Environmental Pollution (Part - 3) | Environment for UPSC CSE PDF Download

What is Solid Waste?

Solid waste is the unwanted or useless solid materials generated from human activities in residential, industrial or commercial areas. It may be categorized in three ways. According to its:

• origin (domestic, industrial, commercial, construction or institutional)
• contents (organic material, glass, metal, plastic paper etc.)
• Hazard potential (toxic, non-toxin, flammable, radioactive, infectious etc.).

Solid Waste Management reduces or eliminates the adverse impact on the environment & human health. Several processes are involved in effectively managing waste for a municipality. These include monitoring, collection, transport, processing, recycling and disposal. The quantum of waste generated varies mainly due to different lifestyles, directly proportional to the urban population's socio-economic status.

Plastic Waste

Plastics are considered to be one of the wonderful inventions of the 20th Century. They are widely used as packing and carry bags because of cost and convenience. But plastics are now considered as an environmental hazard due to the "Throw away culture".

Source of a generation of waste plastics

• Household 
• Health and medicare 
• Hotel and catering 
• Air/rail travel

Effects

• The land gets littered by plastic bag garbage and becomes ugly and unhygienic.
• Conventional plastics have been associated with reproductive problems in both humans and wildlife.
• Dioxin (highly carcinogenic and toxic) by-product of the manufacturing process is one of the chemicals believed to be passed on through breast milk to the nursing infant.
• Burning of plastics, especially PVC, releases this dioxin and furans the atmosphere. Thus, conventional plastics, right from their manufacture to their disposal, are a major problem to the environment.
• Plastic bags can also contaminate foodstuffs due to leaching of toxic dyes and pathogens transfer.
• Careless disposal of plastic bags chokes drains, blocks the soil's porosity, and causes groundwater recharge problems.
• Plastic disturbs the soil microbe activity. The terrestrial and aquatic animals misunderstand plastic garbage as food items, swallow them and die.
• Plastic bags deteriorate soil fertility as they form part of manure and remain in the soil for years.
• These bags finding their way into the city drainage system results in blockage causing inconvenience, difficult in maintenance, creates unhygienic environment resulting in health hazard and spreading of water-borne diseases.
• Designing eco-friendly, biodegradable plastics are the need of the hour.

Types

Solid wastes are classified depending on their source: 

• Municipal waste, 
• Hazardous waste and 
• Biomedical waste or hospital waste.

(i) Municipal waste

• The municipal solid waste consists of household waste, construction and demolition debris, sanitation residue, and waste from streets. 
• With rising urbanization and change in lifestyle and food habits, municipal solid waste has been increasing rapidly and its composition changing.
• In 1947 cities and towns in India generated an estimated 6 million tonnes of solid waste, in 1997 it was about 48 million tonnes. More than 25% of the municipal solid waste is not collected at all.
• 70% of the Indian cities lack adequate transportation capacity, and there are no sanitary landfills to dispose of the waste. The existing landfills are neither well equipped nor lined properly to protect against soil and groundwater contamination. 
• Over the last few years, the consumer market has grown rapidly, leading to products being packed in cans, aluminium foils, plastics, and other nonbiodegradable items that cause incalculable harm to the environment.

(ii) Hazardous waste

• Industrial and hospital waste is considered hazardous as they contain toxic substances. Hazardous wastes could be highly toxic to humans, animals, and plants and are corrosive, highly inflammable, or explosive. 
• India generates around 7 million tonnes of hazardous wastes every year, most of which is concentrated in four states: Andhra Pradesh, Bihar, Uttar Pradesh, and Tamil Nadu.
• Household waste that can be categorized as hazardous waste includes old batteries, shoe polish, paint tins, old medicines, and medicine bottles.
• In the industrial sector, the major generators of hazardous waste are the metal, chemical, paper, pesticide, dye, refining, and rubber goods industries. 
• Direct exposure to chemicals in hazardous waste such as mercury and cyanide can be fatal.

