水體富營養(yǎng)化英文PPT

1、12021/8/6Eutrophication is one of the water pollution .It is mainly caused by human activities.When a large amount of nutrients , such as nitrogen and phosphorus ,are discharged into large lakes, estuaries, bays and other water bodies which flow slowly, it will cause a phenomenon that algae and othe

2、r plankton in water multiply rapidly, dissolved oxygen decreases , water quality deteriorates and a large number of fish and other organisms die.22021/8/6Excess nutrients(N、P)Autotrophic organisms (especially blue-green algae and red algae) grow quicklyOther algae species gradually reduce Plankton a

3、nd other small organisms die Be decomposed by aerobic microorganismconsume dissolved oxygen in waterFish and other aquatic life die Or be decomposed by anaerobic microorganismProduce hydrogen sulfide and other gases32021/8/6Nitrogen content 0.20.3 ppmBiochemical oxygen demand(BOD) 10 ppmPhosphorus c

4、ontent 0.010.02 ppmThe number of bacteria is more than 100000 in per ml of water(pH=910) The content of chlorophylla in characterized algae 10mg/L42021/8/6Excess nitrogen and phosphorus in the water body mainly come from industrial waste water and domestic sewage, organic waste, livestock and poultr

5、y manure and agricultural chemical fertilizer.52021/8/6Engineering methodsuDigging up the lake sediments Digging up the lake sediments It is the main ways of reducing the self-concentration of nitrogen and phosphorus in eutrophic lake.uDeep aeration Deep aeration Taking artificial lake deep aeration

6、 and supplementing oxygen from time to time is conducive to inhibit the release of phosphorus from sediment. uInject water Inject water Injecting water containing low concentrations of nitrogen and phosphorus into lakes can dilute nutrient concentration.62021/8/6Chemical methodsuCoagulation and Coag

7、ulation and sedimentation sedimentation Many kinds of cations can cause the phosphorus to precipitate from the aqueous solution effectively , such as iron, aluminum and calciumu For For exampleexample, the long lake in western Washington state is a eutrophic water body. In October 1980,people add al

8、uminum salt into the lake to precipitate the lakes phosphate. In the summer of fourth years after the addition of aluminum salt, phosphorus concentration in the lake water became from the original 65 g/L to 30 g/L, the water quality of the lake has been significantly improved.72021/8/6uIn the chemic

9、al method, another way is to kill algae with algaecide. uThis method is suitable for the water body of the lake water bloom. After algaecide kills the algae, the decomposition of algae will still release phosphorus. Therefore , algae killed by algaecide should be promptly removed, or some appropriate chemicals should be added into the water body to make phosphate precipitate.82021/8/6Biological methodsuUse aquatic life to absorb nitrogen and phosphorus in order to remove nitrogen and phosphorus in water.uFor example, some co