Delgado S, Alvarez M, Rodríguez-Gómez L E, Elmaleh S
Dpt. Chemical Engineering, University of La Laguna, Av. Astrof. Fco. Sánchez, S/N. 38200 La Laguna. Spain.
Environ Technol. 2004 Mar;25(3):365-71. doi: 10.1080/09593330409355470.
The agricultural reuse of reclaimed wastewater has become a necessity in places with water shortages. Frequently, this involves the operation of long transportation pipelines, like in the South Tenerife reuse system, whose main element is a completely filled 61 km long gravity pipe in cast iron. Sulphide generation, which could contribute to pipe corrosion, is a usual process taking place during transportation if anaerobic conditions prevail. In the Wastewater Treatment Plant of Santa Cruz (Tenerife, Spain) a partial nitrification process was achieved by increasing the mean residence time through the aeration step at low dissolved oxygen concentration. Such conditions, combined with the right temperature and a free ammonia concentration above 1 mg l(-1), inhibited nitratation and favoured nitritation, which led to concentrations of NO2-N above 8 mg l(-1) in the secondary effluent. During the transportation, nitrite inhibited the appearance of anaerobic conditions, and, consequently, no sulphide generation occurred. At the same time, a nitrite reduction process took place with a first order kinetics and a rate coefficient of 0.052 h(-1)' at 25 degrees C. A parallel behaviour between the nitrite depletion and the oxidation-reduction potential evolution along the pipeline was also observed.
在水资源短缺地区，再生水的农业回用已成为必要之举。通常情况下，这涉及到长距离输水管道的运行，比如在南特内里费回用系统中，其主要部分是一条完全充满水的61公里长的铸铁重力管道。如果存在厌氧条件，在输水过程中通常会发生硫化物生成，这可能会导致管道腐蚀。在圣克鲁斯污水处理厂（西班牙特内里费岛），通过在低溶解氧浓度下增加曝气步骤的平均停留时间，实现了部分硝化过程。这些条件与合适的温度以及高于1 mg l(-1)的游离氨浓度相结合，抑制了硝酸盐化，促进了亚硝酸盐化，使得二级出水的NO2-N浓度高于8 mg l(-1)。在输水过程中，亚硝酸盐抑制了厌氧条件的出现，因此没有发生硫化物生成。同时，发生了亚硝酸盐还原过程，在25℃时具有一级动力学，速率系数为0.052 h(-1)。还观察到沿管道亚硝酸盐消耗与氧化还原电位变化之间的平行关系。
