Pollution of rivers around Dhaka

September 11, 2011

Increasing threats to life
Mohammad Tareq Hasan
With a population of over 15 million Dhaka is one of the most congested cities of the world. This rapidly growing city is located on the northern bank of the river Buriganga and surrounded by other rivers, namely, the Turag to the west, the Tongi Khal to the north and the Balu to the east. The rivers surrounding Dhaka are an advantage to it and essential for the survival of the mega city as these provide drainage system, drinking water, different kinds of fishes and also waterways for traveling. However, being the capital of Bangladesh — one of the poorest and least developed countries in the world — the city has been developed haphazardly without considering its physical and social diminution. As a result, the environmental consequences originating from rapid increase of population along with the increase of polluting effluents from industries, and municipal as well as other waste are having profound negative impacts on rivers around Dhaka city. In turn, the polluted waters of the rivers are posing increasing threats to the living organisms including humans residing by the rivers.
Around Dhaka, river water has altered from its natural state in terms of physical, chemical and microbiological composition and lost its suitability for any safe and beneficial use. The signs of contamination have become obvious through bad taste, offensive odours, unchecked growth of aquatic weeds, and decrease in the number of aquatic animals, floating of oil and grease, colouration of water and so on. Generally, rivers surrounding Dhaka are being polluted by the discharge of untreated industrial effluent, urban wastewater, agrochemicals, sewage water, storm runoff, solid waste dumping, oil spillage, sedimentation and also encroachment.
Over the last couple of decades major industrialisation has been observed in Dhaka, especially in dyeing, washing and textiles sectors. Estimation reveals that there are over 7,000 industries in Dhaka metropolitan area located mostly in three clusters, namely, Hazaribagh, Tejgaon, and Dhaka- Narayanganj- Demra dam area (Roy, 2009). However, among all these the dyeing factories and tanneries are the main polluters of the rivers. Waste from these industries is usually connected to the sewerage system that directly follows to the rivers around the city. As a matter of fact, the rivers have become a dumping ground of all kinds of solid, liquid and other chemical waste.
Dhaka city has been growing without much of plan and the city lacks systematic waste management system as well. Dhaka generates around 0.4 to 0.7 kilograms of solid waste per capita per day but the Dhaka City Corporation (DCC), the main agency responsible for collection, transportation and disposal of the waste cannot manage the task properly with its existing limited logistics. The per capita waste collected in Dhaka per day is 0.2 kilograms (Islam & Rahman, 2002). The waste which is not managed by the DCC is dumped into the rivers by the people living near the river banks.
The rivers, which perform the task of natural drainage for the city are also being polluted as rain water sweeps into them all the waste dumped here and there of the city. Furthermore, liquid waste produced in the city is being poured in the rivers untreated. Of the discharged untreated liquid waste, 61 percent is industrial and 39 percent domestic (Roy, 2009). However, the lone Sewerage Treatment Plant (SWP) situated in Pagla of Narayanganj can treat only 10 percent of the industrial waste. Moreover, Dhaka WASA utilizes the existing canals and sewerage pipes to collect waste water from different residential areas and depose, most of it, into surrounding rivers without any treatment. Apart from domestic and industrial waste, oil and other chemicals which are spilled into the rivers from launches, steamers, and trawlers are also polluting river water. Besides in Dhaka contamination of water is occurring from human excreta as well, as 70 percent of the population of the city does not have access to improved sanitation facilities (Islam & Rahman, 2002).
Encroachment on rivers is a common practice in Bangladesh. Most of the natural drainages of Dhaka City disappeared or are in way to due to illegal encroachment. Encroachment on the rivers through unauthorized construction and dumping of solid waste in clearence of regulations to prevent encroachment making it difficult to drain out the runoff and the pollutants i.e., added particles remaining in the rivers keep polluting the environment (Tawhid, 2004).
Polluted water of Buriganga, Turag, Dhaleshwari, Balu, and Narai flowing around the greater Dhaka city is posing serious threats to public life as it is unfit for human use (Institute for Environment and Development Studies, 2003). People living near the rivers, having no other alternative, are forced to use polluted river water. Some also use the water because they are unaware of the health risks. This causes spread of water borne and skin diseases. Solid waste and different effluents dumped into the rivers make it difficult for fishes and other sub-aquatic organisms to live. When solid waste and effluents run into the river, the Biological Oxygen Demand (BOD) in the water rises, creating oxygen crisis for the sub aqueous life. As the dissolved oxygen (DO) content of the river water is decreased below the critical level of four milligrams per liter it is posing threats to bio-diversity in and around the rivers.
Pollution is so severe in the Buriganga, Shitalakhya and Balu rivers that it is almost impossible to treat the water for making it suitable for human use. The Water and Sewerage Authority (WASA) is supplying stinky water purified by chlorine and ammonia sulfate. Moreover, due to river encroachment and dumping of solid waste into the rivers the rivers are loosing their natural flow. Thus, the waterways are shrinking and the alternative way of communication around Dhaka city through rivers turned unsuccessful.
Like many other countries of the world, river pollution in Bangladesh is a burning issue. Abundant research has been carried out and many recommendations have been forwarded to protect the rivers from pollution. At the government level since the last quarter of the past century several rules, regulations, policies and strategies have been formulated to save the rivers from pollution. But the implementation and enforcement of the policies and the regulations have so far been very ineffective, leading to poorer river water quality and further pollution. In addition, in many cases the policies and strategies are seemingly far from being practical in terms of implementation. Therefore, a proactive approach instead of a reactive approach might provide a practical and sustainable solution to the problem. In this regard, provisions of monetary incentives, rewards and recognitions for the polluters who reduce pollution may work effectively. The direct involvement of community and civil society in protecting rivers can also play a great role.
Over the years the government agencies conducted drives against the polluters; however, yielded small success these. Meanwhile, the polluters continued polluting the rivers. Thus, to overcome these problems community people from all level should be encouraged to take part in taking care of the environment. Encouraging debate regarding priorities and developing local strategies, e.g. through workshops involving experts and mass people would produce a people centric action plan. Actions at the individual as well as household level and community level reducing resource consumption and waste production, cleaning up the urban environment and organizing information sharing campaigns would better protect the rivers around Dhaka.

(Article originally published on The Daily Star)                                              Image credit: Anisur Rahman

 

The writer is an anthropologist and can be reached at e-mail: tareqhasan99@yahoo.com

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