Treatment of Eutrophication
...mainly the release of nutrients from the lake sediments into the water column. 2. Status in quo Eutrophic status of worldwide lakes and reservoirs This histogram rooted in spot check shows us the eutrophic status of lakes and reservoirs of five countries. The baby blue columns represent the percentage of high eutrophication lakes and reservoirs. Yellow and pea green columns separately denote the percentage of middle and light eutrophication. According to the eutrophic status of five countries: We can see that eutrophication is a serious problem. And the United States is the worst one. Canada is the best one. 3. Method of Treatment Let’s see the general method of treatment. There are three methods: biological, physical and chemical method. 3.1 Biological Method Biological Method include Ecotechnology and Biomanipulation. 3.1.1 Ecotechnology Include bacterial agents and water-inhabiting plants renovation. Generally, We are familiar with this technology, and I do not elaborate on it. 3.1.2 Biomanipulation Biomanipulation is based on top down control. (what is called in contemporary limnology) The control in mind is natural, internal control within ecosystem. The principle of biomanipulation is food chain manipulation by keeping the feeding pressure of fish on the zooplankton low. I think that this method will bring unbeknown destroy to ecosystem and will break the ecological balance of the natural water body. 3.1.3 Main advantage The advantage of biological method include: they are cheap, minimize the use of raw materials and Much more environmentally friendly. 3.2 Physical Method Include aeration, dilution and water scrubbing and sediment treatment. The shortcoming: High costs, include a variety of subsequent treatments and the duration of effectiveness is too short. To the water column, sediment can be a major source of nutrients. Let’s have some farther acquaintance with the sediments treatment. * sediment treatment Its options include dredging, capping, and in situ sediment treatment. a. Dredging Let’s see two images about dredging. This image shows us an ongoing dredging, and this is a kind of dredger. Dredging can induce a series of bad sequences. Such as, noise, cost, odour and disposal of dredged sediment b. Capping Physical capping is that a layer of clean material, usually coarse sand is deposited over contaminated sediments. The biggest uncertainty with capping is how quickly new deposition will move over the cap and establish a new layer rich in phosp...