EVALUATION OF PRETREATMENT PROCESSES FOR ZLD PLANTS FOR TREATING COMPOSITE DYEING EFFLUENT STREAMS

摘要

Zero Liquid Discharge (ZLD) Plants, based on Membrane Technologies for reclaiming the resources viz., water and salt, are the emerging strategies for treating composite effluent streams from dyeing industries. The removal of suspended and organic dissolved solids is the pre requisite for the application of membrane based plants, to reclaim inorganic dissolved solids. The removal of COD,TSS,TVS and Color is the primary objective of providing pre treatment, before the effluent is considered to reclaim water or salt, through membrane based plants. The chemical treatment, biological treatment and ozonation are the proven methods for providing necessary pre treatment. On evaluation through laboratory studies on six different methods, their respective merits and demerits are found. Perhaps, ozonation can be concluded as the best available technology for the pretreatment of dyeing effluent in the ZLD plants, for the primary reasons of less sludge and qualified supernatant that can be negotiated in Reverse Osmosis Plants.