Water reuse and recycling according to stream qualities in sugar-ethanol plants

Sugarcane is one of Brazil's most important industries, mainly because of ethanol, one of its products. Ethanol has a low production cost and low GHG emissions per unit of energy produced, as compared to other fossil fuels. However, several authors have expressed concern about the high water consumption expected in the coming years for biofuel production. This work presents a proposal to reduce water consumption in the industrial stage, taking into account demand and supply quality restrictions. A water supply mix is suggested, with direct reuse of 648 L/t of cane, and another 176 L/t of cane covered indirectly by recycled streams. This reduces the required external withdrawal to 405 L/t of cane - a value within the limit mandated for the sugarcane industry in the State of Sao Paulo.