Heavy-metal extraction from sewage sludge using phosphorous-based salts: optimization process with Na2H2P2O7

作者：Navarro Gonzalez Milagros; Ortega Lopez Vanesa^*; Lopez Fernandez Juana I; Amo Salas Mariano; Gonzalez Carcedo Salvador

来源：Environmental Technology, 2017, 38(18): 2305-2313.

DOI：10.1080/09593330.2016.1257658

• Heavy-metal extraction
• sewage sludge
• treatment
• disodium diacid pyrophosphate
• land improvement

Land application is one of the important disposal alternatives for sewage sludge, but availability of potential toxic metals often restricts its uses. Three phosphorous-based salts (Na2H2P2O7, K4P2O7, KH2PO4) were studied as potential metal extractants. The conclusions of the research were that greater extractive efficiency is achieved through a 30-min process of vertical shaking with disodium diacid pyrophosphate - Na2H2P2O7 - at a concentration of 0.2M at pH 2. Alternatively, the optimized process with oscillating shaking equipment would require 60min. In both cases the average of set of extracted metals is around 50%. A second extraction process with potassium pyrophosphate - K4P2O7 at pH 6 achieved the reduction of further total amounts of metal, upper 65% with respect to the initial content. In this way the sludge could be used in land applications, with restrictions on each soil, according to the limit values specified in the future regulations.

• 出版日期2017