Effluent BOD Analysis of Selected Tannery Industries in Hazaribagh Area

The aim of this project is to find the Biological Oxygen Demand (BOD) of the wastewater generated from the tanneries of Hazaribagh and the mixture of tannerys wastewater with Buriganga river water. Hazaribagh is a principal area of Dhaka Metro bounded by Buriganga River on the west and Bangladeshs largest leather processing zone is situated here. Hazaribagh area, widely known for its tannery industry, has been listed among the highest 10 polluted places on earth. The tanneries use backdated processing methods and dump toxic wastes including the cancer-causing toxin hexavalent chromium, into Dhakas mainstream Buriganga. The settlements of tannery workers have developed around the contaminated streams, ponds and canals. Workers and residents of Hazaribagh also face a number of less severe but common health problems of skin and respiratory diseases every day as well as acid burns, rashes, dizziness and nausea. Informal leather recyclers who burn scraps of leather to produce a number of consumer products also heavily pollute the air. Tanneries discharge the effluents and wastes into the river system causing an outsized area of acid sludge alongside the flood protection embankment and therefore the liquid wastes are dumped in the river through flood control regulator-cum-sluice. During dry season dissolved oxygen in the river water is nil because of heavy pollution and no fish or other aquatic animals can live in this condition. Many experimental results showed that tannery wastewater has a very high concentration of organic matter, solids, sulphates, sulphide and chromium in tannery effluent.