ABSTRACT
The study was conducted in the Department of Civil Engineering at Stamford University Bangladesh with the objectives to prepare a project and thesis with a view to partial fulfillment of the requirements for the degree of Bachelor of Science (B.Sc.) in Civil Engineering. The specific objectives of the study were to study the surrounding environment at some selected locations around Buriganga River, to assess the river water quality in terms of some very cardinal water quality parameters, to investigate the reasons behind this extreme water pollution and finally to provide some suggestions to improve the existing condition.
To determine the suitable locations of water collection, the whole area in and around the river was preliminarily surveyed and necessary photographs were taken. Then water samples were collected such that the samples represent the characteristics of river water. To do this assessment for the River Buriganga, the study area was chosen to be Dholaikhal intake point, Sadarghat, Chandnighat, and Hazaribagh.
With a view to finding out the water quality parameters water samples were tested in the laboratory of Stamford University Bangladesh .The pH of water of river Buriganga has shown a variation from 7.3 to 6.8. The left bank of the river contains higher pH value from the right bank and middle. The color of the river water has shown a variation from 318 to 774 mg/l. The turbidity of the river water shows in a variation of 7.2 NTU to 55.5 NTU. The hardness of water of the river Buriganga has shown a variation from 288 mg/l to 467 mg/l as CaCo3. Alkalinity of water of the river Buriganga was found to vary from 366 mg/l to 469 mg/l. Among them 366 mg/l was shown in Hazaribagh and 469 mg/l was showed in Chandnighat. The chloride of water of the river Buriganga was found in a range of 40 mg/l to 180 mg/l. Iron of water of the river Buriganga was found in a range of 0.26 mg/l to 0.93 mg/l. Biochemical Oxygen Demand (BOD) is not actually a water quality parameter but it is the most commonly used indicator of the general health of a surface water body which varies from 72 to 92 mg/l(BOD5) during the test.
As Dhaka city is expanding day by day with the increasing rate of population, now a days it has become a regular event that river area is used up by the land grabbers. As a result all the main rivers are becoming narrow day by day. Because of high growth rate of population the country is expected to have its population more than 280 million by the year 2050. About 40% of these total rural or urban migrations will take place to greater Dhaka. Dhaka has now become a mega city that causes enormous pressure on the surrounding rivers because maximum drainage outlets and sewerage of this mega city falls into the rivers like Buriganga.Literature review reveals that there are many industries developed on the river bank and those discharges about 1.5 million cubic meters of untreated waste water everyday into the river. This is one of the most vulnerable reasons behind the extreme pollution of the river water.The water quality parameters that are tested for the river water showed that most of the samples were within the standard limit set by ECR, 97. Few samples crossed the limit but still some kingfishers are flying over the river to collect their daily meal from it. It is high time to save the river from the devastating effect of urbanization and to establish the flora and fauna of this mega city by giving a new life to Buriganga.
Proper dredging of the existing river and regular removal of non degradable matters from the river bed ,demolishment of unauthorized establishment on the river bank ,maintaining a regular monitoring system against the land grabbers ,providing Effluent Treatment Plant for each and every Industrial unit to reduce the pollutant load on the river, law enforcement and public awareness and finally decentralization of some important industries, e.g. tanneries, dying industries etc from the center of the city to the periphery will reduce the pollution load on the river and will finally help to re-estabish the beauty of this mega city.
INTRODUCTION
Background
Bangladesh is a low-lying riverine country located in South Asia. There are about seven hundred (700) rivers and tributaries. Dhaka is the capital of Bangladesh and it was founded about four hundred (400) years ago on the northern bank of the river Buriganga, about thirteen (13) kilometer above its confluence with the Dhaleshwari river (23° 43´ North Latitude and 90º 24´ East Longitude) The earliest available map shows that, Dhaka extending over an area of about 1.5 square kilometer near the junction of the Dholaikhal and Buriganga river. The river flows by the capital Dhaka, a city of 12 million people, which largely depends on the Buriganga’s water for drinking, fishing and carrying merchandise.
BurigangaRiver a tide-influenced river passing through west and south of DhakaCity. There is a traditional story behind naming it. In ancient times one course of the Ganges used to reach the Bay of Bengal through dhaleshwari. This course gradually shifted and ultimately lost its link with the main channel of the Ganges and was renamed as the Buriganga. The water levels during high and low tides in this river astonished the Mughals.
