HSBTE IInd Semester Water and Soil Pollution.

Water Pollution: Impurities in water, Cause of water pollution, Source of water pollution. Effect of water pollution on human health, Concept of DO, BOD, COD. Prevention of water pollution-Water treatment processes, Sewage treatment. Water quality standard.

Soil Pollution: Sources of soil pollution, Effects and Control of soil pollution, Types of Solid household, Industrial, Agricultural, Biomedical, Disposal of solid waste, Solid waste management E-waste, E-waste management. Unit-III.

Unit-III

Water and soil pollution

WATER POLLUTION

The mixing of foreign substances in water or any factor that makes water unfit for human or animal consumption is called water pollution. Water pollutants may be physical, chemical, or biological.

• 1. Physical: Oil spills and heat (hot water) are physical pollutants.

• 2. Chemical: Organic wastes, pesticides such as DDT, and inorganic chemicals such as arsenic, lead, nickel, mercury, nitrates, fluorides, phosphates, etc are chemical pollutants.

• 3. Biological: Pathogens such as bacteria, viruses, protozoa, algae, helminths, etc are biological pollutants.

Impurities in water: Impurities in water come from several sources. These sources may be natural or human-made. Most of the impurities are from industries, hospitals, residential areas, etc. These impurities can be categorized into the following four categories (Types of impurities):

• 1. Pathogens: Microorganisms that cause diseases are called pathogens. Some examples of pathogens present in water are Salmonella typhi (typhoid fever), Entamoeba histolytica (Amoebiasis), shigella bacteria (dysentery), Escherichia coli, salmonella, nor virus or rotavirus (these all cause diarrhea), Vibrio cholerae (Cholera), etc. Mostly these pathogens enter the water from sewage water.

• 2. Suspended impurities: Suspended particles in water are finely divided particles that remain dispersed in insoluble form in water. Sand, silt, clay, etc are considered suspended impurities in water.

• 3. Colloidal impurities: Colloids or colloidal solutions contain fine insoluble particles visible only under a microscope. Size particles from 1 nanometer to 1000 nanometer (1 nanometer to 1 micrometer). These particles may be organic matter or inorganic matter. Most inorganic matter are clay. Organic matters are human excreta, bacteria, etc.

• 4. Solutes in water: Both inorganic and organic compounds in solution form are present as impurities in water.

• 5. Organic wastes: These are industry wastes, human excreta, bacteria, viruses, and other microorganisms. They may be in solution form, colloid form or suspension form.

• 6. Inorganic wastes: They enter water from industries, rainfall, bathroom water, etc.

• 7. Radioactive wastes: They mainly enter water from atomic power plants, nuclear reactors, etc.

Cause of water pollution:

Water pollutants enter the water from several sources. These water pollutants cause water pollution..

1. Organic wastes: Organic wastes from industrial and domestic sources enter rivers through the sewage system. They pollute rivers and increase biochemical oxygen demand (BOD) in river water.

Some sewage systems are discharged in fields or dumped into pits. This water pollutes (contaminate) groundwater.

2. Inorganic wastes: They enter the water from domestic wastes, industrial wastes, rainfalls, etc.

3. Radioactive wastes: Atomic power plants, nuclear reactors, nuclear bombs, mining and processing of uranium, etc release radioactive wastes. They are dumped in underground tanks or in seawater. They decompose very slowly and pollute underground water. Some radioactive dust from mines enters the river. This pollutes river water.

4. Pathogens: Most pathogens enter water from human excreta, animal excreta, and organic waste decomposition into river or underground water.

5. Heat: Oxygen level in warm water decreases. Most fishes cannot survive at temperatures above 33oC. Effluents from thermal power plants or nuclear power plants have high temperatures. Their disposal into rivers increases river water temperature. This contributes to pollute river water.

6. Insoluble Solids: Rainwater brings silt into river water from the soil. It also settles down tiny dust particles in the air into river water. This increases the turbidity of river water. Turbidity reduces sunlight which affects aquatic plants' photosynthesis and their death. These all contribute in water pollution.

Sources of water pollution:

Sources of water pollution can be divided into two groups or types. These are natural sources and man-made sources.

