L2-Environmental pollution-Water pollution.pdf

ER2643 - Analytical Methods and Environmental Engineering Concepts Lecture 2 Environmental Pollution 1  Environmental Pollution DEFINITION: Environmental p...

ER2643 - Analytical Methods and Environmental Engineering Concepts Lecture 2 Environmental Pollution 1  Environmental Pollution DEFINITION: Environmental pollution is defined as “Any undesirable change in the environment brought about by physical, chemical or biological agents”. 2 Environmental Pollution 3 Environmental Pollution 4  Environmental Pollution Biodegradable and Non-biodegradable Pollutants Biodegradable pollutants Pollutants that are capable of decomposing under natural conditions. Non-biodegradable pollutant An organic compound, usually synthetic, that is not decomposed or mineralized by microorganisms or other biological processes. 5  Environmental Pollution Different types of pollutants in nature Stock pollutants Pollutants that the environment has little or no absorptive capacity are called stock pollutants (e.g. persistent synthetic chemicals, non-biodegradable plastics, and heavy metals). Stock pollutants accumulate in the environment over time. The damage they cause increases as more pollutant is emitted, and persists as the pollutant accumulates. Stock pollutants can create a burden for future generations by passing on damage that persists well after the benefits received from incurring that damage have been forgotten. 6  Environmental Pollution Different types of pollutants in nature Fund pollutants Fund pollutants are those for which the environment has some absorptive capacity. Fund pollutants do not cause damage to the environment unless the emission rate exceeds the receiving environment's absorptive capacity (e.g. carbon dioxide, which is absorbed by plants and oceans). Fund pollutants are not destroyed, but rather converted into less harmful substances, or diluted/dispersed to non-harmful concentrations. 7 Water pollution 8  Objectives of Environmental Engineering 1. To supply water safe in quality and adequate in quantity to the people 2. To collect, treat and dispose the wastewater generated in the community 3. To put in place the methods for pollution prevention in industries and to treat and dispose of individual wastes. 4. To control air pollution from indoor, work environment as well as from the industries. 5. To collect, transport and safely dispose of municipal and hazardous solid wastes. 9  1. Supplying safe water in adequate quantities Drinking water or potable water is water safe enough to be consumed by humans or used with low risk of immediate or long term harm. Quality Quantity If people do not have access to adequate amount of safe drinking water, they might fulfill their needs by using contaminated/ unsafe sources. Hence, both quantity and quality is important. 10  Water Quality Contaminated water contains harmful bacteria 11  Quantity of Water People settled along river banks since ancient times. This has lead great civilizations in the world. Indus Valley Civilization (River Ganga, India), Nile River Valley Civilization (Egypt and surrounding colonies), Yellow River Valley Civilization (China), Tigris/ Euphrates River Valley Civilization (Mesopotamia/ around Iraq) 12  Quality of Water Although, people have realized the importance of the quantity of water since ancient periods, importance of the quality of water was not realized in the same pace. Dr. John Snow (15 March 1813 – 16 June 1858) was an English physician considered as one of the fathers of modern epidemiology, in part because of his work in tracing the source of a cholera outbreak in Soho, London, in 1854. 13  Snow was a questioner of the then-dominant 'miasma theory' that indicated diseases such as cholera were caused by pollution or a noxious form of "bad air". The germ theory of disease had not yet been developed. (It was only in 1900 it was established that cholera is caused by organism called vibrio comma which is a bacterium.) By talking to local residents, he identified the source of the outbreak as the public water pump on Broad Street (now Broadwick Street). Although Snow's chemical and microscope examination of a water sample from the Broad Street pump did not convincingly prove its danger, his studies of the pattern of the disease were convincing enough to make the local council to deactivate the well pump. Snow later used a dot map to illustrate the cluster of cholera cases around the pump. He also used statistics to illustrate the connection between the quality of the water source and cholera cases. He showed that the Southwark and Vauxhall Waterworks Company was taking water from sewage-polluted sections of the Thames and delivering the water to homes, leading to an increased incidence of cholera. Snow's study was a major event in the history of public health and geography. It is regarded as the founding event of the science of epidemiology and Health GIS. 14  Quality of Water Rapidly developing technology allows us to detect pollutants in water through sophisticated analytical instruments, which were unable to detect in the earlier days. 15  Attributes of drinking water Aesthetic: Free from colour, taste, odour and pleasing (Physical perception - subjective) Safety: – Bacteriological (Free from pathogens - disease causing microorganism) – Chemical: (Free from toxicants - natural and anthropogenic) (Eg: Arsenic/ heavy metals in groundwater in West Bengal and Bangladesh due to geological formation, Fish contaminated by Hg, Cd, Zn, Ni in water, Presence of Fl- in water ) Itai itai disease Economical (Cd toxicity) 16  Dental fluorosis Dental fluorosis: Caused by the presence of fluoride in water beyond certain limit, this can decolorize teeth Skeletal fluorosis: Bones become weak and/or develop a stoop Skeletal fluorosis Water quality testing instruments have to be used to detect these substances in water. 