The Buriganga originated from the Dhaleshwari near Kalatia. Its average width and depth are 400m and 10m respectively. This river is only 27 km long. The Turag has joined the Buriganga at Kamrangirchar of Dhaka City. In fact, the main flow of the Buriganga comes from the Turag. It meets with the Dhaleshwari at Munshiganj. The present head of the Buriganga near Chhaglakandi has silted up and opens only during floods, but the lower part is still open throughout the year. The downstream junction with the Dhaleshwari fluctuates from time to time according to changes in the position of the latter river; at present it lies about 3.22 km southwest of Fatullah. Its course by Dhaka is stable, fixed by the resistant clays marking the southern edge of the Madhupur tract.
The Buriganga is of great economic importance to Dhaka. It provides river connection by launch and country boats, but large steamers can no longer ascend the river in the dry season. In 1989, a bridge (the Bangladesh-ChinaFriendshipBridge) was built over the river for vehicles and pedestrians. In 2001, a second bridge over the river was also built at Babubazar for vehicles and pedestrians.
Water pollution in the River Buriganga is as it’s highest. The most significant source of pollution appears to be from tanneries in the Hazaribagh area. In the dry season, the dissolved oxygen level becomes very low or non-existent and the river becomes toxic. The study has been conducted to find out the existing condition of Buriganga and to find out some solutions to save the river.
Objectives
- To study the surrounding environment at some selected locations around BurigangaRiver.
- To assess the river water quality in terms of some very cardinal water quality parameters.
- To investigate the reasons behind this extreme water pollution.
- To provide some suggestions to improve the existing condition.
Scope of the study
- For time limitation only four locations on the basis of extreme pollution were selected for collecting samples.
- Samples were collected once for every location.
- Seasonal variations were not taken into account in this study.
Methodology
- To determine the suitable locations of water collection, the whole area in and around the river was preliminarily surveyed and necessary photographs were taken.
- Then water samples were collected such that the samples represent the characteristics of river water.
- With a view to finding out the water quality parameters water samples were tested in the laboratory of Stamford UniversityBangladesh.
- Then necessary results and relevant conclusions & recommendations were made.
Organization of the Thesis
Apart from this chapter, the reminder of the thesis has been divided into four chapters.
Chapter 2 titled “Literature Review” presents the statistical information on the present condition of water. The chapter also contains the source public health concern, sanitary significance and aesthetic of several water quality parameters. Similar studies carried out in the past are also presented in this chapter.
Chapter 3 titled “Data Collection and Analysis” describes the procedure of selection of the sample taking points, a short description of them and also the procedure of sample collection and testing. The chapter also presents the test results and different tables produced by analyzing the test results.
Chapter 4 titled “Results and Discussions” presents the explanation of the results found from the analysis of the tables generated in chapter 3 and discuss the condition of river water, the trends of change in water quality, etc.
At last chapter 5 titled “Conclusion and Recommendations” present major concluding remarks about the outcome of the study and also provides relevant recommendation for future study.
Present condition
Buriganga was once the lifeline of Bangladesh capital. But the once mighty BurigangaRiver, which flows by Dhaka, is now one of the most polluted rivers in Bangladesh because of rampant dumping of industrial and human waste.
“Much of the Buriganga is now gone, having fallen to insatiable land grabbers and industries dumping untreated effluents into the river,” said Ainun Nishat, a leading environmental study expert. “The water of the Buriganga is now so polluted that all of the fish have died and increasing filth and human waste have turned it into a black gel. Even rowing across the river is now difficult for it smells so badly,” he told reporters.
The plight of the Buriganga symbolizes the general state of many rivers in Bangladesh, a large flat land crisis-crossed by hundreds of rivers.
Bangladesh has about seven hundred (700) small and large rivers and a large chunk of the country’s 140 million people depend on them for a living and for transportation.A World Bank study said four major rivers near Dhaka — the Buriganga, Shitalakhya, Turag and Balu — receive 1.5 million cubic meters of waste water every day from 7,000 industrial units in surrounding areas and another 0.5 million cubic meters from other sources
Unabated encroachment that prevents the free flow of water, dumping of medicinal waste and waste of river passengers has compounded the problem, making the water unusable for humans and livestock.
