Start-up and performance of a full scale passive system in-cluding biofilters for the treatment of Fe, As and Mn in a neu-tral mine drainage. undefined

Passive mine drainage treatment plants are the scene of many chemical and biological reactions. Here, the establishment of iron (Fe), arsenic (As) and manganese (Mn) removal was monitored immediately after the commissioning of the Lopérec (Brittany, France) passive water treatment plant, composed of aeration cascades and settling ponds followed by pozzolana biofilters. Iron and As were almost completely removed immediately after commissioning, while Mn removal took more than 28 days to reach its maximum performance. Investigations were performed during two periods presenting strong variations in feeding flow-rates: from 2.8 m3.h-1 to 8.6 m3.h-1 and from 13.2 m3.h-1 to 31.3 m3.h-1. Design flow rate was reached during the 1st week of the second period. Dissolved Fe and As were not affected by the decrease in residence time while Mn was only slightly affected. Microbial communities in biofilter presented similarities with those of the pond sludge, and genera including Mn-oxidizing species were detected. Proportion of bacteria carrying the aioA gene encoding for As(III)-oxidase enzyme increased in communi-ties during the second period. Results suggest Mn removal is mainly associated with bio-oxidation whereas removal of Fe and As could be mainly attributed to chemical oxidation and precipitation of Fe, possibly helped by As(III) bio-oxidation.

被动矿山排水处理厂是诸多化学反应与生物反应的发生场景。本研究针对法国布列塔尼地区洛佩雷克（Lopérec）的被动水处理厂投产初期的除铁（Fe）、除砷（As）与除锰（Mn）效果开展监测，该厂工艺由曝气梯级池、沉淀池及后置火山灰生物滤池组成。投产初期铁与砷即可实现近乎完全去除，而除锰效果则需超过28天方可达到最优水平。研究在两个进水流量波动显著的阶段开展：第一阶段流量介于2.8 m³·h⁻¹至8.6 m³·h⁻¹之间，第二阶段介于13.2 m³·h⁻¹至31.3 m³·h⁻¹之间，第二阶段第一周即达到设计进水流量。溶解态铁与砷的去除效果不受停留时间缩短的影响，而锰去除仅受轻微影响。生物滤池中的微生物群落与池底污泥菌群具有相似性，且检测到包含锰氧化菌属在内的相关菌群。携带编码三价砷（As(III)）氧化酶的aioA基因的细菌占比，在第二阶段的菌群中有所提升。研究结果表明，锰的去除主要与生物氧化过程相关，而铁与砷的去除则主要归因于铁的化学氧化与沉淀作用，该过程或可通过三价砷的生物氧化得到辅助。