Study On Treating And Reusing Ship Greywater

Water pollution from sewage aboard ships is too severe with the rapid development of marine industry to be ignored. Some conventions have been formulated to prevent the water pollution from sewage aboard ships by both international and domestic. According to these conventions, the blackwater must be treated before discharge but not necessary for greywater only when which mixed with blackwater. Though the requirement for greywater is not as strict as for blackwater, the huge amount of greywater has induced the attention all over the world. We believe the global legislation of greywater treatmen will be established soon.On the base of analyzing the existent problems of ship sewage treatment equipment, this paper has studied UF operation principle through working on ultrafilm separation technology and linking to sewage active sludge treatment facing above issues, designed a new Marine MBR in order to treat and reuse ship greywater, so as to achieve the recycle of the ship freshwater resources.In the paper, a primary experiment of ship greywater was carried out using Membrane Bioreactor. During the operation, the removal efficiencies of pollutants were investigated. The result shows that the average removal efficiency of COD_Cr, ammonia nitrogen, LAS and turbidity has reached 93.7%, 51.7%, 93.7% and 93.9% respectively under the operation period 4.5h. The membrane separation process can enhance the waste water treatment effect. The effluent quality was superior to the standards for water reuse. The variety of the flux and several cleaning methods are compared.On the base of the primary experiment, design the ship greywater disposal apparatus for 250 persons on the ship, determine parameters of treatment unit and analysis its economy. Economic analysis indicates that the total project investment is 4.78 ten thousand yuan and the resuing cost is 2.22 yuan/m³. This expense is significantly lower than the cost of desalination device.