollution:
Transport Noise
It mainly consists of traffic noise which has increased in recent years with the increase in the number of vehicles. The increase in noise pollution leads to deafening of older people, headache, hypertension, etc.
Neighbourhood Noise
The noise from gadgets, household utensils etc. Some of the main sources are musical instruments, transistors, loudspeakers etc.
Industrial Noise
It is the high-intensity sound which is caused by heavy industrial machines. According to many researches industrial noise pollution damages the hearing ability to around 20%.
Causes of Noise Pollution
Following are the causes and sources of noise pollution:
- Industrialization: Industrialization has led to an increase in noise pollution as the use of heavy machinery such as generators, mills, huge exhaust fans, etc are used resulting in the production of unwanted noise.
- Vehicles: Increased number of vehicles on the roads are the second reason for noise pollution.
- Events: Weddings, public gatherings involve loudspeakers to play music resulting in the production of unwanted noise in the neighbourhood.
- Construction sites: Mining, construction of buildings, etc add to the noise pollution.
Effects of Noise Pollution
Noise pollution can be hazardous to human health in the following ways:
- Hypertension: It is a direct result of noise pollution which is caused due to elevated blood levels for a longer duration.
- Hearing loss: Constant exposure of human ears to loud noise that are beyond the range of sound that human ears can withstand damages the eardrums resulting in loss of hearing.
- Sleeping disorders: Lack of sleep might result in fatigue and low energy level throughout day affecting everyday activities. Noise pollution hampers the sleep cycles leading to irritation and uncomfortable state of mind.
- Cardiovascular issues: Heart related problems such as blood pressure level, stress, and cardiovascular diseases might come up in a normal person and person suffering from any of these diseases might feel the sudden shoot up in the level.
Control Measures
Some noise pollution preventive measures are provided in the points below.
- Honking in public places like teaching institutes, hospital, etc. should be banned.
- In commercial, hospital, and industrial buildings adequate soundproof systems should be installed.
- Musical instruments sound should be controlled to desirable limits.
- Dense tree cover is useful in noise pollution prevention.
- Explosives should be not used in forest, mountainous, and mining areas.
Soil Pollution
Soil pollution refers to the contamination of soil with anomalous concentrations of toxic substances. It is a serious environmental concern since it harbours many health hazards. For example, exposure to soil containing high concentrations of benzene increases the risk of contracting leukaemia. An image detailing the discolouration of soil due to soil pollution is provided below.
Types of Soil Pollution
Soil pollution mainly occurs due to the following:
1. Industrial wastes
2. Urban wastes
3. Agricultural practices
4. Radioactive pollutants
5. Biological agents
Causes of Soil Pollution
Some common causes of soil pollution are listed below,
- Improper disposal of industrial waste: industries are believed to be one of the leading causes of soil pollution due to improper management and disposal of the toxic wastes generated during industrial activities.
- Excessive and inefficient usage of pesticides and fertilizers: the agriculture industry makes extensive use of chemical fertilizers and pesticides for the growth and maintenance of crops. However, excessive and inefficient use of these toxic chemicals can seriously contaminate the soil.
- Petroleum or diesel spills: leaks in fuel transportation pipes can cause fuel spills. These fuels are known to contain toxic hydrocarbons which can cause soil contamination.
Effects of Soil Pollution
1. Effects on Human Beings
Soil contaminants can exist in all three phases (solid, liquid, and gaseous). Therefore, these contaminants can find their way into the human body via several channels such as direct contact with the skin or through the inhalation of contaminated soil dust.
The short term effects of human exposure to polluted soil include:
- Headaches, nausea, and vomiting.
- Coughing, pain in the chest, and wheezing.
- Irritation of the skin and the eyes.
- Fatigue and weakness.
A variety of long-term ailments have been linked to soil pollution. Some such diseases are listed below.
- Exposure to high levels of lead can result in permanent damage to the nervous system. Children are particularly vulnerable to lead.
- Depression of the CNS (Central Nervous System).
- Damage to vital organs such as the kidney and the liver.
- Higher risk of developing cancer.
It can be noted that many soil pollutants such as petroleum hydrocarbons and industrial solvents have been linked to congenital disorders in humans. Thus, soil pollution can have several negative effects on human health.
2. Effects on Plants and Animals
Since soil pollution is often accompanied by a decrease in the availability of nutrients, plant life ceases to thrive in such soils. Soils contaminated with inorganic aluminium can prove toxic to plants. Also, this type of pollution often increases the salinity of the soil, making it inhospitable for the growth of plant life.