17 18  Groundwater Shallow wells/ Shallow tube wells – Normally 5-30m deep – Prone for bacteriological contamination – Pathogenic bacteria can be present though there might be no turbidity in this water. Deep tube wells – Typically around 30m or more deep – Less amount of pathogenic bacteria (filtered from top soil layers) – Inorganic contaminants/ inorganic toxicants might be present (Fl, As) Fe and Mn present in groundwater can cause laundry stains. 19 20  Surface water Surface water is also more easily contaminated than groundwater. Sources of contamination: Agriclutural, domestic and industrial effluents Pathogens, organic and inorganic pollutants might be present. Turbidity Algal growth in lakes causing odour, taste, etc. Acid mine drainage 21  Sea Water Salinity has to be removed before using for domestic or industrial uses. Further, total dissolved solids have to be removed. Desalination plants Reverse Osmosis High energy consumption Solar Energy 22 23  Treated Effluent Treated effluent can be used for gardening, flushing, cooling, etc. Sometimes secondary and/or tertiary treatments are required. 24  Quality of water Raw water quality: Source and point of intake River Ganga (India) River Ganga traverses for 2525km over different cities before enters into the Ocean. – Gangothri – Himalaya Mountains – Haridwar – Plains (Mass bathing by pilgrims) – Kanpur – Domestic & industrial (more than 100 tanneries called as Manchester of India) – Allahabad & Varanasi – Pilgrim centre (Mass bathing – Kumba mela, partially burnt dead bodies into river, etc.) – Patna – Domestic and Industrial 25 26  Water Treatment Haridwar > Good raw water quality > Less treatment is required Kanpur, Patna, Allahabad > Polluted water > Extensive treatment is required > High cost Ganga action plan (Govt. of India): Divert all the wastewater to treatment plants (specially at Kanpur) and treated effluent is discharged to the River Ganga. This is a forerunner to the National River Action Plan. 27  Carrying Capacity Carrying capacity can be explained as the ability of the environment to assimilate the pollution. Environment has a good carrying capacity of natural biodegradable pollution. But, environment cannot assimilate anthropogenic (man made) pollution that easily (Eg: Plastics, pesticides, etc.) These pollutants are accumulating in the environment without degradation. This is called as Conservative Pollution. Environment has no carrying capacity to these pollutants. Self cleansing/ purification capacity of a river is called as its carrying capacity. 28  Level of Pollution Before rapid industrialization and green revolution, pollution level was less than carrying capacity. Presently, due to intensive industrialization, population growth, modernization and green revolution (fertilizers, pesticides, insecticides) pollution level has become higher than the carrying capacity (PL> CC). However, industrialization, modernization and green revolution are unavoidable. We can see the adverse consequences of this, in main cities. 29  Water Treatment The main objectives of water treatment: – Aesthetic water – No colour, taste, odour, turbidity (suspended solids) – Safe water – No micro-organisms, No toxic chemicals (Heavy metals, pesticides, etc.) Therefore, the units in a water treatment plant are designed to address the above two objectives. i.e. Removal of turbidity, colour, taste, odour Safety from pathogens, toxic chemicals Therefore, water quality analysis should be carried out as the first step in a water treatment plant to assess the water quality. 30  Water Treatment Typical municipal water treatment plant consist of following steps; – Sedimentation – Coagulation and flocculation – Filtration – Disinfection (Chlorination) – Aeration – Etc. 31 32  Water Treatment 33 2. Collecting, treating and disposing the wastewater generated in the community There are three types of wastewater, or sewage: Domestic sewage, industrial sewage, and storm sewage. 1. Domestic sewage carries used water from houses and apartments; it is also called sanitary sewage. 2. Industrial sewage is used water from manufacturing or chemical processes. 3. Storm sewage, or storm water, is runoff from precipitation that is collected in a system of pipes or open channels. 34 3. To put in place the methods for pollution prevention in industries and to treat and dispose of individual wastes. Environmental Engineer’s Role: Prevent/ minimize waste generation in industries Treat the generated waste before discharge 35 Thank you…! 36