| With the rapid development of maritime trade,the marine environment has been polluted to varying degrees.The International Maritime Organization has proposed the MEPC.227(64)standard for the issue of domestic sewage discharge and pollution from ships.At present,marine membrane bioreactors(MBR)have attracted much attention in the field of marine wastewater treatment due to their high removal efficiency and small footprint.In order to investigate the processing efficiency of marine MBR and whether it meets the IMO emission standards,a bench-scale aerobic-electric flocculation-anaerobic membrane bioreactor(O-E-A MBR)and an engineering prototype aerobic-anaerobic membrane bioreactor(O-A MBR)were used for experimental research.The effects of different environmental and ecological factors were studied using O-E-A MBR,a bench-scale pilot plant sewage treatment plant.In the test under a certain range of volume load conditions,it was found that lower volume load is not conducive to the removal of COD(chemical oxygen demand)and TN(total nitrogen).The removal effect is better when the volume load is 0.94 kg COD/(m~3×d)it is good.In different aerobic section hydraulic retention time(HRT)impact tests,the highest average COD and TN removal rates were achieved at 8 h in the aerobic section,which were 91.51%and 84.78%,respectively,which fully met the MEPC.227(64)standard.The ambient temperature was suitable for the stable removal of MBR between 20℃and 30℃.In examining the influence of different phosphorus removal methods on the phosphorus removal effect,the external phosphorus removal efficiency was the highest.The bench-scale test proves that the hydraulic retention time,temperature,and volume load have a greater impact on the test,and it need to be monitored and adjusted daily during the test.An engineering prototype O-A MBR with a black-water treatment capacity of 30 people was developed,and the actual wastewater removal effect was studied to find the best treatment conditions.Examining the effect of temperature on the processing efficiency of the engineering prototype,the results show that when the temperature was below 15±1℃,the effluent of the prototype was difficult to meet the discharge requirements,and the removal rate was highest at27±1℃;The research on the membrane module retention function shows that the biofilm on the membrane module has a high removal efficiency of TN,and regular backwashing can slow down membrane pollution and ensure the normal operation of MBR;Due to the lower C/N of the actual inlet water,the aerobic section with HRT of 7 h had a higher sludge load.Extracellular polymer substances(EPS)and sludge volume index(SVI)studies show that at this time,the sludge has high stability and compactness,good sludge sedimentation,and the highest COD removal rate was 85.8%.Effluent TN was below 20 mg/L,which meets the MEPC.227(64)standard.The high-throughput sequencing of the organisms in the prototype showed that the relative bacterial abundance and the number of the same predicted genes in the aerobic HRT was 7 h.and Caldilinea accounted for the highest 6.74%,indicating that the sludge was in good condition and the highest removal efficiency was obtained at this time,that was High species diversity facilitates removal of pollutants.The BP neural network was used to simulate the environmental ecological factors during the prototype process,and the average prediction error obtained was small.At the same time,the relative importance ranking of the environmental factors was obtained by the separation weight method.The research provides a technical basis for the effective regulation of marine membrane bioreactors in the treatment of sewage,and has certain theoretical and engineering significance. |
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