Denitrification filter tank of modular macroporous combined filler

The invention provides a denitrification filter tank of modular macroporous combined filler. The denitrification filter sequentially comprises a sludge discharge system, a water inlet system, a perforated rectifying plate I, a supporting layer, a perforated rectifying plate II, a modular filler system and a water outlet system from bottom to top, the modular filler system comprises macroporous biological filler modules and macroporous iron-carbon modules which are sequentially and alternately arranged from top to bottom; the porosity of the macroporous biological filler module and the macroporous iron-carbon module ranges from 30% to 60%. Phosphate removal and nitrate removal are achieved through iron-carbon micro-electrolysis products, meanwhile, the modularized macroporous iron-carbon biological filler is convenient to install and replace, filler blockage can be effectively prevented, gas-water backwashing is not needed, nitrogen and phosphorus removal is achieved under the condition that no external carbon