Di Capua Francesco, Esposito Giovanni
Department of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, Bari, Italy.
Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, Naples, Italy.
Water Environ Res. 2022 May;94(5):e10721. doi: 10.1002/wer.10721.
This study demonstrates the feasibility of pyrite-assisted denitrification to treat mildly acidic wastewaters and proposes a convenient solution for nitrogen removal from acidic mining waters. Pyrite is a highly available and low-cost electron donor for autotrophic denitrification, whereas mining waters represent a source of nitrogen (N) contamination due to the use of N-containing explosives during mining operations and cyanide (CN)-based compounds for ore processing. In this study, the denitrification performance of a recirculated pyrite-packed biofilter (RPPB) treating simulated N-contaminated acidic mining waters is evaluated under decreasing pH conditions. The effect of feed organic carbon on the autotrophic process has been also investigated. N removal efficiencies (NRE) > 60% could be achieved at feed pH ≥ 4.5 and HRT ≥ 5 h. Decrease of influent pH to 3.0 reduced the NRE to 20%. The addition of 10 and 20 mg/L of ethanol to the influent did not significantly impact NRE of the RPPB. PRACTITIONER POINTS: Pyrite-assisted denitrification is proposed for treating acidic wastewaters. Nitrogen removal >60% was maintained at feed pH as low as 4.7. Decrease of feed pH to 3 strongly inhibited denitrification. The presence of organic carbon in the feed did not affect the autotrophic process.
本研究证明了黄铁矿辅助反硝化处理微酸性废水的可行性，并提出了一种从酸性采矿废水中去除氮的便捷解决方案。黄铁矿是自养反硝化中一种易于获取且低成本的电子供体，而采矿废水由于在采矿作业中使用含氮炸药以及在矿石加工中使用基于氰化物（CN）的化合物而成为氮（N）污染的来源。在本研究中，评估了在pH值降低的条件下，循环式黄铁矿填充生物滤池（RPPB）处理模拟含氮酸性采矿废水的反硝化性能。还研究了进水有机碳对自养过程的影响。在进水pH值≥4.5且水力停留时间（HRT）≥5小时的情况下，氮去除效率（NRE）>60%。进水pH值降至3.0时，氮去除效率降至20%。向进水中添加10和20mg/L的乙醇对RPPB的氮去除效率没有显著影响。从业者要点：提出采用黄铁矿辅助反硝化处理酸性废水。在进水pH值低至4.7时，氮去除率仍保持>60%。进水pH值降至3会强烈抑制反硝化作用。进水中有机碳的存在不影响自养过程。
