The invention provides a double-threshold (SI, Ca / P) closed-
loop device and a double-threshold (SI, Ca / P) closed-loop method taking a hydroxyapatite (HAP)
skeletonization window as a core, aiming at
rapid prototyping of
anammox granular
sludge in a high
ammonia nitrogen sewage treatment process. The device comprises an SBR (
sequencing batch reactor), an online DO / pH / TDS (dissolved
oxygen / pH /
total dissolved solids) and Ca / P feeding and linkage controller, is matched with a coaxial double-ring microporous injection component to realize short pulse (lagging for 2-10 seconds) of'first
calcium and then
phosphorus', and is provided with a replaceable sacrificial
nucleation cylinder to capture Ca-P microcrystals and reduce scale. The controller adjusts Ca and P pulses and SBR
phase time in a linkage mode according to DO, pH, TDS and a manually-input target window (SI = 0.2-0.6, Ca / P = 1.4-1.8); when TDS / pH exceeds a
limit value or an excessive mineralization symptom (for example, the HAP
peak area in XRD is greater than 15%) occurs, Ca is automatically reduced, and hunger time is prolonged. OCT / FBRM can be selectively accessed, mu t /
void ratio or chord
length distribution is used as auxiliary triggering, and integration of structure-
chemistry-operation is achieved. According to the scheme,
anammox granulation is stably and efficiently achieved, an HAP
nucleation-growth window is used as a main target, the
volume fraction of particles with the particle size larger than or equal to 0.5 mm and larger than or equal to 80% can be obtained within 2-4 weeks, the strength and settleability are remarkably improved, and over-mineralization
embrittlement is avoided.