Biological PRB (permeable reactive barrier) system for underground in-situ remediation of coal mine acid wastewater

The invention relates to a biological PRB (permeable reactive barrier) system for underground in-situ remediation of coal mine acid wastewater, and belongs to the technical field of water pollution control. The system comprises a water inlet groove, a biological PRB body and a water outlet tank, wherein the water inlet groove is higher than the goaf ground for 0.3-0.5 m; the biological PRB body adopts a four-layer structure, and sequentially consists of a buffer protecting barrier, a ferrous powder PRB, a biological medical stone PRB and a buffer protecting barrier; the water outlet tank adopts the sectional separating plate type, so as to ensure that the interior of the biological PRB is always in the water filling anaerobic state in the running process of system. The system is arranged on the coal mine goaf, and the defects of land occupation during ground treatment, pollution to environments, laying of long-distance conveying pipelines and the like are overcome. The system has the advantages that the structure is simple, the cost is low, the safety is realized, the efficiency is high, and the manned watching is not required in the running process. On the basis of the traditional PRB, the novel PRB with biological strengthening function is established in the method that the medical stone is fixed and mixed with sulfate reducing bacteria.