Research And Application Of Activated Carbon On Adsorption And Thermal Energy Conversion For Coking Wastewater Treatment

Coal chemical industry accounts for about16%of the total national economy, in thepollution of which coking industry is representative. Hundreds of organic matter is found incoking wastewater. Biological treatment, chemical treatment and physico-chemical treatmentmethod are all used for coking wastewater treatment. Adsorbents used for adsorption mainlyincluded commercial activated carbon, waste-reused activated carbon, zeolite and resins.Activated carbon after adsorption was directly used for coking or landfill disposal because ofregeneration conditions difficult to control resulting in high cost. How to reuse the activatedcarbon is one of the important factors. Another important consideration is how to pretreatmenthigh concentration of coking wastewater (COD≥4500mg/L) before biological systems,thereby ensuring the efficiency operation of biological systems.Powdered activated carbon, for example, was used in the static adsorption treatment ofbio-tail coking wastewater, and then put into the raw water to a second adsorption to removethe pollutants. GC/MS was used for qualitative analytical analysis of organic matter in theadsorption process. The calorific value of PAC was tested after the secondary adsorption.Adsorption fixed bed was used to study the efficiency of COD removal through controlling oftemperature, pH and flow rate, while to find the optimal operating conditions on granularactivated carbon (GAC) adsorption treatment of coking wastewater. UV-Vis scanning wasused to analyze wastewater samples before and after the adsorption. The competitiveadsorption of phenol and quinoline was studied. The calorific value of GAC was tested afterthe adsorption. The economic costs of activated carbon adsorption to replace the coagulationwere evaluated, and whether it could achieve zero-cost wastewater treatment was alsocalculated.Second Adsorption as a wastewater treatment effective ways, could be used as the newideas of treatment of the coking wastewater. The results indicated that the effluent can meetthe COD standard after small dose of PAC was used. The most unbiodegradatable compoundsand long chain hydrocarbon compounds in tail effluent can be removed after the adsorption.Besides, phenols in original coking wastewater were removed during the second adsorptionprocess, which indicated the removal efficiency was not affected when PAC was reused. Thecalorific value of coking wastewater was calculated byQw （45.9903.521） cm. Afteradsorption of raw water, the calorific value of PAC increased, which was determinedby Q （45.9903.521）(cm ce) V. The process through the energy recovery shouldachieve a significant reduction in project costs and operating costs for the typical wastewater. GAC could be used for the adsorption of high concentration coking raw water to reduce thebio-processing load. The COD efficiency was more than40%at low flow rate on GAC fixedbed for coking wastewater treatment. Flow rate is the most important factors affecting onremoval efficiency, followed by pH, temperature at the last. The adsorption of phenol orquinoline follows pseudo second order kinetics, Competitive adsorption occurs in a mixedsolution of adsorption process. It can save more than￥1.5/m~3using of AC adsorption insteadof the coagulation for coking wastewater treatment.