Chapter 4. Buriganga River Pollution by Tannery Industry 4. 1 Introduction Tannery industry fulfills a growing international appetite for leather and earns a large amount of foreign revenue. But the tanneries which are located at Hazaribagh are the major cause of Buriganga river pollution. Tanneries of that area do not contain any treatment plant for treating their chemical effluents coming from tanneries processing.
These tanneries discharge their liquid chemical and solid wastes into the river Buriganga. As a result Buriganga river pollution has reached to extreme level and its polluting rate is increasing rapidly.
4. 2 Wastes of Tanneries Tanneries of Hazaribagh produce a large quantity of solid and liquid wastes at the time of processing of hides and skins of animals. Table. 4. 1: Average amount of wastes produced by Dhaka Hides and Skins Limited Waste Type |Waste Amount (ton) |Percentage (%) | |Solid |2 |9 | |Liquid |20 |91 | |total |22 |100 | Source: Questionnaire Survey (: July, 2012)
It has been seen that, tanneries produces more liquid toxic waste than solid waste, which are mostly responsible for water pollution on Buriganga.
Tanneries of Hazaribagh produce 25000 tons of solid waste and 40,000 tons of toxic liquid waste everyday (Daniel 2010). Processing and production of leather and leather products are finished in three sectors, named a) Wet Blue – processing of raw hides. b) Crust – coloring of leathers. c) Finishing – producing leather products. [pic] Figure 4. 1: Percentages of waste from three sectors. Source: Questionnaire Survey. Date: July, 2012.
Most of the wastes are produced at the primary stage of raw skin Processing. 4. 2. 1 Solid Waste 250 tanneries located at Hazaribagh produces 150 metric tons of solid waste everyday. These solid wastes are being produced at the initial and final stage of processing. Solid wastes produced from tanneries includes:- • Shaving Dust – while processing raw hides and skins. • Scarp of hides and skins. • Fat. These solid wastes are being reused and produce leather boards, Zyllatic, Chicken feed, fertilizer, soap etc. 4. 2. 2 Liquid Chemical Waste Liquid chemical effluents are produced during tanning and dying.
Different types of Chemicals are being in tanneries at the different stages of leather processing, including processing of raw hides and skins, chrome tanning – turning a skin into bluish white colored leather. These chemicals includes:- • Lime • Sodium Sulfide • Sulphuric acid • Sodium hydrosulfide • Caustic Soda • Arsenic Sulfide • Calcium hydrosulfide • Chromium • Chloride • Dyes. 4. 3 Buriganga River Pollution from Tanneries Water pollution of Buriganga river is being affected and accelerated by 250 large and small tanneries located at Hazaribagh, at the bank of the Buriganga.
These tanneries do not have any effective waste treatment facilities or any treatment plant. [pic] Figure 4. 2: Status of treatment plant containment by tanneries. Source: Questionnaire Survey. Date: July, 2012. The diagram represents that nearly 99 percent of tanneries do not contain any treatment plant, less than 1 percent tanneries contain treatment plants. As these tanneries do not have any treatment plant, the tannery effluent with high organic and inorganic polluting loads is discharged on the Buriganga river in the vicinity of the tannery area. Table 4. 2: Tannery Waste Disposal System. Disposal Place |Percentage (%) | |Buriganga river (Liquid waste) |80. 00 | |Canal |00. 00 | |Road |00. 00 | |Open Space ( Solid waste) |20. 0 | |Others |00. 00 | Source: Questionnaire Survey. Date: July, 2012. From the table it is seen that most of the tannery wastes, which are liquid disposals are being disposed from Buriganga river through drains. And some of that wastes which are solid disposals are being disposed on open space, on the low lands inside the Dhaka flood protection embankment. [pic] Figure 4. 3: Drain carrying liquid chemical wastes from tannery to the river.
Source: Field Survey (June 2012) The wastewater carrying chemicals from the tanneries is discharged through open drains into a stagnant pond named ‘Nimtala Beel’ which is located between the Hazaribagh area and the flood protection embankment along the Buriganga River. Ultimately, this wastewater is released through Rayerbazar sluice gate into the river as every tannery is linked with Buriganga river through drains 4. 3. 1 Location of Tanneries Most of the tanneries are located on the Buriganga river bank and near the Dhaka flood protection embankment.
Every tannery of Hazaribagh is linked with Buriganga river through drains. Generally tanneries are being located besides river because of availability of sufficient amount of water to clean animal skins into the river. (Toriqul Islam, Leather technologist of Dhaka Hides and Skins Limited) And all of these tanneries release their untreated effluents into Buriganga river through these drains, as a result the magnitude of water pollution of Buriganga river is severe. 4. 3. 2 Effluents Discharged to Buriganga River Daily quantity of waste water produced by these tanneries varies from 0. 5 to 0. cubic meter per meter square of hides and skin processed (Ahmed M. A. Feroze) According to DoE, the tanneries discharge 22000 cubic meters of untreated liquid toxic waste into the river daily. Tanneries of Hazaribagh generate 7. 70 million liter liquid waste and 88 metric ton solid waste everyday, which are discharge into the Buriganga river and 80 % of the pollution of the river Buriganga is caused from tannery wastes. 4. 3. 3 Polluting Loads Discharged to Buriganga River Different kinds of chemicals are being used in tanneries at the time of processing of animals skin to turn on leather and leather products.
