Cashew nut processing: Sources of environmental pollution and standards
India is largest producer, processor, exporter and second largest consumer of cashew in the world with annual production of 6,20,000 MT (Anon 2007). India processed about 1.18 million MT of raw cashew seeds through 3650 cashew processing industries scattered in many states of country provided employment to over 0.5 million people, 95% of these are women (Nair, 1995). The cashew industries in India employed different unit operations/ methodology for processing depend on variety of raw material, location, technological mechanization and availability of secured energy supply. There are two commonly followed methods of cashew nut processing, viz. Roasting process and Steam (roasting) Cooking process. Due to lack of skilled man-power for cutting process of cooked nut and difference in taste of nut, many of the industries in India are following roasting process. In the cashew nut roasting process, thick black smoke is released from the rotating roasting drum through the stack. The smoke, when it reaches the ground, has irritating odour and is public nuisance in the neighborhood. Borma heater is also a source of air pollution. Wastewater is generated from the quenching operation of the roasted cashew nut discharged. Cooking process also discharges wastewater from the steam cooker and emits air pollutants by Baby Boiler for steam generation and Borma heater.The sources of different environmental pollutant discharged in to the atmosphere during the cashew nut processing have been revealed in the article. The environmental standards for air pollution emission for roasting process, steam cooking process and broma oven have been presented. The waste water discharge from the quenching operation in roasting process and vessel discharge during steam cooking process have been presented in the article. The solid waste disposal practice and new and relocation sitting criteria have been discussed for cashew processing industries.