Study On Bioaugmentation Treatment Of Port Oily Wastewater

The oily sewage from the port has complex pollutant components.In the process of treatment,it often needs pretreatment operations such as oil separation,flotation and coagulation sedimentation before it can enter the secondary biochemical treatment.In most cases,the COD of the sewage after pretreatment is still very high,and it also contains a small amount of oil and a certain amount of salt ions(such as Cl^-,SO₄^2-,Na⁺,Ca²⁺,etc.),Therefore,the research on salt-tolerant,petroleum-degrading strains and the optimization of biochemical treatment process in hypersaline and petroleum-bearing environment have become the top priority of biochemical treatment of port oily wastewater.Taking the simulated oily sewage from the port as the research object and the A²/O-MBR process unit as the core,this paper applies the artificial construction of bioaugmentation flora to the treatment process of simulated oily sewage from the port,and analyzes the changes of soluble microbial metabolites of activated sludge and the succession law of microbial community in this process,in order to provide reference for the treatment of the oily sewage from the port.The results show that:（1）Four salt-tolerant,petroleum-degrading strains were screened.Identified by16S r RNA,Y1 was Rhizobium petroleum,Y2 was Novosphingobium soli,Y3 was Mycolicibacterium fluorantheniverans and Y7 was Achromobacter pulmonis.Among the 11 compound results,the bioaugmentation flora constructed by the mixing of strains Y3 and Y7 was used to the treatment of the simulated oily sewage from the port.The removal rates of COD,NH₄⁺-N,TN and petroleum were the highest,which were 61.9%,54.8%,43.6%and 81.1%,respectively.（2）Based on the treatment effect of COD,NH₄⁺-N and TN,the operation parameters of the integrated A²/O-MBR process system were optimized.The optimal HRT of the system is 32 h and the optimal reflux ratio is 250%.Based on the optimized integrated A²/O-MBR process system,the influent salt content（calculated by Cl^-）is gradually increased to acclimate salt tolerant activated sludge.The final effluent TN≤10 mg/L,NH₄⁺-N≤1.5 mg/L and COD≤30 mg/L.（3）Based on the A²/O-MBR process system after salt acclimation,the constructed bioaugmentation flora was applied to the treatment of simulated port oily wastewater.Before and after bioaugmentation treatment,the average removal rate of COD increased by 17.8%,the average removal rate of TN increased by 15.5%,the average removal rate of petroleum increased by 18.4%,and the concentration of sludge SMP increased from 5.2 mg/L to 12.5 mg/L.The main dominant bacteria include bacteria with denitrification function,as Denitromonas,Simplicispira,Thermomonas and petroleum hydrocarbon degrading bacteria,as Ramlibacter,Hydrogenophaga,Pseudomonas,which reflect the good nitrogen removal and petroleum hydrocarbon degradation capacity of the activated sludge system.Each index of the effluent is better than the discharge requirements of Tianjin DB12/356-2018 first-level standard.