1. Natural sources: Mainly three pollutants soil particles, minerals, and organic matter are from natural sources.

1. Soil erosion produces clay and soil particles. They enter the water body as pollutants.

2. Rock and soils release minerals that pollute the water body.

2. Organic matter, dead animal bodies, and fallen leaves and trees pollute water body

3. Man-made sources: Man-made sources to pollute water are

• 1. Organic compounds from domestic wastes, sewage systems, industrial effluents, dead animal body waste from slaughters, etc.

• 2. Soaps and detergents

• 3. Runoff water containing pesticides, and fertilizers from agricultural land.

• 4. Oil spills

Sources of surface water pollution can be divided into the following two sources: point source and nonpoint source (diffusion source).

1. Point source: The source of pollutants that supply a regular flow of pollutants into water is called a point source. It is a fixed source of polluted water. eg. Municipal wastewater, industrial wastewater, oil spills. They all pollute water bodies such as rivers, ponds, groundwater, etc. They are considered man-made pollutants (Anthropogenic pollutants). It can be minimized by using treatment plants.

Some natural sources of water pollution are soil erosion and organic matter on the banks of rivers and ponds.

2. Nonpoint source (Diffusion source): The source of pollutants can not be identified. They are present on large areas of land. Some part of pollutants diffuses easily to pollute surface water eg. surface run off water. eg. Fertilizers and pesticides in agricultural land. It is also an example of a man-made source of water pollution.

Effect of water pollution on human health:

Water is the universal solvent. It is an essential resource for life on Earth. Water pollution makes water unsafe for consumption, cooking, swimming, washing, and cleaning. It develops waterborne infectious and noninfectious diseases in humans, animals, and plants.

• · Water-borne infectious diseases:

  Pathogens in water develop deadly diseases in humans. They develop gastrointestinal diseases such as cholera, diarrhea, amoebiasis, abdominal pain, nausea, vomiting, and dehydration. Some cause hepatitis and paralysis. These pathogens may be bacteria, viruses, and parasites. They are dangerous to infants, young children, and disabled persons. They are major causes of morbidity and mortality worldwide.

  • Bacterial diseases:

  • 1. Diarrhea: Campylobacter jejuni is a major cause of diarrhea.

  • 2. Cholera: Vibrio cholerae is the cause of cholera

  • 3. Shigellosis: Shigella bacteria affect the intestine lining.

  • 4. Salmonellosis: Salmonella, Typhoid fever.

• Viral diseases:

  • 1. Hepatitis: Virus infects the liver. It develops jaundice, loss of appetite, high fever, and fatigue. It may cause death.

  • 2. Poliomyelitis: Poliomyelitis virus is the cause of this disease. Sore throat, nausea, constipation or diarrhea, and fever are the main symptoms of it. Sometimes paralysis may also occur.

  • 3. Gastroenteritis: Rotavirus, adenovirus, and calicivirus are major causes of this disease.

  • Parasitic diseases:

  • 1. Amoebiasis: Entamoeba histolytica affects the stomach lining.

  • 2. Giardiasis (Travelers disease): Giardia lambia is the cause of this disease. It affects the intestinal lining. Bloating excess gas, watery diarrhea, and weight loss are symptoms of this disease.

  • 3. Malaria: It is also due to stagnant water.

• ·Water-born noninfectious diseases:

  Disinfectants, disinfection by-products, pesticides, fertilizers, heavy metals, and radioactive compounds in water develop noninfectious diseases in humans. These toxic products develop cancer, cardiovascular diseases, liver diseases, renal diseases, neurological disorders, reproductive problems, etc.

1. Liver damage: Heavy metals cause liver damage cirrhosis.

2. Reproductive disorders: Pollutants such as perchlorate affect sex hormone secretion, sexual maturation, and reproduction.

3. Oncological disorders: Arsenic, fluoride, nitrates, lead, etc in water develop oncological disorders of GIT, kidney, and reproductive system.

