Estimation of industrial pollution load in Bangladesh

Abstract

Information regarding industrial pollution load and its regional distribution is vital for developing sound pollution control and management stratcgies. However, in Bangladesh, reliable estimates of industrial pollution load are not available. Only limited work has been done on determining characteristics of industrial wastewater from selected industries and some estimates of water pollution load have been made for selected industrial clusters. This study attempts to make a preliminary estimate of industrial pollution load in Bangladesh using the Industrial Pollution Projection System (IPPS), developed by the World Bank. The IPPS converts industrial production or employment data into pollution load by using appropriatc coefficicnts, which have been developed based on production, employment and pollution data from over 200,000 industries in the United States. In this study, the industrial employment data reported in the Census of Manufacturing Industries (CMI) have been used to estimate industrial pollution load in Bangladesh using the IPPS. For making the estimates, the manufacturing industries in Bangladesh have bcen categorized according to the ISIC code of classification and then, using IPPS coefficients, estimates of industrial pollution have been made for each category of industry. In accordance with the IPPS, estimation of pollution load has been made in terms of (i) water pollutants (BOD and TSS) (ii) toxic-chemical pollutants, (iii) toxic-metals, and (iv) air pollutants (S02, N01, CO, VOC, TSP, and fine particulates). Estimations have been made for the country as a whole, for major industrial districts of the country (Dhaka Chittagong, Khulna, and Narayangonj), as well as for the major categories of polluting industries. In this study, estimation of industrial pollution has been made for the year 1995-96, the latest year for which the CMI data are available, and for thc year 1991-92. The BOD load from the entire industrial sector has been estimated at around 34,000 metric ton for the year 1991-92 and about 28,000 metric ton for the year 1995-96. Thcse estimates are close to the value (32,000 metric ton) reported for BOD in a study by BKH (1995). The major polluting industrial sectors in Bangladesh, with respect to BOD, are textiles, sugar, pulp paper and paperboard. According to the present estimate, these three industrial sectors together accounted for about 90% of BOD load in the year 1991-92 and about 80% in 1995- 96. Other industrial sectors contributing to the BOD load include oil and fat, tanneries, fish products, dairy products, drugs and medicine, distilleries, industrial chemicals, soap and toiletries, preserved fruits and vegetables, petroleum refineries and fertilizer and pcsticidcs. Thc total TSS load from all industrial sectors have been estimated to be around 40,000 metric ton for the year 1991-92 and about 30,000 metric tons for the year 1995-96. The major industrial sectors contributing to TSS load are textiles, sugar, pulp paper and paperboard. These three industries are also the major contributor of BOD load. Other industrial sectors contributing to the TSS load include oil and fat, iron and stecl, fertilizer and pesticides, tanneries, drugs and medicine, distilleries, industrial chemicals, soap and toiletries, preserved fruits and vegetables, and jewelry. According to the present study, the major toxic-chemical (comprising mainly toxic organic compounds) polluting industrial sectors in Bangladesh are textiles, tannery, iron and steel, drugs and medicines, and chemical products. Other industrial sectors contributing to the toxic-chemical load include structural clay (bricks, ceramics), plastic products, electrical apparatus, printing and publishing, shipbuilding. The total toxic-chemical pollution load in Bangladesh has been estimated to be about 37000 MT and 41000 MT in 1991-92 and 1995- 96, respectively. The major toxic-metal polluting industrial sectors in Bangladesh, are textiles, iron and steel, structural clay (bricks, ceramics), structural metal, fabricated metal, and electrical apparatus. Other industrial sectors contributing to the toxic metal pollution include soap and cleaning preparations, printing and publishing, and chemical products. Estimated total toxic-metal release in the country in 1991-92 and 1995-96 is approximately 7250 MT and 7500 MT, respectively. Chittagong appears to be the most pollution intensive city in terms of toxic metal pollution in Bangladesh. However, since actual data on toxicchemicals and toxic-metals are very limited, the estimated toxic-chemical and toxic-metal pollution load must at be treated as indicative. In terms of estimated total air pollution, textiles, cement and clay (e.g., bricks) products, food industries, paper, tobacco, pharmaceuticals, petroleum, and metal are the major air polluting industry sectors in Bangladesh. Among the air pollutants, estimated emission of S02 has been found to be the highest. In 1995-96, estimated S02 emission is about 0.3 million metric tons, N02 emission around 0.18 million metric tons, CO around 37,000 metric ton, VOC around 49,000 metric tons, and total suspended particulate about 0.11 million metric tons. However, the labor-intensive nature of textiles and food industries are probably responsible for these industries to be identified as significant air polluters. The actual air pollution potential of these and other industries must be ascertained with the help of actual measurements. Percentage contribution of S02 emission from the major industrial districts for the year 1995- 96 shows that the largest contributor of S02 load is Chittagong, accounting for about 13% of the total S02 emission. This is due to the heavy concentration of a number of air pollution industries in the district, including cement/clay, paper-pulp, pharmaceuticals, and industrial chemicals. Dhaka and Narayanganj both accounts for about 10%, and Khulna about 5% of total emission. The pattern of regional variation of industrial N02 and CO emission is almost similar to that for S02. The VOC emission pattern is significantly different from those of S02, N02 and CO. For VOC, Dhaka is the largest contributor, accounting for about 40% of total estimated VOC emission from industrial sector. Tannery industry is the principal contributors of VOCs for Dhaka. The regional distribution of TSP is also different from that of other air pollutant in the country. The four major industrial cities together contribute about 20% of the total particulate matter. In the present study industrial employment data have been used to estimate pollution load, using IPPS coefficients, and hence it is likely to over-estimate pollution load for laborintensive industries. This is particularly true for many industries in Bangladesh, including the textiles, tanneries, etc. Again, the estimated industrial pollution load is questionable for industries which use processes or technologies that are significantly different from those on which the IPPS coefficients are based. This notion is particularly true for industries such as drugs and medicine, iron and steel, dairy products and industrial chemicals. Thus, while IPPS could be useful in developing a preliminary estimate of industrial pollution load and in identifying and ranking major polluting industries, the pollution load estimated by IPPS must be interpreted in light of the technologies, processes and raw materials used in the relevant industries and available data on characteristics of industrial effluents and emissions.