Chemical Composition of Night Soil Sludge Incineration Ash and the Elution of Phosphate

In a project to recover phosphorus from night soil, a possible phosphorus resource, composition of major components and toxic substances, and phosphorus together with its chemical form were determined in night soil sludge incineration ash at 14 facilities in Ehime prefecture. The composition of majo...

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Veröffentlicht in:Journal of Environmental Chemistry 2018/12/18, Vol.28(4), pp.127-139
Hauptverfasser: NAKAMURA, Yousuke, OTSUKA, Masanari, HARUTA, Shinsuke, OMORI, Daisuke
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Sprache:eng ; jpn
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Zusammenfassung:In a project to recover phosphorus from night soil, a possible phosphorus resource, composition of major components and toxic substances, and phosphorus together with its chemical form were determined in night soil sludge incineration ash at 14 facilities in Ehime prefecture. The composition of major components were Al2O3, P2O5, SiO2, Fe2O3, CaO, MgO Na2O and K2O in decreasing order with little seasonal variation. The average phosphorus concentration was about 23.9 wt% calculated as P2O5 and was higher than that of sewage sludge incineration ash. It was found that the concentration of Cd was higher than that in sewage sludge incineration ash but the concentration of toxic substances including Cr, Pb, As, Se and Hg were lower than those in sewage sludge incineration ash. By X-ray diffraction analysis, it was found that major mineral of night soil sludge incineration ash was phosphate mineral and the average concentration of 14 facilities was 42 wt%. Four species of phosphate mineral were identified, and the concentration of aluminum calcium phosphate was the highest in them. It was thought that in view of included phosphate minerals, acid extraction method was more effective than alkali extraction method.About 80 % of phosphorus was eluted by adding sulfuric acid to pH 2.2. The significant equation to estimate the recoverable phosphorus quantity from each quantity of night soil and septic tank sludge was obtained by multiple regression analysis.
ISSN:0917-2408
1882-5818
DOI:10.5985/jec.28.127