Firdaus Khan
About 6.2 Million tonnes of hazardous wastes is annually generated in India from about 35,000 industries, out of which around 3.09 Million tonnes is recyclable, 0.41 Million tonnes is incinerable and 2.73 Million tonnes is land-fillable. This categorization of hazardous wastes into 3 classes is based on the hazard potential and its characteristics guiding its ultimate disposal, in accordance with the Hazardous wastes (Management, Handling & Transboundary Movement) Rules, 2008. Most of these wastes have characteristics suited to their utilization as resource material either for recovery of energy or materials like metals or their utility in construction, manufacture of low-grade articles or recovery of the product itself, which after processing can be utilized as a resource material. Hence a new mind- set treating the hazardous waste as a resource material rather than a difficult disposable material is the need of the hour. Presently, these hazardous wastes are being disposed through incinerator or secured land fill depending upon the calorific value of the wastes.
The cost of providing incinerator would depend on its capacity ranging from Rs 10 crores to 30 crores. Assuming disposal cost of incinerable hazardous waste is about Rs. 16,000/- per MT, it may roughly be estimated that additionally about Rs. 640 crore / annum would be incurred in incinerating hazardous waste in our country. Besides, incinerator if not operated optimally may contribute to emissions including toxic Dioxins and Furans. This coupled with resource conservation and reduced carbon emissions make a strong case for considering co-processing as a sound and better alternative for hazardous wastes disposal in general and incinerable waste in particular.
Thus the co-processing of hazardous substances in cement industry is much beneficial option, whereby hazardous wastes are not only destroyed at a higher temperature of around 14000C and longer residence time but its inorganic content gets fixed with the clinker apart from using the energy content of the wastes. Apart from this, no residues are left, which in case of incineration still requires to be land filled as incinerator ash. Further the acidic gases, if any generated during co-processing gets neutralized, since the raw material is alkaline in nature. Such phenomenon also reduces resource requirement such as coal and lime stone. Thus utilization of Hazardous wastes for co-processing makes a win –win situation.
The production of cement in India is about 200 Million Tonnes per annum, for which estimated coal and lime stone requirement are 40 Million Tons per annum and 320 Million Tons per annum, respectively. The country, therefore, has potential to utilize entire hazardous waste generation, if found suitable otherwise, for co-processing. Apart from this many other substances having high calorific value viz.; tyres and plastic wastes, which are otherwise treated as “waste” but do not fall under the purview of “hazardous waste”as stipulated in the Hazardous wastes (Management, Handling & Transboundary movement) Rules, 2008, can also be co-processed in the Cement industry.
CPCB has already taken up trial run for co-processing of few categories of wastes and granted regular permission for the same. Based on satisfactory performance of trial run, about 25 cement manufacturing units in various States already started co-processing of these few categories of wastes with the approval of CPCB. Further, trial run is also going on for various other categories of waste.
Therefore the need of the hour is to co-process the waste in cement kiln and reduce the burden on common hazardous waste treatment and disposal facility (TSDF). Nevertheless, this solution is a sustainable one which will lead to reduction in energy and costs, immobilisation of toxic and heavy metals and bring down climate change effects.
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