4. Arsenic causes liver damage, skin cancer, and vascular diseases,

5. Fluorides causes bone deformation, yellow teeth, teeth deformation, spinal cord damage,

6. Lead causes CNS damage

7. Nitrates causes blue baby syndrome

8. Petrochemicals cause cancer.

9. Neurological toxicity: Lead

10. Microplastics: They enter into water body from dumped plastics. Their negative effects on human body are still under study.

Concept of DO, BOD, and COD

· DO (Dissolved Oxygen): The amount of free non-compound oxygen dissolved in water available for aquatic organisms is called dissolved oxygen or DO. Free non-compound oxygen is not bound with other elements. Bounded oxygen molecule in water (H 2O) is not considered as DO. Dissolved oxygen enters the water from the air by diffusion at the water's surface. DO tells about water quality. Cold water holds more oxygen than warm water. DO below 4 mg/liter is considered as heavy water pollution. DO below 8 mg /liter is considered polluted water.

· BOD (Biochemical oxygen demand): BOD indicates the amount of dissolved oxygen needed by microorganisms to decompose organic matter in water. It is expressed as oxygen in mg/liter of water. BOD below 1500 mg/liter is considered low water pollution. BOD between 1500 mg /liter and 4000 mg/liter is considered medium water pollution. BOD above 4000 mg/liter is high in water pollution.

· COD (Chemical oxygen demand): COD indicates the amount of dissolved oxygen needed to oxidize all oxidizable materials present in water. The main difference between COD and BOD. COD indicates the presence of all oxidizable materials in a given sample of water.BOD indicates the presence of only organic matter present in a given sample of water.

Application of COD:

• A. Determine the concentration of oxidizable matter in wastewater,

• B. Determine water quality

• C. Determine wastewater treatment effect.

Prevention of water pollution: Water pollution is prevented by adopting the following:

• 1. Prohibition of bathing and washing in drinking water supply sources such as ponds, water steams, etc.

• 2. Water treatment of sewage water, industrial waste, etc

• 3. Controlled use of fertilizers and pesticides,

• 4. Cooling of hot industrial waste before its discharge,

• 5. Recycling of solid waste,

• 6. Storage of domestic and industrial wastes for some duration. Release it after the decomposition of organic waste by bacteria,

• 7. Release of polluted into sewage after proper treatment to make it harmless,

• 8. Release of polluted water after removal of heavy metals from it,

• 9. Oxidation of radioactive products before disposal of industrial waste.

Water treatment process:

Sewage and industrial wastes are properly treated to make them harmless for human beings and the environment. Objectives of water treatment are

• 1. Production of water safe for the environment

• 2. Production of water safe for human beings

• 3. Production of water appealing to human beings,

• 4. Production of a water treatment facility is economical and easy to operate.

· Sewage treatment: Sewage pollutes the water body. It can be made harmless by its proper treatment. Sewage water treatment consists of three steps: Primary treatment, secondary treatment, and tertiary treatment.

• Primary treatment: It is a physical process to separate suspended pollutants from sewage discharge. It consists of sedimentation, floating, fragmentation, and filtration. Sediment collected after primary treatment is called primary sludge. The rest portion is called effluent. Primary sludge is used to generate biogas.

• Secondary treatment: Effluent contains a high concentration of organic matter and other dissolved matter. Secondary treatment helps to remove them. Secondary treatment is also called biological treatment. Microbial flora is used to decompose organic matter. It is carried out in the following two ways:

• 1. Anaerobic secondary treatment: Sludge is stored in a large tank called a sludge digestor or bioreactor. Anaerobic microbes decompose macromolecules such as proteins, lipids, polysaccharides, etc. At the end of decomposition, it releases methane gas and water.

• 2. Aerobic secondary treatment: It consists of two methods: the trickling filter method and the activated sludge method.

  • Tricking filter method: Effluent is passed through a bed of small stones. Bed of small stones have microbial flora. It consumes organic matter present in effluent. At the bottom of the small stone bed, effluents are collected. It is further cleaned by chlorination. Chlorination kills microbes present in effluent obtained after secondary treatment.

  • Activated sludge method: Effluent after primary treatment is aerated in a large tank containing microbial flora mostly algae and bacteria. Algae produces oxygen for bacteria and bacteria decompose organic matter present in effluent. Then effluent is chlorinated to kill microbes.

