Chemical Engineering DepartmentSchool of Science, Institute of Technology

Nirma University

Subject: EPCSM

Handout 1, 2, 3:

IntroductionAtmosphere: It is Gases enveloping earth, planets etc is. There is no further classification.Environment: Environment is surrounding; circumstances affecting person’s life. Globally environment is classified asi) Physical Environmentii) Biotic EnvironmentPollution(Impure): It is the result of the action or present of Pollutant (Substance or materials referred as impurity or contaminants in Environment where it is considered to have deleterious (harmful) effects.)Waste: These are worthless materials for human life. It is the result of man’s interaction with his physical and biological surrounding. If not removed, they reduce the quality of environment.Pollutant: A substance or effect is normally considered to be a pollutant“If it adversely alters the environment by changing the growth of species

Solid Pollutants: Dust, Lead, Urea Phosphate, etc. Medical Waste, Fly ash. Semi Solid pollutants: Greases, Gels, Dispersed Organics etc. Medical Waste,

Sludge. Liquid pollutant: Waste Water from manufacturing activities, Sanitary Water. Gas Pollutant: CO, CO2, NH3, Nox (Oxides of Nitrogen), SO2, Hydrocarbon Vapors.

Pollution Control and Waste Management Pollution Prevention

Pollutants are controlled by various kind of waste treatment methods.

Pollutants are prevented at their sources through integrated measures.

Pollution control is evaluated when process and products have been developed and when problems arise

Pollution prevention is an integrated part of product and process development

Pollution control and environmental improvements are always considered cost factors for company

Pollutants and wastes are considered to be potential resources into useful product and by products, providing they are non-hazardous

Environment challenges are to be addressed by environmental experts such as waste managers.

Environment improvement challenges should be the responsibility of people throughout the company including workers, process and design engineers.

Environmental improvements are to be accomplished with techniques and technology

It includes non-technical and technical approaches

Environmental improvement measure should fulfil standards set by the authorities

Environmental improvement measure should be a process of working continuously to achieve higher standards.

Concept of Cradle to Cradle

• Cradle to Cradle is a design paradigm based on the idea of nutrient management, which enables product materials to be upcycled again and again. Materials are categorized as either “biological nutrients” or “technical nutrients”. Biological nutrients are biodegradable and will easily re-enter water and soil whereas technical nutrients will continually circulate as pure and valuable materials within closed-loop industrial cycles.

Handout 4, 5, 6:Ecology:• The word ecology derived from the Greek word 'Oikos meaning habitation, and logos

meaning discourse or study, implies a study of the habitations of organisms.• Ecology is the branch of science which studies the interactions between organisms & their

environment.

Level of Organisation:Species:• Similar organisms that can reproduce among themselves in their environment.Population:• A population is made of many of the SAME KIND of species that live in the same area .• Compete with each other for food, space, water etc.Community:• It is made of many groups of populations that interact in that area

Forest: population of trees, population of birds, population of animals etc.Lake: Population of insects, population of fish, population of algae etc.Ecosystem:• An ecosystem includes all living organism in that area and all the non living things that

affect it.Forest ecosystem includes grass, animals, sunlight, wind etc.

Biosphere:• The part of the earth that supports all living organisms, made up of all earths

ecosystems

Hydrological Cycle

The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. The carbon cycle is usually thought of as four major reservoirs of carbon interconnected by pathways of exchange. These reservoirs are: The plants, The terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon. The oceans, including dissolved inorganic carbon and living and non-living marine biota, the sediments including fossil fuels.The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth, but the deep ocean part of this pool does not rapidly exchange with the atmosphere.

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. It is a cycle which includes gaseous components.

Earth's atmosphere is approximately 78-80% nitrogen,[1] making it the largest pool of nitrogen. Nitrogen is essential for many biological processes; it is crucial for any life here on Earth. It is in all amino acids, is incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. In plants, much of the nitrogen is used in chlorophyll molecules which are essential for photosynthesis and further growth.

• The Sulfur cycle: Atmosphere receives sulphur through bacterial emission (H2S), fossil fuel burning (SO2), and volcanic emissions (H2S, SO2, SO4

2- ). • Most of the sulphur in the form of SO2 or H2S is converted to sulphur trioxide SO3,

which dissolves in water droplets to form sulphuric acid. The sulphates and the acid then precipitate with rain. 

