摘要:
We disclose a process for the removal of phosphorous and ammonia from an aqueous stream by contacting the aqueous stream with magnesium and base in a first zone having a first pH, to form an (n−1)th mixed stream and a first portion of struvite; separating the (n−1)th mixed stream from the first portion of struvite; removing at least some struvite from the first portion of struvite; contacting the (n−1)th mixed stream with base in an nth zone, wherein n is an integer incrementing from 2 to nmax, wherein nmax is an integer from 2 to about 5, and wherein the nth zone has an nth pH higher than the (n−1)th pH, to form an nth mixed stream and an nth portion of struvite, except no base is added and the nth pH need not be higher than the (n−1)th pH when n=nmax; separating the nth mixed stream from the nth portion of struvite; returning the nth portion of struvite to the (n−1)th zone; and, if n