• Tertiary treatment: Chlorinated effluent has a large concentration of salts. They are precipitated by using alum, ferric chloride, and lime. It removes 90% of solids and 90% of phosphates and nitrates. Then water is released for irrigation.

· Industrial effluents: They consist of acid and alkali neutralization, toxic compound oxidation, colloid coagulation, metallic compounds precipitation, and cooling of industrial waste discharge.

Water quality standard: Water quality standards are used to judge the quality of water. Water quality standards give two values that are target value and the maximum admissible concentration of solutes in water. The main aim of water quality standards is to prevent waterborne diseases in human beings. Many developed countries specify water quality standards.

WHO recommends some guidelines that limit the constituents in water especially those that have harmful effects on the human body.

Arsenic: 10µg/L. Barium: 10 µg/L. Chromium: 50 µg/L. Fluoride 1500 µg/L. Selenium 40µg/L. Uranium 30 µg/L. Organic matters such as Carbon tetrachloride 4 µg/L. Benzene 10 µg/L. Dichloromethane 20 µg/L. xylene 500µg/L. etc.

SOIL  POLLUTION:

Alteration in soil composition by the addition or removal of substances that reduce soil productivity is called soil pollution. Substances that reduce the productivity of soil are called soil pollutants.

Source of soil pollution: There are two types of soil pollution. These are positive soil pollution and negative soil pollution.

A decrease in soil productivity due to the addition of pollutants in the soil is called Positive soil pollution. The source of positive soil pollution is Soil salination. The concentration of salts in soil is called Soil salination. It may be due to poor drainage, saline irrigation water, use of alkaline fertilizers, capillary action, weathering of saline rocks, etc.

Reduction of mineral contents in the top layer of soil decreases soil fertility. This is called negative soil pollution. Sources of negative soil pollution are soil erosion, sand shifting, intensive agriculture, faulty irrigation, overgrazing, etc.

The following soil pollutants alter the physical, chemical, and biological properties of soil to reduce soil productivity:

• 1. Chemicals: Industrial wastes have several chemicals that affect soil productivity. eg. Lead, copper, tin, mercury, cadmium, acid, alkali, cyanide, etc

• 2. Pesticides: Insecticides, herbicides, and fungicides are used in agriculture. They decrease soil productivity.

• 3. Fertilizers and manure: They are used in agriculture to increase soil productivity. However, their excess use affects soil productivity adversely.

• 4. Radioactive substances: Radioactive dusts enter water from radioactive compound mining, nuclear power plants nuclear bombs. Radioactive polluted water is used in agriculture. These radioactive particles enter the soil and decrease soil productivity.

• 5. Domestic Waste: Human beings add these pollutants to the soil as food waste, paper waste, plastic waste, cloth waste, leather waste, etc.

• 6. Electronic waste (E-Waste): Unused and irreparable computers, mobile television, tablets, etc generate E-waste.

• 7. Others: Air pollutants and water pollutants at last enter soil as soil pollutants.

Effect of soil pollution:

The process of forming soil is very slow. Thus soil is considered as non-renewable. Soil pollution develops acute problems for life on earth.

A. Chemicals and pesticides kill essential soil microorganisms. This decreases soil fertility.

B. Chemicals, pesticides, and fertilizers enter crops and plants. These are consumed by human beings and animals. This affects human and animal health adversely.

C. Use of fertilizers in excess amounts or for long duration decreases soil fertility.

D. Human and animal excreta improve soil fertility. But they contain pathogens. These pathogens enter the human and animal bodies after consuming these plants especially vegetables. These pathogens develop disease.

Radioactive waste, e-waste, etc enter human and animal bodies through the food chain. This affects plant, human, and animal health adversely.

Control of soil pollution:

Pollutants are divided into three categories. These are

1. Recyclable pollutants,

2. Biodegradable pollutants, and

3. Non-biodegradable (non-cyclable) pollutants.

Soil pollution is controlled by various methods such as recycling, burning, dumping, and pollutant production reduction.