“Unfortunately, all these bad things — encroachment, dumping of industrial waste — occur in full knowledge of the authorities,” said Professor Abdullah Abu Saeed, an eminent campaigner for “Save Buriganga, Save Lives.” Among the top polluters are dozens of tanneries on the banks of the Buriganga. The government has initiated a move to relocate the tanneries outside the capital, and also asked illegal encroachers to vacate the river. But environmental study groups say they defy such orders by using their political links or by bribing people. The Buriganga flows by the capital Dhaka, a city of 12 million people, which largely depends on the Buriganga’s water for drinking, fishing and carrying merchandise. “The pollutants have eaten up all oxygen in the Buriganga and we call it biologically dead. It is like a septic tank,” said Khawaja Minnatullah, a World Bank specialist on environment and water management. “There are no fish or aquatic life in this river apart from zero oxygen survival kind of organisms.”Chemicals such as cadmium and chromium and other elements such as mercury carried by the industrial waste are also creeping into the ground water.“If the pollution is not controlled, we will face a serious health crisis in a year or two or at best three years,” said Minnatullah. Bangladesh enacted a law in 1995 making it compulsory for all industrial units to use effluent treatment plants in a bid to save river waters from pollution, but industry owners often flout the rule.
“We want the rivers fully dredged, their illegal occupation ended and the laws strictly enforced to prevent abuse of waterways,” Nishat said. “Not many years ago SingaporeRiver was also like our Buriganga. But they cleaned it up and have now turned it into a great resource.”
A Brief Discussion about the River Buriganga Pollution
Pollution of BurigangaRiver began in the Mughal period, since the sewage of the city used to be dumped into the river. Professor Muntasir Mamoon, a historian who has been writing books and articles on Buriganga River and other connecting canals since early 1970s, says, “The historical documents state that people used to get bad smell one and half kilometers away from Buriganga River even in the late 19th century. Then British administration showed concern about the river, since the water level used to decrease to an alarming level during the dry season. Renowned Scottish town planner Patrick Geddes made a master plan for DhakaCity including the BurigangaRiver in 1917. Then administration also made some plans to save Buriganga from the grasp of ongoing pollution caused by domestic sewage. However, the pollution of the river was at the tolerable level till Pakistani period. He said, personally, I saw boat racing and boat hotels on BurigangaRiver even in the 1960s. But after Liberation, everything became Dhaka-centric. And because of encroachment, unplanned urbanization and establishment of polluting industries in the city, water pollution has taken such a devastating shape that the river, mother of the civilization, has been killed by the ‘civilized’ people”
Water Quality Parameters
Commonly used parameters to ensure the quality of supplied water are – pH, color, turbidity, hardness, chloride, alkalinity, iron, and bod. All these parameters have certain environmental study impacts and some of them can be hazardous to human and animal health if their presence in water is beyond the tolerable limits. The Environmental Conservation Rule 1997 (ECR) standards for drinking water quality is given in Table A1 of appendix. The parameters are discussed below.
pH
pH is a term used to express the intensity of the acid or alkaline condition of a solution. Extremes in pH can make a river inhospitable to life. Low pH is especially harmful to immature fish and insects. Acidic water also speeds the leaching of heavy metals harmful to fish. It is important in almost every of environmental study engineering practice.
Color
Most waters available to us are colored to some extent due to the presence of various impurities i.e. iron and manganese in association with organic matter in various stages of decomposition. Impurities may be in colloidal form in the water or it may be in suspended state. Color caused by dissolved and colloidal form of impurities is called true color and that caused by suspended matter. In addition to dissolved and colloidal matters, is called apparent color. Surface waters may appear highly colored because of colored suspended matters when in really they are not. Surface waters may become colored by pollution with highly colored wastewaters such as wastes from dyeing operation in textile industry and pulping operations from paper industry. Ground water may show color due to the presence of iron compounds.