(iii) Hospital waste

• Hospital waste is generated during the diagnosis, treatment, or immunization of human beings or animals or in research activities or the production or testing of biologicals.
• These chemicals include formaldehyde and phenols, used as disinfectants, and mercury, used in thermometers or equipment that measures blood pressure.
• It may include wastes like a soiled waste, disposables, anatomical waste, cultures, discarded medicines, chemical wastes, disposable syringes, swabs, bandages, body fluids, human excreta, etc.
• These are highly infectious and can be a serious threat to human health if not managed in a scientific and discriminate manner.
• Surveys carried out by various agencies show that India's health care establishments are not giving due attention to their waste management. 
• After the notification of the Bio-medical Waste (Handling and Management) Rules, 1998, these establishments are slowly streamlining the process of waste segregation, collection, treatment, and disposal.

Treatment and disposal of solid waste

(i) Open dumps 

Open dumps refer to uncovered areas that are used to dump solid waste of all kinds. The waste is untreated, uncovered, and not segregated. It is the breeding ground for flies, rats, and other insects that spread disease. The rainwater run-off from these dumps contaminates nearby land and water thereby spreading disease. Treatment by open dumps is to be phased out.

(ii) Landfills 
Landfills are generally located in urban areas. It is a pit that is dug in the ground. The garbage is dumped, and the pit is covered with soil every day, thus preventing flies and rats' breeding. Thus, every day, garbage is dumped and sealed. After the landfill is full, the area is covered with a thick layer of mud, and the site can thereafter be developed as a parking lot or a park.
Problems - All types of waste are dumped in landfills, and when water seeps through them, it gets contaminated and pollutes the surrounding area. This contamination of groundwater and soil through landfills is known as leaching.
(iii) Sanitary landfills 
Sanitary landfill is more hygienic and built methodically to solve the problem of leaching. These are lined with impermeable materials such as plastics and clay and are also built over impermeable soil. Constructing sanitary landfills is very costly
(iv) Incineration plants
The process of burning waste in large furnaces at high temperature is known as incineration. In these plants, the recyclable material is segregated, and the rest of the material is burnt, and ash is produced.

Burning garbage is not a clean process as it produces tonnes of toxic ash and pollutes the air and water. A large amount of the waste that is burnt here can be recovered and recycled. In fact, incineration is kept as a last resort and is used mainly for treating infectious waste.
(v) Pyrolysis
It is a combustion process in the absence of oxygen or the material burnt under controlled atmosphere of oxygen. It is an alternative to incineration. The gas and liquid thus obtained can be used as fuels. Pyrolysis of carbonaceous wastes like firewood, coconut, palm waste, corn combs, cashew shell, rice husk paddy straw and sawdust, yields charcoal and tar products methyl alcohol, acetic acid, acetone and fuel gas.
(vi) Composting

• Composting is a biological process in which microorganisms, mainly fungi and bacteria, decompose degradable organic waste into humus like substance in the presence of oxygen.
• This finished product, which looks like soil, is high in carbon and nitrogen and is an excellent medium for growing plants.
• It increases the soil's ability to hold water and makes the soil easier to cultivate. It helps the soil retain more plant nutrients.
• It recycles the nutrients and returns them to soil as nutrients. 
• Apart from being clean, cheap, and safe, composting can significantly reduce disposable garbage.

(vii) Vermiculture
It is also known as earthworm farming. In this method, Earthworms are added to the compost. These worms break the waste, and the worms' added excreta makes the compost very rich in nutrients.
(viii) Four R's
Waste Minimization Circles (WMC)

• WMC helps Small and Medium Industrial Clusters in waste minimization in their industrial plants.
  (i) The World Bank assists this with the Ministry of Environment and Forests acting as the nodal ministry. The project is being implemented with the National Productivity Council (NPC) assistance, New Delhi.
  (ii) The initiative also aims to realize the Policy Statement for Abatement of Pollution (1992) objectives, which states that the government should educate citizens about environmental risks, the economic and health dangers of resource degradation, and the real economic cost of natural resources.
  (iii) The policy also recognizes that citizens and non-governmental organizations play a role in environmental monitoring, enabling them to supplement the regulatory system and recognize their expertise where such exists and where their commitments and vigilance would be cost-effective.

