Environmental pollution in Dhaka city INTRODUCTION: Pollution is an undesirable change in the physical, chemical or biological characteristics of air, water, soil or food that can adversely affect the health, survival or activities of human or other living organisms. The effects of water pollution are far-reaching and affect not only the environment, but human beings and animals as well. The pollution in Dhaka has reached alarming levels, threatening public health, ecosystems and economic growth. OBJECTIVE:
The objective of the report is to create awareness regarding the environmental issues in Dhaka. The types of pollution focused in this assignment are mainly air pollution, water pollution, noise pollution and soil pollution. Everyday we face these pollution in the city some way or the other. The report identifies these problems and their underlying causes. Further, it addresses the major problems created in Dhaka city due to pollution and how it can be prevented. Water Pollution: Water is considered polluted when chemicals, pathogens, or contaminants are detected.
Water pollution in Dhaka is mainly caused due to industrial processes that produce toxic waste, ground water pollution, natural catastrophes, growth of algae and littering on the land. Mainly there are three types of water pollution rainwater pollution, ground water pollution and surface water pollution. Rain water pollution is basically the acid rain and there is no record of rainwater pollution in Bangladesh. Surface water pollution is very common in Dhaka and is caused due to human activities. The sources of surface water pollution are industrial and urban wastes, agrochemicals and sewerage wastes and seawater intrusion.
Groundwater contamination is the degradation of natural water quality as a result of human activities, and pollution occurs when contaminant concentration levels restrict the potential use of groundwater. Ground water is not directly exposed to surface polluting activities, numerous natural and anthropogenic activities cause groundwater pollution. A number of physical, chemical and biochemical (and microbiological) processes cause change in groundwater properties by adding new elements/ions/compounds or by increasing the existing concentrations.
The most widespread anthropogenic sources are the infiltration of industrial and urban wastes disposed on the ground or in surface water bodies. Also infiltration of saline water contaminates groundwater. Extensive use of agrochemicals can lead to groundwater pollution. Groundwater pollution can also lead to diseases caused by arsenic. Pollution in Dhaka city is causing disruption in the life-support systems for humans and species, it is damaging the wildlife and human health.
Dhaka’s sustainability is increasingly under the threat due to severe pollution in khals, rivers and aquifers. Water pollution is caused due to domestic sewage including human excreta, bathroom and kitchen wastewater, industrial wastewater including toxic chemicals, pesticides and fertilizers used in the agricultural fields around city. At present, colour of water of the rivers, canals and ditches in and around the capital has become almost black with bad smells making it impossible for fish to survive as the organic wastes have been absorbing the dissolved oxygen from water.
Surface water pollution in and around capital Dhaka, especially the waters of the rivers Buriganga, Turag, Balu and Tongi canal have been threatening the supply of safe drinking water and public health of over 10 million city dwellers. Because of the damage of the sewerage lines in different places, the WASA sewerage treatment plant at Pagla in Narayanganj receives only one-third of its capacity in dry season, 85 percent of the drinking water supply come from ground water and the rest is provided by treating surface waters.
People in the city are surviving as they use drinking water after boiling to free it from contamination. Industries at Postogola, Fatullah, and a huge number of tanneries at Hazaribagh have been polluting the river Buriganga. These wastes contains sulphuric acid, chromium, ammonium sulphate, chloride and calcium oxides. The industries are the major source of pollution of the Turag River while many others dump their wastes in the rivers Balu and Shitalakhya. Thus, measures should be taken to prevent water pollution in Dhaka city.
The pollution points of domestic sewage and industrial waste should be identified and banned from further polluting the rivers Buriganga, Balu, Sitalakhya and Turag. There should be in-house treatment for both dispersed and cluster of industries. Domestic waste must be treated in treatment plants. Water pollution in Dhaka city requires heightened attention. Both pollution prevention and pollution clean up is required to make Dhaka a better place to live in.