Buriganga ecosystem in danger

Today's Buriganga River is extremely polluted and it is close to biological death for several reasons. The tremendous increase in population of Dhaka City over the last three decades has created enormous environmental problems. Human sewage coupled with municipal garbage, solid wastes, dumping of medicinal wastes, toxic water and hazardous effluent is being dumped into the river every day.  Furthermore, there are several industrial locations within Dhaka city which discharge effluents directly to the river without any regard to environment.
Now, Dhaka city is very densely populated and only a small fraction of the total wastewater is being treated. The untreated wastes, both domestic and industrial, clinical, and pathological, are being released into the Buriganga and this tendency is increasing day by day. In fact, the Buriganga River has become a dumping ground of all kinds of solid, liquid and chemical wastes. Together with encroachment, these activities have caused narrowing of the river and disruption of its normal flow of water. The water of the river has become so polluted that its aquatic life has almost gone extinct.
A study was carried out to observe the ecological health hazards and their risk to human health due to severe pollution of the Buriganga River. Samples were analysed to determine the water quality and environmental health risks. The study showed that the water is high in biological oxygen demand (BOD), chemical oxygen demand (COD), phosphate (PO4-3), ammonia(NH3) and different types of organic matters and nutrients. All these pose huge environmental health risks.
In Dhaka, surface water pollution occurs due to various factors such as human sewage coupled with municipal garbage and industrial effluent that completely destroy  microbial system of decomposition. About nine industrial areas in and around the capital city - Tongi, Tejgaon, Hazaribagh, Tarabo, Narayanganj, Savar, Gazipur, Dhaka Export Processing Zone and Ghorashal - are the prime sources of the pollution. Most of the industrial units of these areas have no sewage treatment plants of their own.
A World Bank study said four major rivers near Dhaka -- the Buriganga, the Shitalakhya, the Turag and the Balu -- receive 1.5 million cubic metres of waste water from 7,000 industrial units in surrounding areas and another 0.5 million cubic metres from other sources every day. Nearly 4.0 million people directly face the consequences of poor water quality of the river system caused by untreated textile industry waste alone. Beside, Dhaka city discharges about 4,500 tonnes of solid waste every day, of which maximum 30 per cent are disposed at designated dumpsites or waterbed without any regard to environment.
Dhaka was established as a provincial capital of the Mughal ruler on the north-eastern bank of the Buriganga River during 1608-10 period. This river has enormous significance to the residents of Dhaka. Not only does it surround the city, but also provides important services including water supply, navigation, recreation, sanitation, fish production, tourism, biodiversity and flood control.
A cruise on the historic Buriganga River used to be a must for visiting dignitaries but now it's simplly impossible for excursion as foul smell results from massive pollution without any regard to environment. Besides, the Buriganga River has enormous significance for survival and economic growth of Dhaka City. By destroying the carrying capacity of this river, heavy costs are likely to be imposed on current and future generations. Failure to protect the Buriganga River from pollution points to failure of the policy-makers who have underestimated benefits of ecosystem as well as environmental protection, restoration programmes and economic growth.
--The writer is a journalist and columnist
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