Water containing coloring matter derived from the natural substances undergoing decay in swamps and forests are not generally considered to possess harmful or toxic properties. The natural coloring materials, however give a yellow-brownish appearance to the water, somewhat; like that of urine, and there is a natural reluctance on the part of water consumers to drink such water because of the associations involved. Also, disinfection by chlorination of water containing natural organics results in the formation of chloroform, other trihalomethanes, and a range of other chlorinated organic, leading to problems of such current concern. No matter how safe the supply water may be from hygienic viewpoint, where it is not aesthetically acceptable, consumers often shun safe domestic supplies and use water from uncontrolled springs or private wells which may serve as foci for dissemination of pathogenic organism. So it is important to limit the color of water for domestic water supplies.
Turbidity
The term turbid is applied to waters containing suspended matter that interferes with the passage of light through the water or in which visual depth is restricted. Turbidity may be caused by a wide variety of suspended materials which range in size from colloidal to coarse dispersions. It can be even due to extremely fine dispersions. Again materials causing turbidity may range from purely inorganic to those that are largely organic in nature.
Turbidity is an important consideration in public water supplies. Consumers of public water supplies expect and have a right to demand turbidity free water. Lay people are aware that domestic waste water is highly turbid which directly fall into the river. Any turbidity in the drinking water which takes from river is automatically associated with possible waste water pollution and the health hazards occasions by it. Turbidity in water can harbor and transport bacteria and other harmful pathogenic organisms and absorbed contaminants which is highly risky for river water life.
Hardness
Hard water are generally considered to be those waters that require considerable amounts of soap to produce foam or lather and that also produce foam or lather and that also produce scale in hot water pipes, heaters, boilers and other units in which the temperature of water is increased materially. Hardness is caused by multivalent metallic cat ions.
Hard water is high in dissolved minerals, both calcium and magnesium. As water moves through soil and rock, it dissolves small amounts of these naturally. Occurring minerals and carries them into the ground water supply.
Hard water interferes with almost every cleaning task, from doing the laundry to washing dishes to taking a shower. Clothes can look dirty and feel rough and scratchy. Dishes and glasses get spotted and film may build on showers doors, bathtubs and sinks. Finally hard water can cause a residue to build up in pipes that can lower water pressure throughout the house.
Hardness does not pose a health risk and is not regulated by United States federal agencies. In fact calcium and magnesium in drinking water can help ensure the average daily requirements for these minerals in diet.
But hard water can be a nuisance due to the mineral build up on plumbing fixtures and poor soap and detergent performance.
Chloride
Chlorides occur in all natural water in widely varying concentration. The chloride content normally increases as the mineral content increases. Upland and mountains supplies usually are quite low in chlorides, where as river and ground waters usually have a considerable amount. Sea and ocean waters represent the residues resulting from partial evaporation of natural waters that flow into them, and their chloride levels are very high.
Chlorides gain access to natural waters in many ways. The solvent power of water dissolves chlorides from topsoil and deeper formations. Spray from the ocean is carried inland as droplets or as minute salt crystals, which result from evaporation of the water in the droplets. These sources constantly replenish the chlorides in inland areas where they fall.
Chlorides in reasonable concentrations are not harmful to humans. At concentrations above 250 mg/l, they give a salty taste to water, which is objectionable to many people. High concentrations of chlorides are corrosive to metal.
Alkalinity
The alkalinity of water is the measure of its capacity to neutralize acids. The alkalinity of water is the measure of its capacity to neutralize acids. The alkalinity of natural waters is due primarily to the salts of week acids, although weak or strong bases may also contribute. A few organic acids, that is quite resistant to biological oxidation, from salts that ass to the alkalinity of natural waters.
As far as known, the alkalinity of water has little health significance. Highly alkaline waters are usually unpalatable. Chemically treated waters sometimes have rather high pH values which have met with some objection on the part of consumers. For this reasons, standards are sometimes established on chemically treated waters.
Iron
Iron as well as manganese, creates serious problems in public water supplies. The problems are most critical for ground water. Iron exists in soils and minerals as insoluble ferric oxide/hydroxide and iron sulfide. In some areas it also occurs as ferrous carbonate, which is very slightly soluble.
