Example of Chromium Removal from Wastewater in a Synthetic Chlorine Dioxide Production System
In this paper,a new engineering example for the treatment of chromium-containing waste water in pulp and paper mill as the re-search object,for the intermittent hexavalent chromium(Cr6+)comprehensive treatment system that developed by the comprehensive use of self-produced chemicals and existing equipment,the reasons for the generation of Cr6+wastewater in the chlorine dioxide workshop and the properties of the wastewater were analysized.Based on the effects of different pH value of reaction pool,reaction temperature,reaction time,and sulfur dosage on the reduction effect of Cr6+in wastewater,the optimum reaction conditions of the sulfur dioxide reduction process for removing Cr6+were determined,and the reduction effect of Cr6+was demonstrated in combination with the actual production data.The re-sults showed that the optimum conditions for the effective removal of Cr6+from high concentration chromium-containing wastewater were that pH value of 2～4,reaction temperature of 40～60 ℃,sulfur dosage of 1.4～1.6 times of the theoretical dosage required for the reaction,and reaction time of 40 min.The content of Cr6+in the effluent of wastewater from the three shutdowns of chlorine dioxide workshop was lower than 0.005 mg/L,and the content of total chromium was lower than 0.06 mg/L,which were in line with the requirements in the GB 8978-1996,confirming the effectiveness of the treatment of the intermittent Cr6+comprehensive treatment system.
chlorine dioxidesulfur dioxide reduction methodchromium-containing wastewaterremoval rate of hexavalent chromium
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