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Nutrient recovery from digested sludge centrate using alkali metals from steel-making slag
Chemical Engineering Journal Số , năm 2022 (Tập 450, trang -)
ISSN: 13858947
ISSN: 13858947
DOI: 10.1016/j.cej.2022.138186
Tài liệu thuộc danh mục:
Article
English
Từ khóa: Alkalinity; Membrane fouling; Metal recovery; Molar ratio; Nutrients; Phosphorus; Slags; Anaerobically digested sludges; Centrate; Digested sludge centrate; Digested sludges; Forward osmosis; Nutrient recovery; Phosphate recovery; Pre-treatments; Sand-filtration; Steelmaking slag; Ammonia
Tóm tắt tiếng anh
Results in this study highlighted the potential of nutrient recovery from anaerobically digested sludge centrate using calcium and other alkali metals from steel-making slag. Up to 96% phosphate and 71% ammonia could be recovered from sludge centrate at the optimal conditions. Mass balance calculation confirmed precipitation and volatilisation as the main mechanisms for phosphorus and ammonia recovery, respectively. Morphology and elemental analysis of obtained precipitates confirmed that phosphorus was recovered in the form of dicalcium phosphate dihydrate (CaHPO42H2O). The results also showed that sludge centrate pre-treatment by sand filtration and forward osmosis (FO) enrichment was essential to achieve high nutrient recovery. Sand filtration pre-treatment decreased the total suspended solid of sludge centrate by eightfold, leading to mitigated membrane fouling and reduced nutrient loss during FO pre-concentration. The production of slag liquor with high calcium and alkaline content from steel-making slag for nutrient recovery was demonstrated. Slag liquor with high pH increased ammonia recovery significantly, but only enhanced phosphate recovery slightly. Phosphate recovery was more dependent on the initial Ca:PO4 molar ratio than the final pH. The process demonstrated in this study has potential and significant practical implications to nutrient recovery from wastewater and beneficial use of steel-making slag. 2022