The polluting loads which are generated from tanneries are being discharged to Buriganga river includes: • Suspended Solids • Chromium (Cr) • Chloride (Cl-) • Different types of acids such as Nitric acid (HNO3), Sulphuric Acid (H2SO4), Formic Acid (HCOOH) • Salt’s of sodium Chloride (NaCl) • Lime (Calcium Hydroxide-CaOH) • Sodium Sulphate (Na2SO4) • Caustic Soda • Hazardous dyes etc. Due to indiscriminate discharge of these polluting loads to Buriganga. The quality of water of Buriganga as degraded to a great extent. The physical look and smell of the water of Buriganga is frightening, intolerable and horrendous. . 4 Status of Buriganga River Pollution at Hazaribagh 250 tanneries and their generated wastes cause huge pollution of Buriganga river at Hazaribagh. To realize the level of pollution at Hazaribagh a few water quality parameters pH, TDS, DO, BOD, COD and Cr are being analyzed by comparing with standard drinking water quality determined by DoE. pH is the indicator of acidic or alkaline condition of water status. The standard for any purpose in-terms of pH is 6. 5-8. 5; in that respect the value of Buriganga River water are 7. 8 to 8. 9 in dry season. The overall result indicates alkaline water.
From 1983 to 1993 the increasing rate of pH concentration was very high and in 2011 it has slightly decreased. pH. [pic] Figure 4. 4: Concentration of pH on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). TDS. [pic] Figure 4. 5: Concentration of TDS on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). In case of TDS Bangladesh Standard in terms of inland surface water is 1000 mg/L. Figure 4. 4 shows that TDS concentrations in Buriganga river in dry season was found to be 6583 mg/L in 1983, 2475 mg/L in 1993 and 1188 in 2011, which indicates that TDS concentration is decreasing.
Alkalinity. [pic] Figure 4. 6: Concentration of Alkalinity on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). Bangladesh standard Alkalinity concentration in drinking water is 100ppm. Figure 4. 5 reveals that in Buriganga river water at Hazaribagh Alkalinity concentration was 1580 in 1983, 1220 in 1993 and 284 in 2011. Alkalinity concentration at Hazaribagh in Buriganga river water is too high and this water is not suitable for drinking and sustaining aquatic life. DO. [pic] Figure 4. : Concentration of DO on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). DO standard for sustaining aquatic life is 4 mg/L, whereas for drinking purposes it is 6 mg/L. Figure 4. 5 reveals that DO concentration at Hazaribagh in Buriganga river water from 1983 to 2011 was 0 in dry season, which indicates that the water is not suitable for sustaining aquatic life BOD. [pic] Figure 4. 8: Concentration of BOD on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). In the case of BOD standard for drinking purpose is 0. 2mg/L.
Figure 4. 7 shows that BOD concentration at Hazaribagh in Buriganga river water was 55mg/L in 1983, 386 in 1993 and 42 in 2011. [pic] Figure 4. 9: Concentration of COD on Buriganga river at Hazaribagh (dry season). Source: DoE (June 2012). Chemical oxygen demand (COD) is other important parameter of water quality assessment. A standard for drinking purposes is 4 mg/L, which are not acceptable in-terms of Buriganga river water. From figure 4. 8 it is seen that concentration of COD at Hazaribagh in Buriganga river water was 1010mg/L in 1983 and 116mg/L in 2011.
Cromium. [pic] Figure 4. 10: Concentration of Cr on Buriganga river at Hazaribagh (dry season). Source: WASA (June 2012). A standard for drinking purposes for Cr is 0. 5 mg/L. But figure 4. 9 shows that concentration of COD at Hazaribagh in Buriganga river water was 0. 104 mg/L in 1983 and 0. 093 mg/L in 1993 and 0. 097in 2011. 4. 5 Affected Area The pollution of Buriganga river from tanneries not only affect the environment and people of Hazaribagh, it also affects the downstream areas as well as some upstream areas of the river.
The tannery pollution exposed to the residents of Rayerbazar, Zhigatala, Keraniganj, southern part of Dhanmondi and Savar. [pic] Map 4. 1. Areas affected by Buriganga river pollution. Source: Banglapedia 2012. The pollution is even bleaker in the villages along the river, in the upstream of the Buriganga. Thousands of families living in Zinzira, Kholamora, Kamrangichar, Jhaochar, Modhyerchar, Wasspur, Basila and Looterchar. These areas face severe water crisis for at least six months a year.
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