Plants that are grown in polluted soil may accumulate high concentrations of soil pollutants through a process known as bioaccumulation. When these plants are consumed by herbivores, all the accumulated pollutants are passed up the food chain. This can result in the loss/extinction of many desirable animal species. Also, these pollutants can eventually make their way to the top of the food chain and manifest as diseases in human beings.
3. Effects on the Ecosystem
- Since the volatile contaminants in the soil can be carried away into the atmosphere by winds or can seep into underground water reserves, soil pollution can be a direct contributor to air and water pollution.
- It can also contribute towards acid rain (by releasing huge quantities of ammonia into the atmosphere).
- Acidic soils are in hospitable to several microorganisms that improve soil texture and help in the decomposition of organic matter. Thus, the negative effects of soil pollution also impact soil quality and texture.
Control Measures
Several technologies have been developed to tackle soil remediation. Some important strategies followed for the decontamination of polluted soil are listed below.
- Excavation and subsequent transportation of polluted soils to remote, uninhabited locations.
- Extraction of pollutants via thermal remediation – the temperature is raised in order to force the contaminants into the vapour phase, after which they can be collected through vapour extraction.
- My core mediation involves the use of fungi for the accumulation of heavy metal contaminants.
Source reduction is one of the fundamental ways to reduce waste. This can be done by using less material when making a product, reuse of products on site, designing products or packaging to reduce their quantity. On an individual level we can reduce the use of unnecessary items while shopping, buy items with minimal packaging, avoid buying disposable items and also avoid asking for plastic carry bags.
Recycling is reusing some components of the waste that may have some economic value. Recycling has readily visible benefits such as conservation of resources reduction in energy used during manufacture and reducing pollution levels. Some materials such as aluminium and steel can be recycled many times. Metal, paper, glass and plastics are recyclable. Mining of new aluminium is expensive and hence recycled aluminium has a strong market and plays a significant role in the aluminium industry. Paper recycling can also help preserve forests as it takes about 17 trees to make one ton of paper. Crushed glass (cullet) reduces the energy required to manufacture new glass by 50 percent. Cullet lowers the temperature requirement of the glassmaking process thus conserving energy and reducing air pollution.
Solid Waste Disposal and Management
Garbage arising from human or animal activities, that is abandoned as unwanted and useless is referred as solid waste. Generally, it is generated from industrial, residential and commercial activities in a given area, and may be handled in a variety of ways. However, waste can be categorized based on materials such as paper, plastic, glass, metal and organic waste. Solid waste disposal must be managed systematically to ensure environmental best practices. Solid waste disposal and management is a critical aspect of environmental hygiene and it needs to be incorporated into environmental planning.
Methods of Solid Waste Disposal and Management:
Here are the methods of solid waste disposal and management:
1) Solid Waste Open Burning
2) Sea dumping process
3) Solid wastes sanitary landfills
4) Incineration method
5) Composting process
6) Disposal by Ploughing into the fields
7) Disposal by hog feeding
8) Salvaging procedure
9) Fermentation/biological digestion
1. Solid Waste Open Burning
Solid waste open burning is not the perfect method in the present scenario.
2. Sea Dumping Process
This sea dumping process can be carried out only in coastal cities. This is very costly procedure and not environment friendly.
3. Solid wastes sanitary landfills
Solid wastes sanitary landfills process is simple, clean and effective. In this procedure, layers are compressed with some mechanical equipment and covered with earth, leveled, and compacted. A deep trench of 3 to 5 m is excavated and micro-organisms act on the organic matter and degrade them.
In this procedure, refuse depth is generally limited to 2m. Facultative bacteria hydrolyze complex organic matter into simpler water soluble organics
4. Incineration method
Incineration method is suitable for combustible refuse. High operation costs and construction are involved in this procedure. This method would be suited in crowded cities where sites for land filling are not available.
It can be used to reduce the volume of solid wastes for land filling.
5. Composting process
Composting process is similar to sanitary land-filling and it is popular in developing countries. Decomposable organic matter is separated and composted in this procedure. Yields are stable end products and good soil conditioners. They can be used as a base for fertilizers.
Two methods have been used in this process:
a)Open Window Composting
b) Mechanical Composting
6. Disposal by Ploughing into the fields
Disposal by ploughing into the fields are not commonly used. These disposals are not environment friendly in general.
