A device and method for achieving dual short-range coupled Anammox deep denitrification and phosphorus recovery using in-situ sludge fermentation.

Abstract

This invention discloses an apparatus and method for achieving deep nitrogen removal and phosphorus recovery through dual short-range coupled anammox fermentation using in-situ sludge fermentation. First, calcium chloride solution is added to the anammox reactor at the rear end of a two-stage PNA process to form recoverable phosphorus crystals such as Ca-P precipitates. Anaerobic ammonia oxidizing bacteria attach to the surface of the precipitates, thereby enriching and retaining them within the anammox reactor. During the continuous formation of anaerobic ammonia oxidizing particles, unfermented waste activated sludge is added to the PNA process. The slow hydrolysis and acidification of the waste activated sludge provide a carbon source for the short-range denitrifying bacteria, completing the transformation from single-stage PNA autotrophic nitrogen removal to dual short-range coupled anammox synergistic nitrogen removal. In this invention, the anaerobic ammonia oxidizing bacteria in the granular sludge after operation can reach 12%, 73% of the sludge exhibits a particle size greater than 200 μm, and the total nitrogen removal rate remains above 90%, with most phosphorus existing in the recoverable form of Ca-P crystals.

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