Use of Zero-Valent Iron Powder for Nitrate Reduction in Soil under Saturated and Unsaturated Conditions

摘要

This paper presented a potential use of zero-valent iron (ZVI) powder for the reduction and retardation of nitrate in soil columns under saturated and unsaturated flow conditions. Uniform mixture ratios of ZVI powder with soil were of concern in the range of 30% by weight of soil in order to investigate the change of mobility and reduction of nitrate. As a comparison, layered formations of ZVI powder within soils were also comprised with a certain height, which corresponded to a prescribed weight of ZVI powder. Temporal moment approaches allowed to identify the degradation rate constant and retardation factor based on experimental breakthrough curves of nitrate leachate and to quantify mass recovery fractions associated with NO₃-N and NH₄-N. The results showed that the increase of the amount of ZVI powder resulted in the increase of the degradation rate constant and retardation factor values up to 1.3 per hour and 1.7, respectively. The decrease of NO₃-N and the increase of NH₄-N were observed and were significant under saturated conditions due to the corrosion. Moreover, there was a slight difference between two repacked formations of ZVI powder in soil columns in terms of mobility and reduction of nitrate.