Design Criteria and Required Chemistry for Removing Manganese in Acid Mine Drainage Using Subsurface Flow Wetlands
Design Criteria and Required Chemistry for Removing Manganese in Acid Mine Drainage Using Subsurface Flow Wetlands
复制标题
利用地下流湿地去除酸性矿山排水中锰的设计标准和所需化学物质
DOI：
10.2175/106143000x138111
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发表时间：
2000
影响因子：
3.1
通讯作者：
H. N. Taylor
中科院分区：
文献类型：
--
作者：
F. Sikora;L. Behrends;G. A. Brodie;H. N. Taylor
锰（Mn）是在酸性矿井排水中难以去除的金属，因为Mn氧化形成Mn氧化物沉淀物需要高pH。然而，锰的去除可以加快在砾石系统提供一个大的表面积和高pH值的锰氧化发生与微生物调解。设计了12个9.8 m3 × 6.7 m3 × 0.6 m3的砾石床围隔生态系统，以确定优化除锰的最佳设计标准。试验设两种锰负荷（1.1和2.7 g/m2·d）和两种砾石类型（石灰石和河卵石），重复3次，连续734 d。
石灰石中锰的去除比河砾石中锰的去除更有效。锰的去除不受水温5至30 °C的影响。锰的去除率范围从100至600米/年的石灰石湿地和10至60米/年的河流砾石湿地。石灰石（约6.9）与河流砾石（约5.5）相比，更大的pH值有利于锰氧化物沉淀。更大的pH值，再加上氧化还原电位（氧化还原）值大于430毫伏的石灰石，导致水化学预测锰氧化物附近的条件是占主导地位的锰相。理想的pH值和氧化还原条件为pH值6.8至7.2，氧化还原大于500 mV。各种湿地中去除Mn所需的溶解氧（DO）范围为3至5 mg/L，约一半的DO损失由Mn氢氧化物形成引起，另一半归因于生物消耗。
每去除1 mg/L Mn，进水DO应至少为0.35 mg/L。石灰石和河卵石对锰的去除率分别为1 ~ 17 g/m2·d和1 ~ 2 g/m2·d。石灰石是地下流湿地除锰的首选材料。在这项研究中确定的去除率和所需的化学品可以用来设计最佳的锰去除地下流湿地。
Manganese (Mn) is a difficult metal to remove in acid mine drainage because of high pH requirements for oxidation of Mn to form Mn oxide precipitates. However, Mn removal can be quickened in a gravel system providing a large surface area and high pH for Mn oxidation to occur with microbiological mediation. An experiment was designed with 12 gravel bed mesocosms that were 9.8 m3 × 6.7 m3 × 0.6 m3 to determine the best design criteria for optimizing Mn removal. Treatments consisted of two Mn loading rates (1.1 and 2.7 g/m2·d) and two gravel types (limestone and river gravel) and were replicated three times.
Water flowed through the experimental wetlands for 734 days. Manganese removal was more effective in limestone than in river gravel. Manganese removal was not affected by water temperature ranging from 5 to 30 °C in either rock material. Manganese removal rates ranged from 100 to 600 m/a in the limestone wetlands and 10 to 60 m/a in the river gravel wetlands. Greater pH in limestone (approximately 6.9) compared with river gravel (approximately 5.5) favored Mn oxide precipitation. Greater pH, coupled with oxidation–reduction potential (redox) values greater than 430 mV in the limestone, resulted in water chemistry near conditions predicting manganite to be the dominant Mn phase. Ideal pH and redox conditions for Mn removal are pH from 6.8 to 7.2 and redox greater than 500 mV.
The range of dissolved oxygen (DO) required to remove Mn in the various wetlands ranged from 3 to 5 mg/L, with approximately one‐half of the DO loss caused by Mn hydroxide formation and one‐half ascribed to biological consumption. The influent DO should be at least 0.35 mg/L for every 1 mg/L Mn removed. Removal rates for Mn ranged from 1 to 17 g/m2·d in limestone and from 1 to 2 g/m2·d in river gravel. Limestone is the material of choice for subsurface flow wetlands for Mn removal. Removal rates and required chemistry determined in this study can be used to design subsurface flow wetlands for optimum Mn removal.