Achieving zero water use and zero discharge in the Chinese sugarcane industry

Sugar making from cane is a water-consuming process, and the generation of organic compounds as liquid effluents is a major environmental problem in the sugarcane industry. The volume of freshwater required can be reduced significantly to zero by fully re-using the intrinsic water in sugarcane and by recycling wastewater generated during the sugar making process, such that no wastewater is discharged. In this study, a decontamination triage and hot-and-cold-stream separation was incorporated at the end of wastewater treatment at a typical Chinese sugar mill; the improved treatment design also ensured the closed recycle of wastewater. Water balance calculations indicated that the intrinsic moisture content of sugarcane could fully satisfy the loss of water in the sugar making process. These calculations were proved correct by the performance of the treatment system. The technology has achieved zero water consumption and zero CODCr discharge since its implementation in the 2011-2012 milling campaign. The results demonstrate that the treatment modifications are feasible in full-scale implementation and can be used to significantly improve the environmental performance of the Chinese sugarcane industry.