As far as known, human suffer no harmful effects from drinking waters containing iron and manganese. In humans, very large does of ingested manganese can cause some diseases and liver damage such waters, when exposed to air so that oxygen can enter, become turbid and highly unacceptable from an aesthetic viewpoint, owing to the oxidation of iron and manganese to the Fe(III) and Mn(IV) states which from colloidal precipitates. Both iron and manganese interfere with laundering operations, impart objectionable stains to laundry and porcelain and plumbing fixtures, and cause difficulties in distribution systems by supporting growths of iron bacteria. Iron also imparts a bitter or an astringent taste to water which is detectable at very low concentrations.
BOD
Biological Oxygen Demand (BOD) is one of the most common measures of pollutant organic material in water. BOD indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water. Dissolved oxygen (DO) is consumed by bacteria when large amounts of organic matter from sewage or other discharges are present in the water. DO is the actual amount of oxygen available in dissolved form in the water. When the DO drops below a certain level, the life forms in that water are unable to continue at a normal rate. The decrease in the oxygen supply in the water has a negative effect on the fish and other aquatic life. Fish kills and an invasion and growth of certain types of weeds can cause dramatic changes in a stream or other body of water. Energy is derived from the oxidation process. BOD specifies the strength of sewage. In sewage treatment, to say that the BOD has been reduced from 500 to 50 indicates that there has been a 90 percent reduction.
The BOD test serves an important function in stream pollution-control activities. It is a bioassay procedure that measures the amount of oxygen consumed by living organisms while they are utilizing the organic matter present in waste, under conditions similar in nature. The other traditional tests or indicators for water quality are chemical oxygen demand (COD) and pH.
For results of the BOD test to be accurate, much care must be taken in the actual process. For example, additional air cannot be introduced. Temperature must be 20°C, which is the usual temperature of bodies of water in nature. A five-day BOD test is used in environmental study monitoring. This test is utilized as a means of stating what level of contamination from pollutants is entering a body of water. In other words, this test measures the oxygen requirements of the bacteria and other organisms as they feed upon and bring about the decomposition of organic matter. Time and temperature, as well as plant life in the water, will have an effect on the test. High BOD burdens or loads are added to wastewater by food processing plants, dairy plants, canneries, distilleries and similar operations, and they are discharged into streams and other bodies of water.
DATA COLLECTION AND ANALYSIS
General
For determination of river water quality of the River Buriganga, samples need to be collected from different places and should be should be taking few in numbers. Study area was chosen carefully considering its enormous importance to the residents of Dhaka city. To do this assessment for the River Buriganga, the study area was chosen to be Dholaikhal intake point, Sadarghat, Chandnighat, and Hazaribagh. The study area is shown in figure 3.1.
2 Selection of locations for sample collection
The Buriganga River is the main out late of waste water of Dhaka city. About eighty percent (80%) of Dhaka’s sewage is said to be untreated. A large number of industries including tanneries discharge their chemical wastes directly in to the river. Land grabbing is also a reason for river water pollution. This is why four different locations for collecting sample were carefully chosen to correctly measure the water quality parameters.
- The sampling points are selected on the river Buriganga i.e. Dholaikhal intake point, Sadarghat, Chandnighat, and Hazaribagh.
- Water samples were collected from three chosen points of each selected locations. One from the left bank of the river, one from the right bank of the river, and the rest from middle of the river.
- The samples were then tested for a wide range of water quality parameters included pH, color, turbidity, alkalinity, hardness, chloride, iron, and BOD5.
Test Procedure
The samples were collected in 1.5 liter plastic bottles. One of which shown in photo 3.2 Before sampling, the bottles were thoroughly cleaned up by fresh water. The bottle mouth and caps were carefully cleaned. The collected samples were transported to laboratory as quick as possible.
In this study, pH was measured using the HANNA instrument and HANNA pH meters Turbidity was measured DR LANGE turbid meter. Titration method was used for determination of Alkalinity, Hardness and Chloride. For measurement of color, DR-2010 Spectrophotometer was used.
Test Results and Analysis:
After the collection of the samples, tests were carried out in the laboratory of Stamford University Bangladesh. The test results are shown in table form below.
Overall Water Quality at Different Location.
The entire test result is shown in table form parameter wise in Figure.
