Integrated membrane-based processes to obtain organo-mineral fertilizer, water, and energy from sugarcane vinasse

This work presents three integrated systems to obtain organo-mineral fertilizers, water, and biogas from sug-arcane vinasse. The first system (a) combined ultrafiltration (UF) and a two-stage anaerobic bioreactor (2S-AnMBR); the second (b) UF, 2S-AnMBR, and reverse osmosis (RO), and the third (c) UF and nanofiltration (NF). The reuse of RO and NF may reduce by 10.5 % the water uptake from primary sources and all systems equipped with the 2S-AnMBR presented a positive energy balance. The organo-mineral fertilizer production from vinasse membrane concentrate presented technical and economic advantages compare with raw vinasse direct appli-cation via fertigation, especially in the granulated form. Theoretically, the organo-mineral fertilizer would be capable to attain the nutritional demand of sugarcane crops, differently from what was observed in fertigation, besides the lower transportation and production cost. It was estimated an organo-mineral fertilizer production from 0.2-0.68 m3per m3 of vinasse processed, which would be capable to fertilize an area of 44,260-150,503 ha annually. The organo-mineral fertilizer production is directly linked with the flowrate of each system (raw vinasse: 527 m3/h, UF: 105.4 m3/h, NF and RO: 168,6 m3/h). Overall, both economic and environmental gains were obtained from the integrated systems, with the potential to promote a higher valorization of vinasse beyond the treatment for disposal.