Process for enriching phosphorus and recovering blue iron ore by using biofilm method

A process for enriching phosphorus and recovering vivianite by a biofilm method, specifically comprising the following steps:

• 1) an aerobic phosphorus absorption stage:
• under an aerobic condition, controlling dissolved oxygen of phosphorus-containing wastewater in a biofilm reactor to be greater than 4 mg/L, and discharging the wastewater after aerobic phosphorus absorption for a period of hydraulic retention time;
• 2) an anaerobic phosphorus release stage:
• under an anaerobic condition, feeding liquid in a phosphorus recovery device into the biofilm reactor as base liquid, adding a carbon source at a preset carbon-phosphorus ratio through a carbon source dosing device, and discharging the phosphorus-containing solution to the phosphorus recovery device after anaerobic phosphorus release for another period of hydraulic retention time;
• 3) a cyclic enrichment stage:
• performing multiple rounds of operation, each round comprising one cycle of the aerobic phosphorus absorption phase according to step 1) and one cycle of the anaerobic phosphorus release phase according to step 2) so that the base liquid reaches a phosphorous-rich solution with a preset concentration, and recovering the phosphorous-rich solution to the phosphorus recovery device;
• 4) a seed crystal forming stage:
• further discharging the phosphorus-rich solution in the phosphorus recovery device to an up-flow reactor, adding a ferrous ion solution to the up-flow reactor, and continuously operating a backflow system to fully mix the ferrous ion solution and the phosphorus-rich solution in the up-flow reactor to form ferrous phosphate seed crystals;
• and
• 5) a crystal forming stage:
• continuously feeding the phosphorus-rich solution and the ferrous ion solution into the up-flow reactor at a preset speed, and continuously operating the backflow system to circularly crystallize the phosphorus-rich solution and the ferrous ion solution in the up-flow reactor, so that the ferrous phosphate seed crystals form ferrous phosphate crystals with a preset particle size.