Phosphorus recovery as vivianite from waste activated sludge via optimizing iron source and pH value during anaerobic fermentation

Phosphate substances transformation and vivianite formation in P-Fe containing sludge during the transition process of aerobic and anaerobic conditions

“…The Fe/P mole ratios of each sample were 0.91, 1.04, 0.56, 1.28 and 1.06, respectively ( Supplementary Information ). It was previously reported that the molar ratio of Fe/P was 1.5 for the optimal formation of vivianite, and only about 0.2–0.4 of Fe/P ratio was needed before vivianite precipitation occurred ( Cao et al, 2019 , Prot et al, 2020 ). EDS results also indicated that the P-Fe mole ratio of each sample was similar and no obvious change was occurred during the aerobic and anaerobic transformation process, although the structure of P-Fe substances were changed totally.…”

“…At present, the most commonly used method for recovering vivianite is achieved by addition of FeCl 3 under acidic conditions to recover phosphorus from waste activated sludge ( Cao et al, 2019 ). However, this method requires large quantities of chemicals, which may cause secondary pollution to the environment.…”

Hydrochar derived from municipal sludge through hydrothermal processing: A critical review on its formation, characterization, and valorization

“…However, this process is highly selective on P species in hydrochar, as only NAIP can be extracted at alkalic conditions (pH ≥ 12) (Cao et al, 2019;Falayi, 2019) of NH 4 -N). Interestingly, there was also 2% of K recovered from the sludge in the struvite precipitates.…”

Efficient phosphate recovery as vivianite: synergistic effect of iron minerals and microorganisms

“…11 However, industrial researchers have just recently confirmed the potential of phosphorus recovery in the form of vivianite. [12][13][14][15][16] Wilfert found that vivianite-bound phosphorus made up 10-30% and 40-50% of total phosphorus in biological P removal plants and iron-based P removal plants, respectively. 17 Wu investigated the transition of phosphate substances and vivianite production in P-Fe containing sludge and discovered that Fe-P compounds accounted for 93-97% of TP in sludge where vivianite was the primary product.…”