Environment Risk Assessment of Hazardous Waste Generating Small Scale Metal Finishing Industries, India: A Case Study

摘要

Small scale industries have been regularly dumping extremely hazardous waste mainly fatal toxic metals in North Delhi region every year. As per NCAER (2001) 13,785 industrial units are presented in 28 approved industrial areas in Delhi. Out of these 27% are polluting units and generating 151.6 tons HW/Day. Approximate 70% hazardous waste of total solid waste is from metal finishing industries in Delhi (DPCB, 2001). The paper discusses the environmental problems due to hazardous waste generation in Wazirpur industrial area in Delhi. Wazirpur industrial area is largest polluting unit having clusters of more than 424 small scale industries. More than 80% are metal finishing industries. The hazardous waste are being disposed off indiscriminately on open land or along with municipal solid waste with in or outside the premises of units. Metal finishing wastes is highly acidic (pH, 2-3) with high concentration of toxic metals such as chromium ( > 5000 ppm), nickel ( > 600 ppm), copper ( > 450 ppm), iron (4-5%) and Mangnese (1.5 - 2%). The high nutrient content such as available nitrogen ( > 700 ppm), percentage organic carbon ( > 4 -5%), NH)_4~+-N ( > 120 ppm) and NO_3-N (250 ppm) of the waste showing the potentiality of generated waste for agriculture uses. Toxic waste also gets leached down upto the surface water table and influencing the ground water quality. Microbial contamination of metal finishing waste a serious risk to human health. Pathogenesis of waste causes gastrointestinal disorders, genital infections, pulmonary infection, skin disorder and various other manifestation in area workers. The common pathogens were from protozoan (40%), nematodes (14%), bacteria (70%) and fungi (38.5%). A practicable H.W. management strategy has been developed in approved industrial areas in NCT of Delhi. Ninety percent of total H.W. to be disposed in secured land fill and remaining 10% of H.W. for physicochemical treatment, incineration, and recycle/reuse. The detail results of physicochemical and microbial characteristics of waste will be discussed.