Biological filler, preparation method and application of biological filler in sewage treatment

The invention provides a biological filler, a preparation method and an application of the biological filler in sewage treatment, and the method comprises the following steps: carrying out biological treatment on slag generated in the ore dressing and smelting process of low-grade sulfide ore, drying, and screening to obtain a target filler required in the sulfur autotrophic denitrification process. As the main components in the target filler are pyrite, pyrrhotite and metal defect type polysulfide, energy required by growth and metabolism can be provided for iron-sulfur autotrophic denitrification bacteria, so that ammonia nitrogen, COD (Chemical Oxygen Demand), total phosphorus and a small amount of heavy metal are efficiently removed, the emission of pollutants in industrial sewage and domestic sewage is effectively reduced, and the environmental pollution is reduced. The method is simple in process and low in cost, almost does not generate sludge, avoids sludge bulking and subsequent sludge treatment, and