Characterization and performance of low cost amendments to immobilize lead in contaminated soil

Abstract

Immobilization is a method of remediation to reduce lead (metals) mobility by soil amendments to prevent from uptaking of plant roots and ground water contamination. This research aims to produce, characterize, and assess the efficacy of low cost solid amendments in immobilizing lead in naturally contaminated soil. Biochars [produced from chicken manure (CM), chicken bone (CB), farmyard manure (FM)] and bioslurry (BS) were characterized with FTIR, SEM, and XRF. Amended soils were incubated and sequentially extracted prior to Pb measurement with AAS. Chars were made by pyrolysis at 450°C for 90 minutes. Characterization data from FTIR showed that all amendments had similar spectra showing the existence of hydroxyl, carbonyl, C=C, C-H, C-O-C groups in the amendments. SEM images showed porous structure of the chars having pores diameter between 1.95 and 13.4 μm. XRF spectra revealed that dominant elements possessed by amendments were Ca, Na, Si (BS & FM), and P (TA & CM). The immobilization study showed that performance order from the most effective was CB > CM > FM > BS. Chicken bone biochar (CB) was the best amendment which immobilized up to 79.71% Pb and remediated soil from very high contamination-moderate risk into low contamination-low environmental risk status.