Confirmatory Study On Persistence And Effectiveness Of Remove Alage By Micro-Pore Filtration

The marine environmental problems caused by ballast water have been paid great attention. Therefore, it is significant to find an effective method for controlling and preventing from the harmful biological and pathogens spreading via ballast water. A ballast water treatment system was designed and established in the lab. Micro-pore ceramic filter as a primary method for filtration in the system, was used to treat the test water with suspended particles. The gravimetric method (GB11901-89) was used to measure concentrations of TSS (Total Suspended solids), and the microscopical counting method to determine concentrations of nitzschia closterium.Firstly, the optimal flow rates of four type filters were determined experimentally, and the relationships between water pressure in front of the filters and accumulative total treatment volume of the test water were studied under the optimal flow rate of each filter. In this way, the running persistency of micro-pore filter can be obtained. The experimental results show that while the TSS concentrations in the test water is greater than 50mg/L, the accumulative total treatment volumes are greater than 11m3 for each micro-pore filter. It means that the filter has a long continued running time, i.e. and it has good persistency.Secondly, using the micro-pore ceramic filter, the removal efficiency of algae was studied experimentally. In the experiment, nitzschia closterium was chosen to be test because the size of the algae is small, and the initial concentrations of the algae were in a range of 3×104～3.5×104ea/mL. It can be concluded that the removal efficiency is proportional to the meshes per square inch of the filter. For the filter with 100meshes/in2, the average removal efficiency is up to 85%～91%, and it is up to 93%～100% for the filter with 200meshes/in2.Finally, in order to recover the filtration capacity, single water backwash was used to regenerate micro-pore ceramic filter. After single water backwash with the water volume of about 2m3, the membrane flux recovery rate of each filter is up to 90%. The more water volume in backwash, the higher average membrane flux rate will be.