STRUVITE FORMING POSSIBILITY BASED ON THE COMPONENT CONCENTRATION IN LIQUID PHASE OF ANAEROBICALLY DIGESTED SLUDGE AT VARYING TEMPERATURE AND pH AND PHOSPHORUS RECOVERY USING ACETATE AND TRIS BUFFER SOLUTION A CASE STUDY AT AALBORG WEST WASTEWATER TREATMENT PLANT

In one hand struvite (MgNH4PO4.6H2O) formation is a plague while on other hand is resource
recovery technique in sustainable wastewater treatment system, more particularly in sludge digestion
process. However, the process and place of formation for struvite plays a vital role whether a
problem or method of obtaining nutrients from highly concentrated sludge. Present research is
related to release of chemical components into liquid phase from anaerobically digested sludge at
various level of temperature. Further, it is investigated for struvite formation possibility from the
obtained concentration in the liquid phase. The project aim is restricted to; (i) Analysis for
spontaneous struvite formation possibility into the digester and post-digestion phase; and (ii)
Nutrients recovery particularly the phosphorus as non-spontaneous struvite formation.
Experimentally, the sample sludge was processed under varying temperature from 25oC to 60oC in
a laboratory. Hence, the liquid fraction containing dissolved chemical constituents was separated by
centrifugation and filtration technique. The residual solid fraction further used for extraction of
struvite components using acetate and tris buffer solutions. The final outcome for spontaneous
struvite formation from total produced sludge concludes insignificant possibility for struvite problem
in the digester and post-digestion phase depending upon the supernatant constituent concentration.
This is because of low magnesium concentration. But on adding magnesium source, maximum of
11.70% phosphorus recovery can be done as non-spontaneous struvite from the total daily anaerobic
digested sludge.