Table 3.1: pH values of samples collected from different locations
Location | places | pH |
Hazaribagh | Left Bank | 7.3 |
Middle | 6.9 | |
Right Bank | 7.1 | |
Dholaikhal | Left Bank | 6.9 |
Middle | 6.8 | |
Right Bank | 6.8 | |
Sadarghat | Left Bank | 7.3 |
Middle | 7.1 | |
Right Bank | 7.2 | |
Chandnighat | Left Bank | 7.3 |
Middle | 7.1 | |
Right Bank | 6.9 |
Table 3.2: Color values of samples collected from different locations
Location | places | Color(TCU) |
Hazaribagh | Left Bank | 774 |
Middle | 698 | |
Right Bank | 712 | |
Dholaikhal | Left Bank | 318 |
Middle | 354 | |
Right Bank | 341 | |
Sadarghat | Left Bank | 732 |
Middle | 674 | |
Right Bank | 656 | |
Chandnighat | Left Bank | 662 |
Middle | 648 | |
Right Bank | 666 |
Table 3.3: Turbidity values of samples collected from different locations
Location | places | Turbidity(NTU) |
Hazaribagh | Left Bank | 54.8 |
Middle | 47.3 | |
Right Bank | 41.5 | |
Dholaikhal | Left Bank | 8.9 |
Middle | 7.6 | |
Right Bank | 7.2 | |
Sadarghat | Left Bank | 14 |
Middle | 14 | |
Right Bank | 13.7 | |
Chandnighat | Left Bank | 53.3 |
Middle | 55.5 | |
Right Bank | 51.5 |
Table: 3.4 Hardness values of samples collected from different locations
Location | places | Hardness(mg/l asCaCO3) |
Hazaribagh | Left Bank | 322 |
Middle | 288 | |
Right Bank | 302 | |
Dholaikhal | Left Bank | 486 |
Middle | 467 | |
Right Bank | 473 | |
Sadarghat | Left Bank | 466 |
Middle | 450 | |
Right Bank | 452 | |
Chandnighat | Left Bank | 382 |
Middle | 410 | |
Right Bank | 391 |
Table: 3.5 Chloride values of samples collected from different locations
Location | places | Chloride(mg/l) |
Hazaribagh | Left Bank | 180 |
Middle | 175 | |
Right Bank | 178 | |
Dholaikhal | Left Bank | 167 |
Middle | 160 | |
Right Bank | 163 | |
Sadarghat | Left Bank | 61 |
Middle | 55 | |
Right Bank | 59 | |
Chandnighat | Left Bank | 59 |
Middle | 40 | |
Right Bank | 54 |
Table: 3.6 Alkalinity values of samples collected from different locations
Location | places | Alkalinity(mg/l as CaCO3) |
Hazaribagh | Left Bank | 387 |
Middle | 366 | |
Right Bank | 382 | |
Dholaikhal | Left Bank | 460 |
Middle | 469 | |
Right Bank | 463 | |
Sadarghat | Left Bank | 462 |
Middle | 449 | |
Right Bank | 457 | |
Chandnighat | Left Bank | 464 |
Middle | 461 | |
Right Bank | 461 |
Table: 3.7 Iron values of samples collected from different locations
Location | places | Iron(mg/l) |
Hazaribagh | Left Bank | 0.91 |
Middle | 0.93 | |
Right Bank | 0.91 | |
Dholaikhal | Left Bank | 0.33 |
Middle | 0.26 | |
Right Bank | 0.31 | |
Sadarghat | Left Bank | 0.61 |
Middle | 0.63 | |
Right Bank | 0.63 | |
Chandnighat | Left Bank | 0.88 |
Middle | 0.80 | |
Right Bank | 0.83 |
Table: 3.8 BOD values of samples collected from different locations
Location | DOi | DO5 | BOD(mg/l) |
Hazaribagh | 11.2 | 5.7 | 92 |
Dholaikhal | 11.2 | 6.9 | 72 |
Sadarghat | 11.4 | 5.7 | 92 |
Chandnighat | 11.2 | 5.8 | 90 |
Over all study of surrounding environment
Dholaikhal
Dholaikhal, an area on the bank of the river Buriganga in the old part of Dhaka city. The area was an important centre of the city and the historic Lalbagh fort, Ahsan manzil, Bara katra and Chhota katra located in its surroundings. Many big merchants, Nawab families and aristocratic people lived in the area. For many years Dholaikhal was used for boat race and other sports, including swimming. Annual fairs were held at different places on the banks of the canal on festive occasions. One of the famous ghats was the Panch Bhai Ghat at Rokanpur. The Hindu community threw images of their deities into the holy water of the Dholaikhal after puja. Dholaikhal area of present Dhaka Metropolitan City is a small block covering only 550 sq yards. It borders with Tipu Sultan Road on the north, Victoria park on the south, Narinda on the east and English Road on the west. Dholaikhal is now a busy centre of trade and commerce. There are more than 5,000 shops in the area. Also in the area are innumerable small workshops for repair or manufacturing of many types of household items, machinery parts and some dockyard on the opposite bank. Major business activity in the area is the sale of automobile parts and spares, sanitary fittings and computer accessories.