7. Disposal by hog feeding
Disposal by hog feeding is not general procedure in India. Garbage disposal into sewers including BOD and TSS increases by 20-30%. Refuse is ground well in grinders and then fed into sewers.
8. Salvaging procedure
Materials such as metal, paper, glass, rags, certain types of plastic and so on can be salvaged, recycled, and reused.
9. Fermentation/biological digestion
Biodegradable wastes are converted to compost and recycling can be done whenever possible. Hazardous wastes can be disposed using suitable methods.
To reduce the risk of damage to healthcare personnel, the population, and the environment
To reduce the amount of waste
To ensure the segregated collection of waste
To establish proper waste collection sites in medical departments and in hospitals
To establish a proper in-house transportation route
To recover waste to the greatest extent possible
To dispose of waste in an environmentally and health-friendly way
Thermal pollution is the degradation of water quality by any process that changes ambient water temperature. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers.
The term thermal pollution has been used to indicate the detrimental effects of heated effluent discharge by various power plants. It denotes the impairment of quality and deterioration of aquatic and terrestrial environment by various industrial plants like thermal, atomic, nuclear, coal-fired plants, oil field generators, factories, and mills.
Sources of Thermal Pollution
1. Nuclear Power Plant
2. Coal-fired power Plant
3. Industrial Effluents
4. Domestic Sewage
5. Hydro-electric power
6. Thermal Power Plant
The discharged effluents of these sources have a higher temperature than the intake water that reduces the concentration of oxygen from the water which causes the deleterious effects on the marine ecosystem.
Harmful effects of the thermal pollution
1. Reduction in dissolved Oxygen
The pollutant from various industrial plants are heated decreases the concentration of oxygen with an increase in the temperature of water.
2. Change in water properties
The decrease in density, viscosity and solubility of gases in water increases the setting speed of suspended particles which seriously affect the food supplies of aquatic organism.
3. Increase in toxicity
The concentrated pollutant causes the rise in the temperature of water which increases the toxicity of the poison present in water. The toxicity in water will increase the death rate in marine life.
4. Disruption of Biological activities
Temperature changes disrupt the entire marine ecosystem because changes in temperature causes change in physiology, metabolism and biological process like respiration rate, digestion, excretion and development of an aquatic organism.
How biochemical cycles stabilizes the biosphere?
5. Damage of biotic organism
Aquatic organisms like juvenile fish, plankton, fish, eggs, larva, algae and protozoa which pass through screens and condenser cooling system are extremely sensitive to abrupt temperature changes. They are habitual of warmer water may suddenly face increase or decrease in temperature of water bodies and thus die because of sudden changes in the temperature of water.
Prevention for Thermal Pollution
The following measures can be taken to prevent or control high temperature caused by thermal pollution:
1. Heated water from the industries can treated before discharging directly to the water bodies.
2. Heated water from the industries can be treated by the installation of cooling ponds and cooling towers.
3. Industrial treated water can be recycled for domestic use or industrial heating.
4. Through artificial lakes: In this lake Industries can discharge their used or heated water at one end and water for cooling purposes may be withdrawn from the other end. The heat is eventually dissipated through evaporation.
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According to International Atomic Energy Agency (IAEA), a nuclear and radiation accidents/ hazards is an event that has led to significant consequences to people, the environment or the facility. Nuclear hazards. Risk or danger to human health or the environment exposed by the radiation emanating from the atomic nuclei is called as nuclear hazard. Nuclear hazard is an actual or potential release of radioactive material at a commercial nuclear power plant or a transportation accident.
Nuclear power plant accidents:
- The SL-1 accident(1961)
- The Three Mile Island Accident(1979)
- Chernobyl Disaster (1986)
- Fukushima Daiichi nuclear disaster(2011)
Control measures
- Laboratory generated nuclear wastes should be disposed off safely and scientifically.
- Nuclear power plants should be located in areas after careful study of the geology of the area, tectonic activity and meeting other established conditions.
- Appropriate protection against occupational exposure
- Leakage of radioactive elements from nuclear reactors, careless use of radioactive elements as fuel and careless handling of radioactive isotopes must be prevented.
- Safety measure against accidental release of radioactive elements must be ensured in nuclear plants.
- Unless absolutely necessary, one should not frequently go for diagnosis by x-rays.
- Regular monitoring of the presence of radioactive substance in high risk area should be ensured.
Reference Books
- Environmental pollution and Control by Ruth Weiner et al
- Environmental Pollution Control Engineering by C S Rao
- Environmental Engineering-1 by H.S Vishwanath et al
