Pollution, Ecological, and Health Risk Assessments of Heavy Metal Remediated Soil by Compost Fortified with Natural Coagulants

Abstract

The present study assessed the pollution, ecological, and health risks of heavy metals (HMs) in remediated soils by compost fortified with natural coagulants (Moringa, Neem, and Pawpaw).The polluted soils were mixed with the stabilized composts at varying ratios of 1:200, 1:100, 1:66, and 1:50. Heavy metals(Cu, Zn, Ni, Mn, Cd, and Pb) were determined in compost and soil samples using Atomic Absorption Spectrophotometry. Data collected were analyzed for descriptive and inferential statistics. Removal efficiencies (REs) of HMs by the compost types were also determined. Results showed Mn as the highest observed HM in composts with values ranging from 179.6 ± 1.25 mg kg− 1 in Neem to 206.3 ± 5.01 mg kg− 1 in Moringa. The levels of HMs (except Zn) observed in composts were generally less than the target values expected in unpolluted soil. Application of the three composts to contaminated soils reduced the HMs by 5–37, 17–47, 25–43, 43–57,59–71, and 69–75% for Cd, Cu, Ni, Pb, Mn, and Zn, respectively. Removal of HMs in contaminated soils followed the distribution pattern of Zn > Mn > Pb > Cu > Ni > Cd. All the compost types were effective in cleaning up Mn and Zn in contaminated soils. However, Moringa appeared to indicate the highest removal efficiency followed by Neem and Pawpaw, in that order.