Delgado S, Alvarez M, Rodríguez-Gómez L E, Elmaleh S, Aguiar E
Department Chemical Engineering, University of La Laguna, Av. Astrof. Fco. Sánchez, S/N 38200 La Laguna, Spain.
Water Sci Technol. 2001;43(10):133-8.
Reclaimed wastewater transport is studied in a concrete-lined cast iron pipe, where a nitrification-denitrification process occurs. The pipe is part of the Reuse System of Reclaimed Wastewater of South Tenerife (Spain), 0.6 m in diameter and 61 km long. In order to improve wastewater quality, at 10 km from the inlet there is injection of fresh water saturated in dissolved oxygen (DO), after which a fast nitrification process usually appears (less than two hours of space time). The amount of oxidized nitrogen compounds produced varies between 0.8 and 4.4 mg/l NOx(-)-N. When DO has disappeared, a denitrification process begins. The removal of nitrite is complete at the end of the pipe, whereas the nitrate does not disappear completely, leaving a concentration of about 0.4-0.5 mg/l. For a COD/NOx(-)-N ratio higher than 5, a first order nitrification rate in NOx(-)-N has resulted, with the constant k20 = 0.079 h-1, for a NOx(-)-N concentration range of 0.8-4.4 mg/l. Finally the following temperature dependency for the first order denitrification rate constant has been found: k = k20 x 1 x 15T-20. Although nitrogen could be used as nutrient in the agricultural reuse, its removal from reclaimed wastewater could be useful in order to diminish the chlorine needs for reclaimed wastewater disinfection.
在一条内衬混凝土的铸铁管道中研究了再生水的输送情况，管道内会发生硝化 - 反硝化过程。该管道是西班牙南特内里费岛再生水回用系统的一部分，直径0.6米，长61公里。为了提高废水质量，在距离进水口10公里处注入溶解氧（DO）饱和的淡水，之后通常会出现快速硝化过程（时空小于两小时）。产生的氧化态氮化合物量在0.8至4.4毫克/升NOx(-)-N之间变化。当溶解氧消失后，反硝化过程开始。管道末端亚硝酸盐的去除是完全的，而硝酸盐并未完全消失，残留浓度约为0.4 - 0.5毫克/升。对于COD/NOx(-)-N比率高于5的情况，在0.8至4.4毫克/升的NOx(-)-N浓度范围内，得到了NOx(-)-N的一级硝化速率，常数k20 = 0.079小时-1。最后，发现了一级反硝化速率常数与温度的如下关系：k = k20×1×15T - 20。虽然氮在农业回用中可作为养分，但从再生水中去除氮有助于减少再生水消毒所需的氯量。
