Treatment of Textile Waste Water by using ZnO Nano-particle based Reactor

Population explosion has put a pressure on water as a resource; hence we must ensure sustainable use of water. Industrial effluent, especially waste water from textile industries, is one of the major sources of water pollution in western Rajasthan. Large amount of effluents with very high Biochemical Oxygen Demand (BOD) is generated in textile industries and is discharged in the rivers or on land without proper treatment. Conventional waste water treatment methods fail to provide efficient treatment. Present study deals with treating the textile wastewater of Jodhpur city in Rajasthan, India employing photo-catalysis technique. Jodhpur has a large number of small scale textile industries and efficient treatment of its effluents has been a problem for many years. An effort has been made to resolve this issue through this study. ZnO based semiconductor, coated on Galvanized Iron plates, attached to a rotating reactor was used to oxidize biodegradable organic matter present in the wastewater in presence of sunlight. The sunlight was used as a source for UV radiations required in the nano-reactor for the reaction. A pilot plant waste water treatment unit was set-up to carry out experiments. This pilot plant consisted of a sedimentation unit, sand filter, nano-reactor unit and activated carbon filter. The waste water quality parameters removal efficiency at the end of each treatment unit was recorded for different detention periods in the nano-reactor. The water quality parameters considered in this study were, BOD, Total Dissolved Solids (TDS), Total Suspended Solids (TSS) and pH. The reduction in BOD, TDS, TSS and pH for 2 hour detention period was found to be 88.81%, 22.37 %, 99.26% and 5.49% respectively, and for 4 hour detention period was found to be 96.62%, 24.80 %, 99.16% and 8.69% respectively. The reduction in BOD, TDS, TSS and pH for 6 hour detention period was found to be 97.08%, 24.80 %, 99.23% and 4.49% respectively, and for 8 hour detention period was found to be 97.43%, 25.19 %, 99.24% and 3.40% respectively. The results reveal that the 4 hour detention time was optimal for BOD reduction. The untreated wastewater had BOD values ranging between 750 790 mg/l which reduced drastically to 20-25 mg/l after treatment. Thus this technology can be used for the treatment of waste water generated from the textile industries.