Sadarghat
Sadarghat is one of the most dynamic areas in Dhaka, but its fullest potential has not yet been realized. It is part of one of the historic centers of Dhaka where the city begins and a vital riverine node, the area has now become the symbol of sharp physical and environmental study deterioration of the river and its banks. All along the roads to Sadarghat, on the pavements have a wide range of merchandise. Sadarghat Launch Terminal is a large “ghat” or wharf in Sadarghat at Dhaka. Located on the banks of the Buriganga river, it is also referred to as Sadarghat Port. It stands a little left in front of the Ahsan Manzil. One of the largest river ports in the world, it is the main port and dock of Dhaka. It was built as a place for landing boats, launches and even ships coming to Dhaka. According to officials at the terminal, an average of 30,000 people use the terminal for departure and arrival every day, each paying Tk 2.50 for entrance. About 200 large and small passenger launches depart and arrive at the terminal every day.
Chandnighat
There is a water treatment plant in Chandnighat which is established 1890 by Nawab Khawaja Abdul Ghani to supply potable water in the city and a narrow canal falls in the rivers main stream.
Hazaribagh
Hazaribagh is famous for tanneries and lather industries. Tanneries in the city’s Hazaribagh area discharge some 21,600 square meters of liquid wastes every day, and Leather sector also produces 150 tons solid waste a day. These harmful wastes, including chromium, lead, sulphur, ammonium, salt and other materials, are severely polluting the capital city and the river Buriganga.
RESULTS AND DISCUSSIONS
General
This chapter includes a discussion on the overall water quality in Buriganga River. It includes the expected range of values for each water quality parameter, whether they are exceeding the recommended limit, etc. this chapter also includes the expected pattern of variation of water at different points of the river Buriganga.
Overall Water Quality
pH
The pH of water of river Buriganga has shown a variation from 7.3 to 6.8. The left bank of the river contains higher pH value from the right bank and middle. Photosynthesis uses up dissolved carbon dioxide which acts like carbonic acid (H2CO3) in water. CO2 removal, in effect, reduces the acidity of the water and so pH increases. In contrast, respiration of organic matter produces CO2, which dissolves in water as carbonic acid, thereby lowering the pH. For this reason, pH may be higher during daylight hours and during the growing season, when photosynthesis is at a maximum. Respiration and decomposition processes lower pH. Like dissolved oxygen concentrations, pH may change with depth in a lake, due again to changes in photosynthesis and other chemical reactions. There is typically a seasonal decrease in pH in the lower layers of a stratified lake because CO2 accumulates. There is no light for plants to fix CO2 and decomposition releases CO2. The pH of water at different places is given below in bar chart format.
Hardness
The hardness of water of the river Buriganga has shown a variation from 288 mg/l to 467 mg/l as CaCo3. 288 mg/l was showed in Hazaribagh and 467 mg/l was showed in Dholaikhal. The hardness of water at different place is given below.
The ECR 97 recommends a range of hardness for drinking water will be the range in 200 to 500 mg/l as CaCo3. No sample was found to have crossed the upper or lower limit. According to test result, the hardness of water is of the river is very good.
Iron
Iron of water of the river Buriganga was found in a range of 0.26 mg/l to 0.93 mg/l. Among them 0.26 was found in Dholaikhal and 0.93 was found in Chandnighat. The iron of water at different place is given below.
