Study On Advanced Treating Process Of Reused Coking Wastewater

Despite of biochemical treatment of coking wastewater, the concentrations of suspend, organic contaminants, and salt are still high. Advanced effective treatment process must be carried out to remove or reduce large amount of impurities for the purpose of reusing the wastewater as circulating cooling water.Based on effluent of two stage biochemical treatment in Baosteel coking company, this research experiment introduces the pretreatments of Coagulation and Sedimentation, Sand Filter Process, chlorine dioxide catalytic oxidation, Granular Activated Carbon (GAC) Adsorption, etc, in order that the effluent can meet the inlet requirements of Reverse Osmosis. Further more, proper running parameters are chosen for desalting using Reverse Osmosis, the ultimate effluent completely meet the water quality requirement of circulating water system. The detailed water quality analyses of effluents on each stage are conducted, and the influence factors of each unit are discussed in this dissertation. In the end, the optimal process parameters are determined as well as the existed format of organic contaminants.The result indicates that using PAC as flocculant (dosing of 100 mg·L^-1) with the assisting flocculant of PAM (dosing of 1.5 mg^-1), without the adjustment of pH value, the Coagulation and Sedimentation is carried out at normal temperature followed by still sedimentation for 30 minutes and Sand Filter Process. The COD_crof effluent decreases from 251mg^-1 to 156mg^-1, with the removal rate of 37.8% while turbidity decreases from 65 NTU to 1.3 NTU, with the removal rate of 98.0%.The appropriate preparation condition of carrier catalyst obtained in this research experiment is: the concentration of Cu²⁺ in solution is 4%, baking at 350℃ for 4 hours. When the volumetric ratio of chlorine dioxide solution to wastewater is 1: 5, conduct catalytic oxidation at normal temperature without the adjustment of pH value. When the velocity of filtration reaches l3.9ml·min^-1, the removal rate of COD_cr is above 50% steadily, and can reaches optimistically 61 mg·L^-1. Meanwhile, the catalyst can be reused, the effectiveness of reused catalyst can be 80% of the new one.The appropriate condition of treating with Granular Activated Carbon (GAC)...