Application Of Nano Bubble Remediation Technology In The Treatment Of Severe Polluted Lake

Eutrophication is one of the most important problems of water environment management in our country. As a result of domestic wastewater, agricultural wastewater and industrial wastewater emissions, eutrophication phenomenon exists in lakes and rivers widespreadly. There is a huge threat to the natural environment and human healt. With the development of society and science technology, eutrophication has always been the hot spot of reseach, the management technologies are also developed and applicated. In recent years, with the strengthening of environment protection by the government, it is urgent to solve the eutrophication with effective technologies, and the integration of comprehensive treatment technologies are the main force of practical application.This study put forward a new kind of technology for eutrophication management—nano bubble water restoration technology. The technology keeps nano bubble as the center, combined air flotation and the ecological floating island as subsidiary. The study researched the application of nano bubble water remediation technology in a severe polluted lake, explored the mechanism and effectiveness of the technology from macro and micro perspective. The water qualities were track detected. After 3 months treatment, the dissolved oxygen (0.5 mg/L to 5 mg/L) and transparency (0.2 m to 0.5 m) of the lake were increased obviously. The pollutants (COD, N, P) were removal effectively, the CODCr reduced from 37 mg/L to 25 mg/L, the ammonia nitrogen (NH4--N) and total nitrogen (TN) decreased from 20 and 25 mg/L to 11 and 15 mg/L repectively, the total phosphorus (TP) declined from 3.5 mg/L to 1.1 mg/L. In addition, the lake’s phytoplankton and sediment microorganisms were compared before and after treatment. The remediation effect was analysised from micro perspective. Before the treatment, Euglena Acus, Scenedesmus and Cyclotella Meneghniana which mark of severe eutrophication were replaced by Phormidium Corium, Spirulina Platensis, Nostoc Linckia, Pandorina Morum, Actinastrum Hantzschii, Pediastrum Boryanum. It implied the decreasing of degree of the eutrophication. The lake sediment microorganism structure was analysised by high-throughput sequencing technology. It found that the relative abundance of main functional bacteria—Proteobacteria was increased from 28.4% to 45.1%. Chloroflexi, Cyanobacteria and Chloroplas which mark eutrophication were decreased from 16.8%,9.8% and 7.7% to 8.2%,1.3% and 1.1% respectively. It indicated that the nano bubble water restoration technology could enhance the microbial system of lake sediment.In summary, nano bubble remediation technology of eutrophic water have significant repair effect, significantly improve the dominant species in Lake phytoplankton and sediment microbial, strengthen the ecological system of the lake. There was a great application prospect in the treatment of lakes and river.