Major Current Environmental problems:• Pollution: Pollution of air, water and soil require millions of years to recoup. Industry and

motor vehicle exhaust are the number one pollutants. Heavy metals, nitrates and plastic are toxins responsible for pollution. While water pollution is caused by oil spill, acid rain, urban runoff; air pollution is caused by various gases and toxins released by industries and factories and combustion of fossil fuels; soil pollution is majorly caused by industrial waste that deprives soil from essential nutrients.

• Global Warming: Climate changes like global warming is the result of human practices like emission of Greenhouse gases. Global warming leads to rising temperatures of the oceans and the earth’ surface causing melting of polar ice caps, rise in sea levels and also unnatural patterns of precipitation such as flash floods, excessive snow or desertification.

• Overpopulation: The population of the planet is reaching unsustainable levels as it faces shortage of resources like water, fuel and food. Population explosion in less developed and developing countries is straining the already scarce resources. Intensive agriculture practiced to produce food damages the environment through use of chemical fertilizer, pesticides and insecticides. Overpopulation is one of the crucial current environmental problem.

•  Natural Resource Depletion: Natural resource depletion is another crucial current environmental problems. Fossil fuel consumption results in emission of Greenhouse gases, which is responsible for global warming and climate change. Globally, people are taking efforts to shift to renewable sources of energy like solar, wind, biogas and geothermal energy. The cost of installing the infrastructure and maintaining these sources has plummeted in the recent years.

• Waste Disposal: The over consumption of resources and creation of plastics are creating a global crisis of waste disposal. Developed countries are notorious for producing an excessive amount of waste or garbage and dumping their waste in the oceans and, less developed countries. Nuclear waste disposal has tremendous health hazards associated with it. Plastic, fast food, packaging and cheap electronic wastes threaten the wellbeing of humans. Waste disposal is one of urgent current environmental problem.

• Climate Change: Climate change is yet another environmental problem that has surfaced in last couple of decades. It occurs due to rise in global warming which occurs due to increase in temperature of atmosphere by burning of fossil fuels and release of harmful

gases by industries. Climate change has various harmful effects but not limited to melting of polar ice, change in seasons, occurrence of new diseases, frequent occurrence of floods and change in overall weather scenario.

• Loss of Biodiversity: Human activity is leading to the extinction of species and habitats and loss of bio-diversity. Eco systems, which took millions of years to perfect, are in danger when any species population is decimating. Balance of natural processes like pollination is crucial to the survival of the eco-system and human activity threatens the same.

• Deforestation: Our forests are natural sinks of carbon dioxide and produce fresh oxygen as well as helps in regulating temperature and rainfall. At present forests cover 30% of the land but every year tree cover is lost amounting to the country of Panama due to growing population demand for more food, shelter and cloth. Deforestation simply means clearing of green cover and make that land available for residential, industrial or commercial purpose.

• Ozone Layer Depletion: The ozone layer is an invisible layer of protection around the planet that protects us from the sun’s harmful rays. Depletion of the crucial Ozone layer of the atmosphere is attributed to pollution caused by Chlorine and Bromide found in Chlorofloro carbons (CFC’s). Once these toxic gases reach the upper atmosphere, they cause a hole in the ozone layer, the biggest of which is above the Antarctic. The CFC’s are banned in many industries and consumer products. Ozone layer is valuable because it prevents harmful UV radiation from reaching the earth. This is one of the most important current environmental problem.

• Acid Rain: Acid rain occurs due to the presence of certain pollutants in the atmosphere. Acid rain can be caused due to combustion of fossil fuels or erupting volcanoes or rotting vegetation which release sulfur dioxide and nitrogen oxides into the atmosphere. Acid rain is a known environmental problem that can have serious effect on human health, wildlife and aquatic species.

• Water Pollution: Clean drinking water is becoming a rare commodity. Water is becoming an economic and political issue as the human population fights for this resource. One of the options suggested is using the process of desalinization. Industrial development is filling our rivers seas and oceans with toxic pollutants which are a major threat to human health.

• Urban Sprawl: Urban sprawl refers to migration of population from high density urban areas to low density rural areas which results in spreading of city over more and more rural land. Urban sprawl results in land degradation, increased traffic, environmental issues and health issues. The ever growing demand of land displaces natural environment consisting of flora and fauna instead of being replaced.

