title: Evaluating the Mobility of Arsenic in Synthetic Iron-containing Solids Using a Modified Sequential Extraction Method.
abstract: Many water treatment technologies for arsenic removal that are used today produce arsenic-bearing residuals which are disposed in non-hazardous landfills. Previous works have established that many of these residuals will release arsenic to a much greater extent than predicted by standard regulatory leaching tests (e.g. the toxicity characteristic leaching procedure, TCLP) and, consequently, require stabilization to ensure benign behavior after disposal. In this work, a four-step sequential extraction method was developed in an effort to determine the proportion of arsenic in various phases in untreated as well as stabilized iron-based solid matrices. The solids synthesized using various potential stabilization techniques included: amorphous arsenic-iron sludge (ASL), reduced ASL via reaction with zero valent iron (RASL), amorphous ferrous arsenate (PFA), a mixture of PFA and SL (M1), crystalline ferrous arsenate (HPFA), and a mixture of HPFA and SL (M2). The overall arsenic mobility of the tested samples increased in the following order: ASL > RASL > PFA > M1 > HPFA > M2.
authors: Los Angeles County Sanitation District, 1955 Workman Mill Road, Whittier, CA 90601.
authors: Jilei
authors: J
authors: Shan
authors: A Eduardo
authors: AE
authors: Sáez
authors: Wendell P
authors: WP
authors: Ela
keywords: Arsenic leaching; Arsenic-bearing residual; Crystallization; Ferrous arsenate; Iron oxide; Sequential extraction