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Phosphorus release and recovery from Fe-enhanced primary sedimentation sludge via alkaline fermentation

Chen, Yun, Lin, Hui, Shen, Nan, Yan, Wang, Wang, Jieai, Wang, Guoxiang
Bioresource technology 2019 v.278 pp. 266-271
X-ray diffraction, batch fermentation, coagulation, ferric chloride, iron, magnesium, magnesium ammonium phosphate, organic matter, pH, phosphorus, sewage, sludge
Phosphorus release and recovery from Fe-based chemically enhanced primary sedimentation (CEPS) sludge via alkaline fermentation was investigated. The coagulation results showed that 78% of organic matter and 95% of phosphorus were concentrated from sewage into sludge with the optimum dosages of 25 mg/L FeCl3. The batch fermentation results revealed that 69.35% of the phosphorus in the Fe-sludge can be released and the maximum phosphorus concentration was 20.57 mg/L at pH 11. In the recovery stage, 90% of the P released in the fermented sludge supernatant was precipitated at a 2:1 ratio of magnesium to phosphorus and pH 11. The result of X-ray diffraction indicated that magnesium ammonium phosphate (MAP) was the major component of the precipitated solids. Thus, the present study provides an alternative option for phosphorus release and recovery as MAP from CEPS sludge via alkaline fermentation.