• Public Health Issues: The current environmental problems pose a lot of risk to health of humans, and animals. Dirty water is the biggest health risk of the world and poses threat to the quality of life and public health. Run-off to rivers carries along toxins, chemicals and disease carrying organisms. Pollutants cause respiratory disease like Asthma and cardiac-vascular problems. High temperatures encourage the spread of infectious diseases like Dengue.

Group Activity based on Environmental problems: Students has to select any one problem and discuss their views how to overcome this problems in front of other groups.

Lecture 7, 8:Solid Waste ManagementIntroduction of solid waste treatments and management:What is solid waste????????

Objective of solid waste management:

The objective of solid waste management is to reduce the quantity of solid waste disposed off on land by recovery of materials and energy from solid waste. This in turn results in lesser requirement of raw material and energy as inputs for technological processes. Such techniques and management programs have to be applied to each and every solid waste generating activity in a society to achieve overall minimization of solid waste.

Effective management of solid waste:Effective solid management systems are needed to ensure better human health and safety. They must be safe for workers and safeguard public health by preventing the spread of disease. In addition to these prerequisites, an effective system of solid waste management must be both environmentally and economically sustainable.

Environmentally sustainable: It must reduce, as much as possible, the environmental impacts of waste management.

Economically sustainable: It must operate at a cost acceptable to community.

Waste management systems and their impact on environment:

How to manage the solid waste:

Collection of municipal solid wastes Segregation of municipal solid wastes Storage of municipal solid wastes Transportation of municipal solid wastes Processing of municipal solid wastes Disposal of municipal solid wastes

Handout 9, 10:

Source Typical waste generators Types of solid waste

Residential Single and multifamily dwellings Food wastes, paper, cardboard, plastics, textiles, leather, yard wastes, wood, glass, metals, ashes, special wastes (e.g., bulky items, consumer electronics, white goods, batteries, oil, tires), and household hazardous wastes.).

Industrial Light and heavy manufacturing, fabrication, construction sites, power and chemical plants.

Housekeeping wastes, packaging, food wastes, construction and demolition materials, hazardous wastes, ashes, special wastes.

Commercial Stores, hotels, restaurants, markets, office buildings, etc.

Paper, cardboard, plastics, wood, food wastes, glass, metals, special wastes, hazardous wastes.

Institutional Schools, hospitals, prisons, government centers. Same as commercial.

Construction and demolition

New construction sites, road repair, renovation sites, demolition of buildings

Wood, steel, concrete, dirt, etc.

Reuse

Reduce waste

Recycle

Incineration with energy recovery

Open dumpLandfillIncineration without energy recovery

Maximum impact on the environment

Minimum impact on environment

Municipal services

Street cleaning, landscaping, parks, beaches, other recreational areas, water and wastewater treatment plants.

Street sweepings; landscape and tree trimmings; general wastes from parks, beaches, and other recreational areas; sludge.

Process (manufacturing, etc.)

Heavy and light manufacturing, refineries, chemical plants, power plants, mineral extraction and processing.

Industrial process wastes, scrap materials, off-specification products, slay, tailings.

Agriculture Crops, orchards, vineyards, dairies, feedlots, farms.

Spoiled food wastes, agricultural wastes, hazardous wastes (e.g., pesticides).

Transformation Processes:

Transformation process Transformation means or methods

Transformation or principal conversion products

PhysicalComponent separation Manual and/or mechanical

separationIndividual components found in commingled municipal waste

Volume reduction Application of energy in the form of a force or pressure

The original waste reduced in volume

Size reduction Application of energy in the form of shredding, grinding or milling

The original waste components altered in form and reduced in size

ChemicalCombustion Thermal oxidation Carbon dioxide, sulphur

dioxide, other oxidation products, ash

Pyrolysis Destructive distillation A gas stream containing a variety of gases, tar and/or oil, and a char

Gasification Starved air combustion A low-Btu gas, a char containing carbon and the inerts originally in the fuel, and pyrolytic oil

BiologicalAerobic composting Aerobic biological conversion Compost (humus-like

material used as a soil conditioner)

Anaerobic digestion Anaerobic biological conversion

Methane, carbon dioxide, trace gases, digested humus or sludge

Anaerobic composting Anaerobic biological conversion

methane, carbon dioxide, digested waste

Handout 11, 12: Thermal conversion technologies: Thermal processing of solid waste can be defined

as the conversion of solid waste into gaseous, liquid and solid conversion products, with the concurrent or subsequent release of heat energy.