• 1. Recycling: There are various domestic and industrial wastes that are recycled to be reused. Such as tins, cans, other metals, glass, plastic, paper, cardboard, cloth, etc.

• 2. Burning: Non-biodegradable wastes and non-recyclable wastes are burnt. However, burning is not preferred because it pollutes the air and produces an offensive odor. These problems can be minimized by using incineration and pyrolysis. Incineration is the burning of wastes under a closed chamber at temperatures 900 to 130○C in the presence of oxygen. Pyrolysis is the burning of wastes in a closed chamber at a temperature of 1650 degrees C in the absence of oxygen.

• 3. Dumping: Dumping is the collection of wastes in low-lying land. It may be open dumping or sanitary dumping. Open dumping is also called open landfilling. Sanitary dumping is also called sanitary landfilling. It means wastes are collected in low-lying land and then covered with a layer of earth.

• 4. Reduction of pollution at source: Domestic wastes are used for manure, compost, and biogas production.

• 5. Construction materials: Several industrial wastes such as fly ash is used to construct roads, make bricks and other construction materials.

Types of solid wastes:

There are several types of solid waste depending upon their sources.

1. Household waste: It is also known as residential waste or domestic waste. These are disposable waste generated by day-to-day activities in residential areas, hotels, motels, etc. It includes garbage, trash, sanitary waste septic tanks, etc. Household waste may be hazardous or non-hazardous wastes.

Wastes capable of producing harmful effects on humans, animals, or the environment are called Hazardous wastes. They include Pesticides, fertilizers, dyes, toxic chemicals, metals, inflammable chemicals, etc Even hospital solid waste also comes under hazardous waste. Non-hazardous wastes are not dangerous to humans or animals but may produce harm to the environment. They include food scrap, paper, cardboard, bottles, cans, cloth, leather, plastics, garden waste, etc.

Household wastes are also considered as municipal wastes.

2. Agriculture wastes: Agriculture wastes are unwanted waste generated from agricultural activities related to crop and animal rising. They includes paddy husk, cereal stems, coconut fibrous parts, tobacco wastes, crushed sugar cane, animal excreta, etc. Most of them are used to make compost or paper and boards.

3. Biomedical wastes (Hospital wastes): Wastes generated during diagnosis, treatment, and vaccination of human and animal diseases is called biomedical wastes. They contain infectious or partially infectious components.

WHO categorized biomedical wastes into eight categories.

• 1. Infectious wastes: They contain infectious microorganisms.

• 2. Pathological wastes: They contain human or animal body parts such as tissues, blood, body fluids, etc.

• 3. Pharmaceutical wastes: They contain unused drugs, expired drugs, disposable syringes, etc.

• 4. Radiological wastes: They contain radioactive dust and residues.

• 5. Chemical wastes: They contain wastes from machines, disinfectants, batteries, etc.

• 6. Genotoxic wastes: They contain toxic wastes

• 7. Sharps: They contain needles, razors, broken glass pieces, etc.

• 8. Other wastes: They are Non-hazardous wastes such as used bandages, cloth, dressings,

Disposal of solid wastes: Solid waste disposal means to remove, recycle, or destroy to decrease pollution and hazards to the environment. There are several methods to dispose of solid wastes such as landfill, incineration, pyrolysis, biogas generation, compost formation, and recycling.

· Landfill: It is most commonly used to dispose of solid non-recyclable wastes. Solid wastes are cut into smaller pieces, pressed to form a compact mass (waste compaction), and then filled in low-lying land. Then layer of soil is spread over it to cover it. This part of the land is not used for the next 20 years for activities like building constructions, agriculture, etc. Normally a park or playground is developed over this land.

· Incineration and Pyrolysis: Incineration is the burning of wastes under a closed chamber at temperatures 900 to 130oC in the presence of oxygen. Pyrolysis is the burning of wastes in a closed chamber at a temperature of 1650 degrees C in the absence of oxygen. These processes decrease the waste quantity, however, there will be disposal of residues is a problem. It further pollutes soil, water, and air. These processes are also very costly and consume large amounts of energy.