Thermal Pollution

• Thermal pollution is the rise or fall in the temperature of a natural aquatic environment caused by human influence. This has become an increasing and the most current pollution, owing to globalization's increasing call everywhere.
• Thermal pollution is caused by either dumping hot water from factories and power plants or removing trees and vegetation that shade streams, permitting sunlight to raise the temperature of these waters, the release of cold water which lowers the temperature. Like other forms of water pollution, thermal pollution is widespread, affecting many lakes and vast numbers of streams and rivers in various parts of the world.

(i) Major sources

• power plants creating electricity from fossil fuel
• water as a cooling agent in industrial facilities
• deforestation of the shoreline
• soil erosion

(ii) Ecological Effects - Warm Water

The change in temperature impacts organisms by
(a) decreasing oxygen supply, and
(b) affecting ecosystem composition.

• Warm water contains less oxygen. The elevated temperature typically decreases the level of dissolved oxygen (DO) in water. So there is a decrease in the rate of decomposition of organic matter. Less desirable blue-green algae replace green algae. Many animals fail to multiply.
• It also increases the metabolic rate of aquatic animals, resulting in more food consumption in a shorter time than if their environment were not changed. An increased metabolic rate may result in food source shortages, causing a sharp decrease in the population. 
• Changes in the environment may also result in a migration of organisms to another, more suitable environment and in-migration of fishes that normally only live in warmer waters elsewhere. This leads to competition for fewer resources; the more adapted organisms moving in may have an advantage over organisms that are not used to the warmer temperature. As a result, one has the problem of compromising food chains of the old and new environments. Biodiversity can be decreased as a result.
• Temperature changes of even one to two degrees Celsius can cause significant organism metabolism changes and other adverse cellular biology effects. Principal adverse changes can include rendering cell walls less permeable to necessary osmosis, coagulation of cell proteins, and altering enzyme metabolism. These cellular-level effects can adversely affect mortality and reproduction.
• Primary producers are affected by warm water because higher water temperature increases plant growth rates, resulting in a shorter life span and overpopulation. This can cause an algae bloom which reduces the oxygen levels in the water. The higher plant density results in reduced light intensity decreased photosynthesis and increased plant respiration rate. This is similar to eutrophication.
• A large increase in temperature can lead to the denaturing of life-supporting enzymes by breaking down hydrogen- and disulphide bonds within the enzymes' quaternary structure. Decreased enzyme activity in aquatic organisms can cause problems such as the inability to break down lipids, which leads to malnutrition.

(iii) Ecological Effects — Cold Water
Thermal pollution can also be caused by freezing water from reservoirs' base into warmer rivers. This affects fish (particularly their eggs and larvae), macroinvertebrates and river productivity.

(iv) Control Measures

• Instead of discharging heated water into lakes and streams, power plants and factories can pass the heated water through cooling towers or cooling ponds, where evaporation cools the water before it is discharged. 
• Alternatively, power plants can be designed or refitted to be more efficient and to produce less waste heat in the first place. 
• Cogeneration - a process through which, the excess heat energy from generating electricity can be used in another manufacturing process that needs much energy. Where homes or other buildings are located near industrial plants, waste hot water can be used for heating-an arrangement often found in Scandinavian towns and cities, and proposed in China.
• To prevent thermal pollution due to devegetation, the prescription is simple: do not devegetate and leave strips of trees and vegetation along streams and shorelines. 
• All efforts to control erosion also have the effect of keeping water clearer and, thus, cooler.