The mainly processing systems are:o Combustion o Gasificationo Pyrolysis

Pyrolysis systems: Pyrolysis is the thermal processing of waste in the complete absence of oxygen. This process is highly endothermic require an external heat source. So destructive distillation is often used in place of pyrolysis.Gasification is the general term used to describe the process of partial combustion in which a fuel is deliberately combusted with less than stoichiometric air.PROCESS DESCRIPTION: Solid waste collected by truck is dumped into waste pit and stored temporally. It is then fed into a gasifier through an air-tight feeder. In the gasifier the waste is pyrolytically decomposed into combustible gas, incombustible materials, and ash. In the melting furnace the combustible gas makes complete combustion, reaching temperatures over 1200 ˚C. The ash is melted at this high temperature, forming slag. The slag is continuously discharged, and is water-granulated in the slag cooler. The high-temperature exhaust gas generated in the melting furnace is recovered by the waste heat boiler and used for power generation, or as heat for hot water supply or various facilities that utilize waste heat.The exhaust gas from the waste heat boiler goes through a cooling tower, bag filter, and catalysis tower for treatment, after which it is released through a stack.

Handout 13, 14:Composting:

Landfilling:Site selection criteria:

Land area and volume must be sufficient enough so that the landfill can serve for the projected number of years.

The slope of the region should not be very steep. Irrigation pipelines and water supply wells should not be situated close to the boundary of

the landfill. Residential development should be planned away from the landfill site. Unstable areas posing seismic risks should be avoided. The depth to groundwater and proximity to water wells must be thoroughly analyzed. The visual impact of the landfill must be minimized (landscaping, aesthetic development

of landfill). Agricultural land should not be used for landfill development. The landfill must not cause flood hazard in the event of heavy rainfall.

Life Cycle of a Landfill:

Planning phase: This typically involves preliminary hydro-geological and geo-technical site investigations as a basis for actual design.

Construction phase: This involves earthworks, road and facility construction and preparation (liners and drains) of the fill area.

Operation phase (5 – 20 years): This phase has a high intensity of traffic, work at the front of the fill, operation of environmental installations and completion of finished sections.

Completed phase (20 – 100 years): This phase involves the termination of the actual filling to the time when the environmental installations need no longer be operated. The emissions may have by then decreased to a level where they do not need any further treatment and can be discharged freely into the surroundings. Final storage phase: In this phase, the landfill is integrated into the surroundings for other purposes, and no longer needs special attention.

Handout 15, 16:Water Pollution and Mitigation Measures

Water Pollution

Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater. All water pollution affects organisms and plants that live in these water bodies and in almost all cases the effect is damaging either to individual species and populations but also to the natural biological communities. It occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful constituents.

Point source pollution

Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant, a factory, or a city storm drain. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes.[5] The CWA definition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial stormwater, such as from construction sites.[6]

Non-point source pollution

Non-point source (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often accumulative effect of small amounts of contaminants gathered from a large area. The leaching out of nitrogen compounds from agricultural land which has been fertilized is a typical example. Nutrient runoff in storm water from "sheet flow" over an agricultural field or a forest are also cited as examples of NPS pollution. Contaminated storm water washed off of parking lots, roads and highways, called urban runoff, is sometimes included under the category of NPS pollution. However, this runoff is typically channelled into storm drain systems and discharged through pipes to local surface waters, and is a point source. However where such water is not channelled and drains directly to ground it is a non-point source.

Causes of water pollutionThe specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens, and physical or sensory changes such as elevated temperature and discoloration. While many of the chemicals and substances that are regulated may be naturally occurring (calcium, sodium, iron, manganese, etc.) the concentration is often the key in determining what is a natural component of water, and what is a contaminant.Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff (effluents) and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. Its objective is to produce a waste stream (or treated effluent) and a solid waste or sludge suitable for discharge or reuse back into the environment. This material is often inadvertently contaminated with many toxic organic and inorganic compounds.

Nirma UniversityInstitute of TechnologyHandout – EPCSM_SS

Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use.

Level of wastewater treatment:

Treatment Level DescriptionPreliminary Removal of wastewater constituents such as rags, floatables, grit

and greasePrimary Removal of portion of the suspended solids and organic matter

from the wastewaterSecondary Removal of biodegradable organic matter and suspended solids.

Sometimes nutrients is also removedAdvanced Removal of dissolved and suspended material remaining after

normal biological treatment when required for various water reuse applications.

Handout 17, 18:Treatment of industrial wastewaterThe different types of contamination of wastewater require a variety of strategies to remove the contamination.