Changes in Water Quality from Hazaribagh to Dholaikhal
pH
The weighted average values of pH of water in Hazaribagh were 7.1, where in Chandnighat were also 7.1 and in Sadarghat were 7.2 and in Dholaikhal intake point were 7.2. This indicates that pH is increased from Hazaribagh to Dholaikhal in the direction of water flow.
Color
The weighted average values of Color of water in Hazaribagh were 728, where in Chandnighat were 659 and in Sadarghat were 687 and in Dholaikhal intake point were 338. From the average value, we can easily say that the water color is very high in Hazaribagh, because many tanneries, lather industry and dying industry discharges their waste water directly into the river.
Turbidity
The weighted average values of Turbidity of water in Hazaribagh were 47.87 NTU, where in Chandnighat were 53.43 NTU and in Sadarghat were 13.9 NTU and in Dholaikhal intake point were 7.9 NTU. From the average value, we can easily say that the Turbidity of water is high in Chandnighat.
Hardness
The weighted average values of Hardness of water in Hazaribagh were 304 mg/l, where in Chandnighat were 394 mg/l and in Sadarghat were 456 mg/l and in Dholaikhal intake point were 475 mg/l. From the average value, we can easily say that the Hardness of water is high in Sadarghat.
Alkalinity
The weighted average values of alkalinity of water in Dholaikhal were 464 mg/l, where in Hazaribagh were 378 mg/l and in Sadarghat were 456 mg/l and in Chandnighat were 462 mg/l. From the average value, we can easily say that the alkalinity of water is high in Dholaikhal.
Chloride
The weighted average values of chloride of water in Dholaikhal were 163 mg/l, where in Hazaribagh were 178 mg/l and in Sadarghat were 58 mg/l and in Chandnighat were 51 mg/l. From the average value, we can say that the chloride of water is showed highly variation in Dholaikhal and Hazaribagh with Sadarghat and Chandnighat. So much salt is used in tanneries for processing of lather in Hazaribagh.
Iron
The weighted average values of iron of water in Dholaikhal were 0.3 mg/l, where in Hazaribagh were 0.92 mg/l and in Sadarghat were 0.62 mg/l and in Chandnighat were 0.84 mg/l. weighted average value shows that iron of water was not exceed the limit.
BOD5
Now in present, BOD (Biochemical Oxygen Demand) is very high in river Buriganga. Our experiments have shown that the BOD in Hazaribagh was 92 mg/ l, Dholaikhal were 72 mg/l, Sadarghat were also 92 mg/l and Chandnighat were 90 mg/l.
Conclusions
Based on the analysis of data and information collected, the following conclusions are drawn:
As Dhaka city is expanding day by day with the increasing rate of population, now a days it has become a regular event that river area is used up by the land grabbers. As a result all the main rivers are becoming narrow day by day. Because of high growth rate of population the country is expected to have its population more than 280 million by the year 2050. About 40% of these total rural or urban migrations will take place to greater Dhaka. Dhaka has now become a mega city that causes enormous pressure on the surrounding rivers because maximum drainage outlets and sewerage of this mega city falls into the rivers like Buriganga.
Literature review reveals that there are many industries developed on the river bank and those discharges about 1.5 million cubic meters of untreated waste water everyday into the river. This is one of the most vulnerable reasons behind the extreme pollution of the river water.
The water quality parameters that are tested for the river water showed that most of the samples were within the standard limit set by ECR, 97. Few samples crossed the limit but still some kingfishers are flying over the river to collect their daily meal from it. It is high time to save the river from the devastating effect of urbanization and to establish the flora and fauna of this mega city by giving a new life to Buriganga.
Recommendations:
Some recommendations are suggested to save the existing river whish are as follows:
Proper dredging of the existing river and removing non degradable matters from the river bed.
Unauthorized establishment on the river bank should be demolished and maintain a regular monitoring system against the land grabbers.
By providing Effluent Treatment Plant for each and every Industrial unit to reduce the pollutant load on the river.
Law enforcement should be strictly maintained to prevent abuse of water ways and by creating a special law enforcement force to save Buriganga.
Public Awareness should be increased for proper usage of the river water.
Decentralization of some important industries, e.g. tanneries, dying industries etc from the center of the city to the periphery.
