KWR Water Cycle Research Institute, Groningenhaven 7, 3433, PE, Nieuwegein, the Netherlands; KTH-International Groundwater Arsenic Research Group, Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, SE, 100 44, Stockholm, Sweden; Department of Environmental Technology, Wageningen University and Research (WUR), Droevendaalsesteeg 4, 6708, PB, Wageningen, the Netherlands; Evides Water Company N.V., Schaardijk 150, 3063, NH, Rotterdam, the Netherlands.
KWR Water Cycle Research Institute, Groningenhaven 7, 3433, PE, Nieuwegein, the Netherlands.
Water Res. 2020 Jul 1;178:115826. doi: 10.1016/j.watres.2020.115826. Epub 2020 Apr 17.
In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 μg/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 μg/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.
在这项研究中，我们研究了从人工补给的地下水中生产饮用水，将砷（As）降低到 1μg/L 以下的机会。我们观察到，快速砂滤是使用人工补给地下水作为水源的水处理厂中氧化和去除 As 的最重要处理步骤。As 的去除主要是由于 As 与 Fe(III)(oxyhydr)oxides 共沉淀，这在快速砂滤床中比曝气和上清液储存具有更高的效率。这是由于在滤床中 As(III)被加速氧化为 As(V)，这可能是由锰氧化物和/或 As(III)氧化细菌引起的，因为这两种物质都通过化学分析和细菌群落的分类学分析在快速砂滤料颗粒的涂层中发现。砷的去除不会发生在颗粒活性炭过滤、超滤或慢滤等处理步骤中，因为它们的进水缺乏水解铁，并且 As 与过滤表面之间缺乏吸附亲和力。此外，我们发现通过在快速砂滤器的进水中投加高锰酸钾和氯化铁的组合或仅通过投加氯化铁处理快速砂滤器的出水，可以有效地在水处理厂将 As 降低到 1μg/L 以下。最后，我们观察到降低 pH 值是增加 As 与 Fe(III)(oxyhydr)oxides 共沉淀的有效措施，但仅当水中的氧化砷，As(V)，是主要物种时才有效。