Solids removalMost solids can be removed using simple sedimentation techniques with the solids recovered as slurry or sludge. Very fine solids and solids with densities close to the density of water pose special problems. In such case filtration or ultrafiltration may be required. Although, flocculation may be used, using alum salts or the addition of polyelectrolytes.

Oils and grease removalMain article: API oil-water separator

Removal of biodegradable organics

Biodegradable organic material of plant or animal origin is usually possible to treat using extended conventional wastewater treatment processes such as activated sludge or trickling filter. Problems can arise if the wastewater is excessively diluted with washing water or is highly concentrated such as neat blood or milk. The presence of cleaning agents, disinfectants, pesticides, or antibiotics can have detrimental impacts on treatment processes.

Activated sludge processMain article: Activated sludge

A generalized, schematic diagram of an activated sludge process.

Activated sludge is a biochemical process for treating sewage and industrial wastewater that uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material. In general, an activated sludge process includes:An aeration tank where air (or oxygen) is injected and thoroughly mixed into the wastewater.A settling tank (usually referred to as a "clarifier" or "settler") to allow the waste sludge to settle. Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge is removed for further treatment and ultimate disposal.

Nirma UniversityInstitute of TechnologyHandout – EPCSM_SS

Lecture 19, 20:

Trickling filter process

Image 1: A schematic cross-section of the contact face of the bed media in a trickling filter

A typical complete trickling filter system

A trickling filter consists of a bed of rocks, gravel, slag, peat moss, or plastic media over which wastewater flows downward and contacts a layer (or film) of microbial slime covering the bed media. Aerobic conditions are maintained by forced air flowing through the bed or by natural convection of air. The process involves adsorption of organic compounds in the wastewater by the microbial slime layer, diffusion of air into the slime layer to provide the oxygen required for the biochemical oxidation of the organic compounds. The end products include carbon dioxide gas, water and other products of the oxidation. As the slime layer thickens, it becomes difficult for the air to penetrate the layer and an inner anaerobic layer is formed.

Nirma UniversityInstitute of TechnologyHandout – EPCSM_SS

The components of a complete trickling filter system are: fundamental components:

A bed of filter medium upon which a layer of microbial slime is promoted and developed.An enclosure or a container which houses the bed of filter medium.A system for distributing the flow of wastewater over the filter medium.A system for removing and disposing of any sludge from the treated effluent.

The treatment of sewage or other wastewater with trickling filters is among the oldest and most well characterized treatment technologies.

A trickling filter is also often called a trickle filter, trickling biofilter, biofilter, biological filter or biological trickling filter.

Treatment of other organics

Synthetic organic materials including solvents, paints, pharmaceuticals, pesticides, coking products and so forth can be very difficult to treat. Treatment methods are often specific to the material being treated. Methods include Advanced Oxidation Processing, distillation, adsorption, vitrification, incineration, chemical immobilisation or landfill disposal. Some materials such as some detergents may be capable of biological degradation and in such cases, a modified form of wastewater treatment can be used.

Treatment of acids and alkalis

Acids and alkalis can usually be neutralised under controlled conditions. Neutralisation frequently produces a precipitate that will require treatment as a solid residue that may also be toxic. In some cases, gasses may be evolved requiring treatment for the gas stream. Some other forms of treatment are usually required following neutralisation.

Waste streams rich in hardness ions as from de-ionisation processes can readily lose the hardness ions in a buildup of precipitated calcium and magnesium salts. This precipitation process can cause severe furring of pipes and can, in extreme cases, cause the blockage of disposal pipes. A 1 metre diameter industrial marine discharge pipe serving a major chemicals complex was blocked by such salts in the 1970s. Treatment is by concentration of de-ionisation waste waters and disposal to landfill or by careful pH management of the released wastewater.

Handout 21, 22:Advanced Oxidation Processes

Advanced Oxidation Processes are used to oxidize complex organic constituents found in wastewater that are difficult to degrade biologically into simpler end products. When chemical oxidation is used, it may not be necessary to oxidize completely a given compound or group of compounds. In many cases, partial oxidation is sufficient to render specific compounds more amenable to subsequent biological treatment or to reduce their toxicity. The oxidation of specific compounds may be characterized by the extent of degradation of the final oxidation products as follows:

1. Primary degradation: A structural change in parent compound.2. Acceptable degradation: A structural change in parent compound to the extent that

toxicity is reduced.3. Ultimate degradation: Conversion of organic carbon to inorganic CO2.Unacceptable degradation: A structural change in the parent compound resulting in increased toxicity.

