Redistribution and Desorption Kinetics of Some Heavy Metals in Biosolids Treated Soils Amended with Water Treatment Residual Nanoparticles
Mohamed L. Moharem
The study was designed to demonstrate the effect of water treatment residual naoparticles amendments for 0.3% biosolids treated calcareous and sandy soils on Cu, Pb, and Ni fractions change and release during 60 days incubation period; included five wetting drying cycles regime. The redistribution of studied metals fractions for control soil (0%WTR) depended on soil and metal type. There was a pronounced decrease in metal-residual fraction at the end of the incubation period (60 days); while other fractions were occupied with these residual fraction- released metals. Application of nWTR to both soils substantially reduced the non-residual fractions (NORS) of Cu and Ni and simultaneously increased residual (RS) both metals fractions. Furthermore, both Pb-oxides and RS fractions were increased as a result of nWTR addition. The metals forms transformation for nWTR amended soils as the incubation time prolonged from 30 to 60 days was studied. The Cu-forms transformation remained relatively unaltered with slightly increase of RS Cu versus decrease of exchangeable and carbonate Cu. With respect to Pb and Ni, residual fraction was increased significantly and this increase was arisen from either the decrease of all fractions of Ni- NORS or Pb-organic fraction. The amount of desorbed Cu, Pb, and Ni from both soils using DTPA extraction was significantly decreased after application of nWTR within the five wetting drying cycles. All the kinetic data were well expressed using both intraparticle diffusion and Elovich models due to the high coefficient of determination (R2) and low standard error (SE) values. The final results indicate the ability of nWTR to reduce heavy metals mobility in biosolid treated calcareous and sandy soils.
Key words: Biosolid, water treatment residual naoparticles, incubation period, fractionation, desorption kinetic.