检查井内污水跌落充氧试验研究

Study on Water-dropping Aeration in Manhole

检查井是污水管道内水流与外界空气接触的重要场所,管内氧含量对污水自净能力有明显影响。对西安市城区部分检查井内氧含量的调查发现,井内氧组分稀缺现象较普遍,而跌落水流可有效改善此现象。利用竖桶试验模拟研究检查井内跌水充氧的影响因素,结果表明:增大竖桶顶部孔径时,跌落水流的复氧效率和顶部小孔卷吸气量均增加,但随着孔径的增大此影响逐渐变小;随着跌水流量的增加,水垫层复氧效率与小孔卷吸气量缓慢增加;当水流跌落高度为0.6 m时,复氧效率约为0.4 m时的2倍;顶部小孔位置在跌落水流正上方且水平距离入口最远时,水垫层复氧效率最大,当小孔在桶盖边缘处时,水垫层复氧效率均低于小孔在水流正上方的复氧效率。

Manhole is an important place where wastewater flow is in contact with the outside air in sewers in which oxygen content has a significant effect on wastewater self-purification. The oxygen content in some manholes in Xi＇ an urban area was investigated. It was found that the oxygen-deficient phenomenon in wastewater manholes was relatively common, and the nappe flow could effectively improve this phenomenon. The factors influencing the water-dropping aeration in wastewater manholes were studied in the plexiglass vertical bucket test. The results showed that when the hole diameter at the top of the vertical bucket was increased, the aeration efficiency of nappe flow and the air inflow at the top were both in- creased. However, the influence gradually reduced with the increase of the hole diameter. The aeration efficiency and the air inflow were slowly increased with the increase of nappe flow. When the nappe height was 0.6 m, the aeration efficiency was almost twice as much as that at the nappe height of 0.4 m. When the hole at the top was just above the nappe flow and horizontally farthest from the inlet, the aeration efficiency was maximum. However, when the hole was at the edge of the vertical bucket cover, the aeration efficiency was less than that above the nappe flow.