Theory of Advanced Oxidation: Advanced oxidation processes typically involve the generation and use of the hydroxyl free radical (HO∙) as a strong oxidant to destroy compounds that cannot be oxidized by conventional oxidants such as oxygen, ozone and chlorine. The relative oxidizing power of hydroxyl radical along with other oxidants is shown in Table:1. The hydroxyl radical reacts with the dissolved constituents, initiating a series of oxidation reactions until the constituents are completely mineralized. Nonselective in their mode of attack and able to operate at normal temperature and pressures, hydroxyl radicals are capable of oxidizing almost all reduced material present without restriction to specific classes or groups of compounds, as compared to other oxidants.

Oxidizing Agent Oxidation Potential, V

Fluorine 3.06Hydroxyl radical 2.80Atomic Oxygen 2.42Ozone 2.08Hydrogen peroxide 1.78Hypochlorite 1.49Chlorine 1.36Chlorine dioxide 1.27Oxygen 1.23

Advantages and disadvantages of AOP:

Sr.No.

AOP Advantages Disadvantages

1. H2O2&UV -UV promote •OH formation-High efficiency

-Turbidity can interfere with UV radiation

2. Sonolysis -Versatile technology-Suitable for small volumes-Interesting upgrade applications

-Energy consuming technology-Sonotrode erosion issues

3. Fenton based processes

-Not as energy intensive as other AOPs

-Developing technology-Sludge formation take place-Need for acidic conditions

4. Photolysis -Can be performed at higher wavelengths than other UV based processes

-Developing technology-Need for pre-treatment

5. Ozone based processes

-Rapid reaction rates. -Potential to reduce toxicity and

possibly complete mineralization of organics treated.

-Does not concentrate waste for further treatment with methods such as membranes.

-Does not create sludge as with physical chemical process or biological processes (wasted biological sludge).

-Capital Intensive. -Complex chemistry must be

tailored to specific application. -For some applications quenching of excess peroxide is require.-complete mineralization cannot take place in some cases.

Handout 24, 25:Air Pollution and Mitigation MeasuresClassification of pollutantsPrimary pollutants - products of natural events (like fires and volcanic eruptions) and human activities added directly to the airSecondary pollutants - formed by interaction of primary pollutants with each other or with normal components of the airSources of air pollution:

Source type Source Air pollutants

Natural Electrical storms NO2

Volcanic eruptions SO2, H2S, HCl

Seepage of natural gas

H2S, CH4

Photochemical reactions Ozone, PAN, Photochemical smog

Plants respiration CO2

Soil, vegetation Dust, micro organisms

Radioactive minerals in earth’s top layers

Radioactive substances

Man made Transport, Combustion of fuel, Industrial processes, Solid waste disposal, Pesticide spray application

CO, NO2, HC, SO2,

Particulates

Industries Cement SO2, NO2, Particulates

Coal combustion

CO, HC, SO2, NO2,

Aldehyde

Pulp & Paper SO2, CO2, H2S, Particulates

Petroleum refining

SO2, CO, HC, NO2,

Aldehyde, NH3

Natural sources

Dust from natural sources, usually large areas of land with little or no vegetation. Methane, emitted by the digestion of food by animals, for example cattle.Radon gas from radioactive decay within the Earth's crust. Smoke and carbon monoxide from wildfires.Volcanic activity, which produce sulfur, chlorine, and ash particulates.

Anthropogenic sources (human activity) related to burning different kinds of fuel

Industrial source, Utilities, Personal source

"Stationary Sources" as smoke stacks of power plants, manufacturing facilities, municipal waste incinerators (A stationary source in air quality terminology is any fixed emitter of air pollutants, such as fossil fuel burning power plants, petroleum refineries, petrochemical plants, food processing plants and other heavy industrial sources.)

"Mobile Sources" as motor vehicles, aircraft etc. (A mobile source in air quality terminology is a non-stationary source of air pollutants, such as automobiles, buses, trucks, ships, trains, aircraft and various other vehicles.)

Combustion-fired power plantsControlled burn practices used in agriculture and forestry management Motor vehicles generating air pollution emissions.Marine vessels, such as container ships or cruise ships, and related port air pollution.

