Solar energy is an important energy sector that plays a crucial role in reducing greenhouse emission in different industrial sectors, including the leather sector, to control the pollution. Stringent environmental regulations of Zero Liquid Discharge (ZLD) in Indian tanneries are implemented as directed by regulatory authorities. The ZLD system resulted in the generation of saline rejected from membrane systems being evaporated by spending considerable energy. In this paper, the potential of solar energyfor evaporation of reject from ZLD in a closed accelerated solar dryer has been investigated. In this study, the evaporation of reject/ saline water using a solar dryer with different volumes has been experimented and the volume reduction and increase in Total Dissolved Solids (TDS) are monitored during the drying period. It is evident that the closed accelerated solar dryer has shown an increase in evaporation rate with reduction in the volume of water in a given area. The outcome of this study would lead to avoidance of mechanical evaporators in case of smaller capacity ZLD plants and also reduce the amount of water to be evaporated in the Multiple Effect Evaporator (MEE) in case of larger ZLD plants. By the application of the accelerated solar dryer for the evaporator, the potential CO2 emission reduction due to replacement of different fuels used for evaporation of reject has been estimated to reduce the carbon footprint and to ensure the sustainability of the leather industry.
Read full abstract