Acidification and alkali precipitation for phosphorus recovery from municipal digested sludge

• Published in: Water and environment journal : WEJ Vol. 38; no. 2; pp. 259 - 268
• Main Authors: Seckin, İsmail Yigit, Altiner, Mahmut, Kayranli, Birol, Yilmaz, Turan
• Format: Journal Article
• Language: English
• Published: London Wiley Subscription Services, Inc 01.05.2024
• Subjects: Acidification; alkali precipitation; Calcium hydroxide; Chemical precipitation; cost effectiveness; dissolved phosphorus; Dry matter; environment; industry; Liquid phases; liquids; Materials substitution; municipal digested sludge; Phosphate rocks; Phosphates; Phosphorus; Phosphorus pentoxide; phosphorus recovery; Precipitates; Precipitation; Raw materials; Recovery; Sewage; Sewage treatment; Sewage treatment plants; Slaked lime; Sludge; Sludge digestion; sludge valorization; Sodium hydroxide; Solid phases; Struvite; Sulfuric acid; Sulphuric acid; Wastewater treatment; Wastewater treatment plants; water
• ISSN: 1747-6585; 1747-6593
• DOI: 10.1111/wej.12915

Municipal digested sludge (MDS) has considerable phosphorus content that is between 1% and 15% in dry matter and it is a potential source for phosphorus recovery. A high amount of MDS is generated from sewage treatment plants in large cities and has many environmental concerns with its organic and inorganic constituents. In this study, phosphorus was recovered by precipitation with Ca(OH)2 and NaOH. Acid pretreatment was applied to MDS with H2SO4 and 58.7% of phosphorus was extracted from the solid phase to the liquid phase at pH 2. Up to 99% of dissolved phosphorus in the liquid phase was recovered with Ca(OH)2 and NaOH. Almost similar phosphorus precipitation rates were achieved with both bases but higher phosphorus contents (17% as P2O5) in precipitates were obtained by NaOH. The product obtained in this study can serve as a high‐quality raw material substitute for the low‐grade phosphate rocks (<15% P2O5) commonly utilized in the phosphate industry. Furthermore, this research presents a practical, environmentally friendly and cost‐effective approach for sustainable sludge management and phosphorus production. Highlights The research provides cost‐effective methods for the recuperation of phosphorus for municipal digested sludge. This study is an alternative method for phosphorus (P) recovery, rather than struvite precipitation. Recovered products can be utilized as raw materials for various P‐based production.