Study On Treatment Of Ship’s Oil-bearing Ballast Water By The Combination Of Fe-C Microelectrolysis And Biofilm Process

With the development of the world industry,the ship transportation of industrial material oil becomes an important part of marine shipping,and the ship transportation of oil will produce a large amount of oil-bearing ballast water.The difficulty of the treatment of oil-bearing ballast water in ships lies in the treatment of low concentration oily sewage containing a small amount of dispersed oil and dissolved oil.If it is not properly disposed and discharged into the sea,it will cause serious pollution to the marine environment.Therefore,rapid and efficient treatment of low concentration oily wastewater is an urgent problem to be solved in ship oil-bearing ballast water treatment.In this paper,the low concentration of oil-bearing ballast water was pretreated by Fe-C microelectrolysis process.A new Fe-C microelectrolysis filler was developed,and the treatment effect of the Fe-C microelectrolysis filler on low concentration oil-bearing ballast water was evaluated.The biofilm process was used as a follow-up process with it to improve the treatment efficiency.The operation conditions of the two processes were optimized.The simulation experiment was carried out for the treatment of low concentration oil-bearing ballast water by the combined process.The experimental results showed that the new Fe-C microelectrolysis filler had excellent performance and porous surface.It was mainly mesoporous,and contained larger pore.X-ray diffraction(XRD)analysis showed that some of the fillers were metal oxides,most of which were simple metal substances.The removal effect of chemical oxygen demand(COD)and oil content in oil-bearing ballast water was remarkable.The optimal factors affecting Fe-C microelectrolysis were determined and the kinetics of COD removal was analyzed.The result showed that the model was in accordance with the first-order kinetic model.The biofilm membrane culture was carried out by adding petroleum hydrocarbon degrading bacteria.The results of high-throughput sequencing analysis showed that the dominant biofilm bacteria was petroleum hydrocarbon degrading bacteria ASW-2.The influencing factors of biofilm treatment were optimized.The Fe-C microelectrolysis process and biofilm process were combined,and the optimum operating conditions of the two processes were taken as the starting parameters of the experiment.The simulated oil-bearing ballast water was treated.The results showed that the combined process had obvious removal effect on COD and oil content in oil-bearing ballast water.With the increasing of reaction time,the removal rate of COD and oil content remained above 98%.And the residual concentrations of COD and oil were less than 3 mg/L and 1 mg/L,respectively,in accordance with GB 18918-2002 of Grade A(COD≤50 mg/L)and the national standard GB 3552-2018(oil≤15 mg/L)for the discharge of oily wastewater from ships.