There are several reports on simultaneous occurrence of arsenic and nitrate in drinking water sources especially in groundwater at wide range of concentrations. However, there is no report available, so far, on simultaneous successful removal of arsenic and nitrate from contaminated groundwater in absence of iron, and effects of one contaminant on the overall performance of a biological reactor. The present study investigates the roles of sulphate and empty bed contact time (EBCT) on simultaneous removal of nitrate and arsenic to meet the drinking water standards in an attached growth bioreactor in absence of iron.

An attached growth reactor (AGR) was fabricated using Perspex cylinder, inoculated with mixed bacterial culture and operated in downflow mode in absence of oxygen at 30 °C for more than 400 days under varying influent arsenate (200–750 μg/L) and nitrate concentrations (50–200 mg/L), and EBCT of 45–60 min. Acetate was used as external carbon source and electron donor in this study. Complete nitrate removal was observed at all tested concentrations. Arsenic removal was high (up to 99.8%) and was well below drinking water standards from initial concentrations of up to 750 μg/L. The arsenic removal efficiency was found to depend on sulphate reduction and EBCT of the reactor. Results of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analyses suggested that arsenic precipitation in the form of arsenosulphides (orpiment and realgar) was the removal mechanism.

有几篇关于饮用水中砷，硝酸盐同时发生的报道，特别是在浓度范围很广的地下水中。但是，到目前为止，尚无关于在没有铁的情况下同时成功地从受污染的地下水中成功去除砷和硝酸盐以及一种污染物对生物反应器整体性能的影响的报道。本研究调查了在没有铁的情况下，附着生长生物反应器中硫酸盐和空床接触时间（EBCT）在同时去除硝酸盐和砷以满足饮用水标准方面的作用。

使用有机玻璃圆筒制造一个附着的生长反应器（AGR），接种混合细菌培养物，并在不同的进水砷酸根（200–750μg/ L）和硝酸盐下，在无氧条件下于30°C下以向下流模式运行400天以上。浓度（50–200 mg / L）和EBCT为45–60分钟。在这项研究中，乙酸盐被用作外部碳源和电子供体。在所有测试浓度下均观察到硝酸盐被完全去除。砷的去除率很高（高达99.8％），并且从最初的最高浓度750μg/ L远远低于饮用水标准。发现砷的去除效率取决于反应器的硫酸盐还原和EBCT。