· Biogas generation: Biodegradable wastes are animal waste, municipal waste, organic wastes from industries, unused vegetables and fruits, etc. They are decomposed by a microorganism that produces biogas. Biogas is used as fuel and other remaining materials are used as manure.

· Compost formation: Municipal wastes such as food wastes, peels of vegetables and fruits, unused vegetables and fruits, and garden wastes are buried under soil. Microorganisms decompose them to form compost. White worms, earthworms, and other worms are also used to decompose these organic wastes. They form vermicompost. Compost is used as manure in agriculture and gardening.

· Recycling: Recycling reduces the garbage. It also protects natural resources. Examples of recycling are the Conversion of agricultural waste into paper, board, and electricity, the conversion of paper waste to recycled paper, and the conversion of dung to biogas. Conversion of industrial water waste to water for gardening. etc.

Solid waste management:

Solid waste management includes the collection, treatment, and disposal of solid wastes.

1. Collection and transportation: Proper solid waste collection protects the environment, safety, and public health. Mostly it is carried out by the municipality by using special vehicles. This vehicle can be loaded from the left side, right side, and rear side. The compaction of solid wastes reduces the volume of solid wastes. Collection is mostly carried out daily or at least every week. The size of collected garbage is reduced by using a garbage grinder. Collection of garbage into two containers is preferred. One is for recyclable garbage and the other is non-recyclable garbage.

2. Solid waste treatment: Discussed under control of solid waste.

3. Solid waste disposal: Already discussed.

The following help to manage solid wastes.

• 1. Recycling of wastes

• 2. Controlled use of fertilizers and pesticides

• 3. Use of biological methods to control pests,

• 4. Forestation,

• 5. Use of pneumatic conveyors to transport garbage from the city to disposal sites,

• 6. Use of modern techniques in mining

• 7. Following proper crop pattern

• 8. Using low-lying lands for solid waste disposal.

E-wastes:

Unwanted, unused, not working electrical and electronic products are E-waste. Electrical Electronic equipment for reuse, resale, disposal, or recycling are also considered as e-waste. Computers are 70% of total E-waste, telecom products are 12% of total E-waste, Medical equipment is 7% of total E-waste, and Electrical equipment is 8% of total E-waste. E-waste consists of

• 1. Plastics,

• 2. Valuable metals such as gold, copper, silver, platinum, etc

• 3. Toxic substances such as lithium, mercury, nickel, selenium, arsenic, barium, cadmium, cobalt, etc.

Examples of E-wastes:

• i. E-waste as home appliances: Microwaves, electric cookers, electric heaters, Electric fans, home entertainment devices, CFL, compact fluorescent lamps, etc.

• ii. E-waste as entertainment devices: Stereo, DVD player, ray player, television, photocopiers, fax machines, printer, etc

• iii. E-waste as information technology products: Desktop computers, laptops, hard drives, cell phones, smartphones, landline phones, etc.

• iv. Medical equipment: Electronic BP apparatus, autoclaves, BOD incubators, dialysis machines, defibrillators, etc.

E-waste management in India:

E-waste is hazardous to humans and the environment. In India, e-waste management is regulated by E-waste management rules -2016. This rule states that producers, manufacturers, dealers, and refurbishers are accountable for collecting e-waste and their exchange. Some highlights of this rule are

• 1. A local body shall be established in cities with a population of more than one lakh within two years,

• 2. A local body shall be established in cities with a population of less than one lakh within three years,

• 3. Old dump sites shall be shut down within five years

• 4. The municipality shall be responsible for managing garbage.

It is also the responsibility of consumers to act judiciously while using electrical and electronic equipment (EEE).

• a. Life span of product: Always choose EEE with a long life span. It is common practice for manufacturers to manufacture products having shorter life spans.

• b. Educate yourself: Do some research to find out the raw materials used to manufacture EEE. Avoid to purchase EEE containing toxic chemicals,

• c. Environment label: Select a product having a certificate from the government about the environment-friendly product.

• d. Limit EEE: Purchase extra EEE only if it is required otherwise use EEE with multifunction activity.

• e. Kids awareness: Teach kids and make them aware of recycling of EEE.

Dr Pramila Singh.