tailieunhanh - AERATION: Principles and Practice ( VOLUME 11 ) - Chapter 8

Hệ thống sục khí trong vùng nước tự nhiên 8,1 sục khí - sông suối Trong mùa hè năm 1963, tác giả chính là một kỹ sư lĩnh vực ở Virginia đánh giá một hệ thống sục khí trong dòng sông Jackson (Burns et al, 1966). Hai 11,2 kW (15 hp) thiết bị sục khí bề mặt được đặt 1,8 dặm hạ lưu của các Pulp West Virginia và giấy Covington Mill, đã đạt được 85 đến 90% loại bỏ BOD trong nhà máy xử lý nước thải đa tầng. Mục tiêu là để tăng DO trong dòng các giá trị đo. | 8 Aeration Systems in Natural Waters AERATION STREAMS AND RIVERS In the summer of 1963 the senior author was a field engineer in Virginia evaluating an in-stream aeration system in the Jackson River Burns et al. 1966 . Two kW 15 hp surface aerators were located miles downstream of the West Virginia Pulp and Paper Covington Mill which was achieving 85 to 90 percent BOD removal in a multistage wastewater treatment plant. The objective was to increase the DO in the stream to measurable values to prevent nuisance conditions. The location of the aerators was at the critical deficit where the rate of natural reaeration of the stream is equal to the deoxygenation rate due to BOD decay. The difference between the upstream and downstream DO measurements multiplied by stream flow provided the rate of oxygen transfer due to mechanical aeration with no correction for deoxygenation or natural reaeration since they cancelled each other out. The aerators were installed as floating units but were found sitting on the stream bottom after unknown sharpshooters had targeted the metal floats for practice. This event led to the installation of polyurethane filler to prevent intentional or unintentional sinking. After successful operation DO profiles were measured upstream and downstream of the aerators along with the velocity profile and cross-sectional areas to provide flow. It was determined that the aerators were performing as desired producing about kg O2 kWh lb O2 hph . Stream DO increased from an upstream value of zero to approximately 2 mg L at the downstream location 61 m 200 ft below the aerators. At the aerator stations average stream depth was m ft upstream and m ft downstream with the stream width approximately 61 m 200 ft . Two problems however prevented meeting desired DO levels in the stream both due to natural causes. The first was that the stream flow was the lowest on record during that hot dry summer with anoxic conditions .

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