Application Of Powdered Activated Carbon From Coal In The Biological Treatment Of Petrochemical Wastewater

A large amount of petrochemical wastewater is produced during processing,production,transportation and storage in the petrochemical industry,and its pollutants are complex in composition,which can harm the ecological environment and eventually pose a threat to human health through the food chain if not treated properly.In this paper,the petrochemical wastewater comes from a petrochemical industrial park in Liaoning Province,where the secondary A/O ponds of the park wastewater treatment plant have low biochemical degradation treatment efficiency and the effluent quality problem needs to be solved.The powdered activated carbon-activated sludge（PAC-AS）process can improve the system loading capacity and treatment efficiency by adding powdered activated carbon to the aeration tank,which is a cost-effective process for upgrading the old process.But it is rarely used in petrochemical wastewater treatment.In this paper,the application of powdered activated carbon from coal in petrochemical wastewater biological treatment was studied through activated carbon selection,comparison experiments and activated carbon regeneration in order to analyze the strengthening effect of powdered activated carbon and provide a basis for parameter regulation to optimize the process and improve the efficiency of petrochemical wastewater biological treatment.The experimental results show that:（1）The adsorption processes of COD_crand TOC by the 11 powdered activated carbon from coal were in accordance with the quasi-second-order kinetic equations.The equilibrium adsorption amount of COD_crby the preferred activated carbon No.11was 58.217 mg/g,and its adsorption isotherm for COD_crcould be well fitted by Freundlich model.（2）PAC-AS process has greatly improved the treatment effect of petrochemical wastewater.The removal of COD_crand TOC in PAC-AS system are 4 times and 2times of that in AS system,and the removal of TN and NH₃-N are 3 times and 2 times of that in AS system,respectively.The TP removal of PAC-AS system was about 62%,while the TP concentration of AS system increased.In addition,adding PAC can increase the biomass in the system and improve the settling property of sludge obviously.（3）Wet air oxidation of powdered activated carbon from coal was carried out at245℃,and the regeneration effect increased with the increase of regeneration pressure（3.6～6.9 MPa）.The iodine number and methylene blue adsorption of the regenerated carbon were up to 670 mg/g and 54 mg/g,and the recovery rates were about 65%.The decolorization of caramel was about 6 times that of fresh carbon.The recovery rates of specific surface area and total pore volume were 80.4%and 91.8%respectively.The proportion of micropores decreased,while the proportion of mesoporous and macroporous increased.The particle size of regenerated activated carbon particles decreased significantly,and the particle size distribution range was more concentrated,tending to be in the range of 4～30 microns.