Natural pyrrhotite biological filter and method for utilizing same to synchronously remove nitrate-nitrogen and phosphorus from water

A method for synchronous removal of nitrate-nitrogen and phosphorous in wastewater using a natural pyrrhotite biofilter, comprising the following steps:

• (1) preparing packing material and construction of the natural pyrrhotite biofilter comprising a reactor:
• preparing pyrrhotite in the granular form with the grain size between 2-20 mm;
• packing the granular pyrrhotite in the reactor and then washing the reactor with clean water before start-up of the natural pyrrhotite biofilter and until the pH of water exiting the reactor reaches 6-7 at which point the washing is stopped;
• the reactor is designed with a water inlet on the bottom and a water outlet on the top;
• (2) starting-up of the natural pyrrhotite biofilter:
• mixing an anaerobic sludge and nutrient solution into a mixed nutrient solution, using a pump to pump the mixed nutrient solution into the bottom of the reactor via the water inlet;
• the mixed nutrient solution then flows out of the reactor via the water outlet, and is pumped back into the reactor again as part of a cyclical process;
• continuing the cyclical process till the removal rate of nitrate-nitrogen reaches a stability point;
• and
• (3) operating of the natural pyrrhotite biofilter:
• pumping the wastewater to be treated via the water inlet into the reactor that has been started up through Step (2), adjusting the hydraulic retention time to 12-48 hours;
• the nitrate-nitrogen and phosphorous in the wastewater will be synchronously removed and the up-to-standard discharge of final effluent can be achieved;
• wherein the method is conducted without the use of limestone.