Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany E-mail:
Water Sci Technol. 2013;68(4):756-62. doi: 10.2166/wst.2013.278.
Sediments in combined sewers may negatively affect the performance of sewer systems and significantly promote the formation of hydrogen sulfide. To prevent this, German sewer systems are cleaned regularly but at high costs. In order to optimize the cleaning intervals, this study investigates how deposits build up and change over a defined period under constant conditions. The experiments were performed using real wastewater at a pilot plant consisting of three 10 m long acrylic glass pipes with a diameter of 300 mm, a slope of I = 1‰, a discharge of Q = 2 L/s and a roughness of kS = 0.4 mm. Within the first 30 d, a slow increase of the deposit height (averaged over the pipe length) of 0.75 mm/d was observed. The deposits did not build up continuously, but in between times also decreased due to erosion. The daily changes in deposit amounts occurred partly as a function of the rainfall conditions and could go beyond the average growth many times. Within a day, the deposit height (averaged over pipe length) changed by up to 20 mm, at single measuring points even up to 100 mm. After about 50 d under constant test conditions, the deposit height came to a state of equilibrium between sedimentation and erosion.
合流制污水管道中的沉积物会对污水系统的性能产生负面影响，并显著促进硫化氢的形成。为了防止这种情况发生，德国的污水系统会定期进行清理，但成本很高。为了优化清理间隔，本研究在恒定条件下，调查了在规定时间段内沉积物是如何积累和变化的。实验是在一个由三个 10 米长、直径 300 毫米、坡度为 I = 1‰、流量为 Q = 2 L/s 和糙率为 kS = 0.4 毫米的有机玻璃管组成的中试工厂中，使用实际污水进行的。在最初的 30 天内，观察到沉积物高度（沿管道长度平均）以 0.75 毫米/天的速度缓慢增加。沉积物不是连续积累的，而是由于侵蚀而在一段时间内减少。沉积物量的日变化部分取决于降雨条件，有时甚至会超过平均增长率。在一天内，沉积物高度（沿管道长度平均）变化高达 20 毫米，在单个测量点甚至高达 100 毫米。在恒定测试条件下约 50 天后，沉积物高度在沉降和侵蚀之间达到平衡状态。