Burning wood, fireplaces, stoves, furnaces and incinerators

Other anthropogenic sources

Oil refining, power plant operation and industrial activity in general. Chemicals, dust and crop waste burning in farming, (see Dust Bowl).Fumes from paint, hair spray, varnish, aerosol sprays and other solvents. Waste deposition in landfills, which generate methane.Military uses, such as nuclear weapons, toxic gases, germ warfare and rocketry.

Handout 26:Effect of Air PollutantsGeneral

a. Effect of pollution on human beingsb. Effects of air pollutions on Vegetationc. Effect of air pollutions on property or materials

GREEN HOUSE GAS EFFECT

“The process of warming of earth surface due to blanketing of CO2 in the atmosphere is called

as GREENHOUSE EFFECT” The major sources of greenhouse Effect are CO2 , Methane, Chloro floro carbon, NO2.Effect of greenhouse gases

ACID RAIN

Acid rain literally means the free acids present in rain water. H2SO4 is the major contributor (60-70%) to acid precipitates where HNO3 is 30 – 40% contributes for acid rain. And HCl is also responsible for the same. Various oxides which are emitted from various industries & Automobiles such as (SO2, SO3, NO2, etc.)

Effect of Acid Rain

OZONE DEPLETION

The ozone is an allotrope from of oxygen which is produced about 2 k.m above the earth surface in the atmosphere which is formed oxygen gas by absorption of ultraviolet radiations.Importance of Ozone lagerCauses of depletion of ozone layer Effect of Ozone depletionPHOTOCHEMICAL SMOGPhotochemical smog is a mixture of pollutants which includes particulates, nitrogen oxides, ozone, aldehydes, peroxyethanoyl nitrate (PAN), unreacted hydrocarbons, etc. The smog often has a brown haze due to the presence of nitrogen dioxide. It causes painful eyes.Factors Affecting Photochemical Reactions Effects of Photochemical Smog

Lecture 27, 28 29:Air pollution control equipments:Source correction methods Raw material changes Process changes Equipment Modification or Replacement Improve Dispersion Good Operating Practices Plant Shutdown/Relocation

Air pollution control equipment:• The cleaning techniques are applied where emissions of pollutants can not be prevented

and pollution control equipment is necessary to remove them from the main gas stream.• The emissions from the plant are passed through a control device before releasing to

atmosphere.  • The pollutants are removed, destroyed or transformed in the control device before

discharging into ambient air.

Cyclone Separators

It consists of a vertically placed cylinder which has an inverted cone attached to its base. The particulate laden gas stream enters tangentially at the inlet point into the cylinder. The outlet pipe for the purified gas is a central cylindrical opening at the top. The dust particulates are collected at the bottom storage hopper. It uses centrifugal force as a means of exerting inertial effect of dispersion solids The gas path follows a double vortex. First, the gas spiral down ward at the outer periphery of the cylindrical portion & reduces

the bottom The gas then moves upward in narrow spiral, concentric with the first & leaves through the

outlet pipe.

FILTERSFiltration is one of the most reliable, efficient and economic methods by which particulate matter can be removed from gases. Filters can be broadly divided into the following two types:

1. Fabric or cloth filter2. Fibrous or deep bed filters

The dust particles along with gas is passed through a fabric filter from the bottom The dusty gas passes through the filters which are arranged in bag house. The particle which are present in the gas are deposited inside the fabric filter The cleaning of bags is accomplished by shaking at fixed interval of time. The dust particles which are deposited inside the hopper are removed by using rotary or screw values in the hopper The cleaned gases send in to the atmosphere from the top of fabric filter

ELECTROSTATIC PRECIPITATOR

The electrostatic Receptors is one of the most widely used device for controlling particulate emission from industries like power plants cement industries, oil refiners &

paper mills In must cares the particulates to be collected are by producers of combos process. Electrostatic precipitin is a passion process by which the particulates suspended in a gas

stream are charged electrically & under the influence of electrical field, separated from the gas stream

The typical example of e.g. is wire pipe precipitator The precipitation system consists of positively charged collecting surface & the high

voltage discharged electrode wire suspended from a insulator at the top & held in a position by weight at the bottom

The electrostatic field which grated draws the particles to the collection surface where they are deposited.

Wet ScrubbersA wet scrubber is used to clean air, flue gas or other gases of various pollutants and dust particles. Wet scrubbing works via the contact of target compounds or particulate matter with the scrubbing solution. Solutions may simply be water (for dust) or solutions of reagents that specifically target certain compounds.