Experimental study on seeded precipitation assisted reverse osmosis for industrial wastewater reuse

Industrial wastewater reuse and zero liquid discharge (ZLD) has been a growing trend due to increasing water scarcity and tightening environmental regulations. In China, ZLD is becoming mandatory for all coal chemical plants newly built in water scarcity areas. As a promising technology to achieve high water recovery and reduce operation cost, the seeded precipitation assisted RO process was proposed for coal chemical wastewater reuse and the initial feasibility was evaluated in this study. A 100 l/h laboratory system comprising a RO unit and an ambient temperature crystallizer (ATC) was designed, fabricated and tested with real wastewater from a coal chemical plant. This paper presents the detailed design of the laboratory system and major testing results on the pretreatment, the membrane process as well as the seeded precipitation happening in the ATC. Overall the seeded precipitation assisted RO process was proved to be feasible and promising for coal chemical wastewater reuse and future onsite pilot study was also suggested.