System and process for realizing efficient nitrogen and phosphorus removal of agricultural wastewater

The invention discloses a system and a process for realizing efficient nitrogen and phosphorus removal of agricultural wastewater, and belongs to the technical field of sewage treatment. The IFAS process is combined with the pelelith and steel slag filter tank. According to the IFAS technology, nitrifying bacteria and other aerobic microorganisms are enriched on suspended filler through aeration, a biological membrane is formed, the IFAS system is mainly subjected to nitrification, meanwhile, a certain denitrification effect also exists, in an anoxic zone inside the biological membrane, denitrifying bacteria utilize easily-biodegradable COD in inlet water, and in the anoxic zone inside the biological membrane, the denitrification effect is achieved. A small part of nitrate nitrogen generated by the IFAS pool is reduced into nitrogen through denitrification; and further removing total nitrogen and total phosphorus in the sewage by using the pelelith and steel slag filter, wherein the pelelith and the steel sla