Plastic Pollution

• The marine resource covering 70 per cent of the earth's surface is a key asset in the biosphere. Of the nearly 1.5 million species known, nearly a quarter-million live in the world's oceans. More importantly, nearly 50 per cent of the global primary production occurs in seawater's upper stratum. Seafood presently represents 20% of the protein in the global diet.
• The health of the marine food web and the fisheries resources invariably depend upon the autotrophic algae's long-term viability (phytoplankton – primary producer) and the zooplankton (primary consumers) in the marine food pyramid. 
• Plastics represent the latest contaminant in the marine environment; the increased use of plastics has negative environmental impacts.
• Plastics pollution can interfere with the plankton species that form the foundation of the food web, and other organisms adversely affecting the delicate balance in the marine ecosystem.

(i) Plastics as a Waste Material- in Marine Environment

• The amount of plastic waste estimation annually introduced into the marine environment is not available. But, plastic waste is well known to result primarily from fishing-related activities and non-point source influx from beaches.
• There are two clear differences between the fate of plastics debris in the ocean environment and on land environments.
• The rate of U V-induced photo-oxidative degradation of plastics floating or submerged at sea is very much slower than that exposed to the same solar radiation on land.
• Unlike on land, there are no easy means of retrieval, sorting, and recycling plastic waste entering the ocean environment.
• These two factors generally result in extended lifetimes for plastics at sea.
• The plastic waste that has been introduced into the world's oceans must accumulate for the most part, intact and unmineralized in the marine environment. While such plastics' fate is not clear, it is reasonable to expect at least some of it to continue disintegrating into microparticulate debris. Recent reports even indicate an increase in their counts over the last two decades.

(ii) Impact of Microparticles

• Challenging the Antarctic krill and other zooplankton with plastic beads about 20 microns or so in size has demonstrated that these organisms readily ingest these microparticulate. They appear to ingest the particles unselectively, and the ingestion rates depend on the concentration of particles in the environment. 
• Plastics are bio-inert and are not expected to be toxic to the animal in the conventional sense. Physical obstruction or indirect interference with physiology is always possible (as with sea birds showing satiation on ingesting plastics) the material will pass through the animal virtually unchanged.
• However, the concern is that plastics exposed to seawater tend to concentrate toxic and non-toxic organic compounds present in the seawater at low concentrations. These, including PCBs, DDT, and nonylphenols, have very high partition coefficients and are very efficiently concentrated in the plastic material. 
• Plastic-related distress to over 250 species has been documented worldwide. The focus has been on larger species in surface waters or beaches, even though 99 per cent of marine species live in the benthos. The impact of negatively buoyant plastic waste (such as nylon net fragments) on benthic species has remained virtually unaddressed.
• Although years of interest on the topic little research has been carried out by the government agencies or the plastics industry to address the key issues relating to plastics in the marine environment.

(iii) Plastics as a Waste Material- in Land Environment

Problems with the uncollected plastic waste, including

• Choking of drains by plastic carry bags which may lead to the unhygienic environment and water-borne diseases, 
• Causing of illness and possible death of animals that may feed on plastics from garbage bins, 
• Nonbiodegradable and impervious nature of plastics disposed on soil which may arrest recharge of groundwater aquifers, 
• The presence of additives and plasticizers, fillers, flame retardants and pigments used in the plastic products can cause adverse health impact and groundwater pollution.

Bioremediation

• Bioremediation uses microorganisms (bacteria and fungi) to degrade the environmental contaminants into less toxic forms. 
• The microorganisms may be indigenous to a contaminated area or isolated from elsewhere and brought to the contaminated site.

The process of bioremediation can be monitored indirectly by measuring the Oxidation Reduction Potential or redox in soil and groundwater, together with pH, temperature, oxygen content, electron acceptor/ donor concentrations, and concentration of breakdown products (e.g. carbon dioxide)

Bioremediation Strategies

(i) In situ bioremediation techniques

It involves treatment of the contaminated material at the site.

• Bioventing – supply of air and nutrients through wells to contaminated soil to stimulate indigenous bacteria's growth. It is used for simple hydrocarbons and can be used where the contamination is deep under the surface. 
• Biosparging - Injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria 
• Bioaugmentation - Microorganisms are imported to a contaminated site to enhance the degradation process.

