Study On Pollution Characteristics And Countermeasures Of Sewage Aboard Ships

Water pollution from sewage aboard ships is too severe with the rapid development of marine industry to be ignored. As a big country with ocean, shiping, sailors and harbors and shipbuilding, it is necessary to study and carry on the pollution control from sewage aboard ships. It is a important research topic to solve the flowing pollution source, to protect ocean and rivers, to realize the sustainable development of shiping,and also to meet with requirement of the world shipping environmental protection.Through small scale test on land, production test aboard ship and survey at home and abroad, pollution characteristics of sewage from ship, impact assessment mode of water area pollution, affecting factors of sewage treatment aboard ships, law control and management measures, research direction of treatment technology were studied, the integrated measures were given to solve pollution of sewage from ships. The research results would offer theoretic basis and measures to control pollution of sewage from ships in China. The main research results are as follows:(1)Pollution characteristics of sewage from ship and it's impact assessment mode are studied. The arrangement of ship wastewater system, the characteristics of sewage quantity and quality aboard ships were analyzed. Through examination aboard ship, some parameters were gained.Fecal sewage per capital aboard freighter is 14 L/d, BOD₅ pollution load is 23 g, SS is 28 g. The parameters can be used to determine the pollution source intensity of fecal sewage on land with similar living standard, and also to design the sewage separate collection system. The study showed that, compared with sewage from dwelling houses, sewage from ships is very different at production, drainage and quality. It's a main problem for sewage treatment plants aboard ships in China to apply mechanically treatment modes of municipal sewage on land.According to flowing pollution characteristics of ships, sewage coefficient k₁ per capital and pollution load coefficient k₂ were given to count the pollution source intensity, it would offer theoretic basis for exact assessment of pollution impact from sewage aboard ships in water area and for pollutant gross control.(2)In lab UBF+COR+CS was adopted to treat sewage from ships. According to ship's characteristics, experiment was taken under different special conditions. Stable operation experiment showed that, as influent BOD₅ was 140¹ 720 mg/L, SS was 510—2 400 mg/L, effluent BOD₅ was less than 50 mg/L, SS less than 50 mg/L. Special conditions experiment showed that, 2 d's halt needed 8 hrs' operation to meetthe discharge standard, 5 d's halt required 24 hrs, 10 d's halt 72 hrs, 20 d's halt 7d. Refering to ASTM, experiment of toilet flushing with seawater was simulated. UBF unit increased the salt tolerance extent of aerobic biotreatment, the technology can be used to treat sewage from toilet flushing with seawater. Although the treatment efficiency was affected slightly, the effluent can also meet the requirement. Experiment of toilet flushing with seawater and freshwater alternately showed that, the technology can endure larger shock load from freshwater to seawater than from seawater to freshwater. The system need 3 d's adjusting to recover while toilet flushing changed from seawater to freshwater.(3)Through experiment aboard ship, the problems of application of small scale technology to production test were analysed, the special factors influencing sewage treatment aboard ships were summarized. Mechanical pretreatment, sewage quantity adjusting and aeration of sewage treatment plants aboard ships were investigated. The movement effect of ship was analyzed, the factors such as space, type, movement, temperature, available resource, safe and management made sewage treatment aboard ships complicated. Also, measures should be adjusted to local conditions for sewage treatment aboard ships, and technologies on land should not be mechanically applied to ships.(4)According to the characteristics of ship sewage treatment on land, the suitable tec...