TITLE:
Utilization of Agro-Industrial Wastes for Restoration of Degraded Land, Mitigation of Heavy Metals Pollution and Greenhouse Gases Emissions from Selected Industrial Areas of Bangladesh
AUTHORS:
Sk. Md. Fazlay Rabbi, Muhammad Aslam Ali, Hafsa Jahan Hiya, ABM Shafiul Alam, Sanjit Chandra Barman, Tanver Hossain, Zidan Ali Fagun, Sanjida Binta Shafin Mishu
KEYWORDS:
Soil Restoration, Heavy Metals, Silicate, Vermicompost, Tea Waste Biochar, Oyster Shell, CMI, GWP
JOURNAL NAME:
Journal of Agricultural Chemistry and Environment,
Vol.15 No.2,
May
20,
2026
ABSTRACT: Heavy metals are the most significant contaminants for environment arising mainly from industrial activities. Two field experiments were conducted to investigate the soil contamination level, potential remediation of heavy metals pollution, and mitigation of greenhouse gases emissions through interactive effects of rice husk biochar, vermicompost, azolla compost with cyanobacteria, tea waste biochar and oyster shell biochar amendments with reduced number of chemical fertilizers in contaminated fields adjacent to Industrial areas of Mymensingh district. The experimental findings revealed mean maximum concentrations of heavy metals 1.65 mg/kg, 49.5 mg/kg, and 1340 mg/kg for Cd, Pb, and Mn in contaminated soils, which were decreased by Rice husk biochar with Oyster shell, Tea waste biochar with Oyster shell, and Vermicompost with Azolla Cyanobacteria dual cropping with rice. Higher contamination factors for Cd (CF 5.43 - 5.60), Pb (CF 2.28 - 2.64) and Mn (CF 1.45 - 1.71) than that of Cu (1.08 - 1.24) and Zn (0.58 - 0.73), indicates Cd, Pb and Mn were the main pollutants in the study areas. The maximum soil pollution load index (SPLI) value were estimated 1.70 - 1.80, and the maximum potential ecological risk index (ERI) value 184 - 188 and 176 - 185 were estimated for contaminated sites without any soil amendments. The decrease in pollution loads and improvement in ERI through Rice husk biochar, Tea waste biochar and Vermicompost amendments with Oyster shell may be due to the dissolution of metal pollutants. Among the amendments, Vermicompost with silicate fertilization and Azolla Cyanobacterial dual cropping with rice increased rice yield by 10.0% - 13.8% and decreased cumulative methane (CH4) emissions by 9.0% - 13.0%; while rice husk biochar and tea waste biochar with silicate fertilizer amendments were found effective for reducing (27.0% - 36.0%) seasonal cumulative nitrous oxide (N2O) emissions compared to chemical fertilized field plot. The mean maximum GWP 5380 - 5575 kg CO2 eq. ha?1 estimated from a field plot without any organic amendments, was decreased by 14.5% - 15.7%, 11.5% - 14.5% and 7.5% - 12.5% with Vermicompost and silicate fertilization, Tea waste biochar and silicate fertilization and Vermicompost amendments with Azolla Cyanobacteria dual cropping with rice in wetland paddy field ecosystem. The SOC contents and CMI value increased significantly in the amended field soils at both locations under cropping pattern Rice-Sesbania-Rice.