Study On Effect Of Aeration On Water Body Remediation Of Black-odor River

With the urbanization and an increase in population, many rivers were contaminated and became black and odoriferous, because more and more wastewater was discharged into rivers. The main pollutant in the black-odor river was organics and the dissolved oxygen(DO) was very shortage. The phenomenon of black-odor river was widespread in China at present.Aeration technology was widely used in the remediation of polluted rivers in the world because of its low investment and quick response. Aeration can promote the oxygen mass transfer and improve the DO level in the water body. Aeration can also restore and enhance the activity of aerobic microorganisms in water, inhibit the release of nitrogen and phosphorus from the sediment, and improve the liquid mixing and sludge flocculation.Therefore, the pollutants could be removed and the water quality of the river could be improved. In this study, some influencing factors of aeration on remediation performance of polluted river were investigated in lab-scale tests, including aeration equipment and strength, aeration mode, and aeration location. The effect and mechanism of aeration on the remediation of polluted river were analyzed. This study could provide technical support for the remediation of river water.The results were as follows:1) Microbubble aeration can increase the DO content in water body quickly. The removal rates of CODcr, NH4+-N, TN and Geosmin using microbubble aeration were51.39%, 44.10%, 38.96% and 44.80%, respectively, which were much higher than those using conventional aeration. The removal rates of CODcr and NH4+-N with the intermittent aeration were 51.44% and 72.93%, respectively, lower than those with the continuous aeration. However, TN removal rate with the intermittent aeration was significantly higher than that with continuous aeration. Then intermittent aeration could provide more efficient nitrogen removal. Moreover, intermittent aeration can also reduce operation cost.2) The aeration accelerated the pollutant release rate from the river sediment in the early stage, resulting in rapid increase of all pollutants. On the other hand, the activity of the aerobic bacteria were enhanced due to the increase of DO concentration in water,promoteing the degradation or transformation of CODcr、NH4+-N、TN and TP. The average release rates were-0.11g/(m2·d) for TN and-0.02g/(m2·d) for TP, respectively. The releaserates of TN and TP from the river sediment were inhibited effectively when DO concentration increased, and the organic pollutants, TN and TP could be reduced.3) Aeration could change the physical and chemical properties of sediment,influencing the nitrogen content with various forms in the sediment interstitial water.Under the same conditions of aeration, sediment aeration could remove pollutants in sediment better and reduce the release of pollutants from sediment to overlying water again. And the deeper sediments aeration depth was, the better treatment efficiency was obtained. At the end of the test, the corresponding CODcr, NH4+-N, TN and TP removal rates were 69.73%, 78.36%, 45.98% and 84.21%, respectively. Therefore, the sediment aeration technology and the suitable aeration position could be favor for polluted river water environmental remediation.