(ii) Ex situ bioremediation techniques

Ex-situ -involves the removal of the contaminated material to be treated elsewhere.

• Landfarming - contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded. The goal is to stimulate indigenous biodegradative microorganisms and facilitate their aerobic degradation of contaminants.
• Biopiles - it is a hybrid of landfarming and composting. Essentially, engineered cells are constructed as aerated composted piles. Typically used for the treatment of surface contamination with petroleum hydrocarbons.
• Bioreactors involve the processing of contaminated solid material (soil, sediment, sludge) or water through an engineered containment system. 
• Composting – dealt earlier in solid waste management.

Using bioremediation techniques, TERI has developed a mixture of bacteria called 'oilzapper', which degrades oil-contaminated sites' pollutants, leaving behind no harmful residues. This technique is not the only environment friendly but also highly cost-effective.

Genetic engineering approaches

Phytoremediation

Phytoremediation is the use of plants to remove contaminants from soil and water.

➤ Types

• Phytoextraction/phytoaccumulation is when plants accumulate contaminants into the roots and above-ground shoots or leaves. 
• Phytotransformation or phytodegradation refers to the uptake of organic contaminants from soil, sediments, or water and their transformation to more stable, less toxic, less mobile form.
• Phytostabilization is a technique in which plants reduce the mobility and migration of contaminated soil. Leachable constituents are adsorbed and bound into the plant structure to form an unstable mass of plant from which the contaminants will not re-enter the environment. 
• Phytodegradation or rhizodegradation is the breakdown of contaminants through the activity existing in the rhizosphere. This activity is due to proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi.
• Rhizofiltration is a water remediation technique that involves the uptake of contaminants by plant roots. Rhizofiltration is used to reduce contamination in natural wetlands and estuary areas.

The bacterium Deinococcus radiodurans has been used to detoxify toluene and ionic mercury released from radioactive nuclear waste.

• Mycoremediation is a form of bioremediation in which fungi are used to decontaminate the area.
• Mycrofiltration is a similar process, using fungal mycelia to filter toxic waste and microorganisms from water in the soil.

➤ Advantages of bioremediation

• Useful for the destruction of a wide variety of contaminants.
• The destruction of target pollutants is possible.
• Less expensive.
• Environment friendly

➤ Disadvantages of bioremediation

• Bioremediation is limited to those compounds that are biodegradable. Not all compounds are susceptible to rapid and complete degradation.
• Biological processes are often particular.
• It is difficult to extrapolate from the bench and pilot-scale studies to full-scale field operations.
• Bioremediation often takes a longer time than another treatment process.

Environmental Pollution and Health

(i) First

• Pollution inventory and apportionment studies that assess different sources' relative contribution are looked at in isolation and not within a coherent framework of health protection.
• What ultimately should drive policy is not just what source is emitting more but which source is likely to lead to greater exposure to health-damaging pollutants.
• Globally, studies show vehicles contribute from a quarter to close to half of the particulates in cities.

(ii) Second

• Our scientists do not say that people are exposed to much higher health-damaging pollutants than ambient conditions.
• With each breath, we inhale three-four times more pollutants than the ambient air concentration.
• Exposure to vehicular fumes is highest on the road and up to 500 metres from there. The majority in our cities lives in that zone.

(iii) Third

• People are exposed to a mixture of pollutants whose combined effect has serious health impact. The benefits are greater when pollution sources are regulated for multi-pollutants.
• Delhi's air is thick with particulate matter, nitrogen oxides, ozone and air toxins.
• There is merit in NGT's focus on diesel emissions, a multi-pollutant mixture classified as a class one carcinogen for its strong link with lung cancer. Exposure to toxins should be eliminated.

(iv) Fourth

• Our air quality policies are cut off from the reported reality in the health sector.
• India is experiencing a rapid health transition, with a large and rising burden of chronic diseases, estimated to be more than half of all deaths and years lost to illness. 
• Cancer, stroke, and chronic lung diseases are now major public health problems strongly influenced by air pollution.