title: Recovery of phosphorus and nitrogen from alkaline hydrolysis supernatant of excess sludge by magnesium ammonium phosphate.
abstract: Magnesium ammonium phosphate (MAP) method was used to recover orthophosphate (PO₄(3-)-P) and ammonium nitrogen (NH4(+)-N) from the alkaline hydrolysis supernatant of excess sludge. To reduce alkali consumption and decrease the pH of the supernatant, two-stage alkaline hydrolysis process (TSAHP) was designed. The results showed that the release efficiencies of PO₄(3-)-P and NH₄(+)-N were 41.96% and 7.78%, respectively, and the pH of the supernatant was below 10.5 under the running conditions with initial pH of 13, volume ratio (sludge dosage/water dosage) of 1.75 in second-stage alkaline hydrolysis reactor, 20 g/L of sludge concentration in first-stage alkaline hydrolysis reactor. The order of parameters influencing MAP reaction was analyzed and the optimized conditions of MAP reaction were predicted through the response surface methodology. The recovery rates of PO₄(3-)-P and NH₄(+)-N were 46.88% and 16.54%, respectively under the optimized conditions of Mg/P of 1.8, pH 9.7 and reaction time of 15 min.
authors.affiliation: Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, College of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China. Electronic address: 727528369@qq.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Bi
authors.affiliation: Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, College of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China. Electronic address: 350527256@qq.com.
authors.forename: Yiyong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, College of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; State Key Lab of Pulp and Paper Engineering, College of Light Industry and Food Science, South China University of Technology, Guangzhou 510640, PR China. Electronic address: ppyyhu@scut.edu.cn.
authors.forename: Yongyou
authors.initials: Y
authors.lastname: Hu
mesh_terms: D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D009584:Nitrogen / Q000302:isolation & purification*; D010710:Phosphates / Q000737:chemistry / Q000302:isolation & purification*; D012722:Sewage / Q000737:chemistry*; D000069877:Struvite; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D017616:Magnesium Compounds; D010710:Phosphates; D012722:Sewage; D000069877:Struvite; D009584:Nitrogen
keywords: Alkaline hydrolysis; Excess sludge; Magnesium ammonium phosphate (MAP); Nitrogen recovery; Phosphorus recovery